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HISTORY AND PRACTICE 
 
 
 OP 
 
 PHI I'OGENIC 
 
 DRAWING 
 
 ON THE TRUE PRINCIPLES OP THE 
 
 DAGUERREOTYPE, 
 
 WITH THE NEW METHOD OF 
 
 D I ORAM 1C PAINTING; 
 
 i'l'Hl.tsHFD BY ORDKR OF THE PUNCH ■ IENT. 
 
 BY THE INVENTOR 
 
 L. J. M. DAGUERRE, 
 
 OFFICER OF THE LEGION Of HONOUR, AND NBA B 01 , ■ 
 
 TRANSLATED FROM THE ORIGINAL BY 
 
 J. s. MEMES, LL. I>. 
 
 hon. men. • m mi run i it ... m *»r>, at 
 
 “As a recompense for giving the -i 
 French Government has just awardei. » 
 
 LO \ im N ; 
 
 SMITH ELDER AND CO., CORNHILL; 
 
 ' v M HUi'K AND CO., EDINBURGH. 
 
 839 . 
 
* rz 
 
HISTORY AND PRACTICE 
 
 OF 
 
 PHOTOGENIC DRAWING 
 
 ON THE TRUE PRINCIPLES OF THE 
 
 DAGUERREOTYPE, 
 
 WITH THE NEW METHOD OF 
 
 DIORAMIC PAINTING; 
 
 PUBLISHED BY ORDER OF THE FRENCH GOVERNMENT. 
 
 BY THE INVENTOR 
 
 L. J. M. DAGUERRE, 
 
 OFFICER OF THE LEGION OF HONOUR, AND MEMBER OF VARIOUS ACADEMIES. 
 
 TRANSLATED FROM THE ORIGINAL BY 
 
 J. S. MEMES, LL.D. 
 
 HON. MEM. OF THE ROYAL SCOTTISH ACADEMY OF FINE ARTS, ETC. 
 
 “ As a recompense for giving the secret of this splendid discovery to the world, the 
 French Government has just awarded an Annual Pension of Ten Thousand Francs 1” 
 
 LONDON: 
 
 SMITH, ELDER AND CO., CORNIIILL; 
 
 AND ADAM BLACK AND CO., EDINBURGH. 
 
 1839. 
 
PREFACE. 
 
 In presenting this little work to the British public, the 
 translator may perhaps be permitted to observe of his 
 original, that in all its circumstances, it is one of the 
 most interesting works ever given to the world. It is 
 the first Manual of a new science. It is written by the 
 discoverer of that science ; exhibiting a faithful record 
 of the progress — the hopes, disappointments, and success 
 of two men, who, in the term of their successive efforts 
 for twenty-five years, laboured incessantly in search of 
 the invention. That invention constitutes an era in 
 human knowledge. It occupies at this moment the 
 attention of every philosopher throughout Europe, and 
 nations have contended for the honour of priority. 
 
 The monarch, the government, the people of a great 
 and enlightened state, contending in generous emulation 
 how best to reward this discovery, offers a moral spec- 
 tacle, noble and spirit-stirring, the rarity of which, alas ! 
 in the history of genius, forms another, and not the 
 least striking characteristic of the subject. 
 
 The disinterested exertions of the greatest names in 
 the scientific annals of his country — men who occupy 
 the highest places in general estimation — to lift the 
 modest artist into the renown which he merits, and to 
 disclose the real value of his labours, is different evi- 
 dence of the interest belonging to these pages, — a most 
 pleasing, — and to the glory of science be it said, — not a 
 peculiar association. 
 
 Photogenic science, of the practice of which this Manual 
 will render any one master, is to be viewed under two 
 
VI 
 
 PREFACE. 
 
 great relations, — its connexion with science, and its 
 probable influence upon art. 
 
 The importance of the fact, that light in its action 
 upon bodies, can be made to pencil, by its own sponta- 
 neous and etherial agency, the creations of beautiful 
 nature, cannot be questioned. The science of this new 
 art has indeed not yet been evolved. The principle, 
 we are assured by Arago, is latent among the mysteries 
 yet to be revealed. But no one can peruse the details 
 and operations described in the following pages, without 
 perceiving that by them we gain another step in advance 
 towards that consummation to which modern physics 
 are hastening — namely, the identity of light — electricity 
 
 — magnetism — gravity. In this sublime walk, the 
 photogenic discoveries have unfolded a “ new order of 
 possibilities,” and will aid in leading to one mighty 
 cause, ruling the universe of matter in a dominion, 
 second only to the spontaneity of the Creator. 
 
 To the beautiful in art, the invention has yet a nearer 
 relation. It will improve, without materializing its 
 processes. It will give to the artist new subjects of 
 study, in the most difficult department of his profession 
 
 — the union of grandeur in mass — with exquisite 
 detail ; but it arms him with no mechanical contri- 
 vance, as has been feared, which may abate the honours 
 of genius. 
 
 As an English translator, it may perhaps have been 
 expected that I should have said something on the sub- 
 ject of priority so often urged in my original. The 
 question is one in the discussion of which it is hardly 
 possible entirely to lay aside preferences and predilec- 
 tions, and time does not permit either the repetition of 
 the experiments or the re-examination of the documents. 
 
 J. M. 
 
 London, Sept. 13th, 1839 . 
 
CONTENTS. 
 
 CHAPTER I. 
 
 PAGE 
 
 The Importance of the Photogenic Discovery. — Bill for Re- 
 warding its Authors, proposed by the King of France — 
 Speech of the Minister bringing forward the Motion. — 
 Amount of Rewards granted. — Report of M. Arago to the 
 Chamber of Deputies. — History of Photographic Discovery 
 in England — In France. — Biographical Details. — Utility of 
 the New Invention — To the Arts — To Literature — To Science. 
 
 — Astronomical Details. — Report of Baron Gay Lussac to 
 the Chamber of Peers — Principles of Photography. — Its value 
 as national Property to the Arts, Manufactures, and general 
 improvement of a Country i 
 
 CHAPTER II. 
 
