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/ 
 
 
 LIGHT: 
 
 ITS INFLUENCE 
 
 ON LIFE AND HEALTH. 
 
 FORBES WINSLOW, M.D., 
 
 D.C.L. Oxon. (Hon.), 
 &c. &c. 
 
 LONDON: 
 
 LONGMANS, GREEN, READER, & DYER. 
 
 1867. 
 

TO 
 
 SIR WILLIAM FEKGUSSON, Bart., P.E.S. 
 
 Fellow and Member of the Council of the Royal College of Surgeons, England ; 
 Surgeon and Professor of Surgery at King's College, Hospital ; Surgeon Extraor- 
 dinary to Her Majesty the Queen ; and Surgeon in Ordinary to His late Royal 
 Highness the Prince Consort ; late Professor of Human Anatomy and Surgery 
 R.C.S. Eng., and Examiner on Surgery at the University of London, 
 
 }i& Work is Jjebitateb-, 
 
 BY THE AUTHOR, 
 
 AS A TRIFLING MARK OF ADMIRATION AND RESPECT 
 
 FOR 
 
 HIS DISTINGUISHED TALENTS AND BRILLIANT ATTAINMENTS, 
 
 AND 
 
 IN PLEASING REMEMBRANCE 
 
 OF AN UNINTERRUPTED FRIENDSHIP OF TWENTY-SEVEN 
 YEARS. 
 
PREFACE. 
 
 The object of this work is to demonstrate 
 the inestimable value of light as an hygienic 
 agent, and to analytically examine its phy-. 
 siological influence in the development of 
 vital phenomena as manifested in the 
 animal and vegetable kingdoms. 
 
 How impossible it is to exaggerate the 
 amount of blessing which flows from the 
 action of the sun, that 
 
 " Great source of day, for ever pouring wide ' 
 From world to world the vital ocean round" 
 
 not only on organic, but inorganic matter. 
 
 Deprived of its life-generating and health- 
 sustaining power, the whole of animated 
 
vi Preface. 
 
 nature would be a sterile blank, and man, the 
 highest order of intelligent beings, become 
 blighted in mind and degenerated in body. 
 
 In the composition of this volume I 
 have been under the necessity of levying 
 contributions on the writings of established 
 physicists. 
 
 I lay no claim to original experimental 
 research, but desire only to be considered 
 as a wanderer on the vast shore of science, 
 picking up here rare shells, there valuable 
 pebbles, and then classifying them, with 
 the view of illustrating a branch of inquiry 
 of deep philosophical interest. 
 
 It is impossible to contemplate the facts 
 scattered through the following pages with- 
 out being solemnly impressed with a sense 
 of man's deep obligation to God, — the Source 
 of all true Light, — for thus beneficently 
 
Preface. vii 
 
 surrounding our planet by an influence so 
 pre-eminently conducive to the health and 
 happiness of the human race.* 
 
 Cavendish Square, London, 
 April, 1867. 
 
 * A portion of the chapter on the " Lunar Ray" appeared 
 many years ago in a paper of my own, on " Lucid Intervals," 
 published in the Psychological Journal. 
 
TABLE OF CONTENTS, 
 
 PART I. 
 
 THE SOLAR-BEAM. 
 
 Origin of light, i ; Healthful and morbid effects of light 
 upon the animal and vegetable kingdom, 2 ; No vi- 
 tality or healthful structure without light, 4 ; * Solar- 
 air-bath" of the ancients, 4 ; Bodily deformities , crime, 
 and mental disease produced by darkness, 5 ; Health 
 of those who live in the country as compared with the 
 inhabitants of manufacturing towns, 7 ; The absence 
 of light on miners and colliers, 7; Diseases caused 
 by the absence of light, 8 ; Unhealthy condition of 
 those who labour by night and sleep by day, 9 ; Deep 
 mining at Geelong, 10; Development of children re- 
 tarded by working in mines, 1 1 ; Stunted forms ob- 
 served among the miners of Chimay, 12 ; Effects of 
 dampness and deficient nourishment viewed in con- 
 nexion with want of light, 13; Influence of light upon 
 animals, 14 ; Arrest of animal development, 15 ; Blind- 
 ness of fish caused by want of light, 17-19; Dis- 
 colouration of different races of men caused by solar 
 heat, 20 ; The brown skins of the natives of Lapland and 
 
Contents. 
 
 Greenland, 2 1 ; White skins of negroes dwelling in the 
 forests, 22 ; Black colour contrasted with that of red 
 or olive negroes, 22 ; Black, white, and spotted 
 negroes, 23 ; Effect of food on the hair, 24 ; 
 Complexions of intemperate persons, 24; Red In- 
 dians turned white, 25; Influence of the sun in 
 tropical climates, 26 ; Albinos of the torrid zone, 27 ; 
 fish of great oceanic depths, 27 ; Effect of the absence 
 of light on the women of the seraglio, 28 ; Statures of 
 different races of men, 29-31 ; Mental condition of the 
 Arabs, 33 ; Inhabitants of high latitudes possess su- 
 perior muscular force, 34; Northern countries more 
 favourable than southern to longevity, 34 ; Influence 
 of climate upon physical and mental organization, 36 ; 
 Effect of deep sea-water on vegetable and animal life, 
 37 ; The depth of the ocean, 38-41 ; Depth at which 
 solar light penetrates, 41 ; Temperature of the ocean, 
 42 ; Different colours of the sea, 44 ; Causes of the 
 varied tints of the sea, 45 ; Distribution of animal 
 life in the sea, 46 ; Classification of marine animals, 
 47 ; Microscopic shells found in deep sea deposit, 48 ; 
 Animal and vegetable life incompatible with certain 
 altitudes and depths, 50; Amount of pressure at 
 certain oceanic depths, 51-53 ; Tendency of plants to 
 follow light, 53 ; Plants and animals nurtured in dark- 
 ness altered in colour, 56 ; Animal and vegetable sub- 
 stances near the surface of the sea brilliantly coloured, 
 59 ; Brilliant colours of animals and plants in the 
 tropics, 60 ; Action of light necessary for development 
 of vegetable colours, 63 ; Physiological influence of 
 
Contents, xi 
 
 light on the colour of plants, 64 ; A definite quantity 
 of heat required for development of plants, 64 ; Insect 
 life, 70-74 ; Chemical influence of light on certain 
 drugs, 74-77 ; Effect of light passing through dif- 
 ferent coloured media on the germination of plants, 
 78-81 ; Metals discovered in the solar beam by 
 the spectroscope, a Fraunhofer's lines," 82-86 ; Dis- 
 eases caused by exposure to intense solar heat, 87. 
 
 PART II. 
 THE LUNAR-RAY. 
 
 Opinions of the ancients as to the influence of the moon, 
 89-97 ; Different parts of the body under planetary 
 influence, 97 ; The moon's power in causing tidal 
 action, 101 ; Belief of Spaniards and West India 
 negroes that the sick always die at ebb-tide, 102 ; 
 Principal authorities in support of the theory of pla- 
 netary influence, 107-112; Drs. Orton and Balfour's 
 view of the subject, 112, 1 T3 ; Periodicity as exhibited 
 in the phenomena of life, 115-118 ; Historical analysis 
 of lunar influence, 12 t ; Dr. Mead's views of the in- 
 fluence of the moon upon the bodily health stated at 
 length, 120-136; Dr. Pitcairne's case of lunar in- 
 fluence, 136; Mr. Cockburn's singular case, 137; 
 Hemorrhage from the finger said to come on at the 
 fall of the moon, 138 ; Baglioi's singular case, 139 ; 
 Remarkable case of lunar influence occurring to Mr. 
 
xii Contents. 
 
 Ainsworth, 139 ; Van Helmont on the influence of the 
 moon on asthma, 139 ; Historical analysis of Dr. 
 Balfour's treatise on the influence of the moon, 141- 
 146 ; Mr. Francis Day's observations on the influence 
 of the moon at Madras, 147 ; Dr. Orton on the effect 
 of the moon on the diseases of tropical climates, and 
 on the weather, 152-154; Dr. Kennedy's views on 
 the same subject, 154 ; Diemerbroeck on the influence 
 of the moon on the plague, 155 ; Dr. Lardner's 
 opinion of the influence of the moon on the epidemic 
 fever of Italy in 1693, 158 ; Dr. James Johnson on 
 the effect of the moon on the diseases of the liver, 
 159 ; Dr. Scott on planetary influence in modifying 
 diseases of tropical climates, 160 ; Mr. Hutton on the 
 effects of the moon at Prince of Wales's Island, 161, 
 162 ; Dr. Moseley on the effect of the varied phases 
 of the moon on hemorrhages of the lungs, 162-164 ; 
 Remarkable case illustrative of the fact, 165 ; Nicholas 
 Fontana on the influence of the moon on the fever that 
 occurred at Barrackpore in 1777, 166 ; Dr. Millingen 
 on planetary influence, 168 ; Opinions of the Druids of 
 Gaul on the influence of the moon in vegetable produc- 
 tions, 170; The mistletoe gathered with a golden 
 knife when the moon was six days old, 170; The 
 verbena of the ancients supposed to be under plane- 
 tary influence, 171 ; Its medicinal and sacerdotal 
 virtues, 171; Effect of different phases of the moon on 
 the fructification of plants, 172; Instructions for 
 planting seeds according to the position of the moon, 
 173 ; The Lunar rays calorific, 177 ; Effect of moon- 
 
Contents. xiii 
 
 light on the thermometer, 177, 178 ; Sudden death and 
 coma caused by the moon's light, 179 ; Effect of full 
 moon in causing diseases ,of the brain, 179 ; A stroke 
 of the moon, 180; Opinion of the Arabs as to the 
 morbid influence of the moon, 181 ; On the modus 
 operandi of the lunar light, 181 ; Distance of the earth 
 from the sun, 182 ; Velocity of planetary light as com- 
 pared with that of sound, 183; Humboldt's remarks 
 on lunar distances, 185 ; Comparisons of the light of 
 sun and moon, 185 ; Michel and Euler on the same 
 subject, 186; Arago's observations on the polariscope, 
 187; Uses of the polariscope, 188, 189; Sir David 
 Brewster on polarized light, 181-192; State of the 
 barometer at different phases of the moon, 193-195; 
 The influence of the moon on the weather, 198. 
 
 PART III. 
 
 ON THE ALLEGED INFLUENCE OF THE 
 MOON ON THE INSANE. 
 
 " Lucid intervals," origin of the term, 199 ; Legal definition 
 of the word "lunatic," 199; Meaning of the phrase "lucid 
 interval," 200, 201 ; M. D'Aguesseau's analysis of the 
 term, 202, 203 ; Dramatic and poetic references to the 
 influence of the moon on the mind and passions, 204- 
 207 ; The phenomenon of periodicity viewed in relation 
 to insanity, 208 ; Illustrations on the subject from the 
 writings of Pinel, 208-210; Periodical attacks of 
 
xiv Contents, 
 
 drunken madness, or dipsomania, 210, 211 ; The 
 periodicity explained independently of lunar influence, 
 212, 213; Pinel's explanation of the phenomenon, 
 213,214; Bouillon and Sauvage's cases of lunar in- 
 fluence, 215; Celsus on the influence of the moon, 
 215, 216 ; Dr. Haslam's opinion on the same subject, 
 217; Dr. Woodward on the influence of the moon 
 on the insane, 2T9-221 , Effects of sol-lunar influence 
 on maniacal paroxysms, 222 ; Effect of the eclipse of 
 the sun in 1806 on the lunatics in Bethlehem Hospital, 
 223, 224 ; Daquin on the influence of the moon on 
 the insane, 225-228 ; Guislain's opinion on the same 
 subject, 228 ; Effect of meteorological phenomena on 
 the insane, 229; Sleeplessness and agitation noticed 
 among the insane at the full of the moon, 230 ; Effect 
 of light and darkness on the illusions and hallucinations 
 of the insane, 231, 232 ; Influence of different colours 
 on the brain and mind, 234. 
 
 PART IV. 
 HYGIENE OF LIGHT. 
 
 Effect of the absence of light on the blood, heart, brain, 
 and muscles, 235-237 ; Sir David Brewster on the 
 blessings of light, 237 ; On the construction of build- 
 ings with the view to the admission of the maximum 
 degree of light, 237, 238 ; On the unhealthily-housed 
 populations of New York and Bethnal-green, 238, 239 ; 
 
Contents. xv 
 
 The effect of the absence of light on the poor living in 
 courts, narrow streets, &c, 240 ; Sir David Brewster's 
 suggestion for remedying this evil, 240, 241 ; On the 
 physical condition of the working classes of Edinburgh, 
 24 t, 242 ; Sir David Brewster on the value of light as 
 a hygienic agent to the poor, 242-246 ; Scorbutic affec- 
 tions caused by the absence of light, 246, 247 ; On the 
 exclusion of light from young infants and children, 247 ; 
 Rules for the treatment of children with reference to 
 their being exposed to the influence of light, 248, 249 ; 
 Dr. Andrew Wynter's opinion on the subject, 249, 251 ; 
 Humboldt on the robust health of the Mexicans, Peru- 
 vians, Indians, &c, caused by their being freely exposed 
 to light, 251, 252 ; Dr. Bryson on the unhealthy condi- 
 tion of seamen confined in dark holds of ships, &c, 
 252 ; Judicious hygienic arrangements made for the 
 patients of the hospital of St. John, at Brussels, 255 ; 
 Importance of light to persons suffering from disease, 
 255, 256 ; Florence Nightingale on the construction of 
 public hospitals, 257-259 ; The effect of darkness on 
 disease as observed in the hospital at St. Petersburg, 260 ; 
 Singular case of the same kind related by Baron 
 Dupuytren, 260, 261 ; Dr. Hammond on the impor- 
 tance of light to the sick, 262 ; The virulence of 
 cholera increased by the absence of light, 262, 263 ; 
 Injury caused by glaring light and sudden transition 
 from darkness to light, 263, 264 ; On disorders of the 
 vision caused by a prolonged exposure to intense light, 
 265-272 ; The effect of snow and ice upon the eyes of 
 sheep, 272 ; Ditto on the Greek soldiers, as related by 
 
xvi Contents. 
 
 Xenophon, 273 ; The effect of the glare of brilliantly- 
 lighted rooms on the organ of vision, 273 ; Injuries 
 resulting to the eyes from artificial light, 274 ; Medical 
 instructions for the regulation of the different colours 
 of light, 275 ; On the probable effect of the vapour of 
 iron found in the sunlight by the spectrum on the 
 health of the body, 276-278; On the introduction of 
 metallic poisons into the body through the skin, 278. 
 
 Appendix Pages 279-301 
 
ON 
 
 THE INFLUENCE OF LIGHT. 
 
 PART I.— THE SOLAR BEAM. 
 
 cc God said, Let there be light : and there 
 was light."* These were the sublime words 
 of the Almighty, when, by an act of 
 Sovereign power, He willed into existence 
 cc two great lights, the greater light to rule 
 the day, the lesser light to rule the night." 
 
 The object of the following essay is to 
 consider in a philosophical, and I hope a 
 reverential spirit, the physiological and 
 
 * "TIN TV") I")** VP —"Be light ! and light was."— 
 Gen i. 3. 
 
On the Sanatory and 
 
 pathological — the healthful and morbid — 
 effects upon the animal and vegetable king- 
 dom of that principle which, at the fiat of 
 the wise and beneficent Creator, radiated 
 in all its original glory from the Heavenly 
 luminary, and when seen by Him was em- 
 phatically pronounced to be cc good." 
 
 This subject has two aspects : of the life- 
 giving and benign effects of light I purpose 
 fully to speak. It is also my intention to 
 consider the baneful influences of the solar 
 beam and lunar ray, upon the vegetable 
 creation, vital force, physical and mental 
 development. 
 
 When speaking of the unalloyed hap- 
 piness in store for man in a purer, higher, 
 nobler, and beatified state of existence, an 
 inspired prophet places prominently in ad- 
 vance among the great blessings that will 
 
Physiological Influence of Light. 3 
 
 be associated with our exemption from the 
 pernicious operation of those physical agents 
 which in this world are known (under cer- 
 tain conditions) to be obnoxious to our well- 
 being, the promise, that cc the sun shall not 
 smite thee by day nor the moon by night."* 
 
 After so solemn a declaration, need I 
 hesitate in approaching the consideration of 
 not only the sanatory but the morbid in- 
 fluence of the sun upon the human race ; 
 and need 1 offer any apology for analyti- 
 cally investigating the ^normal as well as 
 the normal effects of lunar light on the 
 flora of creation, the material and mental 
 organization of man ? 
 
 As it would be irrelevant for me to enter 
 into the discussion of the varied theories of 
 light that have been propounded, I proceed 
 
 * Psalm cxxi. 6. 
 B 2 
 
On the Sanatory and 
 
 at once in the first place to establish non- 
 essential the solar beam is to the preserva- 
 tion of the bodily and mental health, pro- 
 motion of longevity, beauty of the physical 
 form, serenity and integrity of the mind.* 
 
 There can be no persistent vitality nor 
 healthfully developed bodily structure with- 
 out light. If it were possible for a human 
 being to be placed during the natural term 
 of his existence, in a position of perfect 
 
 * From the earliest periods in the history of Medicine, 
 solar heat was considered to prolong human life. u Old 
 men," says Hippocrates, a are double their age in winter, 
 and younger in summer." In order to obtain the full 
 advantages of the light and heat of the sun, the ancients 
 had terraces built on the tops of their houses called 
 solaria, where they took what was termed their " solar- 
 air-bath." Speaking of his uncle, Pliny observes, "Post 
 cibum csstate si quid otii,jacebat in sole" As the sun rose, 
 disease, according to the views of the ancients, declined. 
 " Le<vato sole levatur morbus," was a recognised medical 
 axiom in former times. 
 
Physiological Influence of Light, 5 
 
 darkness, the physical tissues and mental 
 faculties would undergo serious modifica- 
 tions and degenerations. 
 
 Where light is not permitted to per- 
 meate, there are found, in the highest state 
 of manifestation, bodily deformities, intel- 
 lectual deterioration, crime, disease, early 
 and often sudden death. A material, as 
 well as a moral and mental, etiolation or 
 blanching occurs when the vital stimulus of 
 light is withdrawn. 
 
 A vast body of evidence conclusively es- 
 tablishes the inestimable value of this agent 
 to the health of both body and mind. 
 Compare the bright, ruddy, happy faces 
 and buoyant spirits of those who reside in 
 the country and work in the open fields, and 
 upon whom the sun is generally shining, 
 with the pale phlegmatic faces, emaciated, 
 
On the Sanatory and 
 
 stunted forms and nervous depression of 
 those whose vocation in life deprives them 
 of the health-giving and beneficial influence 
 of light. In order properly to test the 
 question, place side by side the robust, 
 sunny, rosy-cheeked and happy lass or lad 
 of the village with the pallid, sickly, melan- 
 choly girl or boy residing in one of our 
 manufacturing towns, who are pursuing 
 their vocation in a room or hermetically 
 sealed building, where darkness has obtained 
 an undue supremacy. Notice the difference 
 between the two classes of human beings ! 
 It may be enunciated as an indisputable 
 fact, that all who live and pursue their 
 calling in situations where the minimum 
 degree of light is permitted to penetrate, 
 suffer seriously in bodily and mental health. 
 These pathological phenomena are prin- 
 
Physiological Influence of Light. 7 
 
 cipally observed among those confined in 
 dark mines and collieries, badly-constructed 
 houses containing but few windows, holds 
 of ships, factories, and in persons incar- 
 cerated in dungeons and buried for a con- 
 siderable length of time in prisons, as well 
 as the denizens of narrow streets, crowded 
 alleys, confined courts, garrets, or cellars, 
 where the blessed light of the sun has a 
 difficulty in penetrating.* 
 
 The total exclusion of the sun's beams 
 
 * " I never shall forget," says Dr. Hammond, " the ap- 
 pearance presented by the sick of a regiment I inspected 
 about a year since in Western Virginia. They were 
 crowded into a small room, from which the light was 
 shut out by blinds of india-rubber cloth. Pale and ex- 
 sanguined ghost-like looking forms, they seemed to be 
 scarcely mortal. Convalescence was almost impossible; 
 and doubtless many of them died, who, had they been 
 subjected to the operation of the simplest laws of nature, 
 would have recovered."—" Treatise on Hygiene," Phila- 
 delphia, 1863, p. 209. 
 
8 On the Sanatory and 
 
 from the body induces the severer types of 
 chlorosis (green sickness) and other anaemic 
 conditions depending upon an impoverished 
 and disordered state of the blood. Under 
 these circumstances, the face assumes a 
 death-like paleness, the membranes of 
 the eyes become bloodless, and the skin 
 shrunken and turned into a white greasy 
 waxy colour. 
 
 Associated with these symptoms there are 
 emaciation, muscular debility and degenera- 
 tion, cedematous conditions, dropsical effu- 
 sion, softening of the bones ( <c mollities 
 ossium"), general nervous excitability, mor- 
 bid irritability of the heart, loss of appetite, 
 tendency to syncope and haemorrhages, 
 consumption, physical deformity, stunted 
 growth, mental impairment and imbecility, 
 coupled with premature old age. The off- 
 
Physiological Influence of Light. 9 
 
 spring of those so unhappily trained are 
 often deformed, weak, and puny, and are 
 disposed to scrofulous affections. 
 
 The wretchedly unhealthy condition of 
 that portion of the working population of 
 this country who live and work in darkness 
 was satisfactorily proved at the Parliamentary 
 inquiry which took place on this subject 
 many years ago.* 
 
 Similar consequences are observed in all 
 those who labour by night and sleep by 
 day ; such as bakers, police-constables, 
 compositors connected with the daily press, 
 whose occupation necessitates their employ- 
 ment during the greater part of the night. 
 
 * The light in the pent-up dwellings of large towns, 
 inhabited by the poor, is polarized light, it being always 
 only a reflected solar beam. The effect of the light and 
 atmosphere contained in such dwellings on the mind as 
 well as the body is as previously stated. 
 
io On the Sanatory and 
 
 The data collected by foreign writers 
 fully substantiate this truth. I refer par- 
 ticularly to the investigations made and 
 facts recorded in reference to the health of 
 the miners of Belgium, Hungary, and 
 France, as published by Drs. Ozanam, 
 Hoffinger, Halle, and M. Dupectiaux.* 
 According to the observations of these dis- 
 tinguished authorities, the morbid changes 
 
 * I extract the following from the Geelong Advertiser. 
 It must be taken quantum valeat. — " It is a curious fact, 
 connected with deep mining, that from the hours of 
 twelve at night till three in the morning the disturbing 
 influence in the bowels of the earth obtains increased 
 activity. At that time it is observed by miners that 
 water falls from places where none is observable during 
 the day. The volume in the wheel is perceptibly in- 
 creased, the atmosphere is charged with gases which often 
 prevent the lights from burning, and small particles of 
 earth and rock are observed to fall from the tops of the 
 drives. Whether this phenomenon is to be attributed 
 to the diurnal motion of the earth or other causes, it is 
 worthy of the attention of the curious." 
 
Physiological Influence of Light. 1 1 
 
 on body and mind which are consequent 
 upon the exclusion of light are singularly 
 significant and remarkable. 
 
 In numerous instances the general health 
 becomes vitiated, and the function of nu- 
 trition seriously interfered with. Not only 
 are specific diseases generated, but physical 
 as well as mental development arrested. In 
 many young girls and boys who are at an 
 early age consigned to a life of darkness in 
 mines, or in other places, puberty is either 
 never attained or is greatly retarded ; in 
 fact, the mind as well as body becomes 
 impaired in its growth, as the effect of 
 light being excluded from the human 
 organism. 
 
 No doubt the damaged health of those 
 who are constantly working in dark mines 
 and collieries is not altogether attributable 
 to want of light, although observing and 
 
12 On the Sanatory and 
 
 practical men have assigned this as one of 
 the principal reasons for the physical and 
 mental ailments to which this section of the 
 labouring classes is liable. 
 
 Fourcault affirms that where life is pro- 
 longed perhaps to the average term, the 
 evil effects of the want of light are seen in 
 the stunted forms and general deteriora- 
 tion of the human race. It appears that 
 the inhabitants of the arrondissement of 
 Chimay, in Belgium, three thousand in 
 number, are engaged partly as coal-miners 
 and partly as field-labourers. The latter are 
 robust, and readily supply their proper num- 
 ber of recruits to the army ; while among the 
 miners it is in most years impossible to find 
 a man who is not ineligible from bodily de- 
 formity or arrest of physical development.* 
 
 * Causes Generates des Maladies Chroniques. Paris, 
 1844. 
 
Physiological Influence of Light. 13 
 
 In association with the want of light 
 should be considered the deleterious effects 
 of dampness, deficient nourishment, impure 
 air, over work, anxiety of mind, the inhala- 
 tion of noxious and poisonous gases, fine 
 dust, &c, upon the general and specific 
 health of those exposed to the injurious 
 operation of these physical agents. 
 
 With these prefatory remarks I open the 
 subject of light in its physiological and 
 morbid relations. I would, however, pre- 
 mise that it is not my object to discuss the 
 special astronomical phenomena of the solar 
 ray ; neither do I propose to weigh the 
 relative value of the corpuscula, undulatory, 
 or other theories of light. I desire to 
 restrict my remarks to the direct influence 
 of this agent on vital manifestations, and to 
 refer to some of the more remarkable facts 
 
3 4 On the Sanatory and 
 
 illustrative of the effects of the exclusion of 
 light on the bodily and mental health, and 
 on animal and vegetable life. 
 
 In the first place, I have to point out the 
 influence of light on the vital and physical 
 organization of different animals. Dr. 
 Edwards instituted a number of interesting 
 experiments with the view of ascertaining 
 the effect of light, independently of heat, 
 upon the structure and growth of animals, 
 particularly between the interval of concep- 
 tion, fecundation, and adult age.* 
 
 This physiologist placed some frog's 
 spawn in water. The vessel containing it 
 was made impervious to light by being 
 covered with dark paper. A similar 
 experiment was tried in another vessel 
 
 * "On the Influence of Physical Agents on Life." By 
 W. F. Edwards, M.D., F.R.S., 1832. 
 
Physiological Influence of Light. i^ 
 
 which was transparent. The two vessels 
 were exposed to the same degree of 
 temperature, but the transparent one was 
 placed under the influence of the sun's 
 rays. The eggs were developed in succes- 
 sion ; of those in the dark none did well. 
 Unequivocal indications were observed of 
 the transformation of the embryo in a few 
 of the eggs. Dr. Edwards' experiments 
 were confined to the batrachian family. 
 The absence of light did not necessarily 
 interfere with the development of these 
 reptiles. Two tadpoles, out of twelve con- 
 fined in a tin box, pierced with small holes 
 for the change of water, and placed at the 
 depth of several feet in the Seine, under- 
 went the regular change of organic form.* 
 
 *"I have/' says Dr. Hammond, " often repeated Dr. 
 Edwards' experiments, and always with analogous results. 
 
1 6 On the Sanatory and 
 
 It appears that the transformation of two 
 of the animals was retarded by the absence 
 of light. For the purpose of fully settling 
 this question, tadpoles were confined in two 
 large vessels, each containing ten litres of 
 water, both capable of admitting light ; one 
 of glass, but with a partition close to the 
 water, to prevent atmospheric respiration ; 
 the other open, in order to allow the 
 animals an opportunity of rising to the 
 surface, and inflating the lungs. Those who 
 were deprived of fresh air were later in 
 transforming themselves than the others, 
 but this delay was so short that the inter- 
 ference with the respiration appeared to be 
 
 On one occasion I prevented for 125 days the develop- 
 ment of a tadpole, by confining it in a vessel to which 
 the rays of light had no access. On placing it in a recep- 
 tacle open to light, the transformation was at once com- 
 menced, and was effected in fifteen days." 
 
Physiological Influence of Light. 1 7 
 
 too slight to produce any effect on vital 
 development. It was clear that the exclu- 
 sion of the light had a serious influence on 
 the transformation of the tadpoles plunged 
 in water. 
 
 Sir Humphrey Davy refers in one of his 
 most charming works to the arrest of de- 
 velopment that takes place in the Proteus 
 Anguinus consequent upon its exclusion 
 from light.* 
 
 In the grotto of the Madalena, he says, 
 at Adelsburg, in Illyria, many hundred feet 
 below the surface, are seen creatures like 
 slender fish, moving in the mud below the 
 water. These are the protei : the animal 
 is of a fleshy whiteness, and transparent in 
 its natural state, but when exposed to light 
 
 * " Salmonia ; or Consolations in Travel." 
 C 
 
On the Sanatory and 
 
 its skin gradually becomes of a darker 
 colour, arid at last gains an olive tint. 
 Being abundantly furnished with teeth, it 
 is inferred that the animal is one of prey, 
 yet in its confined state it has never been 
 known to eat, and it has been kept alive for 
 many years by occasionally changing the 
 water in which it was placed. They have 
 also been found at a place thirty miles dis- 
 tant from the cavern, thrown up by water 
 from some subterraneous cavity. In dry 
 seasons the protei are very seldom seen in 
 the lake of the Madalena, but after great 
 rains they are often abundant. Their 
 natural residence is an extensive subter- 
 raneous lake, from which in great floods 
 they are sometimes forced through the 
 crevices of the rocks into the place where 
 they are found. 
 
Physiological Influence of Light. \ 9 
 
 These singular creatures Sir H. Davy 
 affirms have no organs of vision, but in 
 their place are two small dots which occupy 
 the position of eyes. It has not been ascer- 
 tained that they have any power of percep- 
 tion. The entire absence of colour, and 
 the imperfect development of their organs, 
 in at least their intermediate condition, 
 between those of a reptile and a fish, seem 
 to be the result of the absence of light. 
 
 Their exclusion from the solar beam is 
 well known to produce organic alterations 
 in the visual organs of animals, such as 
 atrophy of the optic nerve, or those por- 
 tions of the brain (the corpora quadri- 
 gemina) more immediately associated with 
 the sight. It is supposed that the blindness 
 observed among fish found in the dark 
 caves of the Tyrol and Kentucky arises from 
 c % 
 
20 On the Sanatory and 
 
 the arrest in the development of the eyes as 
 the result of a constant deprivation of light. 
 In elaborating this subject I have to con- 
 sider the effect of solar light and heat in 
 discolouring the skin of different races of 
 men by producing minute injections of the 
 capillary vessels on the surface of the body 
 and developing what physiologists term the 
 black figment cells. These peculiarities, 
 however, are not confined to shades of 
 colour, degrees of physical development, 
 stature, and power, but extend to the 
 animal passions as well as mental energy. 
 <c Is not," asks Mr. Hunt, cc the short-lived 
 beauty of the oriental women to be attri- 
 buted to the influence of that sun 
 a Shining on, shining on, by no shadow made tender," 
 
 which is known to give all the grandeur to 
 the vegetable world of the east ?" 
 
Physiological Influence of Light. i\ 
 
 Black, brown, and copper- coloured skins 
 are observed among those who reside in 
 tropical climates in proportion to the inten- 
 sity of the solar light, and the degree to 
 which the body is exposed to its influence. 
 
 This discolouration of the skin is not, 
 however, perceived among those who live 
 in temperate and cold regions. 
 
 As we approach nearer to the pole the 
 skin assumes a browner cast. 
 
 This is evidenced among the Laplanders, 
 Esquimaux, and Greenlanders. In the arctic 
 regions there cannot be said to exist, in the 
 right acceptation of the term, any night. 
 Here a constant light prevails, if not from 
 the sun yet reflected from the snow and ice 
 or emitted by the aurora borealis. According 
 to Captain Ross the natives of these climes 
 suffer from the effects of intense light, and 
 
22 On the Sanatory and 
 
 are subject to inflammation of the eyes and 
 blindness caused by cataract and paralysis of 
 the optic nerve. These diseases are not 
 confined to the natives. 
 
 Even among the African negroes the 
 skin is observed to lose its intense black 
 colour, particularly in those whose occupa- 
 tion enables them to live for many months 
 of the year in the shades of the forest where 
 the sun's rays, owing to the thickness of 
 the foliage and the size of the trees are 
 unable to penetrate. 
 
 It is said that the black colour of the 
 negro race is less permanent in its character 
 than the red or olive tints. The children 
 of olive and copper-coloured parents, ac- 
 cording to the authority of Dr. Mason 
 Good, exhibit the parental hue from the 
 moment of birth, but in those of blacks it 
 
Physiological Influence of Light. 23 
 
 is occasionally six, eight, or ten months 
 before the dark pigment is fully secreted. 
 It frequently happens that the black pig- 
 ment cells are not matured even among 
 negroes. Hence are observed in this 
 race of men children with white skins or 
 bodies interspersed with only interrupted 
 lines of black patches. These are called 
 cc spotted negroes." The black pigment has 
 been known during attacks of severe illness 
 to be entirely absorbed, and a white pigment 
 cell developed in its place, thus affording 
 a remarkable illustration of a black person 
 being suddenly bleached into a white man ! In 
 the cc Transactions of the Royal Society" is 
 an account of a woman whose left shoulder, 
 arm, and hand were as black as an African 
 negro's, whilst all the rest of the skin was 
 perfectly white. This anomalous condition 
 
24 On the Sanatory and 
 
 was said to have arisen from her mother 
 having during pregnancy put her foot upon 
 a lobster ! 
 
 No doubt the coarseness of the wool 
 of animals, and hair of human beings, as 
 well as the amount of colour developed in 
 their skin, is, to a degree, caused by 
 the nature of their food. Oils and 
 spirits are well known to disorder the liver, 
 and those who indulge to excess in these 
 articles of diet have generally an excess of 
 bile circulating in the blood. Intemperate 
 persons addicted to vinous potations have 
 a sallow and olive-hued complexion. The 
 dark and dingy colour of the pigmy people, 
 who live in high northern latitudes, arises 
 principally from the fish and oils of a rancid 
 and often offensive character upon which 
 they mainly subsist. This kind of diet is 
 
Physiological Influence of Light. 25 
 
 believed not only to affect the colour of the 
 skin, but to cause a diminution in the 
 stature of this race, in consequence of 
 their food being difficult of assimilation 
 and defective in nutrition. 
 