 Practical and Historical Details. — Partnership of the two Dis- 
 coverers. — Account of Niepce’s Processes. — His own Notes. 
 
 — Daguerre’s Remarks. — Asphaltum the substance employed 
 for receiving the Impressions of Light — This the old system. 
 
 — The Solvent. — Its application. — Description of some re- 
 sults. — Additional Notices. — Daguerre’s improvements on 
 Niepce’s Processes. — Correspondence. — Experiments. — Dis- 
 appointments. — Daguerre unquestionably prior to Niepce 
 in the application of Iodine. ...... 33 
 
Vlll 
 
 CHAPTER III. 
 
 PAGE 
 
 Practical Description of the Daguerreotype. — Material to be 
 employed in the Photogenic Process. — Five Steps of the Pro- 
 cess explained. — Polishing the White Coating with Iodine. — 
 
 The Camera. — Mercurial Process. — Fixing the impression, 
 
 ■with descriptions of the Apparatus 55 
 
 CHAPTER IV. 
 
 Dioramic Painting. — Daguerre’s principal Subject. — Selection 
 of the Canvas. — Manner of Painting. — First effect. — Second 
 effect. — Difference between them. — Manner of introducing 
 the Light. — The two effects illuminated by different Lights.' — 
 Remarks on Colouring. — Application.— Influence of the Sky 
 on the Colours in Paintings — Effects of this on artists and 
 Connoisseurs 69 
 
EXPLANATION OF THE PLATES. 
 
 N. B. These figures are all drawn to the scale of one French metre, 
 Plate II, which is equal to 39 English inches ; operators may thus 
 have the apparatus constructed with very little trouble. The trans- 
 lator would add, from his own experience, that two requisites are in- 
 dispensable in these experiments : exquisite polish of the plate, and 
 extreme cleanliness in all the operations; dust and stains on the 
 tablet make large blanks in the drawing. 
 
 PLATE I. 
 
 Fig. 1 represents the frame of iron wire for the support of the 
 plate, while undergoing the operation of heating. The 1st view is 
 the plane seen from above; the 2nd, is a section and elevation, 
 shewing the manner in which it is fixed. Fig. 6 B is the spirit 
 lamp applied under the plate ; A its stopple. 
 
 Fig. 2. The plate of plated silver on which the photographic de- 
 sign is made. The dimensions according to the scale are 8^ inches 
 by 6‘4 inches. To operate upon plates of larger dimensions requires 
 all the apparatus to be enlarged, for the same camera which admits 
 light sufficient for such a plate has its intensity too much diminished, 
 when a greater focal distance with the same aperture, and conse- 
 quently same number of rays, spread over a larger surface. In 
 polishing the plate, begin at C, and strike circularly outwards to the 
 circumference. Vary the direction, however, and invert the process. 
 Always press lightly and evenly. Fig. 2, second view, is the plate 
 seen edgeways : the lines represent (nearly) its thickness. Fig. 4 
 muslin bag, with pumice powder. 
 
 Fig. 3. The little board or wooden tablet upon which the plate is 
 fixed for the succeeding operations after the first one of polishing. 
 It is attached by means of four fillets, B B B B, exactly the same 
 material as the plate itself. To each of these are soldered two 
 small projecting pieces, which embrace the plate near the corners. 
 
X 
 
 and the whole apparatus is retained in position by small nails, or 
 better, screws through holes in the fillets, and inserted by the handle 
 or turn-screw, Fig. 5. The purpose of the fillets is not solely to fix 
 the plate, their more important use is to serve as a kind of frame to 
 it, while undergoing the second process ; the application of the 
 iodine: without these, the cooling of iodine would not be equally dif- 
 fused, for the vapour would condense more rapidly along the edges, 
 and consequently, the coating would be too thin in the centre and 
 too thick round the circumference. It is perhaps not easy to ex- 
 plain so as to satisfy all ; but the experimental part is not the less 
 certain. Fig. 3, second view, thickness of the board. 
 
 PLATE II. 
 
 Fig. 1. Section of the box for iodine, used in the second operation. 
 The section is supposed to pass down the middle of the apparatus 
 by the line A B, Fig. 2, which represents the same seen from 
 above. C is a small lid, which fits accurately the interior, dividing 
 the whole into two chambers. It is used at all times, except when the 
 operator is actually employed in coating the tablet. Its use is to 
 concentrate the vapour of the iodine, and preserve the whole in a 
 state for equally and rapidly diffusing the vapour, when the plate has 
 been introduced. D is the capsule or little cup in which the iodine 
 is placed. E the small board with the plate attached, face down- 
 wards. Four small projecting supports, F receive the four angles 
 and retain the plate in the most favourable position for receiving the 
 vaporization of the iodine as it rises upwards. Of course the cover 
 C is withdrawn. G is the lid of the box, always shut except when 
 the plate is to be withdrawn for examination. H, supports for C. 
 K, tapering sides all round, forming a»funnel-shaped box within the 
 other ; the funnel-shaped interior diffuses the vapours of iodine, 
 which thus spread as they rise. J, circle of gauze, stretched over a 
 ring, and placed upon the cup with the iodine. The vapour of 
 which rising through this light covering flows up equally, and not in 
 clouds, also the gauze prevents the particles of this substance from 
 dying about, and probably injuring the plate. 
 
 Fig. 3. Case for preserving the plates from injury, either before or 
 after they have been impressed with images. They slip into grooves 
 formed in two opposite sides of the case, and at some little dis- 
 tance apart, so that the plates cannot touch in any part of their 
 surfaces. If filled with plates, that have designs, the case should 
 
XI 
 
 be wrapped in paper, or better, cloth, to preserve them from dust and 
 light. In travelling, this precaution is always necessary. 
 
 PLATE III. 
 
 Plate III. represents four different positions of the frame into 
 which the plate with its wooden tablet is put, on removal from the 
 iodine process. The object of the apparatus is twofold, — to adapt 
 the plate to the camera obscura, and to protect the iodine coating 
 from the action of light till the moment in which it receives the focal 
 image. 
 
 A, Half circles which open and shut the doors, B B. 
 
 C, Fig. 4. The plate with its wooden tablet fitted into the frame : 
 back view of the plate fronting inwards, the door shut upon it. 
 
 D, Screws to fix the tablet and plate, and to stop the doors. 
 
 E, Thickness of the frame. 
 
 E, Fig. 3. Plate : the whole represents the arrangement for receiv- 
 ing the photogenic impressions on the plate, the doors being open, 
 the focal image falls upon the prepared plate, and leaves its impress 
 pencilled there by the rays of light proceeding from the natural 
 objects. 
 
 PLATE IV. 
 
 The camera obscura, as adapted to photogenic delineation. 
 
 Fig. 1. Perpendicular section lengthways. 
 
 A, a ground glass by which the focus is adjusted. It is then 
 removed, and the photographic plate substituted, as in C, Fig. 2. 
 B, a mirror for observing the effect of objects, and selecting points 
 of view. For these purposes it is inclined at an angle of 45°, by 
 means of the support L. To adjust the focus, the mirror is put down 
 altogether, and the ground glass A used. The focus is easily ad- 
 justed by means of the sliding frame, as represented in the plate. — 
 placing the screws on the double box D, and the projection E: 
 when the focus is adjusted, it is fixed in position by the screw H. 
 The mirror is retained in its place by hooks at F, which catch the 
 eyes at G. 
 
 The object glass is achromatic and periscopic. Its diameter is 
 21 millimetres, and its focal distance 38 centimetres. In English 
 
 measure 
 
 21 X 39 . , , 
 
 inches, and 
 
 1000 
 
 38 X 39 
 
 inches; which can easily be re- 
 
 duced. 
 
 100 
 
XU 
 
 This instrument has the disadvantage of reversing the objects. 
 This can indeed be easily obviated by substituting another mirror 
 outside, as K I, Fig. 2. This arrangement, however, injures the 
 effect on the photographic plate from the loss of light. It is therefore 
 not to be employed unless when the operator has time to spare. It 
 increases the time of the operation by one-third of the whole. 
 
 PLATE V. 
 
 Plate V. represents three views of the same apparatus, — that 
 used for the fourth operation ; submitting the plate to the vapour of 
 mercury. 
 
 Fig. 1. Section of the apparatus. 
 
 Fig. 2. Front view of the same. 
 
 Fig. 3. Right side in which the thermometer is placed. 
 
 A, Lid of the apparatus. 
 
 B, Black board with grooves to receive the small board and plate. 
 
 C, Cup containing mercury. 
 
 D, Lamp with spirit of wine. 
 
 E, Small cock inserted at an angle, through which the mercury is 
 withdrawn after the operation. 
 
 F, Thermometer. 
 
 G, Glass through which to inspect the operation. 
 
 H, Tablet with the plate as removed from the camera. 
 
 I, Stand for the spirit lamp which is placed within the ring N, so 
 as to be under the centre of the cup. 
 
 All the interior of this apparatus should be black and varnished. 
 
 PLATE VI. 
 
 This plate, fronting the title, represents various apparatus for the 
 last operation of washing the plate. 
 
 Fig. 1. Funnel, with plate of paper for purifying the saline wash 
 of salt or hyposulphite of soda. 
 
 Fig. 2. Trough of tinned copper, in the bottom of which is repre- 
 sented one of the plates in the act of being washed. Two such 
 troughs must be prepared, one for salt — the other for distilled water. 
 
 Fig. 3. Little hook for shaking the plate while in the wash. 
 
 Fig. 4. Apparatus in japanned white iron for washing the designs. 
 E, well for receiving the water that flows through the tube C. 
 
 Fig. 5. Bottle with wide 'mouth serving to warm the distilled 
 water and to pour it upon the plate when placed as at B, Fig. 4. 
 
HISTORY AND DESCRIPTION 
 
 OF THE 
 
 DAGUERREOTYPE, 
 
 &C. Sj-c. 
 
 CHAPTER I. 
 
 Bill for Rewarding the Inventors of the Daguerreotype. 
 
 Louis Philippe, King of the French, 
 
 To all present and to come, greeting. 
 
 We have ordered and do order, that the Bill preparatory to 
 a law, the tenor of which follows, shall be presented, in 
 our name to the Chamber of Deputies by our Minister 
 the Secretary of State for the Home Department, whom 
 we charge to explain the principles of the Bill and to 
 support them in debate. 
 
 A rticle First . — The provisional agreement concluded on 
 the 14th June, 1839, between the Secretary for the Home 
 Department and MM. Daguerre and Niepce, jun. is ap^ 
 proved. 
 
 B 
 
2 
 
 Article Second . — There is granted to M. Daguerre, an 
 annual pension for life of 6,000* francs : to M. Niepce, jun. 
 an annual pension for life of 4,000 f francs. 
 
 Article Third . — These pensions shall be inscribed in the 
 list of civil pensions on the Public Treasury, to be engaged 
 from and after the passing of the present Act. They shall 
 not be subject to any deductions. They shall be one-half in 
 reversion to the widows of MM. Daguerre and Niepce. 
 
 Given at the Tuileries this 15th June, 1839. 
 
 (Signed) By the King, LOUIS PHILIPPE. 
 
 (Signed) Minister Secretary of State, DUCHATEL. 
 
 CHAMBER OF DEPUTIES, SECOND SESSION, 1839. 
 BILL PRESENTED BY THE MINISTER OF THE INTERIOR.! 
 
 TO TIIE MEMBERS OF THE CHAMBER. 
 
 15th June, 1839. 
 
 Gentlemen, 
 
 We believe that we only anticipate the wishes of the Chamber 
 in proposing to you to purchase, in name of the State, the 
 right to a discovery as useful as unhoped for, and the publi- 
 cation of which is of vast importance to the arts and sciences. 
 
 You ail know, and some among you have had opportunities 
 of convincing themselves, that after fifteen years of persever- 
 ing and expensive researches, M. Daguerre has succeeded in 
 fixing the images obtained in the camera obscura, and thus 
 producing, by the action of light, designs in which the ob- 
 jects preserve their forms with mathematical precision, even 
 
 * 250/. sterling. f 166/. 13s. 4 d. X M. Duchatel. 
 