 Dr. Mason Good affirms that swine or 
 other animals fed on madder root, or 
 gallium-verum ( cc yellow-ladies'-bedstraw "), 
 have the bones tinged of a deep red or 
 yellow colour. M. Huber, the celebrated 
 naturalist of Lausanne, was able, by the 
 quality of the food given, to convert what 
 is commonly, but improperly, called a 
 neuter into a queen bee. 
 
 Trinocq, when speaking of the effects of 
 light on the colour of the body, affirms, 
 that among the Red Indians the skin that 
 is not exposed to the influence of the sun's 
 rays is quite white ; in other words, the 
 
26 On the Sanatory and 
 
 face, neck, and hands are dark, whilst the 
 limbs which are covered by clothing are of 
 an entirely different hue* 
 
 The same phenomena are observed in all 
 tropical climates. The white colour of 
 animals inhabiting the polar regions is attri- 
 butable to the absence of intense sunlight. 
 
 The changes referred to are clearly trace- 
 able to the direct influence of the sun, and 
 are not exclusively caused by a high degree 
 of temperature. Persons who live in hot 
 and tropical climates and whose occupation 
 exposes them to great heat apart from the 
 solar beam coming into immediate contact 
 with the body, do not suffer from any 
 marked discolouration of the skin.* 
 
 * Gardeners who are occupied for the greater part of 
 the day in hot-houses, exposed to intense heat, are not 
 generally tanned 
 
Physiological Influence of Light. 27 
 
 Among the negroes of the torrid zone, 
 Albinos are seen ; but these become scarce 
 near the equator. It is a commonly ob- 
 served fact that among fish, those parts of 
 the body not exposed to the free action 
 of light become of a pale hue, and are 
 sometimes quite white. This fact is no- 
 ticed among a certain species of flat-fish. 
 The axolotus pisciforniis, syren lacertina, 
 and the triton sit tat us (fish that live at 
 great sea depths, and are consequently ex- 
 cluded from the light), have transparent 
 bodies. 
 
 Certain animals, whose natural hue is 
 white, if bred and brought up in darkness, 
 become completely altered in texture and 
 colour. The cockroach, in its normal state, 
 is intensely black. If this insect be taken at 
 an early stage of its existence and carefully 
 
28 On the Sanatory and 
 
 reared in darkness, instead of assuming an 
 inky hue when it arrives at full growth, 
 it becomes nearly white. 
 
 The larvae of most insects that burrow 
 in the cavities of the earth, of plants, or of 
 animals, are white from the same cause. 
 When confined under glasses that admit the 
 influence of solar light, they exchange their 
 whiteness for a brownish hue. It is said 
 that Asiatic and African women confined to 
 the walls of their seraglios and secluded 
 from the sun are as white as Europeans. 
 
 It is of deep philosophical interest to 
 consider in relation to the present subject, 
 not only the effect of climate, meteorolo- 
 gical changes, combined with the influence 
 of varied degrees of light upon the 
 general health, great nervous centres, 
 and muscular development, but the modi- 
 
Physiological Influence of Light. 29 
 
 fixations which the physical force under- 
 goes from the same causes as far as the 
 growth, stature, and longevity of the inhabi- 
 tants of various countries are concerned. 
 
 Investigations have been made for the 
 purpose of ascertaining the effect of various 
 kinds of climate upon the stature of dif- 
 ferent nations. It has been satisfactorily 
 established that persons placed under the 
 same solar influences have not the same 
 stature; and, reciprocally the same stature is 
 found among people placed relatively to the 
 same influence under very different condi- 
 tions. The subjoined facts in illustration 
 of this subject are quoted from M. Sanson- 
 Alphonse's thesis on the influence of light 
 and the development of health. 
 
 In the southern hemisphere the Papoes 
 of Vaigion, at i° from the Equator, the 
 
30 On the Sanatory and 
 
 Vankoros at 12 , the Bushmen mountaineers 
 at 30 (an Ethiopic race), who receive 
 the rays of the sun with great intensity 
 of light and heat, have a stature of 
 5 ft. 1 in., very little above that of people 
 who dwell in the northern hemisphere, the 
 Kamschatdales, the Tartars and the Esqui- 
 maux (a Mongol race), in latitude 6o° to 70 
 north, where only the oblique rays of the 
 sun reach them, people of whom the stature 
 is 4 ft. 3 in. to 4 ft. 7 in. 
 
 High stature is met with equally in very 
 different latitudes ; thus in the southern 
 hemisphere we find 5 ft. 10 in. to be the mean 
 height of the Caribs (an American race), 
 who inhabit regions situate between i° and 
 8°, the natives of the " lies Marquises " 
 at io°, the inhabitants of the Navigator's 
 Islands at 14 . People whose countries 
 
Physiological Influence of Light. 31 
 
 are very near each other differ considerably 
 in stature. Thus the Patagonians, of 
 whom the mean height is 5 ft. 10 in., are 
 only separated by the narrow straits of 
 Magellan from the inhabitants of Terra 
 del Fuego, of whom the stature is only 
 4 ft. 3 in. ; thus the people of Sweden 
 and Finland join the Laplanders ; and the 
 New Hebrides, so near the Navigator's 
 Islands, whose population have a very high 
 stature, are inhabited by a short and badly 
 made race. 
 
 People of the same stature dwell either 
 in maritime regions on the continents up to 
 a level sufficiently elevated above the sea. 
 Temperature has certainly more influence 
 upon stature than light. 
 
 The inhabitants of very cold regions, 
 whether situated near the poles or on the 
 
32 On the Sanatory and 
 
 tops of mountains covered with snow, are 
 small. 
 
 Increase of stoutness is observed among 
 people who inhabit regions far from the 
 equator, and especially those in which there 
 is much moisture. It is there especially that 
 the marks of a lymphatic temperament are 
 apparent. Under the same zones, but on 
 more elevated plains, are seen men who 
 combine the greatest bodily development 
 with the maximum of muscular power. 
 They are of a sanguine temperament. 
 
 In ascending further above the level of 
 the sea and up to the regions of snow, the 
 men are small, but thick set. 
 
 As we approach the equator and elevated 
 regions the inhabitants are withered, with the 
 muscular system very moderately developed, 
 but endowed relatively with considerable 
 
Physiological Influence of Light. 33 
 
 energy. Such are especially the Arabs. 
 Their constitutions present the character of 
 a nervo-bilious temperament. 
 
 Although the free life of savages may 
 be favourable to the regular development 
 of their forms, they do not acquire under 
 the influence of climate any remarkable 
 muscular power. 
 
 The natives of Timor, New Holland, 
 and Tasmania are very inferior to the 
 English sailors in trials of strength 
 (Peron). 
 
 The natives of America show the same 
 inferiority of physical force. The negro 
 race, who bear in the highest degree the 
 impress of the effects of light, always ap- 
 pear, although individually not the most 
 active, the best suited for continued labour 
 under the light and heat of the sun. 
 
 D 
 
34 On the Sanatory and 
 
 Within the limits of climate inhabited by 
 the negro race they appear to enjoy a very 
 strong constitution. The same observation 
 applies to the Arabs. 
 
 The inhabitants of high latitudes consume 
 much more food than those who dwell in 
 intertropical regions, and have more corpo- 
 real development. The superior muscular 
 force with which they are endowed is partly 
 explained by this great consumption of 
 food, by their habits of labour, and the 
 consequent increase in the volume of their 
 muscles. 
 
 Growth is more rapid in equatorial re- 
 gions, and puberty is reached earlier ; but 
 the age for marriage ceases sooner. There 
 are more examples of longevity among 
 the people of the north than among those 
 of the torrid zone and more southern 
 
Physiological Influence of Light. 35 
 
 countries ; but some particular facts would 
 lead me to believe that these people would 
 also attain a very advanced age.* 
 
 It is not my intention to consider the 
 ethnological view of this subject. That 
 the influence of solar heat materially modi- 
 fies the national character cannot for ,a 
 moment be doubted. Like plants and 
 animals man, the highest order of intelli- 
 gence obeys the laws regulating the world's 
 zonal arrangements. According to climate, 
 degrees of temperature, &c, the human 
 race becomes passive, savage, doltish, or 
 intelligent. These affect his physiognomy, 
 dialect, and habits of life as well as his 
 mode of subsistence. When speaking of 
 
 * "De l'influence de la Lumiere sur le developpe- 
 ment et la Sante." Par M. Sanson-Alphonse. (Agrege 
 de la Faculte de Medecine de Paris). Paris, 1852. 
 D 2 
 
36 On the Sanatory and 
 
 influences of climate as well as local positions 
 upon the physical and mental organization, 
 a recent writer observes, after glancing at 
 man's geographical position, — cc Here,active, 
 intelligent, and progressive ; there, slug- 
 gish, dull, and stationary : here, enjoying 
 the highest amenities of civilization ; there, 
 grovelling in a condition little elevated 
 above the brutes by which they are sur- 
 rounded. And not merely do they differ 
 in intellectual qualities, but in physical 
 organization, in mien and stature, in form 
 of head and expression of face, in colour of 
 skin, in strength and endurance, and, in 
 fine, in all those purely bodily qualities by 
 which one species of animal is distinguished 
 from another."* 
 
 * iC Advanced State of Physical Geography," by D. 
 Page. London, 1864. 
 
Physiological Influence of Light. 37 
 
 I have now to refer to the influence of 
 deep sea- water on vegetable and animal life 
 ( cc flora" and cc fauna"), so far as its stratum 
 illustrates the effect of the exclusion of light 
 (under these circumstances) in modifying 
 vital force, and in interfering with or arrest- 
 ing physical development. 
 
 It will, however, be necessary to consider 
 preliminarily in connexion with this subject 
 two important and interesting questions : 
 1 st. What, according to well-ascertained 
 data, is the depth of the sea in various 
 portions of the globe? 2nd. To what 
 extent solar light is known to penetrate the 
 ocean ? 
 
 j st. It has been found, owing to the 
 irregularity in the form of its basin and a 
 variety of other causes, impossible to ascer- 
 tain with any degree of scientific exactness 
 
38 On the Sanatory and 
 
 the. mean depth of the ocean. In consequence 
 of the character of the tidal waves and cer- 
 tain undulatory movements which occur in 
 deep waters, four miles has been said by 
 some eminent physicists to be the maximum 
 extent to which the plummet has descended.* 
 
 * 6i The mean elevation of all the land-continents, and 
 islands, mountains, and plains has been estimated by Hum- 
 boldt at somewhat less than 1000 feet ; and the mean 
 depth of the ocean has been calculated by Laplace, from 
 tidal waves and kindred phenomena, to be at least 21,000 
 feet, or about four English miles. We know, however, 
 that a very large proportion of the ocean is comparatively 
 shallow, and not a tithe of this depth ; and therefore, to 
 make up the mean, some other portions must be propor- 
 tionally deeper, and to the extent it may be of eight or 
 ten miles. Indeed, soundings (no doubt open to question) 
 have been made in the South Atlantic, both by British and 
 American navigators, varying from 27,000 to 46,000 feet ; 
 and soundings, perfectly reliable, have been taken in the 
 North Atlantic, off the bank of Newfoundland, to the 
 depth of 25,000 feet ; while from calculations on the velo- 
 city of tidal waves, which are found to proceed according 
 
Physiological Influence of Light. 39 
 
 Reliable authorities, however, affirm that 
 oceanic soundings have been taken at the 
 depth of five, eight, and even to the extent 
 of ten miles. There are numerous instances 
 where twenty, thirty, forty, or even fifty 
 thousand feet of line have been played out 
 without giving distinct evidence of its 
 having reached the bottom of the sea. I 
 state this on the authority of Sir J. 
 Herschel. The average depth of the 
 Pacific (in consequence of its being abun- 
 dantly bestrewn with islands), is said to be 
 less than that of the Atlantic Ocean. 
 
 In 1 7 26' S. latitude and 170 29' W. 
 longitude, Sir James Rosse found the depth 
 
 to the depth of the channel, it has been estimated that the 
 extreme depths of the same ocean are about 50,000 feet, 
 or more than nine miles." — (Advanced Text Book of 
 Physical Geography, by David Page, F.R.S.E.) 
 
40 On the Sanatory and 
 
 of the sea to be 14,450 feet. About 450 
 miles west of the Cape of Good Hope, it 
 was 16,062 feet, or 323 feet more than the 
 height of Mont Blanc ; and 900 miles from 
 St. Helena, a line of 27,000 feet did not 
 reach the bottom of the sea, a depth equal 
 to the height of some of the most elevated 
 peaks of the Himalaya. It is, however, sup- 
 posed that there are many parts of the ocean 
 still deeper. Speaking in general terms, the 
 depth of the Atlantic averages from three 
 to four miles. The cc Telegraphic Plateau," 
 stretching from Cape Clear to Cape Race, a 
 distance of 1640 miles, is only about 11, coo 
 or 12,000 feet in depth ; the greater 
 depths (from 4 to 6 miles) have been 
 determined in the Indian and Southern 
 Oceans. The Arctic is of moderate depth, 
 and characterized by great irregularity and 
 
Physiological Influence, of Light. 41 
 
 diversity. The greatest ascertained depth 
 in the Mediterranean is about 13,000 feet; 
 in the Red Sea, 6300 feet ; Baltic, 840 
 feet ; Caribbean Sea, 14,000 feet ; and in 
 the Gulf of Mexico, about 8000 feet. 
 
 2nd. The depth at which solar light is 
 believed to permeate the ocean is calculated 
 to be about 700 feet.* The distance to 
 which the eye can penetrate the sea depends 
 principally upon its transparency.! 
 
 In experimentalizing as to the depth of 
 the ocean, it has been suggested that inde- 
 
 * In connexion with this subject it is important to 
 notice the fact referred to by Sir J. Herschel, viz., that the 
 light which penetrates to a great depth in the sea, is very- 
 different in its photo-chemical qualities from the solar 
 light of the surface. Again, in calculating the degree to 
 which the solar beam is seen to pierce the sea it will be 
 necessary to bear in mind the effect of various media 
 through which light passes on the refraction of its rays. 
 
 f David Page. 
 
42 On the Sanatory and 
 
 pendently of considering the transparency 
 of the water, we should test its phosphor- 
 escence, the face of the sky, whether clear or 
 cloudy ; the state of the sea, whether rough 
 or smooth ; the condition of the weather, 
 whether calm or windy. 
 
 The heat of the water should also be tried, 
 at various depths and hours of night and 
 day, in order to ascertain not only the maxi- 
 mum temperature and average depth of the 
 warmest stratum in the day, but the differ- 
 ence in its temperature and position by day 
 and by night.* These observations will 
 
 * Accurate calculations have been made as to the tem- 
 perature of the ocean. The results obtained clearly establish 
 that the lowest degrees of temperature are obtainable on 
 the surface of the water. About ten feet below the sur- 
 face the thermometer rises several degrees. Ninety degrees 
 is said by Mr. Agassiz (son of Professor Agassiz) to be 
 the highest temperature he has known the ocean to 
 
Physiological Influence of Light. 43 
 
 afford the data, also, for computing the 
 amount of solar heat that penetrates the 
 bosom of the sea, as well as the amount 
 that is radiated thence again. They will 
 reveal to us knowledge concerning its acti- 
 nometry in other aspects. We shall learn 
 how absorption by, as well as radiation 
 from, the under strata is affected by a 
 rough sea, as when the waves are leaping 
 and tossing their white caps ; and how by 
 its glassy surface, as when the winds are 
 hushed and the sea smooth. 
 
 Mrs. Somerville asserts, that in some 
 parts of the Arctic Sea, shells are dis- 
 tinctly seen as low down as 80 fathoms ; 
 and among the West Indian Islands, at the 
 same depth of water the bed of the sea is as 
 
 attain. At very great depths of the ocean a uniform tem- 
 perature of about 392- degrees has been found. (D. Page.) 
 
44 On the Sanatory and 
 
 clear as if seen in air. At this great depth 
 shells, corals, and seaweeds of every hue 
 display to the eye of the observer the beau- 
 tiful prismatic tints of the rainbow. 
 
 In connexion with this subject it is or 
 interest to consider the varied colour of the 
 sea in different parts of the globe, for upon 
 this principally depends the depth at which 
 the sight can reach. Assuming as a well- 
 established fact that the waters of the ocean 
 derive their colour from animalcules of the 
 infusorial kind vegetable substances and 
 minute particles of matter, it may be affirmed 
 as facts recorded by all writers on Physical 
 Geography, that the sea is white in the 
 Gulf of Guinea, black around the Maldives, 
 vermilion off California (caused by the red 
 colour of the infusoria it contains), and 
 green in the Persian Gulf. 
 
Physiological Influence of Light. 45 
 
 In the Arctic Sea the colour of the water 
 undergoes rapid transitions from ultrama- 
 rine to olive green ; from purity to opacity. 
 The green colour is said to be produced by 
 myriads of minute insects which devour one 
 another and are a prey to the whale. The 
 varied tints of the ocean in its shallow parts 
 depend to a degree upon the sea bed over 
 which it passes. A bottom of chalk or 
 white sand, produces an apple green colour ; 
 over yellow sand, a dark green ; brown or 
 black over dark ground ; and grey over 
 brown mud.* 
 
 Physicists have instituted a series of in- 
 teresting experiments with a view of ascer- 
 taining by carefully executed deep sea 
 soundings, the maximum depth at which 
 
 * Physical Geography. 
 
46 On the Sanatory and 
 
 various species of animals (marine molusca 
 and those belonging to the inter vertebrate 
 class), as well as plants, are capable of 
 sustaining life. 
 
 With this object Professor Forbes was 
 engaged for a period of eighteen months in 
 the iEgean Sea, and on the coast of Asia 
 Minor, in sea bottom explorations by means 
 of the dredge. He has demonstrated by 
 actual observation that below the depth of 
 55 fathoms, the number of animals di- 
 minishes as we descend, until at the depth 
 of about 200 fathoms the number of tes- 
 tacea was found to be only eight, and a 
 zero in the distribution of animal life was 
 indicated at probably about 300 fathoms. 
 Green fuci was not found below 55 fathoms, 
 and millepoza not deeper than L05 fathoms. 
 Similar phenomena are observed in some 
 
Physiological Influence of Light. 47 
 
 portions of the British Channel, viz., the 
 south coast of Cornwall.* 
 
 Professor Bailey of West Point, an emi- 
 nent American geographer, naturalist, and 
 
 * The following is the classification of marine animals 
 according to the zones of depth at which they live : — 
 
 1 st. Littoral found between high and low water marks, 
 a species capable of living in air as well as water, such as 
 crustaceous animals, crabs, testacea shell-less animals which 
 close themselves up or seal themselves hermetically on the 
 rocks and remain dormant during the recess of the water. 
 Among these are found the petallas mytilli and littorinas 
 purpuras, and among the zoophytes the common sea 
 anemone. 
 
 2nd. The circumlittoral zone existing at 15 fathoms. 
 
 3rd. The median zone from 15 to 50 fathoms. 
 
 4th. The infra-median ; and 
 
 5th, the abyssal zone ; the former from 50 to 100 fathoms, 
 the latter from thence to the lowest depths at which life is 
 possible. 
 
 Sir John Herschel says, when referring to this subject, 
 each of these zones is characterized by species which 
 belong to no other, and each passes into the other by the 
 intermixture of species common to several. 
 
48 On the Sanatory and 
 
 microscopist, says in a letter to a brother phi- 
 losopher, cc the bottom of the ocean at the 
 depth of more than 2 miles I hardly hoped 
 ever to have a chance of examining ; but, 
 thanks to Brooke's contrivance, we have it 
 (the deep sea deposit) clean and free from 
 grease, so that it can at once be put under 
 the microscope. I was delighted to find 
 that all these deep soundings are filled with 
 microscopic shells ; not a particle of sand or 
 gravel exists in them. They are chiefly 
 made up of perfect little calcareous shells 
 ( fC foraminifera "), and contain also a num- 
 ber of silicious shells ( cc diatomacece"). It 
 is not probable that these animals lived at 
 the depths where these shells are found, but 
 I rather think that they inhabit the waters 
 near the surface, and when they die their 
 shells settle at the bottom." Lieut. Brooke, 
 
Physiological Influence of Light. 49 
 
 of the North Pacific Exploring Expedition, 
 procured specimens in the coral sea from 
 the bottom at the depth of 2150 fathoms. 
 These soundings yielded representatives of 
 most of the great groups of microscopic 
 organisms. Professor Ehrenberg, of Berlin, 
 found the deep sea specimens to consist 
 principally of calcareous carapaces, filled 
 with soft pulp or fleshy matter. In Dr. 
 Wallach's cc Notes on the Presence of 
 Animal life in the vast depths of the 
 Sea," reference is made to the experiments 
 of Capt. Sir Leopold McClintock during 
 his survey in H.M. steamer the Bull- 
 dog, of the telegraphic route via Green- 
 land. It is said this navigator brought up 
 from the bottom of the ocean living star 
 fish adhering to the deep sea line. Is this, 
 it is asked, conclusive proof of the existence 
 
 E 
 
50 On the Sanatory and 
 
 of animal life in the depths of the ocean ? It 
 is supposed that these living star fish took 
 hold of the line near the surface of the 
 water, and were not actually brought up 
 from the bottom of the sea. 
 
 The preceding facts conclusively establish 
 the intimate relation existing between each 
 solar beam, life and organization as far as 
 the sea is concerned. Speaking in general 
 terms, it may be affirmed that animal and 
 vegetable vitality is incompatible with an 
 altitude of a few thousand feet above the sea 
 level on land, and a few thousand feet be- 
 neath it in the waters. Such is the line of 
 demarcation between organic and inorganic 
 matter, life and sterility ! 
 
 In connexion with this subject it is essen- 
 tial to consider the amount of pressure 
 which exists at great oceanic depths, for 
 
Physiological Influence of Light. 5 1 
 
 upon this often depends the existence of 
 marine life. In the Arctic Sea the specific 
 gravity of the water is lessened on account 
 of the greater proportion of fresh fluid pro- 
 duced by the melting of the ice, the pres- 
 sure at the depth of a mile and a quarter 
 being 2809 pounds on a square inch of sur- 
 face. Capt. Scoresby confirms this fact. 
 He says in his fC Arctic Voyages" that the 
 wood of a boat suddenly dragged to a great 
 depth by a whale, was found, when drawn 
 up, so saturated with water forced into its 
 pores, that it sank in water like a stone for 
 a year afterwards. Even sea water is re- 
 duced in bulk from 20 to 19 solid inches at 
 the depth of 20 miles. The compression 
 that a whale can endure is wonderful. 
 Many species of fish are capable of sustain- 
 ing great pressure, as well as sudden 
 e 2 
 
52 On the Sanatory and 
 
 changes of pressure. Divers in the pearl- 
 fisheries exert great muscular strength, but 
 man cannot bear the increased pressure at 
 great depths, because his lungs are full of 
 air, nor can he endure the diminution of it 
 at great altitudes above the earth.* 
 
 cc According to experiments, water at the 
 depth of iooo feet is compressed ^-h^th of its 
 bulk ; and at this ratio the pressure at the 
 depth of one mile would be equivalent to 
 1 60 atmospheres, or 23201b. on the square 
 inch ; while at the depth of 4000 fathoms, 
 or about \\ miles, it would amount to 750 
 atmospheres ! It is owing to this enormous 
 pressure that closed bottles sunk to great 
 depths have their corks always forced in ; 
 and that pieces of oakwood carried down to 
 
 * Physical Geography, by Mary Somerville. 
 
Physiological Influence of Light. 53 
 
 similar depths, have their fibres and pores so 
 compressed as to be afterwards incapable of 
 floating on the surface."* 
 
 I proceed in the next place to notice the 
 direct as well as indirect influence of light 
 on the vegetable kingdom, particularly in 
 reference to the modifications effected in the 
 colouring principle of plants, as a conse- 
 quence of their exclusion from its opera- 
 tion ; but before doing so, I would briefly 
 refer to some interesting facts illustra- 
 tive of the tendency exhibited by certain 
 plants to follow light, from an apparently 
 instinctive consciousness of its being neces- 
 sary, if not to their existence, at least for 
 their well-being. This phenomenon is 
 beautifully shown by the following facts : — 
 
 * Physical Geography, by David Page, F.G.S., p. 121 : 
 London, 1864. 
 
^4 On the Sanatory and 
 
 In the spring a potato was left behind in a 
 cellar where some tools had been kept during 
 the winter, and which had only a small 
 aperture at the upper part of one of its 
 sides. The potato, which lay in the oppo- 
 site corner, shot out a runner which first 
 ran twenty feet along the ground, then 
 crept up along the wall, and so through the 
 opening by which light was admitted.* 
 
 The Chrysanthemum Peruvianum turns 
 
 continually towards the sun, and is said to 
 
 cover itself with dewy clouds which cool 
 
 and refresh the flower during the most 
 
 „ violent heat of the day. 
 
 * " Natural History," by Jesse. 
 
 Asa general rule all plants bend towards the sun. Mr. 
 Hunt, however, found that light transmitted through 
 red fluid media had the effect of repelling plants from the 
 solar beam. This fact, he says, is not susceptible of expla- 
 nation. 
 
Physiological Influence of Light. 55 
 
 Professor Henslow states that some com- 
 posite as cc Hypo char is radicata " and 
 cc Apirgia autumnalis " are seen in meadows 
 where they abound, inclining their flowers 
 towards the quarter of the heavens in which 
 the sun is shining, Vaucher says the same phe- 
 nomena are observed in the Narcissusses and 
 in certain species of Melampyrum. Similar 
 phenomena have been observed in other 
 plants by Priestley, Sennebier, Theodore de 
 Saussure, Dumas, and Boussingault. 
 
 If a leafy shoot of any plant is bent down 
 without injury so as to reverse the usual posi- 
 tion of the faces of the leaves, the latter will 
 twist upon their petioles and turn their upper 
 surfaces to the light. Shoots of slender- 
 stemmed, quick-growing plants, such as jas- 
 mine, ampelopsis, &c, when trained into a 
 dark recess, turn their growing point back- 
 
$6 On the Sanatory and 
 
 wards on the older part of the stem, also 
 twisting round to face the light. The in- 
 fluence of lateral light is distinctly seen in 
 the plants grown in rooms in front of the 
 windows, while the drawn-up condition of 
 closely packed trees is an equally evident 
 result of preponderating top light, * 
 
 The curious phenomena previously re- 
 ferred to regarding the alteration in the 
 colour of plants caused by the absence of 
 the solar beam are well known to all intel- 
 ligent gardeners and scientific horticulturists. 
 Plants, as well as animals, nurtured and 
 grown in perfect darkness, never acquire 
 their natural colour. The former become 
 white instead of green. f 
 
 * "Botany, Structural and Physiological." — By Arthur 
 Henfrey, F.R.S., 1857. 
 " Audi alteram partem" The following facts appear in 
 
Physiological Influence of Light. 57 
 
 This fact is observed in the etiolation or 
 blanching, as it is termed, of certain kinds 
 of vegetables, such as celery, seakale, endive, 
 &c. Their leaves deprived of the sun's 
 
 a slight degree to contradict the general law just enuncia- 
 ted. u The absence of light exercises a very great influ- 
 ence over the power possessed by food in increasing the 
 size of animals. Whatever arouses and excites the atten- 
 tion of the animal, and makes it restless, increases the 
 natural waste of the different parts of the system, and 
 diminishes the tendency of food to enlarge the body. 
 To the rearers of poultry the rapidity with which 
 fowls fatten when kept in the dark is well known ; and 
 direct experiment on other animals, whether by keeping 
 them in the dark or by the cruel practice of sowing up 
 their eyelids, as is adopted in India, have led to similar 
 results. Absence of light, from whatever cause produced, 
 seems to exercise a soothing and quieting influence on all 
 animals, increasing their disposition to take rest, making 
 less food necessary, and causing them to store up a greater 
 portion of what they eat, in the form of fat and muscle." 
 — From a Paper on the " Scientific Principles involved in 
 the Feeding and Fattening of Stock," read by Ed. W. 
 Davey, M.B.M.R.I., at the Roy. Dub. Soc, April 14, 
 1859. 
 
5 8 On the Sanatory and 
 
 rays do not attain their normal growth or 
 form, neither is the natural odour of such 
 plants fully developed. Professor Robinson, 
 descending into a coal mine, accidentally met 
 with a plant growing luxuriantly. Its form 
 and qualities were new to him. The sod on 
 which it grew was removed, potted and care- 
 fully attended to in his garden.* The etio- 
 lated plant languished and died ; but the roots 
 speedily threw out vigorous shoots which, 
 from the form of the leaves and their peculiar 
 odour, he readily recognised as tansey. He 
 repeated similar experiments upon other 
 plants, viz., lovage, carvi, and mint, with 
 analogous results. 
 
 Ihe data obtained from the study of 
 physical geography conclusively establish 
 that animal and vegetable substances near 
 
 * " Encyclopaedia Britannica." 
 
Physiological Influence of Light, 59 
 
 the surface of the sea are, in consequence of 
 their free exposure to light, brilliantly 
 coloured, and that they gradually lose the 
 brightness of their hues as they descend 
 into deep sea water, until the animals of the 
 lowest zone are found nearly colourless. 
 cc Here," says Mr. Hunt, cc an everlasting 
 darkness prevails in the region of silence 
 and eternal death." 
 
 The rich colour of seaweed found near 
 and on the surface of the water is owing to 
 its free exposure to light. The same may be 
 said of the lovely tints of some of the zoo- 
 phytes {actina) living in shallow waters, 
 particularly the sea anemone, which, under 
 the influence of the bright sun, is seen, 
 whilst adhering to the rocks, to expand 
 itself like the blossoms of a flower. 
 
 On the surface of the globe the influence 
 
60 On the Sanatory and 
 
 of solar rays is shown in a marked manner. 
 The animals and plants of tropical climates 
 grow with a richness of colour, far exceed- 
 ing in beauty and brilliancy those of tem- 
 perate zones. The latter are less exuberant 
 in their growth, and are of a darker hue. 
 In the Arctic regions they are found nearly 
 colourless. The changes in vital develop- 
 ment which are observed as we approximate 
 towards the pole are believed to be governed 
 more by the isothermes than by the parallels 
 of latitude ; in other words by the mean 
 amount of heat diffused.* " Though vege- 
 
 * " The strength of evidence appears to be in favour of 
 considering Light, Heat, and Actinism as three distinct 
 principles or powers, active in regulating the great pheno- 
 mena of Nature. In the sunbeam these powers are 
 balanced against each other, and thus are determined those 
 differences of climate which are not influenced by the phy- 
 sical conformation of the earth's surface."— Hunt. 
 
Physiological Influence of Light. 61 
 
 tation may greatly differ," says Dr. Draper, 
 cc in its luxuriance in different climates of 
 the globe, the manner of action of the light 
 is always the same. Nothing is gained 
 
 It has been proved by well-conducted observations, that 
 with variations of latitude there are variations in the rela- 
 tions of these three principles. 
 
 In the temperate regions of the earth the Actinic power 
 is active; as we advance to the Tropics, where Heat 
 increases, and, 
 
 " The sun shines for ever unchangeably bright ;" 
 the chemical power is weak. The photographic picture 
 which could be taken in London in a second or two, could 
 not be obtained within the Tropics in less then a quarter 
 of an hour. It often happens, indeed, that prolonged 
 exposure under a blazing sun is insufficient to produce 
 any chemical change. Everything appears to favour the 
 view that the distribution of plants and animals on the 
 surface of the earth is regulated by the balance of physical 
 forces in the sunbeam. 
 
 In the Seasons we detect the same influences at work, 
 Actinism or chemical power is greatest in the Spring ; as 
 the bright Light of Summer advances, the power of the 
 Solar rays to produce any chemical change is diminished ; 
 
62 On the Sanatory and 
 
 under the brilliancy of the tropical skies 
 beyond a shortening of the time required 
 for the accomplishment of a given amount 
 of work. No substances are there decom- 
 posed, even in the organism of plants, 
 which could not equally well be decomposed 
 by the feebler light of more temperate 
 climates, only in these it would demand 
 more time. The oils and other substances, 
 almost or quite free from oxygen, which 
 abound in the plants of the torrid zone, are 
 not exceptions to, but illustrations of, the 
 doctrine here set forth."* 
 
 What is the modus operandi of solar light 
 
 and as we advance to Autumn, the peculiar Heat-rays 
 come more evidently into action." — Mr. Hunt, in the 
 " Popular Science Review," July, 1862. 
 
 * "Human Physiology, Statical and Dynamical." — 
 J. W. Draper, M.D., [858, p. 462. 
 
Physiological Influence of Light. 63 
 
 in altering if not altogether destroying the 
 chlorophyll, or, to use Dr. Hope's term, the 
 chromogen or colouring principle of plants ? 
 Do these changes depend, as Sir John Her- 
 schel suggests, on a cc chromatic analysis by 
 which the two distinct elements of colour 
 are separated by destroying the one and 
 leaving the other outstanding" ? 
 
 Chlorophyll is a substance similar to 
 wax in its nature, and is contained in the 
 deep cells or mesophyllum of leaves. It 
 depends upon the action of light for its 
 elaboration, and is intimately associated with 
 the phenomena of active vegetable life, has 
 a granular form, and is soluble in alcohol.* 
 As light decreases in the autumn the chloro- 
 
 * u Chromogen " is said to consist of two separate prin- 
 ciples, one of which forms a red compound with acids, 
 and the other yellow with alkalies. Dr. Hope attributes 
 
64. On the Sanatory and 
 
 phyll in many cases diminishes. The 
 alteration is caused by the plant losing a 
 portion of its carbon. Thus may be ex- 
 plained the changes that take place in the 
 evergreen and deciduous leaves, producing 
 what is commonly known by the autumnal 
 tints.* 
 
 The late Professor Lindley made many 
 interesting experiments with a view of 
 illustrating the physiological influence of 
 light on the colour of plants, f He esta- 
 
 the green colour produced by the latter to the mixture of 
 the yellow matter with the blue infusion. 
 