3 
 
 to the most minute details; in which, also, the effects of 
 linear perspective, and the gradations of tone, depending 
 upon aerial perspective, are brought out with a delicacy 
 hitherto unknown. 
 
 We need not insist upon the utility of an invention like 
 this. It is obvious that resources and facilities altogether 
 new, will thus be afforded for the study of the sciences ; and 
 as to the arts, the services yet to be rendered, cannot be 
 calculated. 
 
 Even the most accomplished draughtsmen and painters, 
 will find subjects of inexhaustible observation and study 
 in these, so perfect reproductions of nature. On the 
 other hand, this process will furnish them with a speedy 
 and easy means of forming collections of studies, not 
 otherwise to be obtained, save at the expense of much time 
 and trouble, and yet in a style infinitely less perfect. 
 
 The art of engraving, when employed to multiply by re- 
 producing these images, etched by nature herself, will assume 
 a new degree of importance and interest. 
 
 In short, for the traveller, the antiquary — as well as for 
 the naturalist — the apparatus of M. Daguerre will come into 
 continual and indispensable use. It will enable them to 
 give permanency to their several thoughts, without having 
 recourse to the hand of a stranger. Henceforth every author 
 will compose the chorographic portion of his own works : by 
 stopping but for a few minutes beside the most complicated 
 monument, or before the most extended landscape, he will 
 instantly obtain a true fac-simile of his subject. 
 
 Unfortunately, for the authors of this beautiful discovery, 
 it is impossible for them to bring their labour into the mar- 
 ket, and thus indemnify themselves for the sacrifices incurred 
 by so many attempts, so long fruitless. Their invention does 
 not admit of being secured by patent. So soon as it becomes 
 known, every one may avail himself of its advantages. The 
 most unskilful will produce designs, with the same exact- 
 
 B 2 
 
4 
 
 ness, as the most accomplished artist. Of necessity, then, 
 this process must belong to all, or remain unknown. How 
 just would be the regrets expressed by every friend of art and 
 science if such a secret were left impenetrable to the public, — 
 if it were to perish and die with its discoverers ? 
 
 In circumstances like these, it is the duty of the State to 
 come forward. Government ought to put society in possession 
 of an invention which its general interests demand should be 
 known, provided the price, or rather reward of the discovery 
 be secured to its authors. 
 
 Such are the motives that have induced us to conclude 
 with Messrs. Daguerre and Niepce, a provisional arrange- 
 ment, as explained in the Bill, which we have now the 
 honour to submit for your sanction. But before we can 
 explain the basis of this agreement, some details are neces- 
 sary. 
 
 The possibility of arresting for a space the images of the 
 Camera has been known since the last century ; but this 
 discovery produced no result of utility, because the substance 
 upon which the solar rays painted these images, did not 
 possess the property of preserving them, turning it com- 
 pletely black when 'exposed to the day-light. 
 
 M. Niepce, sen., discovered a method of rendering these 
 images permanent; but, though he resolved this difficult 
 problem, his invention, nevertheless, remained very imper- 
 fect. He obtained only a silhouette, or black profile of 
 objects, and twelve hours, at least, were required to produce 
 even the smallest design. 
 
 It was by following out views entirely different, putting 
 aside altogether the processes of M. Niepce, that M. Daguerre 
 arrived at those admirable results which we now behold, — 
 namely, extreme promptitude of operation, and repro- 
 duction of the aerial perspective, with all the play of 
 light and shadow. The method of M. Daguerre is his own ; 
 it belongs exclusively to him, and is distinguished from that 
 
5 
 
 of his predecessor, both in its cause and by its effects. At 
 the same time, as there had passed between M. Daguerre 
 and the late M. Niepce, certain agreements, mutually to 
 divide whatever advantages might accrue from their disco- 
 veries ; and as this stipulation had been continued with 
 M. Niepce, jun., on the death of his father, it would be 
 impossible to treat now with M. Daguerre alone, even con- 
 cerning a process which he has not merely brought to per- 
 fection, but which he invented. 
 
 It must not be forgotten, besides, that the method of M. 
 Niepce, even although it has continued imperfect, may per- 
 haps be susceptible of receiving some improvements, of being 
 usefully applied in certain circumstances, and, consequently, 
 for the history of science it is important that it be published 
 along with M. Daguerre’s system of photographic delinea- 
 tion. 
 
 These explanations, gentlemen, will enable you to com- 
 prehend from what cause, and under what relations Messrs. 
 Daguerre and Niepce come before you as parties interested 
 in the bill to be brought before the house. 
 
 A sum of 200,000 francs* was at first asked of us as the 
 price of the inventions of MM. Niepce and Daguerre; and it 
 ought to be stated that offers coming from foreign sovereigns 
 justified this demand. We have, however, arranged that in 
 place of the capital stipulated, a life interest shall be granted, 
 namely, a pension of 10,000 francs, f with only the half in 
 reversion to the widows. The assignment of this pension 
 to be as follows : — 
 
 To M. Daguerre . . 6000 francs 
 
 To M. Niepce . . . 4000 francs 
 
 Independent of the considerations mentioned above, there 
 is one circumstance, which of itself justifies this division. M. 
 Daguerre has consented to give up for publication the pictorial 
 
 * Nearly eight thousand guineas. 
 
 f 416/. 13s. 4 d. 
 
6 
 
 and philosophical processes by which he produces the effects 
 of Dioramic art, an invention of which he alone possesses the 
 secret, and one most desirable to be known. 
 
 Before signing the agreement, M. Daguerre placed in 
 our hands, under seal, the description of M. Niepce’s pro- 
 cess, an account of his own, and lastly the secret of the 
 Diorama. 
 
 We can assure the Chamber that these descriptions are 
 complete and faithful ; for a member of this assembly, whose 
 name is incontestible authority,* who received from M. Da- 
 guerre the confidential communication of all his processes, 
 and who has himself tested them, has had the kindness to 
 examine these papers and to guarantee their accuracy. 
 