 * Balfour. 
 
 f Every plant, from the time of its germination till the 
 close of its organic activity, requires for its full develop- 
 ment a definite quantity of heat. On this subject Schleiden 
 has made some inquiries, and has taken as his subject the 
 case of barley. He says " in Egypt, on the banks of the 
 Nile, barley is sown at the end of November, and harvested 
 at the end of February ; the period of vegetation, there- 
 
Physiological Influence of Light, 65 
 
 blished that the flowers of the hydrangea 
 become blue in a soil impregnated with 
 carbonate of iron, and that all the brilliant 
 spectacle of vegetable colours disappear 
 either in consequence of accidents or on the 
 approach of death. In connexion with this 
 subject it is curious to notice, he remarks, 
 that the discoloration of plants is often 
 
 fore, amounts to about 90 days, and the mean temperature 
 of this season is 69 48'. In Tuqueres, near to Cumbal, 
 under the equator, the time of harvest the middle of No- 
 vember, the mean temperature of this vegetating season of 
 168 days is 50 12'. At Santa Fe de Bogota they num- 
 ber 122 days between seed time and harvest, with a mean 
 temperature of 57 24'. If, now, the number of days is 
 multiplied by the figures of the mean temperature, we 
 obtain 6282 for Egypt, 8433!^ f° r Tuqueres, for Santa 
 Fe, 6489m ; therefore, as nearly the same number as the 
 uncertainty in the estimate of the days, the accurate mean 
 temperature, and the want of knowledge whether or 
 not the same kind of barley is cultivated in all the places, 
 will allow us to expect. 
 The general result as above detailed is thus generalized 
 
66 On the Sanatory and 
 
 determined by the same agents, as in other 
 cases produce colour, and that certain 
 organs which have no colour whilst alive 
 when dead have a decided tint! If the 
 light be too powerful, a discoloration 
 takes place in the plant. Cultivators of 
 tulips with a knowledge of this fact place 
 their flowers under a tent in order to pre- 
 serve them from the effect of the direct 
 action of the sun, which is known to alter 
 
 by Dr. Draper: " Every cultivated plant requires a cer- 
 tain quantity of heat for its development, but it is the same 
 thing whether this heat is distributed over a shorter or 
 longer space of time, so that certain limits are not ex- 
 ceeded ; for where the mean temperature sinks below 
 36 24', or where it rises above 71 36', barley will no 
 longer ripen. Consequently, to define accurately the con- 
 ditions of temperature which a plant requires to maintain 
 it in a flourishing condition, we must state within what 
 limits its period of vegetation may vary, and what quan- 
 tity of heat it requires. This was first observed by Bous- 
 singault."— •" Human Physiology." 
 
Physiological Influence of Light. 67 
 
 their colours. The organic series of plants 
 exhibit the same phenomenon. 
 
 Most aquatic plants, like human beings, 
 are said to acquire in death a whitish hue. 
 Seaweeds of a most brilliant hue or green 
 colour become white when they die. The 
 same change is observed in the freshwater 
 conferveae. 
 
 Although the parts of plants which 
 originally are white or black become more 
 or less coloured when exposed to the action 
 of light, yet organs, once coloured, do not 
 in reality lose their hues when kept in 
 'darkness ; if they sometimes appear to do 
 so it is owing to this, — that if half developed 
 leaves are placed in the dark, they grow 
 larger, and the green matter which coloured 
 them, being diluted by water and spread 
 f 1 
 
68 On the Sanatory and 
 
 over a greater space, appears to be paler 
 without being itself less coloured.* 
 
 When speaking of the influence of the 
 sun's light on plants, Dr. Draper says: 
 cc Through this agent the decomposition of 
 carbonic acid is effected, and the plant 
 obtains from the air the carbon it requires, 
 out of which its solid structures are for the 
 most part built. The rapidity with which 
 the reduction of the carbonic acid takes place 
 depends upon the brilliancy of the light, 
 and the amount of carbon thus obtained 
 upon that condition and the time of ex- 
 posure conjointly. The amount of light 
 received from the sun in any locality depends 
 in a general way, as does the heat, upon the 
 
 * On Botany, by Dr. Lindley. 
 
Physiological Influence of Light. 69 
 
 latitudes, but in both cases a multitude of 
 disturbing agencies intervene. Variations 
 of moisture control the supply of light by- 
 permitting a translucency, or establishing 
 its opposite, a cloudiness or murkiness of 
 the air. Other meteorological causes, as, 
 for example, winds, by condensing or re- 
 moving moisture, act in like manner ; so 
 also do astronomical conditions, especially 
 by influencing the relative length of the day 
 and night ; for, as we advance towards the 
 pole, the summer sun is above the horizon 
 longer and longer. In Northern Europe, 
 during the month of June, the sun never 
 sets, but remains all night, if night it can be 
 called, above the horizon ; and, as Berzelius 
 well remarks, cc Under the influence of this 
 midnight sun of the North, the life of plants 
 runs through the same cycle of change in 
 
70 On the Sanatory and 
 
 six weeks which it takes four or five months 
 to accomplish in beautiful Italy." 
 
 In connexion with this subject it is of 
 great interest to consider not only the effect 
 of the sun on the colour of man, animals, 
 and plants, but its influence on the varied 
 phases of insect life. Their maximum 
 degree of vital manifestation as well as their 
 variety, richness of hue, &c, are found in 
 countries where the solar beam attains its 
 highest point of development. 
 
 The rate of increase of insect life, in pro- 
 ceeding from either pole to the equator, is 
 said to be very various in different longi- 
 tudes. Their numbers are small in both 
 the polar regions— more abundant in Tas- 
 mania and New South Wales — more so in 
 Southern and Western Africa, Columbia, 
 and a maximum in Brazil; but North 
 
Physiological Influence of Light, 71 
 
 America has fewer species than Europe in 
 the same latitude ; and Asia is compara- 
 tively poor in species, in proportion to its 
 great extent. The horrors of insect annoy- 
 ance in the swamps of the great rivers of 
 tropical America are vividly described by 
 Humboldt. 
 
 The air is one dense cloud of poisonous 
 insects to the height of twenty feet. In 
 Brazil the vivid colours and metallic brilliancy 
 of many of the beetles are extraordinary. 
 
 Among the more remarkable varieties of 
 insect life deserve special mention, 1st, the 
 bees and ants. Of the former each country 
 has peculiar species; but it is singular that 
 the honey-bee of North America has been 
 introduced from Europe. 
 
 The ants, of which the species are almost 
 innumerable, are found chiefly in hot and 
 
72 On the Sanatory and 
 
 dry climates, and are, perhaps, of all in- 
 sects, the most remarkable in their habits. 
 The termite of tropical Africa builds pyra- 
 midal nests ten or twelve feet in height, 
 hollowed into chambers of elaborate struc- 
 ture. The white ant of India devours 
 everything of animal and vegetable origin, 
 ascending by covered galleries (for they can- 
 not bear the light) to the sap of furniture, 
 beams, &c. But perhaps the most singular 
 species of all is that of the parasol ants 
 of Trinidad in the West Indies, which walk 
 in long procession each carrying a cut leaf 
 over its head, as a parasol in the sun, and 
 these they deposit in holes ten or twelve 
 feet deep under ground apparently with no 
 other object than to form a comfortable nest 
 for a species of white snake, which is invari- 
 ably found coiled up among them on digging 
 
Physiological Influence of Light. 73 
 
 out the deposit.* The scorpion extends in 
 Europe to the north coasts of the Medi- 
 terranean, but is more abundant in Africa, 
 both North and South, where its bite has 
 the singular peculiarity, that, although ex- 
 cessively painful on the first occasion of its 
 infliction, and even dangerous to life, the 
 constitution becomes hardened to it, the 
 suffering is less on every subsequent occa- 
 sion, and at length comes to be little re- 
 garded. Brazil produces a scorpion six 
 inches in length. The locust, one of the 
 most formidable scourges in countries in- 
 fested by it, migrates in such masses as to 
 darken the air for successive days, and when 
 driven into the sea is sometimes thrown up 
 
 * Mrs. Carmichael's <( Domestic Manners, &c. &c, in 
 the West Indies," ii. 327. — Mary Somerville's "Physical 
 Geography," from whose works these facts are quoted. 
 
74 On the Sanatory and 
 
 as banks on the shore, poisoning the air by 
 their decomposition for many miles in 
 length. They are frequent in Syria and 
 Barbary, whence they occasionally migrate 
 to Italy, and during the summer of 1858 
 several species were taken in the coun- 
 try, and one or two in London. They 
 are even said to cross the Mozambique 
 Channel from the African Coast to Mada- 
 gascar.* 
 
 This section of my subject would be im- 
 perfectly elaborated if I were to omit all 
 reference to the marked effect produced by 
 the chemical influence of light in modi- 
 fying the active principle of certain medi- 
 cinal drugs. f The phenomena referred to 
 
 * As quoted by Sir John Herschel : « Physical Geo- 
 graphy," 
 f Dr. Draper performed some interesting experiments 
 
Physiological Influence of Light. 75 
 
 are of deep practical importance, not only 
 to the pharmaceutical chemist but to the 
 physician. If the powdered leaves of hem- 
 lock, aconite, foxglove, or henbane, are ex- 
 posed for any length of time to a strong 
 light, their colour becomes changed, cc pass- 
 ing," says Mr. Hunt, Cf slowly from a green 
 into a slaty grey, and ultimately into a dirty 
 yellow." A decomposition also takes place 
 by which the medicinal activity of the plant is 
 seriously altered if not made altogether inert. 
 Hence the importance of preserving the 
 previously mentioned pharmaceutical pre- 
 
 on the production of hydrochloric acid by the direct 
 union of chlorine and hydrogen under the influence of 
 light, both artificial and solar, and also on the decom- 
 position of peroxalate of iron, from which the carbonic 
 acid is readily disengaged, by which he established that 
 the primary condition essential for the chemical action of 
 light is the absorption of some of its rays, 
 
j 6 On the Sanatory and 
 
 parations in well-covered bottles, thus care- 
 fully excluding them from the influence of 
 the sun's rays. 
 
 By what chemical or physiological laws 
 are we to explain the curious facts referred 
 to by Mr. Hunt, when alluding to the 
 effect of light in modifying the potency of 
 some vegetable tinctures, and particular 
 medicinal powders ? Pulverized rhubarb 
 and ginger adhere with considerable firmness 
 to the sides of the bottles exposed to the 
 light, whereas the sides in shadow are left 
 clear. If camphor is kept in a bottle, crys- 
 tals will be formed on the sides of the glass 
 upon which the light falls. If that side is 
 turned from the light the crystals will be 
 gradually removed, and again be deposited 
 on those parts upon which the rays of light 
 first impinge. 
 
Physiological Influence of Light. 77 
 
 Hydrocyanic acid is supposed to undergo 
 decomposition if exposed to the action of 
 light ; hence it is preserved in blue-coloured 
 bottles. 
 
 Gum guaiacum is well known to turn green 
 under the prolonged influence of the solar 
 light. Dr. Wollaston took two specimens 
 of paper coloured with a yellow solution of 
 this gum in alcohol, and exposed one of 
 them to air and sunshine, the other to air 
 in the dark. The former was turned per- 
 ceptibly green in five minutes, and the 
 change was complete in a few hours, while 
 the latter was not discoloured after the lapse 
 of many months. 
 
 In connexion with this subject, I have to 
 consider in detail the exceedingly interesting 
 experiments which have been made with a 
 view of ascertaining the modifications that 
 
78 On the Sanatory and 
 
 take place in the vital and chemical influence 
 of light when passed through media of 
 varied tints. Apart from the coloured rays 
 observed when the spectrum is subjected to 
 the effects of some absorbing medium, there 
 is an agent which is said to permeate the 
 glass or fluid, which has a decided thermic 
 influence. These phenomena are recorded 
 with philosophic exactness by Mr. Hunt. 
 The following is a summary of the facts he 
 has conclusively established in relation to 
 this subject : the highest degree of tempera- 
 ture is not obtained behind red media, but a 
 yellow or orange tint ; in fact, the maximum 
 degree of temperature is found behind a 
 colourless fluid. Red glasses and fluids 
 absorb a larger quantity of the heat rays 
 than any others excepting black ones. The 
 effect of the rays of light passing through 
 
Physiological Influence of Light. 79 
 
 different coloured media on the germination 
 of plants has been beautifully illustrated. 
 
 The following is the order in which the 
 colours standi when viewed in relation to 
 their vital or germinating effects : 1, orange ; 
 2, red ; 3, ruby ; 4, yellow ; 5, blue ; 6, 
 green. " The roots of tulips/ says Mr. 
 Hunt, fC under the orange glass, developed 
 the cotyledons a week earlier than those 
 under the yellow, blue, or green glasses. 
 The greatest progress in germination was 
 made by the tulips under the yellow and 
 orange glasses ; but the leaves under each of 
 these were by no means healthy, particularly 
 under the yellow glass, but which had a 
 singular delicate appearance, being of a very 
 light green colour, and covered with a most 
 delicate white bloom." 
 
 Under the influence of the colour pre- 
 
80 On the Sanatory and 
 
 viously referred to, the leaf stalks of the 
 tulips shot up remarkably long, and were in 
 both cases white. Under the orange glass, 
 a small flower bud appeared in the plant ; 
 it, however, soon perished with the plant 
 itself. Under the yellow glass no buds 
 appeared, and the vitality of the plant soon 
 failed. Tulips exposed to the influence of 
 light passing through ruby and red glasses 
 shot up in a single lobe. The duration of 
 the life of the plant did not extend over 
 three or four weeks, and it did not rise over 
 two or three inches above the soil. Under- 
 neath the green glass the plants grew slowly 
 but strongly. The stem was long, having a 
 small leaf at the end, not more than two- 
 thirds of an inch in diameter. The flower- 
 buds generated under these circumstances 
 never could be made to blossom, notwith- 
 
Physiological Influence of Light, 81 
 
 standing the greatest care and attention was 
 bestowed upon them. The attempt to 
 develop the bud appeared to exhaust the 
 vitality of the plant, and it soon died. 
 Under blue glasses the roots germinated 
 less quickly than in the open ground, but 
 exhibited a greater degree of vitality. Some- 
 what similar phenomena were observed with 
 regard to the germination of seeds when 
 exposed to the influence of light passing 
 through various coloured media, solid or 
 fluid in their nature. Dr. Draper found 
 that under the influence of the bright sun 
 of Virginia, plants have grown well in the 
 light which has been made to permeate 
 through a considerable thickness of intense 
 yellow solution. 
 
 When considering the chemical and phy- 
 siological influence of light it is impossible 
 
82 On the Sanatory and 
 
 to overlook the important results obtained by 
 Professors Bunsen and Kirchhoff by the aid 
 of the spectroscope, or analysis of the sun- 
 light by the prism. When this instrument 
 is applied to the investigation of a solar beam 
 it is found to be traversed by a number 
 of vertical dark lines, ( cc Fraunhofer's lines," 
 as they are designated.)* The* sunlight is 
 
 * " In order to explain the occurrence of the dark lines 
 in the solar spectrum, we must assume that the solar 
 atmosphere incloses a luminous nucleus, producing a con- 
 tinuous spectrum, the brightness of which exceeds a 
 certain limit. The most probable supposition which can 
 be made respecting the Sun's constitution is, that it con- 
 sists of a solid or liquid nucleus, heated to a temperature 
 of the brightest whiteness, surrounded by an atmosphere 
 of somewhat lower temperature. This supposition is 
 in accordance with Laplace's celebrated nebular theory- 
 respecting the formation of our planetary system. If 
 the matter, now concentrated in the several heavenly 
 bodies, existed in former times as an extended and con- 
 tinuous mass of vapour, by the contraction of which sun, 
 planets, and moons have been formed all these bodies 
 
Physiological Influence of Light. 83 
 
 thus proved to contain various metals. 
 Among these are iron, nickel, sodium, 
 calcium, magnesium, chromium, and in small 
 quantities, barium, copper, and zinc. Gold, 
 silver, mercury, aluminium, cadmium, tin, 
 lead, antimony, arsenic, strontium, and 
 lithium are not, according to the experiments 
 of Professor Kirchhoff, found in the solar 
 
 must necessarily possess mainly the same constitution. 
 Geology teaches us that the earth once existed in a state 
 of fusion ; and we are compelled to admit that the same 
 state of things has occurred in the other members of our 
 solar system. The amount of cooling which the various 
 heavenly bodies have undergone, in accordance with the 
 laws of radiation of heat, differs greatly, owing mainly 
 to difference in their masses. Thus whilst the moon has 
 become cooler than the earth, the temperature of the 
 surface of the sun has not sunk below a white heat. 
 Our terrestrial atmosphere, in which now so few elements 
 are found, must have possessed, when the earth was' in a 
 state of fusion, a much more complicated composition, as 
 it then contained all those substances which are volatile at 
 a white heat. The solar atmosphere at this present 
 
 G 2 
 
84 On the Sanatory and 
 
 atmosphere. It is supposed that the rays 
 of light which form the solar spectrum and 
 present the interesting phenomena previously 
 referred to have passed through the vapour 
 of iron, and have thus suffered the absorp- 
 tion which the vapour of iron must exert. 
 It has been maintained that these iron 
 
 time possesses a similar constitution. The idea that the 
 sun is an incandescent body is so old, that we find it 
 spoken of by the Greek philosophers. When the solar 
 spots were first discovered, Galileo described them as 
 being clouds floating in the gaseous atmosphere of the 
 sun, appearing to us as dark spots on the bright body of 
 the luminary. He says that if the earth were a self- 
 luminous body, and viewed from a distance, it would 
 present the same phenomena as we see in the sun. — 
 u Researches on the Solar Spectrum and the Spectra of 
 the Chemical Elements." By G. Kirchhoff, Professor of 
 Physics in the University of Heidelberg. Translated by 
 Henry E. Roscoe, B.A., Professor of Chemistry, Owen's 
 College, Manchester. London, 1862. 
 
Physiological Influence of Light. 85 
 
 vapours are contained in the atmosphere of 
 the sun or in that of the earth. cc It is 
 not easy to understand," says Professor 
 KirchhofF, cc how our atmosphere can con- 
 tain such a quantity of iron vapour as would 
 produce the very distinct absorption lines 
 which are seen in the solar spectrum. This 
 supposition is rendered still less probable 
 by the fact that these lines do not appreci- 
 ably alter when the sun approaches the 
 horizon. 
 
 cc It does not, on the other hand, seem at 
 all unlikely, owing to the high temperature 
 which we must suppose the sun's atmo- 
 sphere to possess, that such vapours should 
 be present in it. Hence the observations 
 of the solar spectrum appear to prove the 
 presence of iron vapour in the solar atmo- 
 sphere with as great a degree of certainty as 
 
86 On the Sanatory and 
 
 can be attained in any question of natural 
 science.* 
 
 The important results thus obtained re- 
 garding the properties of light by means of 
 the solar spectrum, will in all probability 
 tend greatly to elucidate the physical consti- 
 tution of the sun, the nebular theory respect- 
 ing the formation of the planetary system, 
 and the geological character of the earth ; 
 but into the consideration of the various 
 hypotheses suggested to explain the pheno- 
 mena relating to these interesting philoso- 
 phical points, it would be foreign to my 
 purpose to enter. 
 
 When addressing myself to the hygienic 
 influence of light, I purpose again recurring 
 to Professor Bunsen and KirchhofPs dis- 
 
 * " Researches on the Solar Spectrum, &c." By Pro- 
 fessor Kirchhoff. 
 
Physiological Influence of Light. 87 
 
 covery, for the purpose of ascertaining to 
 what extent the development of the red- 
 blood cell and the iron found in the general 
 circulation depend upon the mechanical or 
 chemical effect of the solar beam (contain- 
 ing in its composition this metal) upon the 
 portions of the body exposed to its opera- 
 tion. 
 
 It is not my intention to analyse the 
 morbid effects of solar light in the gene- 
 ration of specific diseases. I leave the 
 consideration of this portion of the sub- 
 ject in the able hands of Sir James Ranald 
 Martin, and other well-known writers on 
 the Diseases of Tropical Climates. 
 
 That a prolonged exposure to the intense 
 rays of the sun injuriously affects the 
 health is generally admitted. Inflammation 
 and congestion of the brain ; engorgement, 
 
88 On the Sanatory and 
 
 inflammation, enlargement, and torpidity 
 of the liver ; intermittent, remittent, gas- 
 tric, yellow, and congestive fevers ; dysen- 
 tery, and cholera, are among the principal 
 maladies incidental to a protracted residence 
 in the tropical zone. 
 
 Fatal attacks of what in India is termed 
 cc heat apoplexy," or cc coup-de-soleil," are 
 common in various parts of that country, 
 as the effect of an indiscreet exposure to 
 the vertical rays of the sun. 
 
Physiological Influence of Light. 89 
 
 PART II. 
 
 THE LUNAR RAY. 
 
 I would refer briefly to the ancient opinions 
 respecting the influence of the moon. 
 From the earliest periods of antiquity, 
 the idea generally prevailed, not only that 
 the moon exercised a specific effect in 
 the production and modification of dis- 
 ease, mental and bodily, but played a pro- 
 minent and important part in the develop- 
 ment of the character of nations, and in 
 determining the destinies of the human 
 race. Amongst the ancients the moon 
 was viewed as an object of superstitious 
 regard. They held her in great religious 
 
90 On the Sanatory and 
 
 veneration, considering her influence supe- 
 rior even to that of the sun ; in fact, they 
 worshipped her as a Deity. The new 
 moons, or the first days of the month, were 
 kept with great pomp and ceremony as 
 national festivals. The people were obliged 
 to rest on those days. The feast of new 
 moons was a miniature of the feasts of the 
 prophets. Eclipses, whether of the sun or 
 moon, were looked upon as evidences of 
 Divine displeasure. The Greeks consulted 
 the different phases of the moon before con- 
 tracting marriage, and the full moon, or 
 the times of conjunction of sun and moon, 
 were considered the most favourable periods 
 for celebrating the ceremony, in conse- 
 quence of the impression that the reproduc- 
 tive functions were under lunar influence. 
 
 " This connexion of the moon," says Dr. 
 Laycock, cc with the measure of time seems 
 
Physiological Influence of Light. 9 1 
 
 to have brought that planet into relation 
 with the religious rites of ancient nations, 
 as the Egyptians and Jews ; and, also, to 
 have given origin (in part) to the mytho- 
 logical idea so extensively prevalent of a 
 lunar influence on marriage and child-bear- 
 ing. Even the barbarous Greenlanders, as 
 Egede informs us, believe in this super- 
 stitious notion. They absurdly imagine that 
 the moon visits their wives now and then ; and 
 that staring long at it when at its full will 
 make a maid pregnant! Amongst the ancient 
 nations the general idea was, that the lunar 
 influence varied according to the age of the 
 moon. Bubastis, the Egyptian Diana, was 
 not equally favourable to parturient females 
 and their offspring in her different phases. 
 Amongst the Jews the full moon was 
 believed to be lucky, and the other phases 
 disastrous." 
 
92 On the Sanatory and 
 
 cc The full moon/' says the Rabbi Abra- 
 vanel, cc is propitious to new-born children : 
 but if the child be born in the increase or 
 wane, the horns of that planet cause death ; 
 or, if it survive, it is generally guilty of 
 some enormous crime." The Greeks and 
 Romans entertained a similar idea respect- 
 ing the lunar phases. The general opinion 
 seems to have been, that the moon was 
 propitious in proportion as its luminous 
 face was on the increase. The ancient 
 Greeks considered the day of the full 
 moon to be the best day for marriage. 
 Euripides makes Agamemnon answer, 
 when asked on what day he intends to 
 be married, 
 
 u Orav "2e\r)vr]s evrvxrjs e'X^?y kvkXos" * 
 
 Hesiod asserted that the fourth day of 
 
 * u Iphigenia," act v. 717. 
 
Physiological Influence of Light. 93 
 
 the moon was propitious, but the eighteenth 
 was bad, especially to females. Aristotle 
 maintained that the bodies of animals were 
 cold in the decrease of the moon, and that 
 the blood and humours are then put in 
 motion, and to those revolutions he ascribes 
 the various derangements peculiar to women. 
 
 Lucilius, the Roman satirist, says that 
 oysters and echini fatten during lunar aug- 
 mentation, which also, according to Gellius, 
 enlarges the eyes of cats ; and that onions 
 throw out their buds in the decrease of the 
 moon, and wither in her increase, which 
 induced the people of Pelusium to avoid 
 their use. Horace also notices the supe- 
 riority of shell-fish during the moon's in- 
 crease. 
 
 Pliny takes notice of the same fact. He 
 also adds that the streaks on the livers of 
 
94 On the Sanatory and 
 
 rats answer to the days of the moon's age ; 
 and that ants never work at the time of the 
 lunar changes. He also informs us that 
 the fourth day of the moon determines the 
 prevalent wind of the month, and con- 
 firms the opinion of Aristotle that earth- 
 quakes generally occur about the new moon. 
 Pliny asserts that the moon corrupts all 
 dead carcases exposed to its rays, and pro- 
 duces drowsiness and stupor in those who 
 sleep under her beams. He further con- 
 tends that the moon is nourished by rivers, 
 as the sun is fed by the sea. Galen asserted 
 that all animals who are born when the 
 moon is falciform, or at the half quarter, 
 are weak, feeble, and short-lived ; whereas 
 those who come into the world during the 
 full moon are healthy, vigorous, and long- 
 lived. 
 
Physiological Influence of Light. 95 
 
 Lord Bacon adopted the notion of the 
 ancients. He maintained that the moon de- 
 veloped heat, induced putrefaction, increased 
 moisture, and excited the motion of the 
 spirits.* Van Helmont affirmed that a 
 wound inflicted during the period of moon- 
 light is most difficult to heal, and boldly 
 asserted, that if a frog be washed clean and 
 tied to a stake under the rays of the moon 
 in a cold winter's night, on the following 
 morning the body will be found dissolved 
 into a gelatinous substance bearing the 
 shape of the reptile, and that coldness 
 alone, without the lunar action^ will never 
 produce the same effect ! 
 
 The Spartans considered the moon to 
 have great influence, and no motive could 
 
 * It is recorded that this great philosopher always had 
 a severe attack of syncope at the time of a lunar eclipse. 
 
9 6 On the Sanatory and 
 
 induce them to enter upon an expedition, 
 or march against the enemy, until the full 
 of the moon. The Greeks and Romans 
 believed that the moon presided over child- 
 birth. The patricians of Rome wore the 
 figure of a crescent upon their shoes, to 
 distinguish them from the inferior order of 
 men. The crescent was called lulula. Hero- 
 dotus records that when the Lacedaemonians 
 visited Athens, after the battle of Marathon, 
 they waited until the moon had passed its 
 full before they continued their march.* 
 The ancient alchymists attempted to localize 
 planetary influences, maintaining that the 
 heart, which represented, according to their 
 physiological notions, the vital principle, was 
 under the special protection of the sun ; that 
 
 * Erato, lxx. 
 
Physiological Influence of Light. 97 
 
 the brain was regulated and controlled by the 
 moon ; that Jupiter presided over the lungs, 
 Mars the liver, Saturn the spleen; that 
 Venus took the kidneys under her kind con- 
 trol, and Mercury sat in judgment upon the 
 reproductive functions. They were also of 
 opinion that the morning regulated the 
 blood, noon the bile, evening the atra-bile, 
 and night the cold phlegmatic constitution. 
 
 It will appear by the previously recorded 
 data that from the earliest periods in the 
 history of the world the idea of the phe- 
 nomena of organic life being subject to 
 planetary control, was popular amongst 
 enlightened and philosophic men.* The 
 
 * " A knowledge of the ancient and popular belief in 
 Sidereal influence will enable us to explain many super- 
 stitions in physic ; the custom, for instance, of adminis- 
 tering cathartic medicines at stated periods and seasons, 
 originated in an impression of their being more active at 
 
98 On the Sanatory and 
 
 following passage proves that the great 
 
 particular stages of the moon, or at certain conjunctions 
 of the planets ; a remnant of this superstition still exists 
 to a considerable extent in Germany ; and the practice of 
 bleeding at < spring and fall/ so long observed in this 
 country, owed its existence to a similar belief. It was in 
 consequence of the same superstition that the metals were 
 first distinguished by the names and signs of the planets ; 
 and as the latter were supposed to hold dominion over 
 time, so were astrologers led to believe that some, more 
 than others, had an influence on certain days of the week; 
 and, moreover, that they could impart to the correspond- 
 ing metals considerable efficacy upon the particular days 
 which were devoted to them ; from the same belief, some 
 bodies were only prepared on certain days in the year ; 
 the celebrated earth of Lcmnos was, as Galen describes, 
 periodically dug with great ceremony, and it continued 
 for many ages to be highly esteemed for its virtues ; even 
 at this day, the pit in which the clay is found is annually 
 opened with solemn rites by the priests, on the 6th day 
 of August, six hours after sunrising, when a quantity is 
 taken out, washed, dried, and then sealed with the Grand 
 Signior's seal, and sent to Constantinople. Formerly it 
 was death to open the pit or to seal the earth on any 
 other day in the year. In the botanical history of the 
 Middle Ages, as more especially developed in Macer's 
 
Physiological Influence of Light, 99 
 
 Roman satirist believed in lunar influ- 
 ences : — 
 
 u Ut mala quern scabies aut morbus regius urguet, 
 Aut fanaticus error, et iracunda Diana, 
 Vesanum tetigisse timent fugiuntque poetam, 
 Qui sapiunt."* 
 
 These notions have not been confined 
 to classical regions, ancient authorities, 
 or to the fanciful creations of the poet. 
 They have existed amongst barbarous, un- 
 civilized, and unlearned nations, who were 
 profoundly ignorant of the views pro- 
 pounded by the astrologers of old, or by 
 the medical writers, who had somewhat en- 
 Herbal, there was not a plant of medicinal use that was 
 not placed under the dominion of some planet, and must 
 neither be gathered nor applied but with observances that 
 savoured of the most absurd superstition, and which we 
 find were preserved as late as the seventeenth century by 
 the astrological herbarists, Turner, Culpepper, and Lovel." 
 — Dr. Paris's " Pharmacologia." 
 
 * Hor. " Ars Poetica." 
 
 H 2 
 
ioo On the Sanatory and 
 
 grafted the study of medicine upon that of 
 astrology and astronomy. In referring to 
 the alliance which formerly obtained between 
 the two sciences, it has been well observed 
 by an able writer and close observer of 
 nature, cc that no judicious person can doubt 
 that the application of astrology to medi- 
 cine, though it was soon perverted and 
 debased till it became a mere craft, originated 
 in actual observations of the connexion be- 
 tween certain bodily affections and certain 
 times and seasons. Many, if not most, of 
 the mischievous systems in physics and 
 divinity have arisen from dim perception or 
 erroneous apprehensions of some important 
 truth, and not a few have originated in the 
 common error of drawing bold and hasty 
 inferences from weak premises."* 
 
 * Southey. 
 
Physiological Influence of Light, toi 
 
 That the theory of planetary influence 
 should have been advocated in early times, 
 and have found zealous supporters, not only 
 amongst the illiterate, but amongst learned 
 and scholastic men, need not excite surprise 
 when we consider how easily susceptible of 
 demonstration is the fact of the moon's 
 powerful effect in producing that regular 
 flux and reflux of the sea which we call 
 tides. Astronomers having admitted that 
 the moon was capable of producing this 
 physical effect upon the waters of the ocean, 
 it was not altogether unnatural that the 
 notion should become not only a generally 
 received, but a popular one, that the ebb 
 and flow of the tides had a material influence 
 over the bodily functions. The Spaniards 
 imagine that all who die of chronic diseases 
 breathe their last during the ebb. Southey 
 
102 On the Sanatory and 
 
 says, that amGngst the wonders of the isles 
 and city of Cadiz, which the historian of 
 that city Suares de Salazar enumerates, one 
 is according to P. Labat, that the sick 
 never die there while the tide is rising or at 
 its height, but always during the ebb. He 
 restricts the notion to the isle of Leon, but 
 implies that the effect was there believed to 
 take place in diseases of all kinds acute as 
 well as chronic. <c Him fever," says the 
 Negro in the West Indies, " shall go when 
 the water come low ; him always come not 
 when the tide high." The popular notion 
 amongst the Negroes appears to be that 
 the ebb and flow of the tides are caused 
 by a "fever of the sea" which rages for six 
 hours, and then intermits for as many more. 
 There exists in the writings of many 
 able, truthful, and conscientious men a 
 
Physiological Influence of Light. 103 
 
 vast body of valuable and indisputable 
 evidence in support of the theory of plane- 
 tary influence. I subjoin the names of 
 the principal authorities on the subject : — 
 Ballonius, Ramazzini,* Joubertus,f Joannes 
 Morellus,! Mead, § Gemma, || Paraeus,^[ Dr. 
 Nicolas Fontana,** Dr. Cullen,tt Dr. 
 Balfour,!! Dr. James Lind,§§ Dr. Jack- 
 
 * De Constitutionibus trium sequentium annorum, 1692, 
 1693, 1694, in mutinense civitate et illius Ditione, Dis- 
 sertatio ; which essay will be found in the first volume of 
 his Opera Omnia Medica et Physiologica. 
 
 f On Epidemics. ! On Putrid Fever. 
 
 § De Imperio Solis et Lunge in corpora humana et 
 Morbis inde oriundis. 
 
 j| On the Plague of 1575. % On the Plague. 
 
 ** Osservazioni sopra le Malattie che attacano li Europei 
 nei Climi caldi, &c. Livorno, T781. 
 
 ff First Lines. 
 
 XX Effects of Sol-Lunar Influence in Fevers. London, 
 1815. §§ On Putrid Fevers. 
 