 We hope, gentlemen, that you will approve both the 
 motive which has dictated these arrangements, and the con- 
 ditions upon which they have been concluded. You will 
 concur in a sentiment which has already awakened uni- 
 versal sympathy, you will never suffer us to leave to foreign 
 nations the glory of endowing the world of science and of 
 art with one of the most wonderful discoveries that honour 
 our native land. 
 
 CHAMBER OF DEPUTIES, SECOND SESSION, 
 1839. 
 
 Report made in name of the Commission charged with the 
 examination of the Bill proposing to grant — 1st, to M. 
 Daguerre an annual pension for life of 6000 francs 
 (250Z.) ; 2nd, to M. Niepce, jun. an annual pension of 
 4000 francs (166/. 13s. 4 d.), for the renouncement 
 made by them of a process for fixing the images of the 
 Camera Obscura.f 
 * M. Arago. 
 
 f This commission was composed of the following members of the 
 Chamber : — MM. Arago, Etienne, Carl, Vatout, de Beaumont, Tour- 
 nouer Delessert (Francois), Combarel de Leyval, and Vitet, all names 
 distinguished in science. 
 
7 
 
 By M. Arago, Deputy for the Eastern Pyrenees, presented to 
 the Chamber at its Sitting 3rd July, 1839. 
 Gentlemen, 
 
 The interest manifested both within these walls and through- 
 out Europe in those labours, the result of which M. Daguerre 
 recently submitted to the public, has been lively, striking, 
 and unanimous. The Chamber, therefore, in all probability 
 expects of its commission only a simple and entire approbation 
 of the Bill presented on this subject by the Minister for the 
 Home Department. After mature reflection, however, it 
 appeared to us that the office with which you had invested 
 us imposed other duties. We have deemed that while applaud- 
 ing the happy ideaof instituting national recompenses in favour 
 of those inventors whose interests the ordinary legislation by 
 patent could not protect, it was requisite, in the very first steps 
 of this new career, to shew with what reserve, with what 
 hesitation the Chamber would proceed. To subject to a 
 minute and rigid examination the work of genius upon 
 which we are this day called to legislate, will be to discourage 
 ambitious mediocrity ; for minds of this character also would 
 otherwise aspire to intrude on your notice their ordinary 
 and inconsequent attempts ; it will prove that you intend to 
 place in a most elevated region the recompenses which 
 shall be demanded of you in the name of national glory, — 
 that you will never consent to bring them down from this 
 elevation, — or by lavishing them to tarnish their splendour. 
 
 These few remarks will enable the House to understand 
 why we have been led to examine, — 
 
 If the process of M. Daguerre be incontestibly an inven- 
 tion, — 
 
 If this invention will render to archeology and the fine 
 arts services of value, — 
 
 If it can become generally applicable, — 
 
 And finally, if we may hope that by it the sciences will 
 be benefited. 
 
8 
 
 Two centuries ago, a philosopher of Naples, Giovanni 
 Battista Porta, discovered that if a very small hole be 
 pierced in the window-shutter of a room completely darkened 
 in other respects ; or better still, if the aperture be perfo- 
 rated in a thin metallic plate applied to the shutter ; all the 
 exterior objects from which rays can enter through this 
 opening will be represented on the opposite wall ; in dimen- 
 sions enlarged or diminished according to the distance. 
 He found also that even with this imperfect apparatus, 
 throughout a large extent of the picture, objects were 
 painted in their natural colours, and with considerable 
 truth of linear perspective. A short time afterwards Porta 
 found that it was not necessary to have the opening 
 very small, thus limiting the view, but that if the perforation 
 were covered with a lentiscus or convex glass, it might be 
 of any dimension. He remarked also the great improvement 
 thus produced in the delineation. The images passing through 
 the simple medium of the hole were without distinctness of 
 position, intensity of colour, or neatness of outline. On the 
 contrary, with the lentiscus, the mimic forms rivalled the 
 vivacity and strength of nature herself, the focal distances 
 being properly adjusted. It is well known that all these 
 discoveries of Porta have become truly astonishing in precision 
 of detail and strength of colouring since the art of construct- 
 ing achromatic glasses has been brought to its present per- 
 fection. Formerly a simple lentiscus composed of one kind 
 of glass only, and consequently acting with as many separate 
 focuses as there are colours in the undecomposed white ray, 
 transmitted a comparatively indistinct image of objects. Now 
 that we employ achromatic glasses which combine all the 
 incident rays in one focus, and that a periscopic construction 
 of the apparatus likewise has been adopted, great perfection 
 has been given of its effects. 
 
 Porta constructed also portable dark chambers ; these 
 were composed of a tube, longer or shorter, armed with a 
 
9 
 
 lentiscus as its optic instrument. A screen of white paper, 
 or some prepared substance, occupied the focus, and upon 
 it the images of external objects were received. The 
 Neapolitan philosopher proposed his simple arrangements 
 for the benefit of those who had not been taught drawing. 
 According to him, nothing else was required in order to 
 obtain the most perfect transcripts of nature than merely 
 to trace carefully the outline of the focal image. 
 
 These anticipations of Porta have not been completely 
 realized. Painters and draughtsmen, those particularly who 
 execute large views for panoramas, dioramas, and theatres, 
 have indeed still recourse to the camera. They, however, em- 
 ploy it merely to groupe objects en masse, to trace their con- 
 tours, and to fix them in their proper position and mag- 
 nitude, according to the principles of linear perspective. As 
 to those effects proceeding from the imperfect transparency 
 of our atmosphere, whence arise all the charms of tone and 
 colouring, which by a sufficiently erroneous appellation are 
 designated by the term aerial perspective, — the most ex- 
 perienced artists are aware that in reproducing these the 
 camera affords them no assistance.* No person, how- 
 ever, has ever witnessed the neatness of outline, precision 
 of form, the truth of colouring, and the sweet gradations of 
 tint, without regretting that an imagery so exquisite and so 
 faithful to nature could not be made to fix itself perma- 
 nently on the tablet of the machine — who has not put up his 
 aspiration that some means might be discovered by which to 
 give reality to shadows so exquisitely lovely ? Yet, in the 
 estimation of all, such a wish seemed destined to take its 
 
 * This is not altogether correct : although the camera can by no direct 
 application give permanently the aerial perspective, it is well known 
 that for the gradation of colour — the comparative strength of near and 
 distant lines — few studies are more advantageous to the artist than to view 
 his object in a camera, and paint from its representations. This perhaps 
 is all that M. Arago meant to be implied. — Translator. 
 
10 
 
 place among other dreams of beautiful things, — among 
 the glorious but impractical conceptions in which men of 
 science and ardent temperament have sometimes indulged. 
 This dream, notwithstanding, has just been realized. Let us 
 take, then, the invention in its germ, and mark carefully its 
 gradual unfolding. 
 
 Long ago the Alchemists had succeeded in forming a 
 solution of silver in muriatic acid. This compound, which 
 assumes the appearance of a white salt, they called lunar or 
 caustic silver .* This salt possessed the remarkable property 
 of becoming black by light, and of blackening more or less 
 rapidly in proportion to the intensity of the incident rays. 
 Cover a sheet of paper with a wash of lunar caustic, or, as 
 we say at present, with a wash of chloride of silver ; form 
 upon this by means of a lens the image of an object ; the 
 shaded parts of the image — the parts, that is to say, upon 
 which no light falls — will remain white ; the portions, on the 
 other hand, strongly illuminated, will become completely 
 black ; the demi-tints will be represented by grays more or 
 less dark. This monochrome, in short, will be the reverse of 
 the real object as respects the lights and shadows. 
 
 Again, if an engraving be placed upon a sheet of paper 
 moistened with a solution of chloride of silver, and both be 
 exposed to the solar light, the engraving being uppermost, 
 the dark lines of the latter will intercept the rays, and the 
 corresponding portions of the paper below will retain their 
 original colour. In those parts, on the contrary, which lie 
 immediately under the lights in the engraving, the solar 
 rays, acting through the imperfect transparency of the print, 
 will blacken the chloride wash. The necessary consequence 
 
 * In the work of Fabricius (De Rebus Metallicis), printed in 1568, 
 there occurs a lengthened account of a kind of mineral called Horn 
 Silver, having the colour and transparency of the artificial substance 
 with the fusibility and softness of wax. This mineral, exposed to the 
 light, passed from yellowish grey to violet, and by prolonging the action, 
 almost to black. This substance was nothing more than Natural Lunar 
 Caustic. 
 
11 
 
 of this operation will be a copy of the engraving, correct in 
 its outlines, but reversed in its effects, the lights being 
 reproduced in shadows and the shadows in lights. 
 
 These applications of this curious property of the chloride 
 of silver, one would think, might have readily occurred to 
 the Alchemists, the first discoverers of the substance, or to 
 their early successors, who devoted more attention to prac- 
 tical results. Not so, however, was the case. We must 
 descend to the first years of the 19th century before we 
 detect even the beginnings of the photographic art. 
 
 About this time our countryman Charles, in his lectures, 
 made use of a prepared paper to produce silhouettes, or black 
 profiles, by the action of light. Charles died without descri- 
 bing the preparation which he employed. As the historian of 
 science, under pain of falling into inextricable confusion, is 
 not authorised to proceed, except upon printed and authentic 
 documents, it is no more thanjustice to assign to Wedgewood, 
 the celebrated porcelain manufacturer and inventor of the 
 pyrometer for high temperatures, the first application of this 
 new art. 
 
 The memoir of Wedgewood appeared in 1802 in the num- 
 ber for June of the Journal of the Royal Institution of Great 
 Britain. The author there proposes by means of skins, or 
 with paper steeped or washed in chloride or nitrate of silver, 
 to copy paintings on glass as in the windows of churches, 
 and also engravings. “The images formed by means of the 
 camera obscura,” we quote faithfully a passage from the 
 article, “ have been found to be too faint to produce, in any 
 moderate time, an effect upon the nitrate of silver.” 
 
 The commentator upon Wedgewood’s experiments, the 
 illustrious Davy, does not contradict the assertion relative to 
 the images of the camera. He merely adds, as to his own 
 experiments, that he has accomplished the copying of very 
 small objects by the solar microscope, but only at a short 
 distance from the lens. 
 
 Finally, neither Wedgewood nor Sir H. Davy discovered how, 
 
12 
 
 the operation once finished, we were to give it permanence, or, 
 if I may be permitted the expression, — to remove from the 
 canvas of their pictures the defect of becoming black by the 
 light. It thence resulted that the copies which they had ob- 
 tained could not be examined in day-light, for in a very short 
 time they became uniformly black, and all lineaments of the 
 previous objects disappeared. What was this in reality but 
 to produce imagery so evanescent that only a furtive glance 
 could be cast upon the work, and that by the light of a 
 lamp? The whole would have vanished in a few seconds if 
 these delineations had been examined in day-light. 
 
 After these imperfect, these unimportant essays, of which 
 we have just given an analysis, we arrive at the researches of 
 Messrs. Niepce and Daguerre, without encountering in our 
 course any intermediate experimenters of any country. 
 
 The late M. Niepce was a country gentleman, who lived 
 on his property near Chalons, on the Saone. He devoted the 
 leisure of a studious and retired life to the pursuits of science. 
 One of his discoveries in reference to a contrivance for sub- 
 stituting heated atmospheric air in place of steam in ma- 
 chinery, underwent, with considerable success, a very rigorous 
 trial, — an examination before the Academy of Sciences. The 
 Photographic researches* of M. Niepce appear to have been 
 begun so early as the year 1814. His first connexion with M. 
 Daguerredates from the month of January 1826. Theindiscreet 
 revelations of an optician at Paris disclosed to him the experi- 
 ments of Daguerre, then also engaged in researches whose 
 object was to fix by some chemical or other process the 
 images obtained with the camera. These facts are authen- 
 ticated by letters which have been submitted to our perusal. f 
 In the event then of dispute or previous claim, the first 
 
 * Or Photogenic, according to the more popular expression in this 
 country. I have used the former, because throughout my original, 
 except in one instance, it is exclusively employed. Either is equally cor- 
 rect, signifying delineated or formed by light. — Translator. 
 
 t These letters are inserted in Chapter II. 
 