104 On the Sanatory and 
 
 son,* Dr. James M c Grigor,t Dr. James Gil- 
 christ, t Dr. James Johnson,§ Dr. Liddell,|| 
 Dr. Diemerbroeck ;% and in our own imme- 
 diate epoch, Drs. Orton,** RadclifFe, and 
 Laycock on the periodicity connected with dis- 
 ease and associated with the vital phenomenaft 
 —Sir James Ranald Martin, C.B., F.R.S.,tt 
 Dr. Milligan,§§ William Ramsay, |||| Dr. 
 
 * Treatise on the Connexion of the New and Full 
 Moon with the Invasion and Relapse of Fevers. — London 
 Medical Journal for 1787. Also, his Treatise on the 
 Fever of Jamaica. 
 
 f Medical Sketches of an Expedition to Egypt. 
 
 J On the Diseases of India. 
 
 § On the Diseases of Tropical Climates. 
 
 || On the Diseases of Tropical Climates. 
 
 ^| On the Plague. 
 
 « On Cholera. 
 
 ■j-j- Vols. ii. and iii., Lancet ; 1842-3. 
 
 ++ On the Diseases of Tropical Climates, Second 
 Edition. 
 
 § § Curiosities of Medical Experience. 
 || Astrologia Restaurata. 
 
Physiological Influence of Light. 105 
 
 Prichard,* Arago,t and Dr. Lardner.J 
 Many of the great medical authorities of 
 antiquity were clearly of opinion that the 
 celestial bodies exercised a marked influence 
 upon the bodily and mental functions. 
 Dr. Haslam asserts that Hippocrates, whom 
 he designates as a cc philosopher and correct 
 observer of natural phenomena," did not 
 place any faith in the generally received 
 notion respecting the influence of the moon. 
 This is clearly an error. Hippocrates im- 
 bibed so strong a belief regarding the effects 
 of the celestial bodies upon the vital mani- 
 festations that he expressly recommends no 
 physician to be entrusted with the treatment 
 of disease who was ignorant of astronomical 
 science ; and he expressly advises his son 
 
 * Analysis of the Egyptian Mythology, 
 f Meteorological Essays. 
 
io6 On the Sanatory and 
 
 Thessalus, to study the science of numbers 
 and geometry, affirming that the "rising 
 and setting of the stars have great effect 
 upon the distempers."* 
 
 The critical days, or crises as they were 
 termed, were said to correspond with the in- 
 terval between the moon's principal phases.f 
 Galen adopted the Hippocratic notion. 
 Hence the lunar periods were said by him 
 to be connected with the exacerbation of 
 particular diseases. 
 
 The doctrine of lunar influence has de- 
 scended to modern times, and notwithstand- 
 ing a section of the scientific world has 
 
 * Epist. ad Thessalum de aere, aquis, et locis. 
 f The crises which Hippocrates describes by the words 
 imperfecte judicabantur, were, according to Dr. Balfour, 
 nothing more than intermediate inter-lunar crises; and 
 those to which he applies the terms perfecte judicabantur, 
 were final inter-lunar crises. 
 
Physiological Influence of Light. 107 
 
 altogether repudiated the idea, it has never- 
 theless found zealous advocates among 
 learned men. Writers of admitted judg- 
 ment and sagacity have been recognised in 
 the ranks of those who support this theory. 
 At the threshold of this important and 
 interesting inquiry it will be well to pause 
 and consider, why any number of men of 
 science should exhibit a disposition to dis- 
 countenance this notion of planetary in- 
 fluence ? Dr. Orton endeavours to answer 
 the question. 
 
 cc The difficulty of explaining lunar in- 
 fluence appears to be the great obstacle 
 which in modern times has stood in the way 
 of the belief of its existence and general 
 prevalence. The ancients, who less minutely 
 scrutinized the chain which connects effects 
 with remote causes, implicitly believed in 
 
io8 On the Sanatory and 
 
 the existence of this power, simply be- 
 cause they saw the coincidence of its 
 effects and certain states of the heavenly 
 bodies, although they knew not that these 
 bodies in other respects exert a physical 
 influence on the earth. But since the pro- 
 gress of science has enabled men to trace 
 more distinctly the manner in which changes 
 arise from and produce other changes, this 
 empirical mode of reasoning has ceased to 
 be satisfactory ; and the improvement of 
 philosophy seems, in some instances, to have 
 actually operated as a barrier to its further 
 progress, by furnishing negative arguments 
 against the existence of causes which we are 
 unable to connect by any satisfactory theory 
 with their effects. Every occurrence in 
 Nature has been attempted to be accounted 
 for on rational and general principles, and 
 
Physiological Influence of Light. 109 
 
 it has been found much easier to deny than 
 to explain the operation of the sol-lunar 
 power. If, however, these principles were 
 to be applied in all their extent to the other 
 branches of medicine, they would strike at 
 the very root of that imperfect science ; for 
 we know little more of the modus operandi 
 by which ipecacuanha produces vomiting, 
 or jalap produces purging, than we do of 
 that by which the new or full moon pro- 
 duces attacks of intermittent fever, of 
 mania, or epilepsy. We have the same 
 kind of evidence of the agency of both these 
 classes of causes ; and after the proofs which 
 have been adduced of sol-lunar influence, it 
 would be nearly as preposterous to deny its 
 existence — because we cannot account for it, 
 because it does not produce its effects on all 
 persons, or because the same occurrences 
 
no On the Sanatory and 
 
 frequently arise without its agency, as it 
 would be to assert that a common dose of 
 ipecacuanha or jalap will not produce vomit- 
 ing or purging for precisely the same 
 reasons. It does not, nevertheless, appear 
 to be impossible to make some approach to 
 the explanation of the nature of sol-lunar 
 influence on known principles. It is proved, 
 on the known laws of gravitation, that the 
 various situations of the moon necessarily 
 must have determinate effects on the 
 atmosphere. Observations have shown 
 that such is the case, and on these 
 data considerable progress has already been 
 made in the elucidation of this interesting 
 subject. 
 
 cc It appears to be very evident that 
 sol-lunar influence is much more powerful 
 within the tropics than in other parts of the 
 
Physiological Influence of Light. 1 1 1 
 
 world ; and this may in some degree account 
 for the little credit which it has met with ; 
 for little information, in comparison to the 
 opportunities which are presented, has been 
 conveyed from these countries to the native 
 regions of philosophy. Dr. Balfour has 
 indeed been impressed with all the impor- 
 tance of his subject, and even more than all ; 
 his situation and experience were such as to 
 entitle his opinions to the highest attention, 
 and he has given them to the world in the 
 fullest manner ; but he has failed in gaining 
 a complete credit, probably from the dog- 
 matical style which he has adopted, and 
 from his having fallen into the error which 
 is usually fatal to theorists — that of aiming 
 at too much."* 
 
 * Dr. Reginald Orton's "Essay on the Epidemic 
 Cholera of India," p. 202. 1831. 
 
ii2 On the Sanatory and 
 
 Dr. Balfour's treatise will form the basis 
 of some remarks when I come particularly 
 to analyse the facts recorded by the different 
 authorities relative to lunar influence in the 
 production of disease. There has, I think, 
 been a disposition to discourage of late years 
 any minute, special, and scientific investiga- 
 tion of the facts recorded by men of veracity, 
 on the presumption that the subject is alto- 
 gether fanciful, visionary, and Utopian. If 
 the question has been seriously considered 
 with a view to elicit truth, has the inquiry 
 been calmly and dispassionately pursued, 
 and that, too, by competent observers, 
 possessed of the preliminary amount of 
 mathematical, astronomical, and meteoro- 
 logical science indispensably necessary in 
 order to arrive at anything like a satisfactory 
 result or scientific conclusion ? I much 
 
Physiological Influence of Light. 1 13 
 
 doubt the fact. In general conversation on 
 the subject^ the observation is often made, 
 cc Oh, I have not overlooked the study of 
 the subject ; I have been careful to observe 
 whether the moon does really exercise any 
 influence in modifying the type of disease, 
 and have arrived at the conclusion that the 
 notion is a puerile and fallacious one." 
 But when the question is asked as to the 
 mode of investigation which has been adopted, 
 it will generally be found to have been loose 
 and unscientific. With undoubtedly a 
 sincere disposition to arrive at the truth, the 
 method adopted by the inquirer has not been 
 so sufficiently philosophic, logical, and exact 
 as to entitle it to the respect of learned men. 
 To establish the inconsistency displayed by 
 writers on the subject, Dr. Orton cites 
 passages from two standard works of 
 
r 14 On the Sanatory and 
 
 scientific reference, relating to the subject 
 of lunar light, in which the authors deny 
 in toto its effects on the human organism. 
 "The hypothesis of planetary influence," 
 says one of the authorities, cc has originated 
 and passed by with the age of astrology."* 
 Another writer remarks that, Cf as the 
 most accurate and sensible barometer is not 
 affected by the various positions of the 
 moon, it is not thought likely that the 
 human body should be affected by them." 
 cc But in the following page," says Dr. 
 Orton, cc the writer furnishes a body of 
 evidence to establish that the barometer has 
 been found to be very remarkably affected by 
 the various positions of the moon" It is not 
 easy to reconcile such statements. 
 
 * Rees' a Encyclopaedia." " Encyclopaedia Britannica." 
 
Physiological Influence of Light. 115 
 
 Before proceeding to analyse the facts 
 cited by the authorities previously referred 
 to, as illustrative of the influence of lunar 
 light in the production of bodily disease, I 
 would briefly direct attention to some of 
 the well-known data regarding periodicity , as 
 associated with the origin, progress, and type 
 of disease. The theory of lunar influence 
 is in a great measure based upon this well- 
 established law. The doctrine of periodi- 
 city, as exhibited in the phenomena of life, 
 is not altogether of modern origin.* The 
 ancients were too close and accurate stu- 
 dents and observers of nature to have 
 
 * Certain plants appear, in an inexplicable manner, to 
 be influenced by the law of periodicity as well as by light. 
 Dr. Balfour, when referring to this subject, observes that a 
 plant accustomed to flower in daylight at a certain time 
 will continue to expand its flowers at the wonted time, 
 even when kept in a dark room. De Candolle made a 
 
 I % 
 
n6 On the Sanatory and 
 
 overlooked the fact. The phenomena of 
 menstruation were the subject of particular 
 observation in all ages, and its singular and 
 well-marked periodical character was attri- 
 buted to the operation of causes acting 
 independently of those organic laws sup- 
 posed to regulate the special functions of 
 life. This periodicity is observed in a large 
 class of febrile affections, particularly in the 
 intermittent, remittent, and bilious fevers 
 of tropical climates, in the class of disease 
 termed neuroses, in all spasmodic and con- 
 vulsive disorders, particularly in epilepsy 
 and its allied affections, in many forms of 
 
 series of experiments on the flowering of plants kept in 
 darkness and in a cellar lighted by lamps. He found that 
 the law of periodicity continued to operate for a consider- 
 able time, and that in artificial light some flowers opened, 
 while others, such as species of convolvulus, still followed 
 the clock hours in their opening and closing. 
 
Physiological Influence of Light. 117 
 
 insanity, and in the diseases classed under 
 the term exanthemata. 
 
 There is much in the recorded facts and 
 observations embodied in the valuable trea- 
 tises of Drs. Mead and Balfour, to strengthen 
 the presumption that the periodicity re- 
 ferred to arises directly or indirectly from sol- 
 lunar influences. Medical meteorology has 
 not yet assumed the character and position 
 of an exact and demonstrative science, and 
 although I would concede much to those 
 who have patiently considered this interest- 
 ing branch of philosophic inquiry, I am in 
 duty bound to pause before attributing too 
 much power to those external agents (active 
 I admit them to be) that are considered to 
 regulate and control the great principle of 
 life, either in its healthy or morbid mani- 
 festations. Can it not be demonstrated that 
 
it 8 On the Sanatory and 
 
 the vital law regulating the phenomena of 
 menstruation acts independently of certain 
 external agencies ? I repeat, is this fact not 
 susceptible of proof? Until we are satisfied 
 that this important uterine function is not 
 dependent upon a special organic law in- 
 herent in or acting specifically upon the 
 uterus itself, shall we not be travelling 
 beyond the limits of a safe and logical 
 induction, by assuming as an indisputable 
 and demonstrable fact, that the phenomena 
 to which I refer are the effect of lunar 
 conditions, or dependent upon certain 
 meteorological states of the atmosphere in- 
 duced by the physical aspects of the moon ?* 
 
 * These periodical discharges are said to be more pro- 
 fuse in countries near the equator than towards the poles. 
 Hippocrates notices this fact, and uses it to explain the 
 sterility of the women of Scythia. 
 
Physiological Influence of Light. 119 
 
 I now proceed with the historical analysis 
 of the subject. 
 
 Dr. Mead's treatise* appeared soon after 
 Sir Isaac Newton's immortal discoveries 
 burst like a flood of dazzling light upon the 
 world. Dr. Mead occupied a high position 
 amongst the literati of Europe. His repu- 
 tation as a scholar, physician, man of 
 letters, and a lover and cultivator of science, 
 was universally established. He was the 
 intimate friend of Pope, Newton, and of 
 Halley. He stood high in the estimation 
 of foreign princes and kings, and the learned 
 and scientific men of all countries eagerly 
 sought his acquaintance, and felt honoured 
 by his friendship. It is recorded in his 
 biography that the King of Naples for- 
 
 a De Imperio Solis et Lunae in corpora humana et 
 Moibis inde oriundis." 
 
120 On the Sanatory and 
 
 warded to Dr. Mead the two first volumes 
 of Signor Bajardi's erudite work on the 
 antiquities of Herculaneum, paying him the 
 compliment of asking in return a complete 
 collection of his own works, and at the 
 same time inviting him to his palace, for 
 the purpose of showing him his valuable 
 collection of Herculaneum antiquities. Con- 
 sidering the position of Dr. Mead, every- 
 thing that fell from his pen was read with 
 avidity, and his observations on all subjects 
 were considered to be based upon a patient 
 and accurate study of the great book of 
 nature. His work, previously referred to, 
 was read with universal interest ; and al- 
 though it gave rise to much controversy, it 
 nevertheless commanded the respect of his 
 learned contemporaries. It was the first 
 modern treatise on the subject, and proceed- 
 
Physiological Influence of Light, 121 
 
 ing from a physician of Mead's reputation, 
 it at once formed the topic of general con- 
 versation and criticism. Such being the 
 character of the work, I proceed briefly to 
 analyse its contents. 
 
 Dr. Mead, in the prefatory part of his 
 treatise, dwells much upon the importance 
 of a previous acquaintance with the mathe- 
 matical principles of natural philosophy, in 
 order fully to comprehend the subject of 
 lunar influences. 
 
 He then attempts to demonstrate, in the 
 first place, that the sun and moon, in pro- 
 portion as they approach near the earth, 
 independently of their influence upon heat 
 and moisture, must, at certain times, mate- 
 rially modify vital phenomena. The author, 
 in the second place, cites facts illustra- 
 tive of his theory, and then makes some 
 
122 On the Sanatory and 
 
 suggestions in reference to the practical 
 division of the subject. 
 
 Dr. Mead enters fully into the considera- 
 tion of the effect of the moon on the winds, 
 observing that the most boisterous seasons 
 of the year occur about the vernal and 
 autumnal equinox. It is a matter, he re- 
 marks, of common observation, that in the 
 calmest weather there is some breeze at 
 mid- day, at mid-night, and also at full sea 
 — that is, about the time the sun and moon 
 arrive at the meridian, either over or under 
 our hemisphere. Without entering more 
 minutely into analysis of Dr. Mead's able 
 and ingenious essay, his theory of sol-lunar 
 influence may be thus briefly epitomized : 
 — According to Dr. Mead, the attraction of 
 the sun and moon being increased at the 
 syzygies (new and full moon), and the 
 
Physiological Influence of Light. 123 
 
 perigees (those situations in the moon's 
 orbit in which she approaches nearest to the 
 earth), and the passages over the equator, 
 the weight of the atmosphere is consequently 
 diminished, and it is rendered mechanically 
 unfit for respiration, and for supporting the 
 due degree of pressure on the surface of the 
 body. Dr. Mead endeavours to establish, 
 on Newtonian principles that in all the 
 situations in which the sun and moon have 
 been found to produce their greatest effects 
 in raising the tides, rarefying and disturbing 
 the atmosphere, and in producing disease, 
 their joint attraction for the earth, or 
 certain parts of it is greatest ; and, on the 
 contrary where these effects are least evi- 
 dent, that these attractions are least. Dr. 
 Mead maintains that the atmosphere is much 
 more under lunar attraction than the ocean, 
 
•124 On the Sanatory and 
 
 owing to its greater height, which removes 
 it further from the earth and nearer to the 
 moon. Dr. Mead supposes that the influ- 
 ence of the moon is most visible in low 
 conditions of vitality and in certain states of 
 disease, and its effects are said to be more 
 manifest on the nerve force than on the blood, 
 or any other of the animal fluids. I consider 
 it, however, fair that Dr. Mead should, to 
 a certain extent, be the exponent of his own 
 views. I therefore make no apology for 
 quoting, in extenso, two important passages 
 from his treatise, having special reference 
 to his theory of lunar influence : — 
 
 cc It has been for a considerable time 
 established that our atmosphere is a thin 
 elastic fluid, one part of which gravitates 
 upon another, and whose pressure is com- 
 municated every way in a sphere to any 
 
Physiological Influence of Light. 1 25 
 
 given part thereof. From hence it follows 
 that if by any external cause the gravity 
 of any one part should be diminished, the 
 more heavy air would rush in from all sides 
 around this part to restore the equilibrium 
 which must of necessity be preserved in 
 all fluids. Now this violent running in 
 of the heavier air would certainly pro- 
 duce a wind, which is no more than a 
 strong motion of the air in some determined 
 direction. If, therefore, we can find any 
 general cause that would, at these stated 
 seasons which we have mentioned, diminish 
 the weight or pressure of the atmosphere, 
 we shall have the genuine reason of these 
 periodical winds, and the necessary conse- 
 quences thereof. The flux and reflux of 
 the sea was a phenomenon too visible, too 
 regular, and too much conducing to the 
 
126 On the Sanatory and 
 
 subsistence of mankind, and all other 
 animals, to be neglected by those who 
 applied themselves to the study of nature. 
 However, all their attempts to explain this 
 admirable contrivance of infinite wisdom 
 were unsuccessful till Sir Isaac Newton 
 revealed to the world juster principles, and, 
 by a truer philosophy than was formerly 
 known, showed us how, by the united or 
 divided forces of the sun and moon, which 
 are increased and lessened by several circum- 
 stances, all the varieties of the tides are 
 accounted for. And since all the changes 
 we have enumerated in the atmosphere do 
 fall out at the same times when those 
 happen in the ocean, and likewise whereas 
 both the waters of the sea, and the air of 
 our earth, are fluids subject in a great mea- 
 sure to the same laws of motion, it is plain 
 
Physiological Influence of Light. 127 
 
 that the rule of our great philosopher takes 
 place here— viz., that natural effects of the 
 same kind are to be attributed as much as 
 possible to the same causes.* What differ- 
 ence that known property of the air, which 
 is not in water, makes in the case, I shall 
 show anon. Setting aside the considera- 
 tion of that for the present, it is certain that, 
 as the sea is, so must our air, twice every 
 twenty-five hours, be raised upwards to a 
 considerable height, by the attraction of the 
 moon coming to the meridian ; so that, 
 instead of a spherical, it must form itself 
 into a spheroidal figure, whose longest 
 diameter, being produced, would pass 
 through the moon. That the like raising 
 must follow, as soon as the sun is in the 
 
 * Sir I. Newton's u Principia," p. 387. 
 
128 On the Sanatory and 
 
 meridian of any place either above or below 
 the horizon ; and that the moon's power of 
 producing this effect exceeds that of the 
 sun in the proportion of four and a half to 
 one nearly. Moreover, that this elevation 
 is greatest upon the new and full moons, 
 because both sun and moon do then conspire 
 in their attraction ; least on the quarters, in 
 that they then are drawing different ways, 
 it is only the difference of their actions that 
 produces this effect ; lastly, that this in- 
 tumescence will be of a middle degree at 
 the time between the quarters and new 
 and full moon. The different distances of 
 the moon in her perigasum and apogaeum 
 likewise increase or diminish this power. 
 Besides, the sun's lesser distance from the 
 earth in winter is the reason that the greatest 
 and least attraction of the air upwards more 
 
Physiological Influence of Light. 129 
 
 frequently happens a little before the vernal 
 and the autumnal equinox. And in places 
 where the moon declines from the equator, 
 the attraction is greater and lesser alternately, 
 on account of the diurnal rotation of the 
 earth on its axis. 
 
 cc Whatever has been said on this head is 
 no more than applying what Sir Isaac 
 Newton has demonstrated of the sea to our 
 atmosphere ; and it is needless to show how 
 necessarily those appearances just now men- 
 tioned of winds, at the stated times, must 
 happen hereupon. It will be of more use 
 to consider the proportion of the forces of 
 the two luminaries upon the air to that 
 which they have upon the waters of our 
 globe, that it may the more plainly appear 
 what influence the alterations hereby made 
 must have upon the animal body." 
 
 K 
 
130 On the Sanatory and 
 
 Dr. Mead then proceeds to demonstrate 
 how much more powerfully the moon in- 
 fluences the atmosphere than the sea, and 
 that the tides in the air, from lunar attrac- 
 tion, are much greater than on those of the 
 ocean ; and, after considering the effect of 
 certain unnatural states of the atmosphere 
 upon the barometer, and then the connexion 
 between certain states of the barometer and 
 special as well as epidemic diseases, he, in 
 the subjoined passage, further developes his 
 views as to the mechanical influence of cer- 
 tain conditions of the atmosphere on the 
 respiratory organs : — 
 
 cc It will not be difficult to show that these 
 changes in our atmosphere at high water, new 
 and full moon, the equinoxes, &c, must oc- 
 casion some alterations in all animal bodies, 
 and that from the following considerations: — 
 
Physiological Influence of Light. 131 
 
 cc 1 st. — All living creatures require air 
 of a determined gravity, to perform re- 
 spiration easily and with advantage, for it 
 is by its weight chiefly that this fluid in- 
 sinuates itself into the lungs. Now, the 
 gravity, as we have proved, being lessened 
 by these seasons, a smaller quantity 
 than usual will insinuate itself; and this 
 must be of smaller force to comminute 
 the blood and forward its passage 
 into the left ventricle of the heart, 
 whence a slower circulation ensues, and 
 the secretion of the nervous fluid is di- 
 minished. 
 
 <c 2nd. — This effect will be the more sure 
 in that the elasticity of the atmosphere 
 is likewise diminished. Air proper for re- 
 spiration must be, not only heavy, but also 
 elastic to a certain degree ; for as this is by 
 k 2 
 
132 On the Sanatory and 
 
 its weight forced into the cavity of the thorax 
 in inspiration, so the muscles of the thorax 
 and abdomen press it into the most minute 
 ramifications of the bronchia in expiration ; 
 where, the bending force being somewhat 
 taken off, and springy bodies, when un- 
 bended, exerting their power every way in 
 proportion to their pressures, the parts of 
 the air push against all the sides of the 
 vesiculae and promote the passage of the 
 blood. Therefore, the same things which 
 cause any alterations in the property of the 
 air will more or less disturb the animal 
 motions. We have a convincing instance 
 of all this in those who go to the top of 
 high mountains ; for the air is there so pure 
 (as they call it) — that is, thin — and wants so 
 much of its gravity and elasticity, that they 
 cannot take in a sufficient quantity of it to 
 
Physiological Influence of Light. 133 
 
 inflate the lungs, and therefore breathe with 
 great difficulty. 
 
 "3rd. — All the fluids in animals have 
 in them a mixture of elastic aura, which, 
 uhen set at liberty, shows its energy, and 
 causes those intestine motions we observe in 
 the blood and spirits, the excess of which is 
 checked by the external ambient air, while 
 these juices are contained in their proper 
 vessels. Now, when the pressure of the 
 atmosphere upon the surface of our body is 
 diminished, the inward air in the vessels 
 must necessarily be enabled to exert its 
 force in proportion to the lessening of the 
 gravity and elasticity of the outward ; here- 
 upon the juices begin to ferment, change 
 the union and cohesion of their parts, and 
 stretch the vessels to such a degree as some- 
 times to burst the smallest of them. This 
 
134 On the Sanatory and 
 
 is very plain in living creatures put into the 
 receiver exhausted by the air-pump, which 
 always first pant for breath, and then swell, 
 as the air is more and more drawn out ; 
 their lungs at the same time contracting 
 themselves, and falling so together as to be 
 hardly discernible, especially in the lesser 
 animals."* 
 
 Making due allowance for the obsolete 
 terms used by Dr. Mead, as well as for the 
 state of pathological and physiological science 
 of his epoch, the reader will be able to detect, 
 in the language which he adopts to enunciate 
 the theory of lunar influence, the germs of 
 some great truths, which have subsequently 
 been confirmed, in all quarters of the globe, 
 by appeals to the great book of nature. 
 Dr. Mead has undoubtedly laid himself 
 
 * " Espericnzc dell' Accademia del Cimento," p. 118. 
 
Physiological Influence of Light* \$$ 
 
 ge of at 
 too much ; 
 
 tors of />sed to the 
 
 ..-i ? 
 
 of fa< l 
 
 -).-, well u the oba 
 
 ,"; ^r 
 of the cases cited 
 
 into which the 
 author has f 
 to substantiate his pet ( 
 
 admit that it is to a great 
 tit based on ■■ and accurate obser- 
 
 and inaccu- 
 
 1. It will be interesting, whilst 
 
13 6 On the Sanatory and 
 
 glancing at the literary history of this sub- 
 ject, to refer to some of Dr. Mead's illustra- 
 tions. Dr. Mead was physician to St. 
 Thomas's Hospital during the time of 
 Queen Anne's wars with France, and whilst 
 occupying this honourable position, a great 
 number of wounded sailors were brought 
 into the hospital. He observed that the 
 moon's influence was visible on most of the 
 men at that time under his care. He then cites 
 a case, communicated to him by Dr. Pitcairne, 
 of a patient, thirty years of age, who was 
 subject to epistaxis, whose affection returned 
 every year in March and September — that 
 is, at the new moon near the vernal and 
 autumnal equinoxes. Dr. Pitcairne's own 
 case is referred to as a remarkable fact 
 corroborative of lunar influence. In the 
 month of February, 1687, whilst at a country 
 
Physiological Influence of Light. 137 
 
 seat near Edinburgh, he was seized, at nine 
 in the morning, the very hour of the new 
 moon, with a violent haemorrhage from the 
 nose, accompanied with severe syncope. 
 On the following day, on his return to 
 town, he found that the barometer was 
 lower at that very hour than either he or 
 his friend Dr. Gregory, who kept the 
 journal of the weather, had ever observed 
 it ; and that another friend of his, Mr. 
 Cockburn, professor of philosophy, had died 
 suddenly, at the same hour, from haemor- 
 rhage from the lungs, and also that six of his 
 patients were seized, at the same time, with 
 various kinds of hemorrhages •, all arising, it 
 was supposed, from the effect of lunar 
 influence on the condition of the barometer. 
 He refers to the case of a young man, of 
 delicate habit who brought on an attack of 
 
138 On the Sanatory and 
 
 haemoptysis by making an effort beyond his 
 strength. The haemorrhage during eighteen 
 months regularly recurred at the full of the 
 moon. Two remarkable instances, illus- 
 trative of the same fact, are recorded in the 
 "Philosophical Transactions."* The first 
 is that of a young man who, from his child- 
 hood till the twenty-fifth year of his age, dis- 
 charged a small quantity of blood from the 
 corner of the thumb-nail of his left hand, 
 every time the moon came to its full. The 
 other is the case of a patient, who from 
 the fifty-third to the fifty-fifth year of his 
 age, had a periodical evacuation of blood 
 from the extremity of the forefinger of 
 his right hand. 
 
 Baglivi cites the case of a student at 
 Rome who had a fistulous ulcer of the 
 
 * Nos. 171 and 172. 
 
Physiological Influence of Light. 139 
 
 abdomen which appeared to have some 
 connexion with the colon. This discharged 
 so abundantly on the increase, and so little 
 on the decrease of the moon, that it served 
 him as a perfect index of the periods and 
 quadratures of that planet. Nephritic 
 attacks, he says, frequently follow the 
 course of lunar attraction. 
 
 Tulpius relates that Mr. Ainsworth, an 
 English clergyman at Amsterdam, constantly 
 suffered from an attack of the gravel, ac- 
 companied with suppression of flatus, at the 
 full of the moon, which continued until she 
 had made some progress in waning. Van 
 Helmont mentions this influence of the 
 moon on asthma; and Sir John Fluyer, who, 
 from being personally afflicted with this 
 disease, had more occasion to attend to its 
 phenomena than most people, asserts that 
 
140 On the Sanatory and 
 
 paroxysms of asthma are always most 
 severe at certain periods of the moon, and 
 commonly recur with the change. Still 
 more extraordinary effects are attributed to 
 the lunar influence. The celebrated Kerck- 
 ringius, in his Anatomical Observations, 
 mentions the case of a young lady who 
 became plump and handsome with the in- 
 crease of the moon, but who completely 
 changed with the decrease of that planet. 
 About the change, she became so disfigured 
 and haggard that she secluded herself from 
 all society for some days. Mead also refers 
 to a lady, whose countenance always de- 
 veloped itself with the increase of the moon, 
 so that the eclat of her charms always de- 
 pended upon that planet. 
 
 Having given the preceding sketch of 
 Dr. Mead's essay, I now proceed to analyse 
 
Physiological Influence of Light. J41 
 
 Dr. Balfour's treatise, the second work of any 
 importance specially devoted to this subject. 
 Dr. Francis Balfour's first dissertation 
 appeared in Calcutta, in 1784.* In 1790, 
 in a cc Treatise on Putrid Intestinal Re- 
 mitting Fevers," published at Edinburgh, 
 the periodical return of febrile paroxysms 
 and their coincidence with the periodical re- 
 volutions and remissions of sol-lunar power, 
 which constitutes the foundation and proof 
 of this theory, was investigated, described, 
 and illustrated by two different plates, ex- 
 hibiting a synoptical view of the whole 
 system. The first part of that treatise is a 
 regular logical synthesis, arising from facts 
 observed and collected by himself to the 
 
 * "Treatise on the Influence of the Moon in Fevers." 
 This was subsequently reprinted in England, and in- 
 serted in Dr. Duncan's "Medical Commentaries." 
 
142 On the Sanatory and 
 
 discovery of certain prevailing tendencies in 
 nature, and thence to axioms or general 
 laws. The second part is an analysis, in 
 which these axioms or laws are employed to 
 explain some of the most remarkable phe- 
 nomena of fevers. The third part is an 
 application of the principles of this theory 
 to form general rules for practice. 
 
 This physician appears to have devoted 
 great attention to the consideration of this 
 subtle and disputed point in science, and, 
 with a view to its satisfactory elucidation 
 placed himself in communication with all 
 the medical men of note resident in our 
 Indian presidencies, eliciting from them the 
 result of their observations on the subject. 
 Dr. Balfour maintains, that every type of 
 fever prevalent in India is, in a remarkable 
 
Physiological Influence of Light. 1 43 
 
 manner, affected by the revolutions of the 
 moon. Whatever may be the form of 
 fever, he says that he has invariably ob- 
 served that its first attack is on one of the 
 three days which immediately precede or 
 follow the full or the change of the moon, so 
 that the connexion which prevailed between 
 the attack of the disease and the moon at 
 or during the time referred to, was most 
 remarkable. Relapses in cases of fever are 
 also said frequently to occur at such times. 
 Dr. Balfour has observed for a period of 
 fourteen years, this tendency to relapse at 
 the lunar full and change ; and, in particu- 
 lar cases, he was able to prognosticate the 
 return of the fever at these periods with 
 almost as much confidence as he could fore- 
 tell the moon's revolution itself. Putrid, 
 
144 On the Sanatory and 
 
 nervous, and rheumatic fevers of India are, 
 according to Balfour, equally under the 
 influence of the moon. In attempting to 
 explain these phenomena, Dr. Balfour says, 
 that along with the full and change of the 
 moon there is constantly recurring some un- 
 common or adventitious state or quality in 
 the air which increases fever and disposes 
 to an unfavourable termination or crisis ; 
 and that along with the intervals there is 
 constantly recurring a state or quality in the 
 air opposite to the former, which does not 
 excite but diminishes fever and disposes 
 to a favourable crisis.* Dr. Balfour has 
 
 * It will be well to state what Dr. Balfour means by a 
 crisis. He defines it to be " favourable changes which 
 never fail to take place, in some degree or other, at the 
 time of their transition from the lunar period in the inter- 
 lunar interval, and generally on the first morning inter- 
 meridional interval after it j at which juncture the 
 
Physiological Influence of Light. 1 45 
 
 collected a vast body of valuable evidence 
 in support of his lunar theory, establishing 
 beyond all dispute that in tropical climates 
 the regular diurnal and septenary changes 
 observed in the character of the fevers of 
 India are coincident and correspondent with 
 periodical sol-lunar conditions. 
 
 In the year 1783-4, Dr. Balfour had for 
 many months the charge of a regiment of 
 sepoys, in Cooch Behar, immediately under 
 the vast range of mountains which separate 
 
 maturity of the critical disposition concurs with the 
 periodical decline of sol-lunar influence in bringing them 
 about; and they are distinguished by one or more of 
 the following symptoms — viz., a sediment, or particular 
 turbid appearance, of the renal secretion ; a more free and 
 natural perspiration ; spontaneous evacuations; and cleaner, 
 moister, and softer tongue, with a more free and natural 
 discharge of saliva, a more loose and copious expectora* 
 tion, and a free discharge of bile, which seems to disappear 
 and be suppressed in the course of the fever," &c. 
 
146 On the Sanatory and 
 
 the northern part of Bengal from Bootan. 
 The prevalent diseases were fevers, or 
 cc fluxes" attended with fevers. During 
 the first month four hundred men were 
 invalided. The greater part, however, of 
 these cases were convalescent in the course 
 of the eight days that intervened between 
 the full and change of the moon ; but 
 during the remaining months of his stay in 
 that district, the diseases previously men- 
 tioned increased to almost double their 
 extent at every full and change of the moon, 
 falling down again to their former standard 
 during the eight days which intervened 
 between these two periods. With regard 
 to small-pox occurring in India, Dr. Bal- 
 four expresses himself as perfectly satisfied 
 that the full and change of the moon 
 interfered with the eruption, and increased 
 
Physiological Influence of Light. 147 
 
 the accompanying fever to a dangerous 
 degree. 
 
 Mr. Francis Day, of the Madras army, 
 thus generalizes Dr. Balfour's observations: 
 
 1. That the influence of the moon is less 
 apparent in Madras than in Bengal, but 
 may be traced over every portion of our 
 Eastern possessions. 
 
 2. That the lunar influence is thus 
 exerted : — The first attack of fever almost 
 invariably commences on one of those days 
 preceding the full or new moon, or on one of 
 those three which immediately follow them, 
 but that the last three are the most violent 
 in their effects. 
 
 3. That the new moon is more injurious 
 than the full. 
 
 4. That during these times the most 
 severe as well as the greatest number of 
 
 l 2 
 
j 48 On the Sanatory and 
 
 cases take place, but that when they occur 
 at other periods they are less severe, and of 
 short duration. 
 
 5. That these laws are as applicable to 
 relapses as they are to primary attacks ; so 
 much so, that the author was often able to 
 prognosticate the return of the fever at these 
 periods with almost as much certainty as he 
 could foretell the revolution (of the moon) 
 itself. 
 
 Mr. Day epitomises the results of care- 
 fully prepared statistical observations as 
 follows: — 
 
 1. That no decided preponderance in the 
 admissions for malarious fever is observed 
 at the time of the new moon. 
 
 2. That a decided preponderance is ob- 
 served at the time of the full moon. 
 
 3. That more admissions occur in the 
 
Physiological Influence of Light. 149 
 
 three days preceding the full moon than in 
 the three days subsequent to those changes. 
 
 4. That a slight increase in the admissions 
 may be present about the first and third 
 lunar quarters. 
 
 5. That the cases admitted at the time of 
 the new moon are generally slightly more 
 severe than the average admissions. 
 
 6. That the cases admitted at the time of 
 full moon are much more severe than the 
 average admissions. 
 
 7. That at times increased severity is 
 also apparent at the first and third lunar 
 quarters. 
 
 8. That the cases admitted during the 
 three days preceding these changes are more 
 severe than those admitted in the three 
 subsequent ones. 
 
 From the entire series of cases, Mr. Day 
 
150 On the Sanatory and 
 
 arrives at the probability that there is a 
 sol-lunar influence which is greater in the 
 equinoctial period than in the respective 
 equinoctial intervals, and considerably 
 more so in the autumn than in the vernal 
 equinoctial period ; that this force is greater 
 at the full and new moon than at the 
 intervals, and much more so at the full 
 than at the new ; that it is greater during 
 the meridional period than at the intermeri- 
 dional intervals, and much more so at the 
 diurno-meridional than at the nocturno- 
 meridional periods.* 
 
 The influence of the moon on the func- 
 tions of life has been made the subject of 
 
 * Quoted from Sir J. Ranald Martin's valuable work 
 on the (i Influence of Tropical Climates in producing 
 the Acute Endemic Diseases of Europeans." London, 
 1861. 
 
Physiological Influence of Light. 151 
 
 observation and speculation in every part of 
 India. The physiological and pathological 
 effects of lunar light have been universally 
 acknowledged by all medical men practising 
 in tropical climates. The natives of India 
 are taught to believe in lunar influence from 
 early infancy. In the northern latitudes 
 the effects of the moon's rays are said to 
 be less sensibly felt than in India. In 
 the latter country, those suffering from 
 attacks of intermittent fever are often 
 able to predict, by watching the phases of 
 the moon, the accession of the disease. 
 Balfour maintains that the fact of diseases 
 appearing during every day of the month 
 is no legitimate argument against lunar 
 influence. 
 
 iC The human body," he says, " is sub- 
 ject to alterations from a thousand external 
 
152 On the Sanatory and 
 
 physical circumstances as well as from many 
 internal moral affections. These lay the 
 foundation of disease at every period of life, 
 but they do not overthrow the evidence of 
 lunar influence, although they are apt to 
 mislead with regard to effects that depend 
 on that alone. The human body is affected 
 in a remarkable manner by the changes of 
 the moon, I am perfectly convinced, 
 although I cannot constantly pretend to see 
 the operation of the general law, nor to 
 account at all times for its perturbation, and 
 agree in thinking that an attention to the 
 power of the moon is highly necessary to 
 the medical practitioner in India." 
 
 cc It is a fact," says Dr. Orton, <c which 
 has been universally observed, particularly 
 in tropical climates, that the moon has a 
 great influence on the weather ; the full 
 
Physiological Influence of Light. 153 
 
 and change tending to produce rain and 
 storms, and the quarters being more fre- 
 quently attended by fine weather." This is 
 so well ascertained, and so thoroughly 
 believed, at least in India, that it is nearly 
 superfluous to adduce arguments or in- 
 stances in support of it. On every side, 
 then, we perceive the intimate connexion 
 which exists between the three series of 
 phenomena which have been noticed — the 
 great lunar periods, disturbed states of the 
 atmosphere, and the attacks of the epidemic. 
 It will also be proved that the other prin- 
 cipal circumstance which has been supposed 
 to attend the prevalence of cholera, the de- 
 pression of the barometer, is likewise pro- 
 duced by the new and full moon. Dr. 
 Orton says, cc Sol-lunar influence is, doubt- 
 less, but one of the causes producing the 
 
154 On the Sanatory and 
 
 state of the atmosphere which gives rise to 
 cholera; and I have no doubt that the 
 disease will often be found to make its 
 appearance when the disturbing power of 
 the sun and moon is least, and to subside 
 when that power is at its height. General 
 exacerbations of other epidemics, as well as 
 of cholera, will usually be found to corre- 
 spond to the moon's syzygies, and the 
 remissions of the quarters." 
 
 Dr. Kennedy bears testimony, in his 
 work on Epidemic Cholera, to the influence 
 of the moon. He observes, <c that the 
 constitution here (India), both native and 
 denizen, is assuredly under lunar in- 
 fluence, or, what is the same thing, under 
 the influence of the changes of weather 
 which invariably accompany the changes 
 of the planet." 
 
Physiological Influence of Light. 155 
 
 Diemerbroeck, in his well-known treatise 
 on the Plague,* when speaking of the 
 epidemic of 1636, says : cc Two or three 
 days before and after the new and full 
 moon the disease was more violent ; more 
 persons were seized at these times than at 
 others, and those who were then seized 
 almost all died in a very few hours. 
 Nescio qua virium labefactione oppressi." 
 In the dedication prefixed to this treatise, 
 which is addressed to the praetor and 
 consuls and the whole senate at Utrecht, 
 he thus describes the nature of his own 
 situation, the opportunities he had of ac- 
 quiring a knowledge of the disease, and his 
 object in publishing the work : — 
 
 * "Isabrandi Diemerbroeck Montferto Trajectini, 
 antehac Noviomagi, nunc Ultrajecti Medici, de Peste." 
 Libri Quatuor Dissertatio, &c. Arenaci, 1646. 
 
1 56 On the Sanatory and 
 
 " As in all well-constituted states it is 
 the duty of every one to contribute his 
 advice and assistance for the public safety, 
 that by their unanimous concurrence the 
 present as well as impending evils of the 
 state may be averted and repelled, I con- 
 ceive that I should not act improperly if, 
 concerning this plague, of all diseases the 
 most cruel, and more destructful than an 
 enemy, I, too, should offer some salutary 
 advice toward the discovery of its hidden 
 nature, together with some more certain 
 method of curing it. For, as in warfare, 
 none can so well elude the designs of the 
 enemy, or repel his attacks, as one who has 
 had experience in the art of war, so none 
 can more effectually resist this cruel disease 
 than one who has intrepidly opposed him- 
 self to its fury. This I did a long time 
 
Physiological Influence of Light. 157 
 
 ago, not only in the year 1633, when a 
 most violent pestilential fever, the fore- 
 runner of this plague, afflicted most grie- 
 vously the whole province of Gelderland, 
 and principally the city of Nimeguen, where 
 I was ordinary physician, and threw upon 
 me so great a load of practice as hardly 
 allowed me to take sustenance, but likewise, 
 in 1636 and 1637, when the true plague 
 raged so violently amongst the people of 
 Nimeguen, and so great a number of sick 
 was thrown upon my hands as to give 
 me no rest or repose. Having at that 
 time, with great danger, and at the risk 
 of my life, investigated most inquisi- 
 tively the nature of this most dreadful 
 enemy, I now make public his portrait, 
 delineated in this book, for the safety 
 of all." 
 
158 On the Sanatory and 
 
 The same writer asserts that during the 
 epidemic fever which raged in Italy in 
 1693, patients died in great numbers on the 
 2 1 st of January, at the period of the lunar 
 eclipse. But as Dr. Lardner observes, 
 when recording the fact, it may be objected 
 that the patients who then died in such 
 numbers at the moment of the eclipse 
 might have had their imaginations highly 
 excited, and their fears wrought upon, by 
 the approach of that event, if popular 
 opinion invested it with danger. That 
 such an impression was likely to prevail is 
 evident from the facts which have been 
 recorded. In 1654, at the time of a solar 
 eclipse, such was the strong opinion enter- 
 tained on this subject, that patients in con- 
 siderable numbers were ordered by their 
 physicians to be shut up in chambers well 
 
Physiological Influence of Light. 159 
 
 closed^ warmed, and perfumed, with the 
 view of escaping the injurious influence of 
 the eclipse. The consternation that pre- 
 vailed amongst all classes was very great, 
 and such crowds rushed to the confessional, 
 that the ecclesiastics found it impossible to 
 exercise their spiritual vocations. 
 
 The late Dr. James Johnson observes,* 
 when alluding to the fevers of India, however 
 sceptical professional men in Europe may 
 be in regard to planetary influence in fevers, 
 &c, it is too plainly perceptible between 
 the tropics to admit of a doubt. cc I have," 
 he continues, "not only observed it in 
 others, but have felt it in my own person 
 in India when labouring under the effects 
 of obstructed liver. That this influence 
 predisposes to, or exacerbates, the parox- 
 
 * " On the Diseases of TroDical Climates." 
 
160 On the Sanatory and 
 
 ysms of fever in India and other tropical 
 climates is incontestably proved by daily 
 observation." 
 
 Dr. Scott, when speaking of the effect 
 of sol-lunar light on the endemic and epi- 
 demic diseases prevalent on the western side 
 of India, says, cc The influence of the moon 
 on the human body in this part of India is 
 observed by every medical practitioner. It 
 is universally acknowledged by the doctors of 
 all colours, castes, and countries. The people 
 are taught to believe in the fact in their 
 infancy, arid as they grow up they acknow- 
 ledge it from experience. I suppose in the 
 northern latitudes this power of the moon 
 is. far less sensible than in India. We here 
 universally think that this state of the 
 weakly and diseased bodies is much influ- 
 enced by the movements of the moon. 
 
Physiological Influence of Light. 161 
 
 Many people know the very day on which 
 their intermittents will make their appear- 
 ance ; and every full and change increases 
 the number of patients of every practitioner. 
 It is no argument against this influence that 
 diseases appear during any day of the 
 month. The human body is subject to 
 alterations from a thousand circumstances, 
 and from many affections of the mind. 
 These lay the foundation for disease at 
 any period ; but they do not overthrow 
 the evidence of lunar influence, although 
 they are apt to mislead with regard to that 
 alone." 
 
 Mr. Hutton, writing to Dr. Balfour from 
 Calcutta, says that he has been at some 
 pains during a considerable practice of some 
 years at Prince of Wales Island to observe 
 the effects of the moon on the prevailing 
 
 M. 
 
1 6% On the Sanatory and 
 
 diseases of that place. The diseases peculiar 
 to that island are of the intermitting and re- 
 mitting kind, dysenteries, diarrhoeas, liver 
 complaints, and rheumatic affections. " I 
 have," he adds, <c generally found the vio- 
 lence of the symptoms (in the above men- 
 tioned diseases) considerably increased 
 during the full and change of the moon. 
 I have noticed relapses to occur from the 
 same cause. By keeping these facts in 
 view, I have been enabled to administer the 
 medicine adapted to the different diseases 
 with a greater degree of certainty and pre- 
 cision. " 
 
 Dr. Moseley remarks that the greater 
 haemorrhages from the lungs or those of 
 plethora, like all periodical attacks of this 
 kind (undisturbed in their natural course by 
 peculiar circumstances), obey the influence 
 
Physiological Influence of Light, 163 
 
 of the moon. Of this, he says, he has had 
 many proofs. That there are not more 
 authenticated by others is owing, he be- 
 lieves, to the theory on which the fact 
 depends not being sufficiently known to 
 prevent the result escaping unnoticed. In 
 another portion of his work he remarks 
 that most of the patients whom he had 
 attended in the spring of the year 1777 
 during attacks of fever were much affected 
 in the head at every new and full moon. 
 He refers to the case of a man who had 
 a severe attack of haemoptysis always at the 
 moon's full. When speaking of the mode 
 of treating these hemorrhagic conditions, 
 he advises the physician to be watchful in 
 every case of the kind when the moon's 
 influence was considered to be greatest on 
 the earth. He cites the history of a gentle- 
 
 M 1 
 
164 On the Sanatory and 
 
 man who suffered from haemorrhage of the 
 lungs, who was advised to leave England 
 during the winter and to reside in the south 
 of France. Whilst there his attacks came 
 on periodically, obeying faithfully the prin- 
 cipal changes of the moon. Dr. Moseley 
 considers this to be one of the most 
 decisive examples of lunar influence re- 
 corded in medical history. The following 
 particulars of his illness deserve attentive 
 consideration. 
 
 On February 14th, 1786, when near Toulon, 
 haemorrhage came on ; the moon was at its 
 full on the preceding day. On February 
 29th, when at Aix in Provence, he had 
 another attack. There was a new moon on 
 the 28th. The moon was again at its full 
 on the 13th of April, and on the 15th the 
 patient had another attack of haemoptysis. 
 
Physiological Influence of Light. 165 
 
 A new moon appeared on the 28th of the 
 same month, and on the 29th, when at 
 Tain upon the Rhone, he had a relapse. 
 At Chalons, in Burgundy, there was a full 
 moon on the 13th of May, and on the 14th 
 his haemorrhage returned. At Dijon, June 
 1 1 th, when the moon was at its full, he had 
 another attack. On July nth, at Paris, 
 the moon was again at its full. At this 
 lunar period the haemorrhage returned. 
 Again, when at Yarmouth in the Isle of 
 Wight, on August 9th, the moon was then 
 at its full. The haemoptysis returned. Dr. 
 Moseley alludes to the remarkable fact that 
 the last three attacks of haemorrhage from 
 the lungs came on at the instant the moon 
 appeared above the horizon* 
 
 * Dr. Moseley has pursued, in a few particulars, 
 these investigations to an extreme point. I say so with- 
 
t66 On the Sanatory and 
 
 Nicholas Fontana says, "that the in- 
 fluence of the moon is very visible in almost 
 all febrile cases. I had a good opportunity 
 of observing this fact in my first voyage to 
 this country (Barrackpore), in the year 1777, 
 and subsequently on board the Liverpool 
 East Indiaman. The ship was driven on a 
 bank in the river Massuma, on the east 
 coast of Africa, at a place called Behagoa 
 Bay. The crew, through hard labour and the 
 
 out intending for a moment to throw discredit on his 
 general statements. He asserts as a positive fact that 
 persons who live to an extreme age, invariably die at the 
 new or at the full moon. After citing a number of 
 instances illustrative of this opinion, he remarks, " Here 
 we see the moon shines on all alike, making (as in death) 
 no distinction of persons in her influence:" — 
 
 u aquo pulsat pede pauperum tabernas 
 
 Regumque turres." 
 
 Hor. lib. 1, 4. 
 — " A Treatise on Tropical Diseases." By B. Moseley, 
 M.D. 1792. 
 
Physiological Influence of Light. 167 
 
 unwholesomeness of the place, suffered much 
 from epidemic bilious fever. We had 60 or 
 70 patients ill out of the crew of 180. 
 Every one was seized with illness, and 
 several died. In the Gulf of Cambay, at 
 the Nicobar Islands, at Kedgeree, in the 
 River Ganges, Houghly, and on our 
 return to St. Jago, one of the Cape de 
 Verde Islands, where the ships went, and 
 remained a certain time in the course of the 
 voyage, the crew was severely and re- 
 peatedly attacked with remittent and inter- 
 mittent fevers. 
 
 "I observed, and was so fully persuaded of 
 the effects of the moon's changes on them 
 that I took notice of the fact in a work I 
 published after my return from Italy. I 
 did so with the view of cautioning succeed- 
 ing surgeons coming from the Mediterranean. 
 
1 68 On the Sanatory and 
 
 In that country the method adopted in 
 our practice was by no means fitted to 
 the treatment of the acute diseases which 
 Europeans were liable to between the 
 tropics." 
 
 <c Daily practice," says a well-known 
 army surgeon, Dr. Millingen, cc shows that 
 paroxysms of fevers and various other 
 maladies are under planetary influence. 
 The evening gun in our garrisons was often 
 the signal of severe exacerbation in certain 
 febrile cases, while the reveillee developed 
 acute aggravation in others." Sydenham 
 and Floyer remark that gout and asthma 
 were usually ushered in after the first sleep ; 
 and that during the prevalence of the 
 cholera the invasion of the disease was 
 noticed to occur towards daybreak. 
 
 The authorities previously cited conclu- 
 
Physiological Influence of Light. 169 
 
 sively establish that lunar influence is not to 
 be viewed as a mere myth, or as an Utopian 
 speculation. A host of intelligent writers 
 and acute observers confirm the fact beyond 
 all dispute. It will remain for me to con- 
 sider, not only the evidence in favour of the 
 lunar theory, but the arguments advanced 
 against the hypothesis. It is only by closely 
 investigating both sides of the question that 
 the philosopher in search of truth will 
 be enabled to arrive . at a safe deduc- 
 tion. 
 
 Before considering the effect of the moon 
 upon the mind in a state of aberration it 
 will be necessary to revert to the morbid 
 and physiological effect of lunar light upon 
 the vegetable kingdom. This has long 
 been the subject of observation and specu- 
 lation. Many curious and apparently inex- 
 
170 On the Sanatory and 
 
 plicable facts are upon record illustrative of 
 the phenomena. It will be well to refer 
 to some of the more reliable data in 
 connexion with this division of my sub- 
 ject ; but before doing so, I would remark 
 that the Druids of Gaul and Britain, who 
 combined the office of physician with 
 that of the priest, believing with the ancients 
 that all vegetable productions, and par- 
 ticularly medicinal plants, were constantly 
 under planetary influence, were instructed to 
 gather the far-famed mistletoe with a golden 
 knife when the moon was six days old. 
 
 It is a question whether the vervain of 
 the ancients was similar to the plant which 
 now bears that name. The appellation Ver- 
 bena or Sagmina was given by the ancients to 
 various plants used in religious ceremonies. 
 
 The vervain, held in such high repute by 
 the Romans, was gathered after libations of 
 
Physiological Influence of Light. 171 
 
 honey and wine at the rising of the dog 
 star, and with the left hand, and, thus col- 
 lected, served for various sacerdotal and 
 medicinal purposes. Its branches were em- 
 ployed to sweep the temples of Jupiter ; it 
 was used in exorcisms for sprinkling lustral 
 water ; and, moreover, it was said to cure 
 fevers, the bite of venomous reptiles, and it 
 was alleged to have the virtue of allaying 
 discord, and appeasing other violent passions. 
 This plant so gathered was always carried in 
 the hand by heralds when sent to sue for peace. 
 It was called Verbenarii. When its benign 
 powers were shed over the festive board, 
 mirth and good temper were said to prevail. 
 When speaking of the all-powerful in- 
 fluence of this plant, Pliny says — 
 
 " Nulla herba Romana nobilitatis plus habet quam 
 hierabotane."* 
 
 * Plinii, lib. 18, c. 44. 
 
172 On the Sanatory and 
 
 It is stated as a fact that if peas are sown in 
 the increase of the nioon they never cease 
 blooming ; that if fruits and herbs are set 
 during the wane of the moon, they are not 
 so rich in flavour, nor so strong and healthy, 
 as when planted during the increase. All 
 vines should be pruned at the wane of the 
 moon, says Sibley, the astrologist. He also 
 asserts that pomegranates will live only as 
 many years as the moon was days old when 
 they were planted. In planting shrubs, if they 
 are desired to shoot up straight and late, 
 and to take little root, they are to be set 
 when the moon is in an airy sign, and in in- 
 creasing light. Flowers that are under the 
 influence of the moon only open their 
 blossoms at night, whilst those that are 
 peculiarly under the government of the sun 
 open every morning when it begins to rise, 
 
Physiological Influence of Light. 173 
 
 and close in the evening when he sinks 
 below the horizon. M. Auguste de Saint- 
 Hilaire states, that in Brazil, cultivators 
 plant during the decline of the moon, all 
 vegetables whose roots are used as food ; 
 and, on the contrary, they sow during the 
 increasing moon the sugar-cane, maize, rice, 
 beans, &c, and in general those which bear 
 the food upon their stocks- and branches. 
 Experiments, however, were made and 
 reported by M. de Chanvalon, at Martinique, 
 on vegetables planted at different times in 
 the lunar month, and no appreciable diffe- 
 rence in their qualities was discovered. 
 There are some traces of a principle in the 
 rule adopted by the South American 
 agronomes, according to which they treat 
 the two classes of plants distinguished by 
 the production of fruit on their roots or on 
 
174 ® n the Sanatory and 
 
 their branches differently ; but there are 
 none in the European aphorisms. The 
 directions of Pliny are still more specific : 
 he prescribes the time of the full moon for 
 sowing beans, and that of the new moon for 
 lentils. cc Truly/' says M. Arago, cc we 
 have need of a robust faith to admit, with- 
 out proof, that the moon, at the distance of 
 240,000 miles, shall, in one position, act 
 advantageously upon the vegetation of 
 beans, and that, on the opposite position, 
 and at the same distance, she shall be pro- 
 pitious to lentils." The wise husbandman 
 is said to prune his vines in obedience to 
 certain phases of the planet. It is a maxim 
 amongst gardeners that cabbages and lettuces 
 which are desired to shoot forth early, 
 flowers which are to be double, trees which 
 it is desired should produce early ripe 
 
Physiological Influence of Light. 175 
 
 fruit, should severally be sown, planted, 
 and pruned during the decrease of the 
 moon ; and, on the contrary, that trees 
 expected to grow with vigour should 
 be sown, planted, grafted, and pruned 
 during the increase of the moon. These 
 opinions Dr. Lardner considers to be 
 altogether erroneous. The increase or de- 
 crease of the moon, he maintains, has no 
 appreciable influence on the phenomena of 
 vegetation ; and the experiments and obser- 
 vations of several French agriculturists, and 
 especially of M. Duhamel du Monceau, 
 have, he observes, clearly established this 
 fact. 
 
 Mantanari has referred to physical causes 
 for an explanation of the alleged lunar 
 influence upon plants. During the day, he 
 says, the solar heat augments the quantity 
 
t;6 On the Sanatory and 
 
 of sap which circulates in plants, by increas- 
 ing the magnitude of the tubes through 
 which the sap moves, while the cold of the 
 night produces the opposite effect by con- 
 tracting these tubes. Now, at the moment 
 of sunset, if the moon be increasing, it will 
 be above the horizon, and the warmth of 
 its light would prolong the circulation of the 
 sap ; but, during its decline, it will not rise 
 for a considerable time after sunset, and the 
 plants will be suddenly exposed to the un- 
 mitigated cold of the night, by which a 
 sudden contraction of leaves and tubes will 
 be produced, and the circulation of the sap 
 as suddenly obstructed. This explanation 
 does not satisfy Dr. Lardner, who remarks, 
 that if it be admitted that the lunar rays 
 possess any sensible calorific power, this 
 reasoning might hold good, but it will have 
 
Physiological Influence of Light, 177 
 
 very little force when it is considered that 
 the extreme change of temperature which 
 can be produced by the lunar light does 
 not amount to the thousandth part of a 
 degree of the thermometer ! Upon this 
 point, however, philosophers are at variance. 
 The lunar rays have, according to the ex- 
 perience of practical men, a decided calorific 
 effect. 
 
 The gardeners of Paris assured Arago that 
 in the months of April and May they found 
 the leaves and buds of their plants, when 
 exposed to the full moon in a clear night, 
 actually frozen , when the thermometer in the 
 atmosphere was many degrees above freezing- 
 point. He mentions these facts as proving 
 that the moon's rays have a frigorific power, 
 but that the largest speculums directed to 
 the moon produced no such indications on a 
 
 N 
 
178 On the Sanatory and 
 
 thermometer placed in their focus.* Dr. 
 Howard, of Baltimore, has affirmed that on 
 placing a blackened upper ball of his 
 differential thermometer in the focus of a 
 thirteen-inch reflecting mirror opposed to 
 the light of the full moon, the liquor sank, 
 in half a minute, eight degrees ! Though 
 the surface of the full moon exposed to us 
 must necessarily be very much heated, says 
 Sir J. Herschel, possibly to a degree much 
 exceeding that of boiling water — yet we 
 feel no heat from it, and even in the focus 
 of large reflectors it fails to affect the 
 thermometer. No doubt, therefore, its 
 heat (conformably to what is observed of 
 that of bodies heated below the point of 
 luminosity) is much more readily absorbed 
 in traversing transparent media than direct 
 
 * Ferguss. " Bull. Univ." 1827, p, 383. 
 
Physiological Influence of Light, 179 
 
 solar heat, and is extinguished in the upper 
 regions of our atmosphere, never reaching the 
 surface of the earth at all. Some proba- 
 bility is given to this by the tendency to 
 disappearance of clouds under the full 
 moon, a meteorological fact (for as such we 
 think it fully entitled to rank), for which 
 it is necessary to seek a cause, and for which 
 no other rational explanation seems to offer. * 
 Cases of sudden death and profound 
 coma are recorded as the effect of an im- 
 proper and prolonged exposure to the 
 intense light of the full moon. Sailors have 
 been found dead on deck after sleeping 
 under the moon's rays. It is also said that 
 convulsions, apoplexy, epilepsy, and in- 
 sanity, sensations of oppression in the head, 
 inertness and heaviness of the senses, have 
 * Outlines of Astronomy, pp. 261, 2. 1849. 
 N-3 
 
i8o On the Sanatory and 
 
 arisen from the same cause. Plutarch 
 observes : — cc Everybody knows that those 
 who sleep abroad under the influence of the 
 moon are not easily awakened, but seem 
 stupid and senseless."* In India, death has 
 occasionally been known to arise from what 
 is termed a coup de lune> or stroke of the 
 moon ; and in Egypt, blindness has often 
 been produced in persons who have impru- 
 dently fallen asleep with their faces exposed 
 to intense lunar light. Does not Edgar 
 Allan Poe refer to this morbid effect of the 
 moon's rays in the following passage ? — 
 
 " 'Neath blue bell or streamer, 
 Or tufted wild spray, 
 That keeps from the dreamer 
 The moonbeam away."f 
 
 * Plut. " Symp." B. 3. 
 
 f "Al Aaraaf." Tycho Brahe suddenly discovered in the 
 heavens a star which attained in a few days a brilliancy sur- 
 
Physiological Influence of Light. 181 
 
 Dr. Madden mentions that the Arabs 
 attribute a morbid influence to the moon, 
 and think it causes ophthalmia and catarrh. 
 He thought there was some influence from 
 it in the desert beyond the common damp- 
 ness of the night.* 
 
 The questions that naturally occur to the 
 mind in reference to this interesting inquiry 
 are, whether the morbid phenomena alleged 
 to result from the moon's rays are dependent 
 upon the mere intensity of lunar light , or are 
 to be considered as the effect of some specific 
 influence in the nature of the light itself? 
 Let me consider the first question. It is an 
 admitted fact that the light of the full moon 
 
 passing that of the planet Jupiter, and then as quickly 
 disappeared ! This phenomenon gave origin to the poem 
 referred to. 
 
 * " Travels in Turkey." 
 
1 82 On the Sanatory and 
 
 is at least 300,000 times more feeble than that 
 of the sun. According to Humboldt, the 
 mean distance of the earth from the sun is 
 12,032 times greater than the earth's dia- 
 meter, therefore 20,682,000 German or 
 82,728,000 English geographical miles. The 
 mean distance of the moon from the earth is 
 51,800 German or 207,200 English geogra- 
 phical miles.* 
 
 It is said that the solar light reflected from 
 the surface of the moon is in every zone 
 fainter than the solar light reflected in the 
 daytime from a white cloud. f 
 
 When estimating the intensity of lunar 
 light, Sir John Herschel affirms, that in the 
 
 * Cosmos, 
 f Sir J. Herschel says that it appears to be placed 
 beyond a doubt that the moon acts directly as a magnet 
 on the earth's magnetism, producing periodical fluctuations 
 in the latter of extremely small amount. 
 
Physiological Influence of Light. 183 
 
 southern hemisphere the moon is 27,408 
 times brighter than a Centauri, which is third 
 in brilliancy of all the stars. In our own cli- 
 mate the light of the moon is said to be 3000 
 times greater than that of the planet Venus. 
 Planetary light requires fourteen minutes to 
 cross the earth's orbit. According to Bradley, 
 the light of the sun takes eight minutes to 
 reach the earth. Reckoning the mean dis- 
 tance of the sun to be 94,879,956 miles from 
 the earth, it follows that light traverses 
 the air with a velocity of about 200,000 
 miles per second.* Robins states that a 
 
 * One hundred and eighty thousand miles per second 
 according to Herschel's calculation, that is 901,000 times 
 faster than sound, which travels at the rate of 1090 feet per 
 second, or nearly thirteen miles in a minute. Were the sun 
 and the earth connected by an iron bar, 1074 days, or 
 nearly three years, must elapse before a force applied at the 
 sun could reach the earth. With a bar of tin, nearly seven 
 years would be necessary. A writer in the " Quarterly Re- 
 
184 On the Sanatory and 
 
 twenty-four-pounder with a common charge 
 of powder discharges its ball with an initial 
 velocity equal to 1600 feet per second. If 
 such a ball were to continue its velocity 
 undiminished, it would require about ten 
 years to traverse a span, which the light of 
 the heavenly bodies pervades in eight 
 minutes ! 
 
 Humboldt, when speaking of this subject, 
 remarks : — <c When taking lunar distances 
 from the sun for determinations of geogra- 
 
 view" has placed this remarkable property of matter in a 
 popular and paradoxical aspect, by imagining Titan and 
 Saturn placed in opposite points of the orbit of the planet 
 which bears the name of the latter, and their ancient com- 
 bats being resumed with weapons of earthly fabric, the deadly 
 blow dealt by the former would not slay its victim till 
 after the lapse of fifty-two years ; and if, one year before 
 this event, Saturn should aim a mortal thrust at his 
 antagonist, it could not prove fatal till fifty-one years after 
 his own death! 
 
Physiological Influence of Light, 185 
 
 phical longitude, it is not unfrequently 
 found difficult to distinguish the moon's 
 disk amongst the more intensely illuminated 
 cumuli. On mountains between 13,000 and 
 17,000 feet high, where in the clearer moun- 
 tain air only light, feathery, cirrous clouds 
 are to be seen, I found it much easier to 
 distinguish the moon's disk ; both being 
 cirrous, from its slighter texture, reflects 
 less of the sun's light, and the moon loses 
 less in passing through the thin atmospheric 
 strata." The ratio of the intensity of the 
 sun's light to that of the full moon deserves 
 further investigation, as Bouguer's generally 
 received determination, 3 00 ' 000} differs so 
 strikingly from the indeed more improbable 
 one of Wollaston, 800 ' 000 . Wollaston's 
 comparison of the light of sun and moon, 
 made in 1799, was based on the shadows 
 
1 86 On the Sanatory and 
 
 cast by wax-light, while in the experiments 
 with Sirius, in 1826-27, images reflected 
 from a glass globe were employed. The 
 earlier assigned ratios of the intensity of 
 solar light as compared to that of the moon 
 differ very much from the results here 
 given. Michel and Euler, proceeding from 
 theoretical grounds, have respectively con- 
 cluded 450,000 and 374,000 to 1. Bou- 
 guer, from measurements of the shadows of 
 wax-lights, had even made it only 300,000 
 to 1. 
 
 I think, after duly weighing the above 
 facts, we must dismiss from the mind the 
 impression that the intensity of the light of 
 the moon, as compared to that of the sun, 
 has any relation to the supposed morbid 
 effect of lunar light. 
 
 I proceed, in the next place, to the con- 
 
Physiological Influence of Light. 187 
 
 sideration of the questions, whether the 
 alleged morbid effect of lunar rays is attri- 
 butable to something specific in the com- 
 position of the light itself ; and secondly, 
 whether the supposed abnormal influence of 
 the moon is not altogether owing to certain 
 barometrical variations and meteorological 
 phenomena consequent upon the phases 
 or position of the planet. Is there 
 anything specific in the composition of 
 lunar light ? 
 
 According to numerous observations 
 which Arago made with his polariscope, 
 the moon's rays contain 'polarized light 
 which carbonizes , and is therefore antago- 
 nistic to the sun's rays, which oxygen- 
 ate. The polarization of light was not dis- 
 covered until five years before the death of 
 Huyghens, viz., in 1690. It has, however, 
 
i88 On the Sanatory and 
 
 been stated that the phenomenon was recog- 
 nised in 1665, by Grimaldi and Hooke. 
 