13 
 
 photographic labours of Daguerre can thus be determined 
 with unquestionable certainty to have attained some shape 
 in the year 1826. 
 
 In the following year M. Niepce repaired to England. In 
 the month of December 1827, he presented a paper on his 
 photographic experiments to the Royal Society of London. 
 This memoir was accompanied with several sketches on metal 
 produced by methods then already discovered by our coun- 
 tryman. On an attempt having been made to establish a 
 priority of invention, these sketches, still in a state of good 
 preservation, were immediately and honourably produced 
 from the collections of certain English philosophers. They 
 prove beyond dispute, as respects both the photographic copies 
 of engravings, and the formation, for the use of artists, of 
 plates in the state of advanced etchings, that M. Niepce 
 in 1827 was acquainted with a method of making the shadows 
 correspond to shadows, the demi-tints to the demi-tints, the 
 lights to the lights. These early essays farther prove that 
 he had discovered how to render his copies, once formed, 
 impervious to the erasing and blackening effects of the solar 
 rays. In other words, the ingenious experimentalist of 
 Chalons, by the composition of his grounds, had so early as 
 1827 resolved a problem, which had defied the lofty sagacity 
 of a Wedgewood and a Davy. 
 
 The deed of co-partnery between Messrs. Niepce and 
 Daguerre, for mutually investigating and following out the 
 subject of photography, is fortunately registered among the 
 public records, and bears date Dec. 16, 1829. Later deeds 
 entered into by M. Isidore Niepce, as his father’s heir, and 
 M. Daguerre, distinctly mention, in the first place, the 
 improvements made upon the earlier methods of the philo- 
 sopher of Chalons, by the Parisian artist:* in the second 
 instance, they also particularize processes entirely new, in- 
 vented by M. Daguerre, and possessing the advantage (in 
 terms of the deed) “ of producing images with sixty or 
 * See Note (1) at the end. 
 
14 
 
 eighty times greater rapidity than the earlier applications of 
 the photographic principle.” 
 
 In what we have just observed, regarding the studies of 
 M. Niepce, these restrictive expressions have doubtless been 
 remarked — “ for the photographic copy of engravings.” It 
 was only, in truth, after a multitude of fruitless attempts, that 
 M. Neipce himself had almost renounced the idea of ever 
 being able to fix the image in the camera. The difficulties 
 which presented themselves in the course of his investiga- 
 tions were chiefly the following. The preparations which he at 
 first employed as the ground of the future design, did not yield 
 with sufficient rapidity to the action of the solar rays, so that 
 ten or twelve hours proved hardly sufficient for producing 
 a single design. During an interval so protracted, the sha- 
 dows cast upon the various points of view were very much al- 
 tered, indeed, entirely changed in place, form, and extent: 
 they had passed, in fact, from the left to the right of objects, 
 and this traverse, wherever it operated, gave birth to flat and 
 uniform tints, without life or distinctness. In the results of a 
 method so imperfect, all the effects arising from the contrasts 
 of light and shadow were lost. Again, amid these manifold 
 inconveniences, the operator was by no means sure of 
 succeeding; after infinite precautions, causes unassignable or 
 fortuitous, gave him sometimes a tolerable result; at others, 
 he obtained only an incomplete image, with here and there 
 extensive blanks. In fine, when exposed to the solar rays, 
 the grounds, upon which the images were impressed, if they 
 did not become black, cracked and came off in small scales. 
 By taking the opposite of each of these defects, an enumera- 
 tion nearly complete will be obtained of the merits of the 
 method discovered by M. Daguerre, after an immense num- 
 ber of minute, difficult, and expensive experiments. 
 
 The feeblest rays impress the substance of the Daguerreo- 
 type. The effect is produced before the shadows have had 
 time to change in any appreciable degree. The results are 
 
15 
 
 certain, by the operator’s acting according to a few very 
 simple directions. Finally, the images being once produced, 
 the solar rays continued for years, affect neither their purity, 
 brightness, nor harmony. 
 
 Your commission have made the necessary dispositions for 
 enabling all the members of the Chamber, during the day 
 appointed for the discussion of the Bill, if they judge it 
 proper, to verify the results of the Daguerreotype, and to 
 form for themselves an opinion on the probable utility of 
 such an apparatus. Upon examining several of the pictures 
 to be submitted for your inspection — all will consider the 
 immense advantages which would have been derived, during 
 the expedition to Egypt for example, of a means of repro- 
 duction so exact and so rapid : all will be struck with this 
 reflection, that if photography had been known in 1798, we 
 should this day have possessed faithful representations of 
 many valuable antiquities now, through the cupidity of the 
 Arabs, and the vandalism of certain travellers, lost for ever 
 to the learned world. 
 
 To copy the millions and millions of hieroglyphics which en- 
 tirely cover to the very exterior the great monuments at Thebes, 
 Memphis, Carnac, &c. would require scores of years, and 
 legions of artists. With the Daguerreotype,* a single man 
 would suffice to bring to a happy conclusion this vast labour. 
 Arm the Egyptian Institut with two or three of Daguerre’s 
 instruments, and on several of the large engravings in that 
 celebrated work, the fruit of our immortal expedition, vast 
 assemblages of real hieroglyphics would replace fictitious or 
 purely conventional characters. At the same time these 
 designs shall incomparably surpass in fidelity, in truth of 
 
 * This is the name given to the apparatus fitted up on the principles of 
 M. Daguerre’s system of photographic or photogenic painting. All 
 scientific terms ought to expiess either a fact or a name. The French 
 generally prefer the latter, English philosophers the former element of 
 nomenclature. — Translator. 
 