 When a polarized ray is passed through 
 a thin slice of transparent substance, its 
 effect is said to be most remarkable. " Its 
 whole molecular constitution/' says Mr. 
 Hunt, cc appears revealed, as if by the touch 
 of a magic wand. The surfaces of many 
 substances, such as thin films of sulphate of 
 lime or mica, become painted with the most 
 beautiful colours. By turning the plate of 
 the polariscope round, these can be made to 
 dissolve or reappear in an exceedingly sin- 
 gular manner. Rings of the most charming 
 colours are seen in some substances, and 
 these are marked with a figure resembling a 
 Maltese cross in black and white. 
 
 Polarized light has been used by chemists 
 for the purposes of making subtle analyses of 
 
Physiological Influence of Light. 189 
 
 certain articles of food. M. Biot has applied 
 the rays of polarized light to sugar with the 
 view of ascertaining the existence of adulte- 
 rations. It is easy by means of the polari- 
 scope to distinguish between sugar made 
 from beet-root and that manufactured from 
 the sugar-cane.* 
 
 What is polarized light? Sir David 
 Brewster thus lucidly explains the pheno- 
 menon : When the ray of light falls on a 
 transparent body, so as to be reflected from 
 it, it is modified or affected in such a manner 
 by this reflection, that upon meeting a second 
 transparent body, it will either be reflected 
 or not, according to the side which it pre- 
 sents to it. It will be reflected if it fall 
 upon that body on either of the opposite 
 sides, but will not be reflected if it fall upon 
 
 * Hunt on Light. 
 
190 On the Sanatory and 
 
 either of the other two, at right angles to 
 the former. Thus, suppose the ray, after 
 being modified by the first transparent re- 
 flector, presents itself to the second, so as to 
 be reflected, and call the side of the ray, on 
 which it meets the second reflector, on the 
 north side ; if the second reflector is turned 
 round, so that the east side of the ray meets 
 it, there will be no reflection, and in like 
 manner it will be reflected on the south and 
 not on the west sides respectively. The 
 same modification, whatever it may be, 
 prevents the ray from being doubly refracted, 
 by passing through Iceland crystal, which it 
 meets on two of its opposite sides, but per- 
 mits it to be doubly refracted by meeting 
 the crystal on the two other sides. And 
 this modification, with respect to double 
 refraction, may be impressed upon the ray 
 
Physiological Influence of Light, 191 
 
 by a first double refraction, as well as by- 
 reflection from a transparent body. But 
 where the modification is produced by reflec- 
 tion, it is most complete at one particular 
 angle of incidence, which varies in different 
 transparent substances. 
 
 Now, the existence of this phenomenon 
 is certain ; it is a fact that a change takes 
 place in the ray by the operation of the 
 first transparent body ; it is a fact that this 
 change has some kind of reference to the 
 four sides of the ray, and affects those sides 
 at right angles to each other differently. 
 The observers of these appearances have 
 explained them, by supposing that each 
 particle of light has its adjacent sides en- 
 dowed with opposite properties, and that 
 the first reflecting, or double refracting 
 body, turns or arranges all the particles of 
 
192 On the Sanatory and 
 
 light in a ray, in such a manner that their 
 similar sides are presented in the same di- 
 rection to the second body. Now this 
 arranging or turning of the particles, or 
 this change operated by the first body upon 
 the ray, whatever it may be, is termed, 
 from analogy to the phenomena of mag- 
 netism — polarization.* 
 
 Having cursorily referred to two modes 
 of explaining the morbid phenomena of 
 moonlight, I have yet to consider the most 
 rational and philosophic theory of lunar 
 influence propounded — viz., the effect of 
 the moon's position upon the wind, temper a- 
 ture> and rain, three meteorological con- 
 ditions universally admitted to play an 
 important part in the origin, spread, and 
 modification of disease. It has been a 
 
 *"On Optics," by Sir David Brewster. 
 
Physiological Influence of Light. 193 
 
 vexed question with natural philosophers, 
 whether the barometer is decidedly influenced 
 by the phases of the moon. The facts 
 illustrative of this point are too significant 
 to justify a doubt upon the question. 
 
 A remarkable correspondence between 
 the phases of the moon and certain states 
 of the barometer has been observed by 
 Luke Howard. This coincidence, he main- 
 tains, consists of a depression of the baro- 
 metrical line on the approach of the new 
 and full moon, and its elevation on that of 
 the quarters. In above thirty out of fifty 
 lunar weeks in one year, the barometer was 
 found to have changed its general direction 
 once in each week, in such a manner as to 
 be either rising or at its maximum for the 
 week preceding and following about the 
 time of each quarter, and to be either fall- 
 o 
 
194 On the Sanatory and 
 
 ing, or at its minimum, for the two weeks 
 about the new and full. It is remarkable 
 that the point of greatest depression during 
 the year — viz., 28*67, was about twelve 
 hours after the new moon on the 8th of 
 November, and that of the greatest and 
 extraordinary elevation of 30*89, on the 7th 
 of February, at the time of the last quarter. 
 The variation from this coincidence seemed 
 to be owing to an evident perturbation of 
 the atmosphere. These observations were 
 confirmed by observations made for ten 
 years in the Royal Society's apartments. 
 Mr. Howard supposes, therefore, that the 
 joint attractions of the sun and moon at the 
 new moon, and the attraction of the moon 
 predominating over the sun's weaker attrac- 
 tion at the full, tend to depress the barometer 
 by taking off the gravity of the atmosphere, 
 
Physiological Influence of Light. 195 
 
 as they produce a high tide in the waters by- 
 taking off from their gravity ; and again, 
 that the attraction of the moon being dimi- 
 nished by that of the sun at her quarters, 
 this diminution tends to make a high baro- 
 meter, together with a low tide, by per- 
 mitting each fluid to press with additional 
 gravity on the earth. It is demonstrated 
 a priori on the principles of the Newtonian 
 philosophy, that the air ought to have its 
 tides as well as the ocean, though in a degree 
 as much less perceptible as its gravity.* If 
 this observation were strictly true, and the 
 tides of the atmosphere were to those of the 
 sea as the specific gravity of air is to that of 
 water, the aerial tides must be extremely 
 small, for the weight of air is very trifling 
 compared to that of water. But it is known 
 
 * " Encyclopaedia Britannica." 
 O 2 
 
ig6 On the Sanatory and 
 
 that the height of the tides of the sea bears 
 some proportion to the extent of the sea, 
 uninterrupted by land, and to its depth. On 
 both these accounts we should expect that 
 the atmosphere would be more influenced 
 by the moon's attraction than the sea, for 
 it is vastly deeper and more extensive 
 than the sea, and entirely unconfined. 
 
 Signor Tolado found that a greater eleva- 
 tion of the barometer takes place at the 
 quarters than at the syzygies ; it is less 
 when the moon is in the northern signs than 
 when in the southern. The mean diurnal 
 height, which corresponds to the Tropic of 
 Cancer, is less by a quarter of a line than 
 that which corresponds to the Tropic of 
 Capricorn. It is one-sixth of a line less at 
 the moon's perigee than at her apogee, and 
 one-tenth of a line less at the syzygies than 
 
Physiological Influence of Light, 197 
 
 at the quarters ; and there are vacillations in 
 the mercury when the new or full moon 
 corresponds to the apogean or perigean 
 points. He found, also, that the perigee, 
 the new and full moon, and the northern 
 lunistice are favourable to bad weather ; 
 whilst the apogee, the quadratures, and the 
 southern lunistice are more favourable to 
 good weather. 
 
 Pere Cotte, from observations of thirty- 
 five years, found that the barometer had a 
 tendency to descend at every new and full 
 moon, and to ascend at the quarterly periods. 
 He likewise found that the perigee and 
 northern declination depressed the barometer, 
 whilst the apogee and southern declination 
 had the opposite effect.* Mr. L. Howard 
 
 * Orton, on " Epidemic Cholera," p. 222 ; and " Lec- 
 tures on Meteorology," by G. Luke Howard. 
 
On the Sanatory and 
 
 has satisfactorily established, that the moon's 
 position, operating by the common effects 
 of the attraction of gravitation, influences 
 alike the course of the variable winds, the 
 daily variations of the temperature, and the 
 rain of any year ; but not in every year 
 alike, there being a constant periodical varia- 
 tion of the variation itself.* 
 
 * M. Kraszewski, of Romano w (as quoted by Andrew 
 Steinmetz in his work on " Sunshine and Showers"), has 
 decided, from a long series of observations: — " i. That 
 63 times in 100 the weather changes to bad when the 
 moon crosses our equator. 2. When the moon's declina- 
 tion is north, bad weather occurs more frequently than 
 when it is south. 3. When the moon is in its perigee, and 
 at the equator, bad weather occurs 67 times in too ; when 
 in its apogee, but still at the equator, there is bad weather 
 63 times in 100 ; and 4. Generally the moon near the 
 equator determines bad weather in the same proportion." 
 
Physiological Influence of Light. 199 
 
 PART III. 
 
 ON THE ALLEGED INFLUENCE OF THE 
 MOON ON THE INSANE. 
 
 The recognised phrase, lunatic, is based on 
 the hypothesis that the moon exercises a 
 decided effect upon the insane, and modifies 
 various forms of morbid intellect which do 
 not amount to actual insanity : hence origi- 
 nated the well known legal term, fC lucid 
 interval."* It was supposed that during 
 
 * Lunatic, according to ancient legal dicta, is one whose 
 imagination is influenced by the moon and has lucid in- 
 ervals : " Lunaticus, qui gaudet lucidis interval/is." 
 
 Sir W. Blackstone defines a person who is non compos 
 mentis to be one " who has had understanding, but by 
 
200 On the Sanatory and 
 
 paroxysms of mental derangement, the pa- 
 tient was liable to periods of lucidity or 
 mental repose, caused by the various phases 
 of the moon. Acting on this assumption, 
 human life was often made contingent 
 upon a satisfactory solution of the ques- 
 tion, was or was there not a lucid interval 
 when a particular crime was committed? 
 The transmission also of property to a 
 vast amount often depended on the reply 
 to a similar interrogatory relating to a 
 period when a certain testamentary dispo- 
 sition was made. A lucid interval legally 
 implies a clear and distinct freedom of the 
 mind from all delusions ; in other words, 
 
 disease, grief, or other accident, has lost the use of his 
 reason ; but that a lunatic is indeed properly one who 
 hath lucid intervals, sometimes enjoying his senses, and 
 sometimes not, and that frequently depending upon the 
 change of the moon" — " Commentaries." 
 
Physiological Influence of Light. 20 1 
 
 such an intelligent repose and restoration of 
 the intellectual powers as to enable the 
 person mentally disordered to discriminate 
 accurately between right and wrong ; thus 
 constituting him morally and legally respon- 
 sible for his conduct, quoad any criminal act 
 of which he may have been guilty, or render- 
 ing him competent to exercise a sound 
 memory, judgment, and reflection relating 
 to any testamentary act he has, during a 
 questionable condition of mind, been called 
 upon to execute. 
 
 Into the judicial view of this important 
 and vexed question it would be foreign to 
 my purpose to enter.* I therefore propose 
 
 * The rule of law upon this subject is, that all acts 
 done during a lucid interval are to be considered done by 
 a person perfectly capable of contracting, managing, and 
 disposing of his affairs. This has most frequently been a 
 question in wills ; and the. Ecclesiastical Courts, which 
 
202 On the Sanatory and 
 
 confining my remarks to the main point at 
 issue,, viz., is it satisfactorily established that 
 
 first promulgated the rule, adopted it from the Roman 
 law, il Furiosi autem si per id tempus fecerint testamentum 
 quo furor eorum intermissus est,jure testatum esse videntur." 
 — (Justin. Inst. lib. it, tit. 12, s. 1). 
 
 A lucid interval consists not in a mere cessation of the 
 violent symptoms of a disorder ; neither is it a cooler 
 moment, an abatement of pain or violence, relaxation from 
 a higher state of torture, or the relief of a mind from ex- 
 cessive oppression. 
 
 But an interval is that in which the mind, having thrown 
 oft the disease, has recovered its general habit. The party 
 must be capable of forming a sound j udgment of what he 
 is doing ; and his state of mind should be such, that any 
 indifferent person would think him able to manage his own 
 affairs. 
 
 M. D'Aguesseau, when pleading before the Parliament 
 of Paris, observed — u That to constitute a lucid interval, 
 there must not be a superficial tranquillity or shadow of 
 repose ; but on the contrary, a profound tranquillity, a 
 real repose; there must be, not a mere ray of reason, which 
 only makes its absence more apparent when it is gone, not 
 a flash ot lightning, which pierces through the dai kness 
 only to render it more gloomy and dismal, not a glimmer- 
 
Physiological Influence of Light. 203 
 
 the moon has any perceptible effect upon 
 the insane ? 
 
 I should be giving but an imperfect 
 sketch of the literature of this subject if I 
 were not to refer to the fact that the poets, 
 as well as philosophers and medical writers 
 of ancient and modern times, have not failed 
 to countenance by the authority of their 
 genius the popular belief in the influence 
 of the moon not only on the bodily health, 
 
 ing which unites the night to the day ; but a perfect light, 
 a lively and continued lustre, a full and entire day, inter- 
 posed between the two separate nights, of the fury which 
 precedes and follows it ; and, to use another image, it is not 
 a deceitful and faithless stillness, which follows or forebodes 
 a storm, but a sure, steadfast tranquillity for a time, a real 
 calm, a perfect serenity ; in fine, without looking for so 
 many metaphors to represent our idea, it must not be a 
 mere diminution, a remission of the complaint, but a kind 
 of temporary cure, an intermission so clearly marked, as in 
 every respect to resemble the restoration of health." 
 
204 On the Sanatory and 
 
 but on the passions, and especially on the 
 mind when in a state of disorder. Most of 
 our great dramatic and epic poets have 
 embodied in their immortal creations this 
 idea. The works of Shakspeare, Spenser, 
 Beaumont and Fletcher, Ben Jonson, Mil- 
 ton, Byron, and Shelley are replete with 
 passages of exquisite beauty in relation to 
 this subject. Our own immortal bard, 
 whose marvellous apprehension and pro- 
 found knowledge of the mind, intuitive 
 insight into the subtle workings of the 
 human heart and passions, and intimate 
 acquaintance with nearly every branch 
 of knowledge, department of science, art, 
 and philosophy, placed him like a bright 
 and brilliant constellation on a giddy emi- 
 nence, far above the rest of mankind, 
 has pointedly alluded to the moral and 
 
Physiological Influence of Light, 205 
 
 mental influence of the moon on the heart 
 and intellect. In the "Twelfth Night/' 
 Viola apostrophizes Olivia as a 
 
 " Most radiant, exquisite, and unmatchable beauty." 
 
 " I heard you were saucy at my gates," replies Olivia, 
 " and allowed your approach, rather to wonder at you than 
 to hear you. If you be not mad, begone; if you have reason, 
 be brief ; 'tis not that time of the moon with me y to make 
 one in so skipping a dialogue" 
 
 Again, in the play of cc Antony and Cleo- 
 patra/' Enobarbus, after entering Caesar's 
 camp, thus appeals to the moon : — 
 
 li Be witness to me, thou blessed moon ! 
 When men revolted shall upon record 
 Bear hateful memory, poor Enobarbus did 
 Before thy face repent !" 
 
 After which, he adds, addressing the 
 moon, previously to expressing his deep 
 contrition for his revolt against Antony — 
 
2o6 On the Sanatory and 
 
 " O sovereign mistress of true melancholy y 
 The poisonous damp of night dispunge upon me ; 
 That life, a very rebel to my will, 
 May hang no longer on me." 
 
 In cc Othello/' after the death of Desde- 
 mona^ when Emilia enters the chamber to 
 announce the foul murder of Roderigo by 
 the hand of Cassio, the Moor, crushed to 
 the earth by an accumulation of horrible 
 misfortunes, exclaims in the agony of his 
 soul, and in the bitterness of wild despair — 
 
 (i It is the very error of the moon y 
 She comes more near the earth than she was wont, 
 And makes men mad." 
 
 In cc King Richard the Third/' the 
 Queen, after rushing whilst in a state of 
 profound distraction, into the presence of 
 the Duchess of York to announce the death 
 of the King, passionately exclaims — 
 
Physiological Influence of Light. 207 
 
 " Give me no help in lamentation, 
 I am not barren to bring forth laments ; 
 All springs reduce their currents to mine eyes, 
 That J, being govern 'd by the <zvafry moon. 
 May send forth plenteous tears to drown the world ! " 
 
 Milton frequently alludes, in kC Paradise 
 Lost," to the morbid effect of the moon. 
 He speaks of 
 
 Ci Demoniac frenzy, moping melancholy, 
 And moon-struck madness" 
 
 In Ben Jonson's cc Alchemist," Tribula- 
 tion says — 
 
 u But how long time, 
 Sir, must the saints expect ?" 
 
 To which Subtle responds — 
 
 " Let me see, 
 How's the moon now ? Eight, nine, ten days hence 
 She will be silver potate ; then three days 
 Before to citronize, — some fifteen days."* 
 
 Apart altogether from the astrological 
 
 * Act iii. scene 1. 
 
2o8 On the Sanatory and 
 
 ideas prevalent in former times as to the 
 specific influence of the moon on the in- 
 sane, it is not difficult to understand why 
 this notion should have found favour among 
 learned, scientific, and experienced men. 
 It must be admitted that there is much of 
 the phenomena of insanity yet mysterious 
 and inexplicable. I refer particularly to 
 the remarkable periodicity that in many 
 cases accompanies the progress of this 
 disease. It is commonly supposed to be 
 difficult physiologically and pathologi- 
 cally to explain why such distinct periods 
 of apparent recovery should take place 
 during paroxysms of acute insanity. Cases 
 occur in which a patient is outrageously in- 
 sane one day, and to ordinary observers 
 sane the next ; furiously mad one week, 
 calm and composed the next ; mischievously 
 
Physiological Influence of Light. 209 
 
 deranged in the mind for about a month or 
 six weeks, and then for an equal duration 
 in a sane state of intellect. Not only 
 are these lucid intervals or remissions often 
 noticed during the existence of the mental 
 malady but the character of the affection also 
 undergoes singular changes and modifications. 
 A patient recently under my care was sad 
 and depressed for one or two days, and 
 then for a similar period was in an exalted 
 and happy state of mental disorder. 
 
 Pinel knew a patient who became insane 
 regularly every year. This illness lasted 
 for three months, and terminated favou- 
 rably towards the middle of the summer. 
 Another patient was annually subject to 
 paroxysms of maniacal furor for a period of 
 fifteen days, but was in the perfect pos- 
 session of his reason for the remaining 
 p 
 
210 On the Sanatory and 
 
 eleven months and a half. In another 
 case this physician noticed the attack of 
 insanity to come on every third day, being 
 in this respect analogous to the periodicity 
 observed in tertian intermittent fevers. 
 
 In cases of acute melancholia, associated 
 with a suicidal feeling, the attacks often 
 come on periodically. For a week or ten 
 days the desire to commit suicide will pre- 
 vail, and then the insane craving for self- 
 destruction will suddenly vanish. A patient 
 may be strongly bent on suicide in the 
 morning and have no inclination to destroy 
 himself later in the day. 
 
 Drunken madness or dipsomania , as it is 
 termed, in some cases comes on periodically. 
 Bruhl-Cramer cites an instance in which vio- 
 lent paroxysms of intemperance occurred re- 
 gularly every four weeks at the new moon. 
 
Physiological Influence of Light. 211 
 
 Most, another authority, confirms this fact. 
 In Henke's Zeitschrift fur Staatsarznei- 
 kunde, a case is related of monthly periodical 
 attacks of drunkenness, each attack occu- 
 pying eight days. The patient was ill in 
 this irregular way for seven years. Friedreich 
 says this periodicity is peculiarly characteristic 
 of attacks of dipsomania. In some cases 
 the paroxysms come on with great regu- 
 larity once in two, three, and four weeks. 
 In other instances several months intervene 
 between the attacks. Occasionally the pa- 
 tient is known to have seizures of dipso- 
 mania regularly every second, third, and 
 fourth year. Guislain mentions the case of 
 a woman whose temperate lucid intervals 
 extended over a period of four years. At 
 the end of this time the drunken madness re- 
 turned, lasting some time with great violence. 
 p a 
 
212 On the Sanatory and 
 
 Esquirol, Pinel, Falret, Cerise, Brierre de 
 Boismont, Baillarger, Foville, Calmeil, and 
 other celebrated French authorities, cite simi- 
 lar illustrations of the remarkable periodicity 
 so often associated with mental disorders. 
 
 Without giving the details of cases that 
 have come under my own personal observa- 
 tion, I may in general terms state that I 
 have frequently observed the phenomenon 
 referred to among insane patients. In this 
 respect, insanity in no way differs from 
 the periodicity which is so characteristic of 
 many forms of general disease ; such as inter- 
 mittent fevers, gout, tic doloureux, cephalal- 
 gia, neuralgia, epilepsy, and other affections 
 in which the nervous system is implicated. 
 
 Is the periodicity alluded to as often 
 accompanying some types of insanity ex- 
 plicable apart from the hypothesis of lunar 
 
Physiological Influence of Light. 213 
 
 influences ? I think there can be but one 
 opinion on this subject. The remarkable 
 remissions that occur during attacks of men- 
 tal derangement depend upon a variety of 
 causes, such as the removal, by appro- 
 priate treatment, of temporary congestion 
 of the brain, and irregularity of the cerebral 
 circulation; or the lucid moments may be the 
 effect of paying strict attention to dietetic 
 regimen, condition of the digestive organs, 
 bowels, liver, skin, and kidneys, or be the 
 result of carefully isolating the patient for 
 a time from all mental worry and excitement. 
 Pinel is . of opinion that the periodicity 
 occasionally associated with insanity is more 
 dependent upon an undue indulgence of the 
 angry passions, intemperance in drinking, 
 inanition ; or mental agitation caused by 
 a remembrance of . the original exciting 
 
214 On the Sanatory and 
 
 cause of the malady, than by direct lunar 
 influences. From a general examination 
 Pinel made during the second year of the 
 republic, of the patients confined in the 
 Bicetre, he found only fifty-two who were 
 subject to paroxysms of insanity at irregular 
 periods, and only six whose attacks were 
 characterized by a regular intermission. 
 
 In considering this subject, it. is not my 
 intention to 'quote the somewhat fabulous 
 cases alleged to be illustrative of the moon's 
 influence on the mind, recorded by ancient 
 and modern writers on astrology. Before, 
 however, referring to the opinions of the 
 great Roman authority in medicine, I think 
 the following facts, when viewed in relation 
 to the subject under discussion, worthy of 
 notice : Aristotle records the case of an 
 innkeeper at Tarentum who, although able 
 
Physiological Influence of Light. 215 
 
 to attend to his business during the day, 
 became insane soon after the setting of 
 the sun ! Bouillon cites the case of a 
 woman who lost the use of her senses at 
 sunset, but who recovered them at day- 
 break ! Sauvage refers to a woman who 
 became maniacal whenever the sun was at its 
 zenith ! An ineffectual attempt was made 
 to cure her of the malady by various strata- 
 gems, such as keeping her in a dark room 
 and deceiving her as to the hour. 
 
 In the chapter treating of Insanity, en- 
 titled cc Be tribus insanice generibus" Celsus 
 makes no special allusion to the influence of 
 the moon on the insane. In the fourth 
 chapter of his first book, commencing cc De 
 suibus caput infirmurn est^ he says c Cui 
 caput infirmurn est y is, si bene concoxerit, 
 leniter perfricare id mane manibus suis debet ; 
 
2i6 On the Sanatory and 
 
 nunquam id, si fieri potest, veste velar e; ad 
 cut em tondere : utile que luna" He then 
 adds the following advice, by which it is 
 clear that he viewed with grave suspicion 
 the injury likely to arise from an injudicious 
 exposure to the influence of the moon, es- 
 pecially cc before her conjunction with the 
 sun." cc Utileque lunam vitare, maximeque 
 ante ipsurn luna solisque concur sum ; sed nus- 
 quam post cibum" 
 
 Do the words cc caput infirmum " mean 
 insanity in the right and generally received 
 acceptation of the term, or do they imply 
 a mere weakness of intellect so often ob- 
 served after attacks of ordinary fever, and 
 seen to follow other bodily diseases ? The 
 latter construction appears to be the one 
 most generally adopted. 
 
 The late Dr. Haslam considered it more 
 
Physiological Influence of Light, % 1 7 
 
 than probable that the origin of the idea of 
 the moon exercising an influence on the 
 insane may be thus traced and explained : 
 The phases of the moon, and particular 
 female indispositions, are alleged to cor- 
 respond. The terms used to designate 
 them, have reference to the time when 
 both are completed. Insanity and epilepsy 
 are often connected with these conditions, 
 and suffer an exacerbation at the time when 
 they occur or ought to take place. If, there- 
 fore, the ailment referred to in an insane 
 person should be coincident with the full of 
 the moon, and the mind should then be more 
 violently disturbed, the recurrence of the 
 same state may be naturally expected at the 
 next full moon. Such has been the preva- 
 lence of this opinion, that when patients were 
 brought in former times to Bethlehem Hos- 
 
 \ 
 
218 On the Sanatory and 
 
 pital, especially from the country, their friends 
 have generally stated them to be worse at 
 some particular change of the moon, and of 
 the necessity they were under, at those times, 
 of having recourse to severe coercion. Some 
 of these patients, after recovering, have stated 
 that the overseer or master of the work- 
 house himself has frequently been so much 
 under the dominion of this planet (keeping 
 steadily in mind the old maxim, cc venienti 
 occurrite morbo"), that, without waiting for 
 any display of increased turbulence on the 
 part of the lunatics, he has barbarously 
 bound, chained, flogged, and deprived them 
 of food, according as he discovered the 
 moon's age by the almanack! 
 
 To ascertain how far this opinion was 
 founded on fact, Dr. Haslam kept, during 
 more than two years, an exact register of 
 
Physiological Influence of Light. 219 
 
 the numerous cases under his care, but with- 
 out finding, in any instance, that the aberra- 
 tions of the human intellect were influenced 
 by the phases of the moon. 
 
 As insane persons, especially those in a 
 furious state, are but little disposed to sleep, 
 even under the most favourable circum- 
 stances, they will be still less so when 
 the moon shines brightly into their apart- 
 ments.* 
 
 Dr. J. B. Woodward, late superintendent 
 of the State Hospital, at Worcester, Massa- 
 chusetts, at the suggestion of one of the 
 most scientific men in New England, com- 
 menced a table of observations on the in- 
 fluence of this planet upon the paroxysms 
 and deaths of the insane, and, after much 
 
 * Haslam's ft Observations on Madness and Melan- 
 choly," pp. 214 — 217. London: 1809. 
 
izo On the Sanatory and 
 
 time devoted to the subject, says : — fC These 
 facts and coincidences we leave for the 
 present, with the single remark, that no 
 theory seems to be supported by them, 
 which has existed either among the ignorant 
 or wise men who have been believers in the 
 influence of the moon upon the insane." 
 
 The report from which the preceding 
 passage is quoted then adds : — 
 
 <c Many patients are certainly more exci- 
 table and restless in pleasant moonlight nights 
 than in dark and gloomy weather ; but this 
 would seem to be occasioned by the real or 
 imaginary sight of objects in or without 
 the building, such as men, trees, animals, 
 &c, or the motion, perhaps, of the passing 
 clouds. An opinion, however, that has 
 existed for so long a period, which has spread 
 so extensively, and which, in this country, 
 
Physiological Influence of Light. 221 
 
 is familiar as c household words/ deserves to 
 be carefully examined ; for it is important to 
 disprove error as well as to establish truth. 
 
 cc Weak and timid females are sometimes 
 alarmed and much agitated during the con- 
 tinuance of lightning and thunder ; but as 
 a general thing, we have not observed the 
 insane to be much disturbed on such occa- 
 sions." 
 
 In the preceding passages I have endea- 
 voured accurately to record the opinions of 
 various accredited medical authorities adverse 
 to the theory of the moon's influence upon the 
 insane. 
 
 Cf Ogni medaglio ha il suo reverso" says 
 the well-known Italian proverb. So it is 
 with the vexed question under consideration. 
 I therefore proceed to an analytical examina- 
 tion of the conclusions which men of great 
 
222 On the Sanatory and 
 
 experience, of undoubted eminence and 
 veracity have arrived at in favour of an 
 opposite hypothesis. 
 
 In the foremost rank among those who 
 advocate the lunar theory, the illustrious 
 Frenchman, Pinel, justly occupies a 
 proud, elevated, and conspicuous position. 
 The scientific world bows with profound 
 respect and reverence to every opinion to 
 which his masterly intellect gives expression. 
 This eminent physician thus addresses him- 
 self to the subject : cc It is curious to trace 
 the effects of sol-lunar influence upon the 
 return and progress of maniacal paroxysms. 
 They generally begin immediately after the 
 summer solstice, are continued with more 
 or less violence during the heat of summer, 
 and commonly terminate towards the de- 
 cline of autumn. This duration is limited 
 
Physiological Influence of Light. 223 
 
 within the space of three, four, or five months, 
 according to deficiency of individual sen- 
 sibility, and according as the season may 
 happen to be earlier, later, or unsettled as 
 to its temperature. Maniacs of all descrip- 
 tions are subject to a kind of effervescence 
 or tumultuous agitation upon the approach of 
 stormy or very warm weather. They then 
 walk with a firm but precipitate step ; they 
 declaim without order or connexion ; their 
 anger is roused by trivial or imaginary 
 causes, and they express their feelings by 
 clamorous and intemperate vociferation.* 
 We must not extend this law of solar 
 influence beyond its natural boundary, nor 
 
 * In the year 1807, Mr. Thornton, then one of the 
 apothecaries of Bethlehem Hospital, paid particular attention 
 to the influence of the morning light upon all the patients 
 that were at the time confined in the asylum. He came to the 
 conclusion that many of them became noisy as soon as the 
 
224 On the Sanatory and 
 
 conclude that the return of maniacal parox- 
 ysms is invariably dependent upon the at- 
 mosphere. I have seen cases in which the 
 paroxysms return upon the approach of 
 winter, i.e., when the cold weather of De- 
 cember and January set in ; and this re- 
 mission and exacerbation corresponded with 
 changes of the temperature of the atmo- 
 sphere from mildness to severe cold." 
 
 The preceding quotation from PinePs 
 treatise on insanity is entitled to profound 
 respect. His sphere of observation was 
 great, his experience large, his veracity 
 unimpeachable, and what he saw he truth- 
 fully recorded. I think, therefore, we are 
 
 day began to break, and that, with the exception of two 
 or three recent cases, they all became silent and quiet 
 after night. During the eclipse of the sun on the 16th 
 of June, 1806, there was a sudden and total silence in 
 all the cells of the hospital! 
 
Physiological Influence of Light. 225 
 
 bounds even in opposition to our own 
 judgment^ to bow with great deference to 
 the conclusion at which this distinguished 
 physician arrived with regard to the in- 
 fluence of the moon on the insane. 
 
 Daquin, another eminent physician, 
 directed his attention to this subject. 
 He occupied a high professional position 
 in France, and was universally respected 
 for the zeal with which he cultivated 
 science, and the faithful accuracy displayed 
 in recording the results of his experience. 
 He was a close observer of nature, a man 
 of truth, and of highly, cultivated under- 
 standing. 
 
 In 1 79 1 he published an able work on 
 insanity. In this he enters at length into 
 a discussion of this vexed question. With- 
 out quoting in detail the remarks of 
 
226 On the Sanatory and 
 
 Daquin, I shall content myself with gene- 
 ralizing the data brought forward in sup- 
 port of the opinion he has formed with 
 reference to the influence of the moon 
 upon the mind when in a state of aber- 
 ration. He says : — 
 
 cc It is a well-established fact that in- 
 sanity is a disease of the mind upon which 
 the moon exercises an unquestionable in- 
 fluence. The new moons and the last 
 quarters of the moon are the lunar phases 
 which influence the insane most frequently 
 and painfully. 
 
 " The first quarters and the full moons 
 are the phases which I have observed to 
 have the least influence in inducing relapses 
 of insanity ; the insane at these periods being 
 less insane and quieter, and they reasoned 
 almost as if they were not ill at all. 
 
Physiological Influence of Light. 227 
 
 cc Those who are still susceptible of being 
 cured, as well as those who have been 
 cured, are precisely those upon whom the 
 two most powerful lunar phases have had 
 the greatest influence during the whole 
 of their illness. 
 
 cc Those who are acutely maniacal are 
 much more susceptible to the influence of 
 the lunar phases than others. 
 
 cc I have also observed a difference be- 
 tween the influence exerted by this planet 
 on madness characterized by excessive joy, 
 and that by sorrow and melancholy. 
 
 " It is proved that this influence is much 
 more marked in parts of the countries 
 bordering on the sea than in those at 
 a distance from it."* 
 
 Amidst this conflict of testimony, what 
 
 * Daquin, " Philosophic de la Folie," 1st edition, 179 1. 
 Q_3 
 
228 On the Sanatory and 
 
 conclusions can legitimately be drawn ? Are 
 we to consider the theory of lunar in- 
 fluence as a myth and an idle fable, or as a 
 well-established fact based upon accurate 
 and scientific data ? It is impossible alto- 
 gether to ignore the evidence of such men 
 as Pinel, Daquin, Guislain, and others, and 
 yet the experience of modern psychological 
 physicians is to a great degree opposed to 
 the deductions of these eminent men.* Is 
 
 * Guislain has recorded the history of an insane patient 
 on whom the influence of the moon was observed. He 
 became maniacal every twenty-eight days. This dis- 
 tinguished physician says, u We have among our female 
 patients a maniac sixty years of age. Her attacks of 
 acute insanity are periodical ; the return of the disease 
 corresponding with the return of the full moon" — \Leqom 
 Orales sur les Phr tenopathies, Gand, 1852.] 
 
 In a work entitled, " De l'Electricite du Corps Humain," 
 by Mons. TAbbe Bertholon, the case of a lunatic is 
 recorded whose periodical accessions of acute mania oc- 
 curred invariably at the full of the moon. 
 
Physiological Influence of Light. 229 
 
 it not probable that there is some degree 
 of truth on both sides of the question ; in 
 other words, that the alleged changes ob- 
 served among the insane at certain phases 
 of the moon may .arise, not from the direct, 
 but the indirect influence of this planet ? 
 It is well known that certain important and 
 easily recognisable meteorological pheno- 
 mena result from the varied positions of 
 the moon ; that the rarity of the air, the 
 electric conditions of the atmosphere, its 
 degree of heat, dryness, moisture, and 
 amount of wind prevailing, are all, more 
 or less, modified by the state of the 
 moon. In the generality of bodily diseases 
 what obvious changes are observed to 
 accompany the meteorological conditions 
 referred to ? Surely those suffering from 
 diseases of the brain and nervous system 
 
230 On the Sanatory and 
 
 affecting the mind cannot, with any show 
 of reason, be considered as exempt from the 
 operation of agencies that are universally- 
 admitted to seriously affect patients afflicted 
 with other maladies ? That the insane do 
 appear to a degree unusually agitated at the 
 full of the moon, particularly if its bright 
 light is permitted uninterruptedly to enter 
 the room where they sleep, there cannot be 
 a doubt.* This phenomenon may, I think, 
 be accounted for apart altogether from the 
 hypothesis of there being anything specific 
 in the composition of the lunar ray. 
 
 In certain forms of insanity, particularly 
 those characterized by illusions of the 
 
 * An intelligent lady, who occupied for about five years 
 the position of matron in my establishment for insane 
 ladies, has remarked, that she invariably observed a great 
 agitation among the patients when the moon was at its 
 full. This must be accepted quantum <valeat. 
 
Physiological Influence of Light. 23 1 
 
 senses or hallucinations of the mind, how 
 materially affected the patients are by the 
 kind and degree of light admitted into their 
 chambers. If exposed to a great degree 
 of natural, or even artificial light, the hallu- 
 cinations often become painfully intensified. 
 Sleeplessness often thus arises, and dormant 
 morbid visual and aural conditions pre- 
 viously in a latent state, become actively de- 
 veloped. Patients afflicted with distressing 
 delusions often imagine that everything they 
 see hasassumed the form of aterrible spectral 
 image. The presence of light emanating 
 from the moon, when at its full greatly tends 
 in these cases to aggravate the lunatic's mental 
 sufferings. It is occasionally most desirable 
 to exclude light altogether from bedrooms 
 occupied by the insane, in order to tranquil- 
 lize them and cause sleep. In other instances 
 
232 On the Sanatory and 
 
 the patient's condition of mental excitement 
 becomes aggravated by being kept for a 
 length of time in darkness. It is therefore 
 often necessary, with the view of dissipating 
 a false creation which has seized hold of 
 his disordered imagination, to admit light 
 freely into the chamber. This has been 
 known immediately to compose the patient, 
 by convincing him of the morbid and illu- 
 sory character of his mental impression, and 
 inducing him to exclaim, — 
 
 " There is no such thing ! 
 Il: is [my disordered brain]* which informs 
 Thus to mine eyes."f 
 
 * I hope I shall not expose myself to critical censure 
 for substituting the words " disordered brain" for " bloody 
 business." 
 
 -j- Shakspeare has with exquisite poetic beauty and 
 wonderful psychological truth delineated, in the passage 
 from which the preceding lines are taken, the sudden 
 transition of the mind from apparent insanity (assuming 
 the form of an illusion of the senses) to that of health. 
 
Physiological Influence of Light. 233 
 
 If I were to confine the concluding re- 
 marks to the result of my own observations 
 on this subject, I fear I should be able to 
 add but little to what others have written 
 in relation to it. I freely admit that, placing 
 but little faith in what has been recorded or 
 said on the subject, I have not kept any 
 systematic register as to the effect of dif- 
 ferent phases of the moon on the insane. 
 
 It has been observed by Some officials 
 connected with lunatic asylums, that occa- 
 sionally, from causes unknown to them, 
 many of the patients have simultaneously 
 exhibited a state of unnatural agitation. 
 This condition of the inmates has occurred 
 several times during the year, and at 
 irregular intervals ; but the state of the 
 moon at the time was not made a matter of 
 observation. It is difficult to assign any 
 
234 On the Sanatory and 
 
 cause for the alleged phenomenon, and it 
 would not be entitled to a moment's con- 
 sideration if the commotion and excitement 
 that are said to take place were confined to a 
 few of the patients; but as many of the 
 insane inmates (several of them occupying 
 separate rooms) were noticed to be thus 
 affected, at the same day and hour, the fact 
 becomes one worthy of record.* 
 
 * There can be no doubt that bright red, and yellow 
 rays stimulate and in some cases irritate the brain and 
 mind. Deep blue is said to depress or exhaust the vital 
 force. Some animals are excited when brought in contact 
 with scarlet colour. This is observed at the bull-fights 
 that take place in different parts of Spain. Green, 'violet, 
 and in fact all the neutral tints, soothe the nervous system 
 and allay mental irritation. Those who have the care of 
 the insane, or medical treatment of patients suffering from 
 great brain irritability, should bear these facts in remem- 
 brance. 
 
Physiological Influence of Light. 235 
 
 PART IV. 
 
 HYGIENE OF LIGHT. 
 
 Having in the introductory part of this 
 work; referred in general terms to the 
 sanatory influence of light, I return to the 
 subject in order to point out more specifically 
 the deleterious effect of its absence on the 
 bodily health. I have previously alluded 
 to the important changes that take place in 
 the constitution of the blood in consequence 
 of the cutaneous vessels on the surface of 
 the body not being freely exposed to the 
 oxygenating and life-generating influence of 
 the sun. 
 
 It is a well-established fact that, as the 
 
235 On the Sanatory and 
 
 effect of isolation from the stimulus of light, 
 the fibrine, albumen, and red blood- cells 
 become diminished in quantity, and the 
 serum, or watery portion of the vital fluid, 
 augmented in volume, thus inducing a 
 disease known to physicians and patho- 
 logists by the name of leukemia, an affection 
 in which white instead of red blood-cells are 
 developed.* This exclusion from the sun 
 produces the sickly, flabby, pale, anasmic 
 condition of the face, or exsanguined ghost- 
 like forms so often seen among those not 
 freely exposed to air and light. The 
 absence of these essential elements of health 
 deteriorates by materially altering the phy- 
 sical composition of the blood, thus seriously 
 prostrating the vital strength, enfeebling 
 
 * Virchow's " Cellular Pathology/' i860. 
 
Physiological Influence of Light. 23 7 
 
 the nervous energy, and ultimately inducing 
 organic changes in the structure of the 
 heart, brain, and muscular tissue.* Do not 
 these facts suggest the great importance, 
 particularly in a northern climate like that 
 of England, where the bright beams of the 
 sun so seldom shine, of so constructing our 
 habitations, both with regard to the number 
 of windows and position of the buildings, as 
 
 * "Where light is not permitted to enter the physician 
 will have to go," is the translation of a well-known Italian 
 proverb. In the eloquent words of Sir David Brewster, 
 " Light is the very life-blood of nature, without which 
 everything material would fade and perish ; the fountain of 
 all our knowledge of the external universe ; and the his- 
 toriographer of the visible creation, recording and trans- 
 mitting to future ages all that is beautiful and sublime in 
 organic and inorganic nature, and stamping on perennial 
 tablets the hallowed scenes of domestic life, the ever-varying 
 phases of social intercourse and the more exciting scenes of 
 bloodshed and war, which Christians still struggle to 
 reconcile with the obligations of their faith." 
 
238 On the Sanatory and 
 
 to admit within their walls a sufficient 
 degree of air and light ; and are we not 
 bound to impress upon the legislature the 
 necessity of enacting some stringent pro- 
 tecting measures, with the view of pre- 
 venting low damp cellars and rooms being 
 crowded together, into which air and light 
 vainly struggle to penetrate, and where 
 so many thousands of the poorer classes 
 in our large towns are compelled to dwell, 
 to the utter sacrifice of every comfort 
 worth living for, and positive ruin to the 
 health of both body and mind ?* In several 
 
 * The following is an extract from a recently published 
 report of the health commissioners of the State of New 
 York : — " In no other city in the civilized world is there to 
 be found half a million of people so unhealthily housed, as a 
 class, as the tenant house population of New York. In less 
 than sixteen thousand houses, on lots that average scarcely 
 twenty- five by one hundred feet, there dwell nearly five 
 hundred thousand people; and in the cellars of those 
 
Physiological Influence of Light, 239 
 
 English manufacturing cities, until within 
 the last few years, the great proportion 
 
 houses nearly sixteen thousand more poor, whose poverty 
 and ignorance allow no election of better homes." 
 
 The Rev. Isaac Taylor, incumbent of St. Matthias, 
 Bethnal Green, thus describes in a printed circular the 
 terrible state of the poor of his parish. The statement 
 is copied from the Pall Mall Gazette of February 12. 
 ft The mortality among young children is something flight • 
 ful. I do not know anything more terrible than the state- 
 ments which one continually hears. It is a common thing 
 for a mother to say that she has buried six or eight, and 
 reared one or two. This mortality among the children is 
 chiefly owing to the deadly overcrowding, and to insuffi- 
 ciency of food and clothing. Last summer we found a 
 family of eight children living with their father and mother 
 in a room some ten feet square, and almost in a state of 
 starvation. All the children had the small-pox out upon 
 them ; they had no medical care or nursing ; the only 
 medicament that had been used was a little oil rubbed 
 over their faces ; this the father said he had heard was 
 good for the small-pox. The man was engaged meanwhile 
 in the delicate work of making white chenille, to be sold 
 in the fashionable West-end shops. Hardly a family in 
 the parish possesses more than a single room, in which all 
 the members live, work and sleep." 
 
240 On the Sanatory and 
 
 of the working classes lived either under- 
 ground, in courts, or in narrow streets, and 
 houses almost destitute of windows, ap- 
 parently constructed for the specific purpose 
 of admitting the minimum portion of air 
 and the smallest possible degree of light 
 consistent with the preservation of health 
 and the maintenance of life.* It was com- 
 puted not many years ago that in Liverpool 
 
 * Sir David Brewster, in his opening address delivered in 
 November of last year at the Royal Society of Edinburgh, has 
 suggested an easy and valuable remedy for these frightful 
 evils. His remarks afford a valuable illustration of the 
 facility with which the great truths of science may be 
 practically applied in promoting the comfort and health of 
 the human race : — " If, in a very narrow street or lane, we 
 look out of a window with the eye in the same plane as 
 the outer face of the wall in which the window is placed, 
 we shall see the whole of the sky by which the apartment 
 can be illuminated. I f we now withdraw the eye inwards, 
 we shall gradually lose sight of the sky till it wholly dis- 
 appears, which may take place when the eye is only 6 in. or 
 8 in. from its first position. In such a case the apartment 
 
Physiological Influence of Light, 241 
 
 between 30,000 and 40,000 people lived in 
 cellars. As a consequence of this state of 
 things, the health of the working classes 
 became seriously affected. Legislative 
 measures were adopted for the purpose of 
 declaring such habitations illegal, and those 
 living in them were ejected by the strong 
 arm of the law. In 1849, 4,7 00 cellars 
 were cleared of 20,000 inhabitants. 
 
 is illuminated only by the light reflected from the opposite 
 wall, or the sides of the stones which form the window ; 
 because, if the glass of the window is 6 in. or 8 in. within 
 the wall, as it generally is, not a ray of light can fall upon 
 it. If we now remove our window, and substitute another 
 in which all the panes of glass are roughly ground on the 
 outside, and flush with the outer wall, the light from the 
 whole of the visible sky, and from the remotest part of the 
 opposite wall, will be introduced into the apartment, re- 
 flected from the innumerable faces or facets which the 
 rough grinding of the glass has produced. The whole 
 window will appear as if the sky were beyond it, and from 
 every point of this luminous surface light will radiate into 
 all parts of the room." 
 
 R 
 
242 On the Sanatory and 
 
 Rightly recognising the life-giving and 
 health-sustaining influence of light, the 
 cc Towns Improvement Clauses Act of 
 Scotland " enacted that no cellars less than 
 seven feet high, without a window, and of 
 which more than two-thirds are below the 
 level of the street, should be inhabited. 
 Acting upon the authority of this statute, 
 the corporation of the city of Edinburgh 
 has considerably improved the physical con- 
 dition of the working classes of that town 
 by peremptorily closing 3,000 dreary, sun- 
 less dens, in which the poor people were in 
 the habit of residing. 
 
 How eloquently and truthfully has Sir 
 David Brewster illustrated this section of 
 my subject. He says : — cc If the light of 
 day contributes to the development of the 
 human form, and lends its aid to art and 
 
Physiological Influence of Light. 243 
 
 nature in the cure of disease, it becomes 
 a personal and national duty to construct 
 our dwelling-houses, schools, workshops, 
 factories, churches, villages, towns, and 
 cities upon such principles and in such 
 styles of architecture as will allow the 
 life-giving element to have the fullest and 
 the freest entrance, and to chase from every 
 crypt, cell, and corner the elements of 
 uncleanness and corruption which have a 
 vested interest in darkness. 
 
 cc Although I have not visited the prisons 
 and lazarettos of foreign countries, to de- 
 scribe the dungeons and caverns in which 
 the victims of despotism and crime are 
 perishing without light and air, yet we have 
 seen enough in our own country — in private 
 houses, in the most magnificent of our 
 castles, and in the most gorgeous of our 
 R % 
 
244 On the Sanatory and 
 
 palaces — to establish the fact that there is 
 hardly a house in town or country without 
 dark apartments which it is in the power of 
 science to illuminate. In most of the 
 principal cities of Europe, and in many of 
 the finest towns of Italy, where external 
 nature wears her brightest attire, there are 
 streets and lanes in which the houses on one 
 side are so near those on the other, that 
 hundreds of thousands of human beings 
 are neither supplied with light nor air, and 
 carry on their trades in almost total dark- 
 ness. Providence — more beneficent than 
 man— has provided the means of lighting 
 up to a certain extent the workman's home, 
 by the expanding power of the pupil of his 
 eye, and by an increasing sensibility of his 
 retina ; but the very exercise of such 
 powers is painful, and every attempt to see 
 
Physiological Influence of Light, 245 
 
 when seeing is an effort, or to read and 
 work with a straining eye and an erring 
 hand, is injurious to the organ of vision, 
 and sooner or later must impair its powers. 
 Thus, deprived of the light of day, thou- 
 sands are compelled to carry on their trades 
 principally by artificial light — by the con- 
 sumption of tallow, oil, or gas — thus in- 
 haling from morning till midnight the 
 offensive odours and polluted effluvia which 
 are more or less the products of artificial 
 illumination. 
 
 "It is in vain to expect that such evils, 
 shortening and rendering miserable the life 
 of man, can be removed by legislation or 
 arbitrary power. In various great cities 
 attempts are making to replace their densely 
 congregated streets and dwellings by struc- 
 tures at once ornamental and salutary ; and 
 
246 On the Sanatory and 
 
 Europe is now admiring that great renova- 
 tion in a neighbouring metropolis, by which 
 hundreds of streets and thousands of 
 dwellings, once the seat of poverty and 
 crime, are replaced by architectural com- 
 binations the most beautiful, and by hotels 
 and palaces which vie with the finest edifices 
 of Greek or of Roman art."* 
 
 Fourcault cites a striking illustration of 
 the sad effects of the absence of light on the 
 health of young children. On one occasion 
 his attention was attracted to the mutilated 
 condition of several large mulberry trees, 
 the branches of which, before their decay, 
 effectually shaded the schoolroom in which 
 a number of orphan girls affected with 
 chronic diseases were educated. On asking 
 
 * " An Address delivered at the Opening of the Session 
 for 1866-7, at the Royal Society, Edinburgh." 
 
Physiological Influence of Light. 247 
 
 the reason for the mutilation, he was in- 
 formed that the shade of the trees visibly- 
 increased the severity of the scorbutic affec- 
 tions that prevailed among the children, 
 and that a very favourable change had taken 
 place in the condition of the girls since their 
 exposure to the unimpeded light of the sun.* 
 Utterly regardless of the principles just 
 enunciated, how often do we see parents, 
 who cannot for a moment be considered in- 
 different as to the present and future health 
 of their offspring, adopting the most in- 
 genious means of effectually excluding light 
 from the bodies of young infants and 
 children ! No course can be more detri- 
 mental to their health than the one just 
 referred to, because the value of an im- 
 
 * a Causes Generates des Maladies Chroniques/' p. 42. 
 
248 On the Sanatory and 
 
 portant vital element is systematically ignored 
 at a period of life when it is of the highest 
 importance it should be brought to bear upon 
 the purification of the blood, and consequent 
 healthy development of organic structures. 
 
 Children, even at an early age, should 
 not be excluded, particularly during the 
 warm periods of the year, from the genial 
 and cheering influence of the sun. The 
 sanatory effect of light can be easily 
 made available even during the winter 
 months (in rooms properly ventilated and 
 heated) with little or no danger. Great 
 benefit to the health would accrue by giving 
 children what the ancients termed solaria, 
 or <c solar-air baths ;" that is, permitting 
 them to lie naked upon the bed or floon 
 free from the incumbrance of swaddling- 
 clothes, so that their bodies may be 
 
Physiological Influence of Light. 249 
 
 thoroughly brought under the influence, 
 for some period of the day, of good air and 
 bright sunlight. The children of savages, 
 as well as of negroes, who are often allowed, 
 as soon as they can walk alone to run about 
 in the open air (in puris naturalibus) freely 
 exposed to the influence of light, have 
 finely-developed muscular structures, and 
 generally enjoy robust health.* 
 
 * " Passing round St. Paul's Churchyard the other day, 
 our ear caught a low confused sound, which seemed to 
 issue from behind a grille under the gloomy portico of St. 
 Paul's School. Attracted by so unusual a sound, and 
 blinded for a moment by passing from the sunlight under 
 the portico, we at length made out that the sound was 
 that of boys' voices in play. After a little time, when our 
 eyes had become accustomed to the darkness, and permitted 
 us to penetrate the dreary recess, we perceived that some 
 score of boys were actually at play within its unhappy 
 shade. Such a profound sanatory error on the part of the 
 authorities of the school as to shut up. their youth in a 
 cage, without light or air, and there bid them play, struck 
 
250 On the Sanatory and 
 
 No amount of artificial, polarized, or 
 reflected light will compensate for the 
 want of the direct action of the sun. 
 
 Humboldt, in the account he has pub- 
 lished of his voyage to the equinoctial re- 
 gions, says, when speaking of the Chaymas, 
 
 us with some astonishment. Boys at their games are like 
 young birds singing on the bough; half their joy is a 
 result of the influence of the sunny air. We are told, 
 indeed, that only a very short time is spent in this gloomy 
 retreat ; but surely it is hard that the hour of recreation, 
 when academic art should give way to nature, should be 
 selected for this depressing process as at present carried 
 on. What would Dean Colet have said to it ? When 
 the St. Martin's national school, leading out of Endell- 
 street, was built some years ago, we noticed with plea- 
 sure that a playground was built at the top of the school, 
 where light and air were plentiful, conditions essential in 
 a playground where children use violent exercise ; but 
 this example we are sorry to see has no effect upon 
 the Mercers' Company. The necessity of light for 
 young children is not half appreciated. Many of the 
 afflictions of children, and nearly all the cadaverous looks 
 
Physiological Influence of Light. 251 
 
 cc both men and women (whose bodies are 
 constantly inured to the effect of light) are 
 very muscular, and possess fleshy and 
 rounded forms. It is needless to add that 
 I have not seen among these people a 
 single case of natural deformity. I can say 
 
 of those brought up in great cities, are ascribable to 
 this deficiency of light and air. When we see the glass- 
 rooms of the photographers in every street high up on 
 the topmost story, we grudge them their application to a 
 mere personal vanity. Why should not our nurseries be 
 constructed in the same manner ? If mothers knew the 
 value of light to the skin in childhood, especially to 
 children of a scrofulous tendency, we should have plenty 
 of these glass-house nurseries, where children may run 
 about in a proper temperature, free of much of that 
 clothing which at present seals up the skin — that great 
 supplementary lung — to sunlight and oxygen. Glass- 
 house nurseries lifted up to the topmost story would save 
 many a weakly child that now perishes for want of those 
 necessaries of infant life." 
 
 I copy the preceding sensible remarks, so strictly in 
 conformity with my own views, from the Pall Mall 
 Gazette. They are from the pen of Dr. Andrew Wynter. 
 
25 2 On the Sanatory and 
 
 the same of many thousands of Caribs, 
 Maysias, Mexicans, and Peruvian Indians, 
 whom I observed during five years. De- 
 formities and deviations from healthy phy- 
 sical development are exceedingly rare in 
 certain races of men, especially those which 
 have the skin strongly coloured, who 
 wander about naked under the brilliant 
 light of the tropical regions. These have 
 muscular fleshy bodies, rounded contours, 
 and present none of those deformities so 
 frequently observed among the inhabitants 
 of other climates." 
 
 Dr. Bryson, in his memorandum to the 
 Lords Commissioners of the Admiralty re- 
 lating to the health of seamen, has pointed 
 out the great difference between the ap- 
 pearance of sailors employed in the dark 
 bread-room and holds of ships, and those 
 
Physiological Influence of Light. 253 
 
 who are freely exposed to air and sunlight 
 on deck, or in open boats, at all hours of 
 the day : he therefore considers it of im- 
 portance to "ascertain whether exclusion 
 from the solar rays be not, to a greater 
 extent than is generally believed, one reason 
 why these men, who have in consequence 
 acquired a pale waxy look from confine- 
 ment below, are more susceptible to disease, 
 and less capable of sustaining its shocks, 
 than are those whose blood is enriched and 
 strengthened by the free exposure to light, 
 heat, and air which their different avoca- 
 tions ensure. The force of these remarks, 
 however, will be best understood by those 
 who have had opportunities of witnessing 
 the rapid change which takes place in the 
 human constitution by exposure for only 
 a short time to the direct rays of a tropical 
 
^54 O n the Sanatory and 
 
 sun. Why, in a state of perfect repose, 
 the blood should acquire a brighter tinge 
 and an increased force of circulation are 
 inquiries the value of which the observant 
 physiologist will not fail justly to appreciate; 
 neither will he fail, as often as opportunities 
 occur, to follow up these phenomena, should 
 they terminate in disease, or unhappily 
 produce death."* 
 
 The inestimable value of light as an 
 element in the preservation of health 
 and treatment of disease, should be fully 
 appreciated in the construction of all streets 
 and buildings, particularly those intended 
 as habitations for the poor, or public 
 hospitals for the treatment of disease. It 
 
 * u Manual of Scientific Inquiry," published by autho- 
 rity of the Lords Commissioners of the Admiralty, edited 
 by Sir John F. W. Herschel, Bart. London, 1849. 
 
Physiological Influence of Light, 255 
 
 is a well-ascertained fact that many mala- 
 dies are more susceptible of amelioration, if 
 not of cure, provided the light of the sun 
 is freely admitted into the rooms or wards 
 where invalids are domiciled.* 
 
 Apart altogether from the cheerfulness 
 and mental serenity (important auxiliaries in 
 the eradication of disease !) which the bright 
 rays of the sun invariably engender, light 
 has a thermic influence upon the mind and 
 
 * Some years ago, when visiting the great hospital of 
 St. John, at Brussels, I was much impressed with the 
 most judicious hygienic arrangements made in the con- 
 struction of that building for the health and comfort of 
 the invalids. On the roof of the hospital an elegant 
 garden is laid out with great taste, and planted with 
 shrubs, small trees, and a grass lawn, interspersed with 
 pretty and sweet-smelling flowers. It is, in fact, a Pare 
 de Monceau in miniature. In this quiet rural retreat, 
 patients, particularly the convalescents, are permitted at 
 certain hours of the day to promenade, indulging in the 
 luxury of good air and bright sunlight. 
 
256 On the Sanatory and 
 
 body when prostrated by serious ailments, 
 and certainly acts beneficially by chemically 
 purifying the blood of the patient, as well 
 as the atmosphere of the apartment he 
 occupies. 
 
 There are, of course, active conditions 
 of bodily and mental disease, such as small- 
 pox, inflammatory conditions of the skin 
 and brain, acute mania, ophthalmia, &c, 
 which require to be carefully excluded from 
 the stimulus of light. I have elsewhere 
 addressed myself to this subject. 
 
 Florence Nightingale has entered so fully 
 into this subject, that I offer no apology 
 for quoting in extenso her extremely judi- 
 cious remarks relative to the importance of 
 keeping prominently in view, in the archi- 
 tectural construction of public hospitals, the 
 sanatory value of light to the sick. She says : 
 
Physiological Influence of Light, 2 S7 
 
 c< Second only to fresh air, however, I 
 should be inclined to rank light in im- 
 portance for the sick. Direct sunlight, not 
 only daylight, is necessary for speedy reco- 
 very; except, perhaps, in certain ophthalmic 
 and a small number of other cases. In- 
 stances could be given, almost endless, 
 where, in dark wards or in wards with a 
 northern aspect, even when thoroughly 
 warmed, or in wards with borrowed light, 
 even when thoroughly ventilated, the sick 
 could not by any means be made speedily 
 to recover. 
 
 cc Among kindred effects of light I 
 may mention, from experience, as quite 
 perceptible in promoting recovery, the 
 being able to see out of a window, in- 
 stead of looking against a dead wall ; the 
 bright colours of flowers ; the being able 
 
258 On the Sanatory and 
 
 to read in bed by the light of a window 
 close to the bed-head. It is generally said 
 that the effect is upon the mind. Perhaps 
 so ; but it is no less so upon the body on 
 that account. 
 
 cc All hospital buildings in this climate 
 should be erected so that as great a surface 
 as possible should receive direct sunlight — 
 a rule which has been observed in several 
 of our best hospitals, but, I am sorry to say, 
 passed over in some of those most recently 
 constructed. Window-blinds can always 
 moderate the light of a light ward ; but the 
 gloom of a dark ward is irremediable. 
 
 cc The axis of a ward should be, as nearly 
 as possible, north and south ; the windows 
 on both sides, so that the sun shall shine 
 in (from the time he rises till the time 
 he sets) at one side or the other. There 
 
Physiological Influence of Light. 259 
 
 should be a window to at least every two 
 beds, as is the case now in our best hospi- 
 tals. Some foreign hospitals, in countries 
 where the light is far more intense than in 
 England, give one window to every bed. 
 The window-space should be one-third of 
 the wall-space. The windows should reach 
 from two or three feet of the floor to one 
 foot of the ceiling. The escape of heat 
 may be diminished by plate or double glass. 
 But while we can generate warmth, we can- 
 not generate daylight, or the purifying and 
 curative effect of the sun's rays."* 
 
 Many facts are on record, illustrative of 
 the decidedly beneficial effect of the free 
 admission of light into public buildings set 
 apart as receptacles for cases of disease. 
 
 * a Notes on Hospitals," by Florence Nightingale. 
 Third edition, pp. 19, 20. London: Longmans, 1863. ' 
 
 S 2 
 
26o On the Sanatory and 
 
 Sir James Wylie, of the Imperial Russian 
 Service, pointed out to an English physi- 
 cian one of the barracks at St. Petersburg, 
 in which three cases of disease occurred on 
 the dark or shaded side of the establish- 
 ment for one on the other, though the 
 apartments on both of these sides com- 
 municated freely with each other, and the 
 discipline, diet, and treatment were in every 
 respect the same.* 
 
 A very remarkable instance of recovery 
 from disease has been related by the late 
 Baron Dupuytren, the eminent French sur- 
 geon, and cited in a work on Light published 
 by the Society for Promoting Christian 
 Knowledge. A lady residing in Paris, had 
 suffered for many years from an enormous 
 
 * " On the Theory and Practice of Ventilation," by 
 R. B. Reid, M.D. 1855. 
 
Physiological Influence of Light. 261 
 
 complication of diseases, which had baffled 
 the skill of all her medical advisers, and 
 her state appeared almost hopeless. As a 
 last resource, the opinion of Dupuytren 
 was requested upon her case, and he, un- 
 able to offer any direct medical treatment, 
 essentially differing from all that had been 
 previously tried in vain, suggested that she 
 should be taken out of the dark room in 
 which she lived, and away from the dismal 
 street, to a brighter part of the city, and 
 that she should expose herself as much as 
 possible to the daylight. The result was 
 quickly manifest in her rapid improvement, 
 and this continued until her recovery was 
 complete. An equally singular instance 
 has been related by Southey, in the case 
 of his own parent.* 
 
 * " In chlorosis, scrofula, phthisis, and, in general, every 
 
262 On the Sanatory and 
 
 tc In the years of cholera, when this 
 frightful disease nearly decimated the popu- 
 lation of some of the principal cities in the 
 world, it was invariably found that the 
 deaths were more numerous in narrow 
 streets and northern exposures, where the 
 salutary beams of light and actinism had 
 
 disease characterized by deficiency of vital power, light 
 should not be debarred to the patient. In convalescence 
 from almost all diseases it acts, unless too intense or too 
 long continued, as a most healthful stimulant, both to 
 the nervous and physical systems. The evil effects of 
 keeping such invalids in obscurity are frequently very de- 
 cidedly shown, and cannot be too carefully guarded against 
 by the physician. The delirium and weakness, which are 
 by no means seldom met with in convalescents kept in 
 darkness, disappear like magic when the rays of the sun 
 are allowed to enter the chamber. I think I have no- 
 ticed that wounds heal with greater rapidity when the 
 light is allowed to reach them than when they are kept 
 continually covered." (Dr. Hammond's "Treatise on 
 Hygiene.") 
 
Physiological Influence of Light. 263 
 
 seldom shed their beneficial influence. This 
 resistless epidemic found an easy prey among 
 a people whose physical organization had 
 not been matured under those benign in- 
 fluences of solar radiation which shed health 
 and happiness over our feftle plains, our 
 open valleys, and those mountain sides 
 and elevated plateaus where man breathes 
 in the brighter regions of the atmosphere."* 
 I have spoken previously of the inesti- 
 mable benefits which accompany a liberal 
 exposure of the body to the action of the 
 solar beam. I cannot pass unnoticed the 
 positive mischief that often arises from a 
 prolonged action of intense light on the 
 visual organs, as well as the injury often 
 caused by a sudden transition from a 
 
 * Sir D. Brewster. 
 
264 On the Sanatory and 
 
 moderate to a great or glaring degree of 
 the sun's influence.* 
 
 Soldiers are said often to suffer in their 
 eyes from the reflection of the rays of the 
 sun from white sand or snow. Levy records 
 that in 1819 trre Swiss troops in garrison at 
 Lyons had many of their number affected 
 
 * A sudden transition from perfect darkness (particularly 
 if of considerable duration) to an intense degree of light 
 produces a most painful and dazzling sensation in the 
 retina, accompanied by a feeling of acute pain in the eye- 
 balls, as well as of the head. These symptoms are often 
 associated with temporary blindness. The tyrant Dionysius, 
 being aware of these facts, inflicted on some of his unhappy 
 prisoners the severe punishment of compelling them to pass 
 rapidly from great darkness to the full blaze of the sun in 
 recently white- washed rooms ! 
 
 An officer of high rank in the army of Charles I. went 
 to Madrid, with the view of executing an important mission 
 for the king, but failing in his generous attempt to do his 
 Majesty a signal service, he was arrested by the Spanish 
 Government, and ordered to be incarcerated in a dark and 
 dismal dungeon, into which light never entered except 
 when a small hole at the top of the cell was opened 
 
Physiological Influence of Light. 265 
 
 with hemeralopia, accompanied with ner- 
 vous symptoms, such as nausea and vomit- 
 ing, caused, it is supposed, by drilling under 
 a hot sun.* 
 
 This disorder of the vision is said to 
 arise from two very different causes : 1st, 
 an exposure to a stronger light than the eye 
 has been accustomed to ; 2ndly, a deficiency 
 of the black pigment which lines the choroid 
 membrane. This affection of the eye is 
 commonly observed among those who live 
 
 by the jailer for the purpose of giving the prisoner 
 food. This unfortunate Royalist was confined in the 
 dungeon for several months : he was then set at liberty. 
 Such, however, was the effect of the darkness upon his 
 nervous system, eyes, and optic nerve, that he was 
 compelled to live for some time afterwards in a dark 
 room, in order gradually to accustom himself to the 
 stimulus of light. 
 
 * A form of intermittent blindness, characterized by 
 the patient being able to see only in broad daylight, and 
 becoming totally blind at sunset. 
 
266 On the Sanatory and 
 
 in dark caverns, mines, dungeons, or prisons. 
 It is frequently seen among the peasants of 
 Italy, who are employed in agricultural pur- 
 suits. This is attributed to the peculiar 
 brightness of the Italian sky, remark- 
 able clearness of the atmosphere, and re- 
 laxingly warm condition of its tempera- 
 ture. The peasants of Italy are thus ex- 
 posed to the joint operation of almost every 
 cause that can produce habitual debility of 
 the iris and irritability of the retina. This 
 complaint is most frequent on return of 
 spring, or at the vernal equinox. 
 
 Ramazzini says that such is the degree of 
 dimness of vision which this exposure to 
 intense light induces, that the peasants lose 
 their way in the fields in the glare of noon, 
 but that on the approach of night they are 
 again able to see distinctly. In the treat- 
 
Physiological Influence of Light. 267 
 
 ment of these cases it is found necessary to 
 keep the patients for some weeks in the 
 shade, or in comparative darkness, until the 
 eyes recover their healthy tone. This disease 
 of the eye is said to be endemic in some 
 parts of France, particularly in the neigh- 
 bourhood of Roche Guion, on the banks of 
 the Seine. So generally does it prevail 
 that we are told upon good authority, that 
 it affects one in twenty of the inhabitants in 
 one village, and in another, one in ten every 
 year. It shows itself in the spring, and 
 continues for three months, returning in a 
 slighter degree in the autumn. The soil of 
 this part of France consists of dazzling 
 chalk, and it is thought that the intensity of 
 the first reflected light after the dreariness of 
 the winter in all probability is the cause of 
 the malady. 
 
268 On the Sanatory and 
 
 This is a common affection in Russia 
 during the summer months, when the eyes 
 are exposed almost without intermission to 
 the constant action of light, as the sun then 
 dips but little below the horizon, and there 
 is scarcely any interval of darkness. The 
 peasants who protract their hard labour in 
 the fields from a very early to a very late 
 hour, and at the same time exhaust and 
 weaken themselves by their daily fatigue, 
 are subject to this malady. Mr. Guthrie 
 has published an account of a detachment 
 of Russian soldiers, in which this disorder 
 suddenly manifested itself. They were 
 ordered to attack a Swedish post at the 
 moment the affection of the eyes developed 
 itself, and had nearly destroyed one another 
 by mistake, owing to their visual powers 
 being impaired. These soldiers had been 
 
Physiological Influence of Light. 269 
 
 harassed by long marches, and exposed 
 night and day to the piercing glare of 
 an uninterrupted range of snowy moun- 
 tains.* 
 
 cc The only persons I have myself seen 
 affected with hemeralopia have been those 
 just returned from sea voyages — most com- 
 monly from the East or West Indies — and 
 who have consequently been exposed to a 
 strong glare of sunlight. The affection is, 
 I believe, also met with among the inhabi- 
 tants of the inland parts of India, who 
 attribute it, just as our own sailors do, 
 to sleeping when exposed to the moon- 
 beams. 
 
 * « Mem. de la Societe Royale de Med., 1786." " Me- 
 moirs of the Medical Society of London," by Mr. Guthrie. 
 " The Study of Medicine," by John Mason Good, M.D., 
 F.R.S. 
 
270 On the Sanatory and 
 
 cc The real cause of hemeralopia appears 
 to be exhaustion of the nervous suscepti- 
 bility of the retina from over-excitement by 
 the sun's rays, whereby the part is rendered 
 incapable of appreciating the milder rays of 
 twilight or moonlight. 
 
 cc But this exposure to strong light is not 
 always the cause of the affection ; for I have 
 met with it among those who had never 
 quitted the temperate parts of the globe. 
 In most of the latter cases, however, the 
 complaint has shown itself after voyages 
 which had subjected the patients to exhaust- 
 ing labour, and exposure to severe weather, 
 when deprived of their proper supply of 
 fresh provisions and vegetables. 
 
 cc I have commonly found that a few 
 weeks' residence on shore, with a whole- 
 some mixed diet and the use of quinine, 
 
Physiological Influence of Light. 271 
 
 has restored their vision to a healthy 
 state."* 
 
 This disorder of the vision is generally 
 associated with a scorbutic condition of the 
 system. It prevailed to a considerable 
 extent among the French and English 
 soldiers during the Crimean campaign. It 
 no doubt arose from their long-continued 
 exposure to an intense glare of light, 
 which their eyes had not been accustomed 
 to. An eminent American ophthalmic prac- 
 titioner, says, that a surgeon attached to the 
 garrison of Strasbourg, in France, has pro- 
 posed what he claims to be a speedy and effec- 
 tual mode of curing this malady, f He con- 
 
 * " A Guide to the Practical Study of Diseases of the 
 Eye," by James Dixon, F.R.C.S. England, Surgeon to 
 the Royal London Ophthalmic Hospital, Moorfields 
 London, 1866. 
 
 t Dr. Henry W. Williams. 
 
272 On the Sanatory and 
 
 fines his patients in an entirely dark room for 
 a considerable number of hours, not allowing 
 light to enter even for an instant. The eyes 
 thus being left in complete repose, recover 
 their normal tone. Relapses, he asserts, 
 are quite rare, provided the seclusion has 
 been of sufficient duration. Soldiers suf- 
 fering from this ailment are advised to be 
 removed into the interior of the country 
 from seaboard stations, particularly if ex- 
 posed there to the glare from white sand. 
 
 Snow and ice blindness is a common affec- 
 tion among those who reside for a considerable 
 time in the Alpine or Arctic regions.* 
 
 Sheep are known to temporarily lose their 
 sight if permitted to wander over mountains 
 
 * Dr. Hammond knew a child who was rendered per- 
 manently blind by looking intently at a bright object 
 while she was having her photograph taken. 
 
Physiological Influence of Light. 273 
 
 covered with snow ; but it returns a short 
 time after the snow and ice are melted. 
 
 The Greek soldiers, as related by 
 Xenophon, suffered severely in their eyes 
 from the reflection of the intense light 
 of the sun as they crossed the mountains of 
 Armenia. 
 
 It is impossible, whilst considering this 
 matter, to leave altogether unnoticed the 
 hygienic treatment of the eyes, when mor- 
 bidly affected by artificial light. 
 
 Persons exposed for an undue length of 
 time to the glare of brilliantly-lighted rooms 
 often suffer from chronic ophthalmia and 
 other affections of the organ of vision. 
 Literary men, from the same cause, are 
 liable to attacks of muscle volitantes and 
 amaurosis. Tailors, sempstresses, shoe- 
 makers, jewellers, watchmakers, and, in 
 
274 On the Sanatory and 
 
 fact, all who work by artificial light, are 
 subject to serious disorders of the eye. 
 Under these circumstances they often be- 
 come acutely sensitive to light.* Ac- 
 cording to a distinguished oculist, light is 
 injurious to the eyes in proportion as the 
 red and yellow rays prevail. These produce 
 cerebral and visual excitement, followed 
 by debility of the retina.f He suggests 
 
 * Mr, Ernest Hart says that when great sensitiveness to 
 light exists tinted (plain) spectacles are indicated. He ob- 
 serves— "The ordinary smoked glasses may be advan- 
 tageously substituted in such cases by those tinted of a 
 cobalt blue, which sufficiently exclude the irritating yellow 
 and red rays, without cutting off too much light, or pro- 
 ducing an unpleasant obscurity." — u On some of the Forms 
 of Disease of the Eye," by Ernest Hart, Ophthalmic Sur- 
 geon to St. Mary's Hospital, &c, p. 21. 1864. 
 
 f It has been established by direct, experiment that the 
 •violet ray of the solar spectrum is actually capable of ren- 
 dering a needle magnetic which has never been touched by 
 the loadstone or by an artificial magnet (Steinmetz). 
 
Physiological Influence of Light. 275 
 
 as a remedy for the injurious effects of 
 red and yellow colours that the light 
 should be surrounded by a shade, tinted 
 blue on its inner surface. The blue rays 
 reflected from it will produce a tolerably 
 pure and white light, by their union with 
 the reddish-yellow rays of the flame. To 
 effect the same purpose the lamp should be 
 enveloped by a glass chimney, tinged inside 
 with a very pale blue, or the light should be 
 made to pass through a fluid of the same 
 colour.* 
 
 In an early part of this work I have re- 
 ferred in general terms to the important 
 results obtained by Fraunhofer, Kirchhoff, 
 and Bunsen, with reference to the existence 
 of metallic lines ( cc Fraunhofer's lines ") 
 
 * " Practical Remarks on Near and Aged Sight," by 
 W. "White Cooper, Esq., F.R.C.S. England. 1847. 
 
 T 2 
 
2 "6 On the Sanatory and 
 
 observed in the sunlight by means of the 
 spectrum.* It has naturally been a matter 
 of discussion with medical men engaged in 
 sanatory investigations, whether the "vapour 
 of iron," found to exist in conjunction with 
 
 * u We can no longer consider light as merely consisting 
 of infinitesimal particles, or as infinitesimal waves ; we 
 may now conclude that it is metallic, — that sunshine con- 
 sists of a metallic i shower,' such as the Greek mythology 
 ascribed to Jupiter in one of his unions with mortals 
 (strange coincidence of fact with emblematic fiction !) ; 
 but, instead of a shower of gold, according to the figment, 
 the beneficent sunshine bathes us with elementary iron, 
 sodium, magnesium, calcium, chromium, nickel, barium, 
 copper, zinc, and hydrogen ! It is Jupiter, not Apollo, 
 that the ancient mythology should have identified with the 
 sun. In the idea of Zeus (or the l Burner') and the Zeuspater 
 (Father Jove) of the Latins, we might translate all the 
 amours of the Father of the Gods into physical facts con- 
 nected with the <arch-chemic sun,' as Dante calls him, 
 and recognise the idea that all animals are children of the 
 sun." — " Sunshine and Showers," by Andrew Steinmetz, 
 Esq., of the Middle Temple, Barrister- at- Law. London, 
 1867. 
 
Physiological Influence of Light, 277 
 
 other metals in the sun's atmosphere, has any 
 hygienic effect upon the physical organism 
 as the result of the therapeutic action of iron 
 on the blood distributed so freely through 
 the minute capillary vessels ramifying on 
 the surface of the body ? In the absence of 
 any hypothesis of a more satisfactory cha- 
 racter to account for the beneficial action of 
 light, it is reasonable to suppose that the 
 iron vapour detected in the sun's beam may 
 have a physiological as well as a mechanical 
 effect upon the composition of the blood 
 by throwing into the general circulation, 
 through the vessels of the skin, a most 
 important vital constituent.* 
 
 In the present state of our knowledge it 
 is impossible to dogmatise on this subject. 
 
 * There does not appear to be anything improbable in 
 this hypothesis ? when we consider that mercury may be made 
 
278 On the Influence of Light. 
 
 The matter in review must still be considered 
 sub judice, and purely speculative^ and until 
 further experiments are made it is wise to 
 hold in reserve any theory that may have 
 been formed in relation to it. 
 
 to affect the system by subjecting the patient to its influ- 
 ence in the form of a vapour-bath, the mercury of course 
 being absorbed principally by the skin, although a portion 
 may pass into the lungs. That persons handling the soluble 
 salts of lead are often poisoned in consequence of the 
 metal passing through the integuments is a generally ad- 
 mitted fact. 
 
 Dr. Th. Clemens, of Frankfort-on-the-Maine (Deutsche 
 Klinik, 1865-6, Schmidt's Jahrbucher, 1866), has "ob- 
 served the immunity from cholera of coppersmiths. Hence 
 he recommends as a cholera disinfectant a spirit of chlorate 
 of copper, and advises the same preparation to be used 
 both internally and externally upon the skin as an actual 
 preservative." — Half-yearly Abstract, 1866, p. 5. 
 
279 
 
 APPENDIX. 
 
 I. THE BLESSINGS OF LIGHT : MILTON S BLINDNESS. 
 
 II. SUGGESTIONS FOR THE REGULATION OF LIGHT 
 IN DARK ROOMS, ETC. 
 
 III. THEORIES OF LIGHT. 
 
 IV. EFFECT OF LIGHT ON THE SKIN. 
 V. THE SUN. 
 
 VI. NUTRITION OF PLANTS. 
 
 VII. VITALITY OF SEEDS. 
 
 VIII. THE MOON. 
 
 IX. ANIMALS INFLUENCED BY THE STATE OF THE 
 WEATHER. 
 
 X. ON THE DISTRIBUTION OF LIGHT BY ARTIFICIAL 
 MEANS. 
 
 XI. ADVANTAGES OF LIGHT IN THE TREATMENT OF 
 THE SICK. 
 
 XII. ON THE REGULATION OF THE QUANTITY OF 
 LIGHT ADMITTED INTO THE CHAMBERS OF 
 THE SICK. 
 
Appendix. 281 
 
 THE BLESSINGS OF LIGHT: MILTON'S 
 BLINDNESS. 
 
 (Vide Preface.) 
 
 In the subjoined lines Milton alludes with touching 
 pathos to his own sad deprivation of sight : — 
 
 " Thus with the year 
 Seasons return, but not to' me returns 
 Day, or the sweet approach of eve or morn, 
 Or sight of vernal bloom, or summer's rose, 
 Or flocks, or herds, or human face divine j 
 But cloud instead, and ever-during dark 
 Surrounds me, from the cheerful ways of men 
 Cut off, and for the book of knowledge fair 
 Presented with an universal blank 
 Of Nature's works, to me expunged and rased, 
 And knowledge at one entrance quite shut out." 
 
 I append to the preceding affecting wail of dis- 
 tress a copy of a posthumous poem (having reference 
 to his blindness) sold to have been written by 
 Milton. I have not been able to ascertain at what 
 period these lines were penned ; bat, assuming them 
 to be genuine, I should suppose they were written 
 long subsequently to the verses previously quoted. 
 They are deeply interesting, as showing the state of 
 
282 Appendix. 
 
 Milton's feelings with regard to his infirmity at 
 different epochs of his life : — 
 
 1. 
 
 " I am old and blind ! 
 Men point at me as smitten by God's frown ; 
 Afflicted and deserted of my mind — 
 Yet I am not cast down. 
 
 11. 
 
 " I am weak, yet strong ; 
 I murmur not that I no longer see — 
 Poor, old, and helpless, I the more belong, 
 Father Supreme ! to Thee. 
 
 hi. 
 
 " O merciful One ! 
 When men are farthest, then Thou art most near ; 
 When friends pass by, my weakness shun, 
 Thy chariot I hear. 
 
 iv. 
 
 " Thy glorious Face 
 Is bending towards me, and its holy light 
 Shines in upon my lonely dwelling-place, 
 And there is no more night. 
 
Appendix. 283 
 
 " On my bended knee 
 I recognise Thy purpose clearly shown : 
 My vision Thou hast dimmed, that I may see 
 Thyself — Thyself alone. 
 
 VI. 
 
 " I have naught to fear ; 
 This darkness is the shadow of Thy wing -, 
 Beneath it I am almost sacred — here 
 Can come no evil thing. 
 
 VII. 
 
 " O ! I seem to stand 
 Trembling where foot of mortal ne'er hath been, 
 Wrapped in the radiance of that sinless land, 
 Which eye hath never seen. 
 
 VIII. 
 
 " It is nothing now : 
 When heaven is op'ning on my sightless eyes, 
 Soft airs from Paradise refresh my brow, — 
 The earth in darkness lies. 
 
284 Appendix. 
 
 IX. 
 
 " Visions come and go ; 
 Shapes of resplendent beauty round me throng j 
 From angel lips I seem to hear the flow 
 Of soft and holy song. 
 
 x» 
 
 " In a purer clime 
 My being fills with rapture — waves of thought 
 Roll in upon my spirit — strains sublime 
 Break over me unsought. 
 
 XI. 
 
 " Give me now my lyre ! 
 I feel the stirrings of a gift divine ; 
 Within my bosom glows unearthly fire, 
 Lit by no skill of mine." 
 
appendix. 285 
 
 SUGGESTIONS FOR THE REGULATION OF 
 LIGHT IN DARK ROOMS. 
 
 (P- 70 
 
 " In all great towns, where neither houses nor 
 palaces can be insulated, there are almost in every 
 edifice dark and gloomy crypts thirsting for light ; 
 and in the city of London there are places of busi- 
 ness where the light of day never enters, and where 
 the precious light which the sky sends down be- 
 tween chimney-tops is allowed to fall useless on the 
 ground. On visiting a friend whose duty confined 
 him to his desk during the official part of the day, 
 we found him with bleared eyes struggling against 
 the feeble light which the opposite wall threw into 
 his window. We counselled him to extend a blind 
 of fine white muslin on the outside of his window, 
 and flush with the wall. The experiment was soon 
 made. The light of the sky above was caught by 
 the fibres of the linen, and thrown straight upon his 
 writing-table, as if it had been reflected from an 
 equal surface of ground glass. We may mention 
 another case equally illustrative of our process. A 
 party visiting the mausoleum of a Scottish nobleman 
 wished to see the gilded receptacles of the dead 
 which occupied its interior. There was only one 
 
286 Appendix. 
 
 small window through which the light entered, but 
 it did not fall upon the objects to be examined. 
 Upon stretching a muslin handkerchief from its four 
 corners, it threw such a quantity of light into the 
 crypt as to display fully its contents." 
 
 Sir D. Brewster. 
 
 THEORIES OF LIGHT. 
 
 I have referred to the two theories that have pre- 
 vailed in the scientific world regarding the nature 
 and propagation of light — viz., the corpuscular 
 theory of the immortal Newton, and the undulatory 
 theory of Huygens, afterwards revived and fully 
 elaborated by Dr. Young. Sir Isaac Newton sup- 
 posed that light was composed of particles of ex- 
 cessive minuteness, which were projected from the 
 luminous body with a velocity equal to 193,000 
 miles in a second. The undulatory theory was 
 based upon the hypothesis, that light was trans- 
 mitted from its source by vibrations or undulations 
 of an ethereal fluid of great elasticity in spherical 
 superficies in the form of waves, similar to the 
 transmission of sound. 
 
Appendix, 287 
 
 The principles of the undulatory theory are thus 
 stated by Sir J. Herschel : — ■ 
 
 1. That an excessively rare, subtle, and elastic 
 medium, or ether, fills all space, and pervades all 
 material bodies, occupying the intervals between 
 their molecules ; and either by passing freely among 
 them, or by its extreme rarity, offering no resistance 
 to the motion of the earth, the planets, or comets 
 in their orbits, appreciable by the most delicate 
 astronomical observations, and having inertia, but 
 not gravity. 
 
 2. That the molecules of the ether are susceptible 
 of being set in motion by the agitation of the par- 
 ticles of ponderable matter ; and that when any one 
 is thus set in motion it communicates a similar 
 motion to those adjacent to it, and thus the motion 
 is propagated farther and farther in all directions, 
 according to the same mechanical laws which regu- 
 late the propagation of undulations in other elastic, 
 media, as air, water, or solids, according to their 
 respective constitutions. 
 
 3. That in the interior of refracting media the 
 ether exists in a state of less elasticity, compared 
 with its density, than in vacuo {i.e., in space empty 
 of all other matter) 5 and that the more refractive 
 the medium, the less, relatively speaking, is the 
 elasticity of the ether in its interior. 
 
288 Appendix. 
 
 4. That vibrations communicated to the ether in 
 free space are propagated through refractive media 
 by means of the ether in their interior, but with 
 a velocity corresponding to its inferior degree of 
 elasticity. 
 
 5. That when regular vibratory motions of a 
 proper kind are propagated through the ether, and, 
 passing through our eyes, reach and agitate the 
 nerves of our retina, they produce in us the sensa- 
 tion of light in a manner bearing a more or less 
 close analog}' to that in which the vibrations of 
 the air affect our auditory nerves with that of 
 sound. 
 
 6. That as, in the doctrine of sound, the fre- 
 quency of the aerial pulses, or the number of 
 excursions to and fro, from the point of rest made 
 by each molecule of the air, determines the pitch, 
 or note ; so, in the theory of light, the frequency 
 of the pulses, or number of impulses made on our 
 nerves in a given time by the ethereal molecules 
 next in contact with them, determines the colour 
 of the light ; and that as the absolute extent of the 
 motion to and fro of the particles of air determines 
 the loudness of the sound, so the amplitude or extent 
 of the excursions of the ethereal molecules from 
 their points of rest determines the brightness or 
 intensity of the light. — Dictionary of Science, Lite- 
 
Appendix. 289 
 
 rature, and Art. By W. T. Brande, D.C.L., 
 F.R.S. L. & E. 
 
 EFFECT OF LIGHT ON THE SKIN. 
 (P. 20.) 
 
 " Amongst the carpenters I noticed one with a 
 remarkable staining of the skin, some portions of 
 his face and neck being intensely bronzed, while 
 other parts remained quite fair, giving the man a 
 very unsightly mottled appearance. In plain terms, 
 he was enormously freckled, the stained skin being 
 about the average colour of the faces of the artisan 
 and labouring classes in the north of China. His 
 disfigurement, consequently, arose from the refusal 
 of the whole of the exposed portions of his body 
 equally to take on the bronzing process. I made 
 him show me his skin where habitually protected 
 from the sun, and it was as fair as an European's." — 
 Peking and the Pekingese. By D. F. Rennie, M.D. 
 London. 1865. 
 
 U 
 
290 Appendix. 
 
 THE SUN. 
 (P. 68.) 
 
 " The sun 
 Had first his precept so to move, so shine, 
 As might affect the earth with cold and heat 
 Scarce tolerable, and from the north to call 
 Decrepit winter, from the south to bring 
 Solstitial summer's heat. To the blank moon 
 Her office they prescribed ; to the winds they set 
 Their corners, when with bluster to confound 
 Sea, air, and shore 5 the thunder when to roll 
 With terror through the dark aerial ball. . . . 
 Beast now with beast gave war, and fowl with fowl, 
 And fish with fish : to graze the herb all leaving, 
 Devoured each other, nor stood much in awe 
 Of man, but fled him, or with countenance grim 
 Glared on him passing." — Milton. 
 
 " The sun's rays are the ultimate source of almost 
 every motion which takes place on the surface of the 
 earth. By its heat are produced all winds, and those 
 disturbances in the electric equilibrium of the atmo- 
 sphere which give rise to the phenomena of light- 
 ning -, and probably, also, to those of terrestrial 
 magnetism and the aurora. By their vivifying 
 
appendix. 291 
 
 action vegetables are enabled to draw support from 
 inorganic matter, and become, in their turn, the 
 support of animals and. of man, and the sources of 
 those great deposits of dynamical efficiency which 
 are laid up for human use in our coal strata. By 
 them the waters of the sea are made to circulate in 
 vapour through the air, and irrigate the land, pro- 
 ducing springs and rivers. By them are produced 
 all disturbances of the chemical equilibrium of the 
 elements of nature, which, by a series of composi- 
 tions and decompositions, give rise to new products, 
 and originate a transfer of materials. Even the 
 slow degradation of the solid constituents of the 
 surface, in which its chief geological changes con- 
 sist, is almost entirely due, on the one hand, to the 
 abrasion of wind and rain, and the alternation of 
 heat and frost ; on the other, to the continual beat- 
 ing of the sea waves, agitated by winds, the results 
 of solar radiation. Tidal action (itself partly due 
 to the sun's agency) exercises here a comparatively 
 slight influence. The effect of oceanic currents 
 (mainly originating in that influence), though slight 
 in abrasion, is powerful in diffusing and transporting 
 the matter abraded 5 and when we consider the im- 
 mense transfer of matter so produced, the increase 
 of pressure over large spaces in the bed of the ocean, 
 and diminution over corresponding portions of the 
 V 2, 
 
292 appendix. 
 
 land, we are not at a loss to perceive how the elastic 
 power of subterranean fires, thus repressed on the 
 one hand, and relieved on the other, may break 
 forth in points when the resistance is barely adequate 
 to their retention, and thus bring the phenomena of 
 even volcanic activity under the general law of solar 
 influence. 
 
 " The great mystery, however, is to conceive how 
 so enormous a conflagration (if such it be) can be 
 kept up. Every discovery in chemical science here 
 leaves us completely at a loss, or rather, seems to 
 remove farther the prospect of probable explana- 
 tion. If conjecture might be hazarded, we should 
 look rather to the known possibility of an indefinite 
 generation of heat by friction, or to its excitement 
 by the electric discharge, than to any actual com- 
 bustion of ponderable fuel, whether solid or gaseous, 
 for the origin of the solar radiation." — Good Words. 
 
Appendix. 293 
 
 NUTRITION OF PLANTS. 
 
 (P- 79-) 
 
 " Since the sun-light is composed of many dif- 
 ferently coloured rays and different principles, it 
 becomes an interesting inquiry which of these is the 
 immediate agent in ministering to the nutrition of 
 plants. In 1843, by causing plants to effect the 
 decomposition of carbonic acid in the prismatic 
 spectrum, I found that the yellow is by far the 
 most effective, the relative powers of the various 
 colours being as follows: — 1, yellow 3 2, green; 
 3, orange; 4, red; 3, blue; 6, indigo; 7, violet." 
 — Draper. 
 
 VITALITY OF SEEDS. 
 
 (P. 79-) 
 
 It has been a question with botanists how to 
 account for the longevity or vitality of seeds : T 
 refer particularly to wheat, which has been found 
 in Egyptian sarcophagi, proved to be many thousand 
 years old. These seeds, when put into the ground, 
 have fully germinated, and been most produclive. 
 The persistent vitality of such seeds, according to 
 
294 Appendix. 
 
 the best botanical authorities, depends upon three 
 principal conditions, viz. : i, uniformity of tem- 
 perature ; 2, moderate dryness j and 3, the exclu- 
 sion of light. Seeds brought from India (says Dr. 
 Lindley) round by the Cape of Good Hope rarely 
 vegetate freely. This he says is owing to the 
 double exposure to the heat of the equator, and 
 the subsequent arrival of the seeds in cold lati- 
 tudes. Seeds brought overland from India, and 
 not exposed to such fluctuations of temperature, 
 retain their active vital principle. Seeds will travel 
 with safety for many months if buried in clay 
 rammed hard in boxes. Seeds of the mango are 
 thus brought alive from the West Indies, as well 
 as the principal part of the araucania pines which 
 have been transported from Chili to England. 
 
 THE MOON. 
 (P. 89.) 
 
 The moon appears to have called forth the fire 
 and sublimity of poetic genius in all ages and in 
 all climes. Some of the most beautiful and touch- 
 ing sonnets that adorn the English language are 
 addressed to the moon. I cannot forbear to quote 
 
Appendix. 295 
 
 an illustration from the pen of Charlotte Smith, 
 one of our most exquisite writers of sonnets, the 
 immortal Milton alone excepted : — 
 
 " Queen of the silver bow ! — by thy pale beam, 
 Alone and pensive, I delight to stray, 
 And watch thy shadow trembling in the stream, 
 Or mark the floating clouds that cross thy way ; 
 And while I gaze, thy mild and placid light 
 Sheds a soft calm upon my troubled breast : 
 And oft I think — fair planet of the night — 
 That in thy orb the wretched may have rest j 
 The sufferers of the earth, perhaps, may go — 
 Released by death — to thy benignant sphere j 
 And the sad children of despair and woe 
 Forget in thee their cup of sorrow here. 
 Oh, that I soon may reach thy world serene ! 
 Poor wearied pilgrim in this toiling scene !" 
 
 " In savage life, especially in high latitudes, the 
 moon is an ever-present power. When the Red 
 Indian speaks of moons as measures of time, he 
 speaks in the tone of affection and reverence for 
 the benign luminary that guides his steps through 
 the trackless forest. The Oriental bows to the sun, 
 but the Red Indian nurtures his grand and impas- 
 sive nature in the mild beams of the moon. In 
 hunting and trapping, the moon is his ever-faithful 
 
296 Appendix. 
 
 ally, and he would as soon think of doubting its use 
 as he would the use of his spear or his traps. 
 
 " But the use of the moon is not confined to light- 
 giving. As a mechanical power, the moon is of 
 much service. The sun is the grand source of 
 power on the face of the earth ; but still some little 
 work is left for the moon. To her chiefly is as- 
 signed the task of raising the tides of the ocean. 
 The tides are of incalculable benefit to man. In a 
 sanitary point of view, the moon may be regarded 
 as the great scavenger of our globe. Twice every 
 day she flushes, with sea-water in abundance, the 
 rivers on which our towns are situated, and keeps 
 them comparatively pure. Again, by her mechani- 
 cal power, she bears ships on the crest of the tidal 
 wave deep into the heart of the country, where the 
 centres of commerce are often found. Insignificant 
 streams are thus rendered navigable, and cities 
 brought into immediate connexion with the ocean — 
 the highway of commerce. By the convenience 
 afforded by the moon, London is at the same time 
 connected with the ocean, and in the heart of the 
 country, where it can be best protected from any 
 invasion. In an island of such limited extent as 
 Great Britain, the rivers must necessarily be small, 
 but the tidal wave compensates for the defect, and 
 gives us the advantages of river navigation. The 
 
Appendix. 297 
 
 mechanical power of the tide is made available by 
 means of the tide-mill. The rise and fall of the 
 tide can be utilized as well as the fall of the river. 
 This source of power has not been very generally 
 turned to account, though there is no mechanical 
 difficulty in applying it." — Good Words. 
 
 ANIMALS INFLUENCED BY THE STATE 
 OF THE WEATHER. 
 
 (P. 229.) 
 
 Many of the diseases of animals are greatly in- 
 fluenced by states of the atmosphere. It is re- 
 marked that immediately before rain, and particu- 
 larly before great falls of snow in winter, dogs are 
 dull : their ears become inflamed, and they lie 
 drowsily by the lire the principal part of the day. 
 Swine are observed to be uneasy in windy weather, 
 and show symptoms of restlessness even before the 
 winds begin to blow by running about with a 
 peculiar tossing up of the head. Hence the popular 
 notion that pigs can foresee the wind. 
 
298 Appendix. 
 
 ON THE DISTRIBUTION OF LIGHT BY 
 ARTIFICIAL MEANS. 
 
 (P- 237-) 
 
 With the object of distributing light, Sir David 
 Brewster suggests that " the opposite sides of the 
 street or lane should be kept whitewashed with 
 lime, and for the same reason the ceilings and walls 
 of the apartments should be as white as possible, 
 and all the furniture of the lightest colours. Having 
 seen' such effects produced by imperfect means, we 
 feel as if we had introduced our poor workman or 
 needle-woman from a dungeon into a summer- 
 house, where the aged can read their Bible, where 
 the inmates can see each other, and carry on their 
 work in facility and comfort." 
 
 ADVANTAGES OF LIGHT IN THE TREAT- 
 MENT OF THE SICK. 
 
 (P- 255-) 
 
 " Who has not observed the purifying effect of 
 light, and especially of direct sunlight, upon the air 
 of a room ? Here is an observation within every- 
 body's experience. Go into a room where the 
 
appendix. 299 
 
 shutters are always shut (in a sick-room or a bed- 
 room there should never be shutters shut), and 
 though the room be uninhabited, though the air 
 has never been polluted by the breathing of human 
 beings, you will observe a close, musty smell of 
 corrupt air — of air, i.e., unpurifled by the effect of 
 the sun's rays. The mustiness of dark rooms and 
 corners, indeed, is proverbial. The cheerfulness of a 
 room, the usefulness of light in treating disease, is 
 all-important. 
 
 " Heavy, thick, dark window or bed - curtains 
 should, however, hardly ever be used for any kind 
 of sick in this country. A light white curtain at the 
 head of the bed is, in general, all that is necessary, 
 and a green blind to the window, to be drawn down 
 only when necessary. 
 
 " ( Where there is sun there is thought.' All 
 physiology goes to confirm this. Where is the 
 shady side of deep valleys, there is cretinism. 
 Where are cellars and the unsunned sides of narrow 
 streets, there is the degeneracy and weakliness of 
 the human race — mind and body equally degenerat- 
 ing. Put the pale withering plant and human 
 being into the sun, and, if not too far gone, each 
 will recover health and spirit. 
 
 " It is a curious thing to observe how almost all 
 patients lie with their faces turned to the light, ex- 
 
300 appendix. 
 
 actly as plants always make their way towards the 
 light ; a patient will even complain that it gives 
 him pain ' lying on that side.' ' Then why do you 
 lie on that side ?' He does not know ; but we do. 
 It is because it is the side towards the window. A 
 fashionable physician has recently published in a 
 Government report that he always turns his patients' 
 faces from the light. Yes, but nature is stronger 
 than fashionable physicians, and depend upon it she 
 turns the faces back, and towards such light as she 
 can get. Walk through the wards of a hospital, 
 remember the bedsides of private patients you have 
 seen, and count how many sick you ever saw lying 
 with their faces towards the wall." — Notes on 
 Nursing. By Florence Nightingale. 
 
 ON THE REGULATION OF THE QUANTITY 
 OF LIGHT ADMITTED INTO THE CHAM- 
 BER OF THE SICK. 
 
 (P. 2570 
 
 " The quantity of light admitted into the sick- 
 chamber is a matter of immense importance to its 
 suffering occupant. As light is an element of cheer- 
 fulness, it is on that account desirable that as much 
 
Appendix. 301 
 
 should be admitted as the patient can bear without 
 inconvenience. The light should be soft and sub- 
 dued, not glaring j and care should be taken that 
 bright, lustrous objects, such as crystals and looking- 
 glasses, should be kept out of the patient's view, and 
 that neither the name of a lamp or candle, nor its 
 reflection in a mirror, be suffered to annoy him by 
 flashing across his field of vision." — Ridge On 
 Health and Disease. 
 
 THE END 
 
LONDON : 
 
 SAVILL AND EDWARDS, PRINTERS, CHANDOS-STREET, 
 
 COVENT GARDEN. 
 
*bim 
 
 DISORDERS OF THE MIND, DISEASES OF THE BRAIN, 
 
 PSYCHOLOGICAL MEDICINE, AND 
 
 THE MEDICAL JURISPRUDENCE OF INSANITY, 
 
 By FOEBES WINSLOW, M.D. 
 
 On the Incubation of Insanity* 
 
 (Pamphlet.) 
 ii. 
 
 The Health of Body and Mind. 
 
 (lVol.,8vo.) 
 
 in. 
 
 The Anatomy of Suicide. 
 
 (1 Vol., 8vo.) 
 
 IV. 
 
 Lettsomian Lectures on Insanity. 
 
 (1 Vol., 8vo.) 
 
 V. 
 
 The Plea of Insanity in Criminal 
 
 Cases. 
 
 (1 Vol., 12mo.) 
 
WORKS BY FORBES WINDOW— continued. 
 
 ON THE 
 
 Obscure Diseases of the Brain, and 
 Disorders of the Mind. 
 
 (Third Edition. 1 Vol., 8vo.) 
 
 Quarterly Journal of Psychological 
 Medicine and Mental Pathology. 
 
 (8vo.) 
 (Seventeen Annual Volumes of this Work have been published.) 
 
 VIII. 
 
 On Uncontrollable Drunkenness, 
 
 CONSIDEBED AS A. TOEM OF 
 
 Mental Disorder. 
 
 ETC. ETC. 
 
 (Pamphlet.) 
 
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