16 
 
 local colour,* the works of the ablest artists. Again, these 
 photographic delineations having been subjected, during 
 their formation, to the rules of geometry, shall enable us, 
 with the aid of a few simple data, to ascertain the exact di- 
 mensions of the most elevated parts, and of the most inac- 
 cessible edifices. 
 
 These reminiscences, in which, if I am not strangely mis- 
 taken, neither the philosophers nor the artists, so zealous 
 and so celebrated, who were attached to the army of the 
 East, can detect the shadow of blame, will doubtless recall 
 the thoughts to those labours now carrying on in our own 
 land, under the superintendence of the Commission of Ancient 
 Monuments. At a glance, each of you, Gentlemen, will per- 
 ceive the important part which these photographic processes 
 are destined hereafter to assume in this great national enter- 
 prise. Each will comprehend, also, that the new method 
 will be distinguished by economy, — a species of merit, be it 
 observed, rarely combined in the arts with perfection of result. 
 
 If, finally, it be asked, can art viewed in its own interests be 
 expected to derive advancement from the examination, from 
 the study of those forms designed by the most subtile, the 
 most refined agency in nature — the rays of light? — M. Paul 
 Delaroche shall reply to the question. 
 
 In a letter written at our request, this celebrated painter 
 declares that the processes of M. Daguerre “ carry to such 
 perfection certain of the essential principles of art, that they 
 must become subjects of study and observation, even to 
 most accomplished artists.” What strikes him in the photo- 
 graphic designs is, that the finish “ of inconceivable minute- 
 ness disturbs, in no respect, the repose of the masses, nor 
 impairs, in any manner, the general effect.” “ The correct- 
 ness of the lines,” remarks M. Delaroche, in another place, 
 
 * I confess myself at a loss exactly to comprehend what M. Arago 
 here means by the expression couleur locale. Photographic designs 
 have no local colour. — Translator. 
 
“ the precision of the forms in the designs of M. Daguerre, 
 are as perfect as it is possible they can be, and yet, at the 
 same time, we discover in them a broad and energetic 
 manner, and a whole equally rich in tone as in effect. The 
 painter will obtain by this process a quick method of making 
 collections of studies, which be could not otherwise procure 
 without much time and labour, and in a style very far in- 
 ferior, whatever might be his talents in other respects.” After 
 combatting, by excellent arguments, the opinions of those 
 who have imagined that photography will be injurious to our 
 artists, and especially to our able engravers, M. Delaroche 
 finishes his letter with this reflection, “ In conclusion, the 
 admirable discovery of M. Daguerre, is an immense service 
 already rendered to art.” We shall not commit the unpar- 
 donable fault of adding anything to such a testimony. 
 
 It will doubtless be remembered that among the inquiries 
 proposed in the commencement of this Report was the ques- 
 tion, — Are the photographic methods likely to become 
 generally applicable ? 
 
 Without divulging what is, and what ought to remain a 
 secret until the passing of the Bill, we may state that the 
 tablets upon which the light delineates the admirable designs 
 of M. Daguerre are plated surfaces, that is to say, sheets 
 of copper covered with a thin coating of silver. It had 
 unquestionably been preferable for the convenience of travel- 
 lers, and also on the score of economy, could paper have 
 been here employed. Paper impregnated with a solution of 
 chloride or nitrate of silver was in fact the substance first 
 selected by M. Daguerre. The want of sensibility, however, 
 in this preparation, the confusion of images it produced, the 
 uncertainty of the results, and the accidents which often 
 marred the operation of transforming the lights into shadows, 
 and the shadows into lights, could not fail to discourage so 
 able an artist. Had he persisted in this first intention, his 
 photographic designs might perhaps have figured in collec- 
 
18 
 
 tions as the productions of a curious philosophical experiment, 
 but assuredly they never would have occupied the attention 
 of this House. Besides, if three or four francs, the price of a 
 single plate such as M. Daguerre employs, appear too much, 
 it is but just to add that the same plate is capable of receiv- 
 ing in succession a hundred different designs. 
 
 The remarkable success of M. Daguerre’s actual method 
 depends in part on the fact that he operates upon a coating of 
 matter of extreme tenuity — on a veritable pellicle. It needs 
 not then that we waste time upon the price of the ingredients 
 of which this surface is composed. This price, from its 
 smallness, would in reality be unassignable.* 
 
 A single member only of the commission has seen the 
 artist operate, and has operated himself. It will then be 
 upon the personal responsibility of this Deputy that we can 
 occupy the attention of the House with details of the 
 Daguerreotype, viewed in reference to its simplicity of appli- 
 cation. 
 
 The Daguerreotype, then, does not demand a single manipu- 
 lation which is not perfectly easy to every person. It requires 
 no knowledge of drawing, and does not depend upon any 
 manual dexterity. By observing a few very simple directions, 
 any one may succeed with the same certainty and perform as 
 well as the author of the invention. The promptitude of the 
 method is perhaps that which has most astonished the public. 
 In reality ten or twelve minutes in the dull weather of winter 
 are amply sufficient for taking a view of a monument, a section 
 of a town or a landscape. In summer this time may be 
 reduced one-half. Under the skies of the south not more 
 than two or three minutes will be necessary. 
 
 * The invention, however, is likely to suffer in its practical application 
 from the high price set upon the apparatus at present in Paris, about 20 1 . 
 From the descriptions now to be given it may be constructed cheaply, and 
 by any one. “ The thickness of the coating,” observes a French philo- 
 sopher, “will be estimated when we shall be able to weigh light, or find 
 a third proportional between time and eternity.” — Translator. 
 
19 
 
 But it is of importance to remark, that these ten or twelve 
 minutes in winter, these five or six minutes in summer, these 
 two or three minutes in southern regions, express merely the 
 time during which the plate of metal is exposed to the len- 
 ticular image. To this space must be added the time of 
 unpacking and adjusting the camera, the time spent in pre- 
 paring the plate, and the few minutes necessary for the final 
 operation of rendering the picture thus obtained insensible 
 to the future action of light. Added together, all these 
 different stages of the process may extend the whole period 
 employed to thirty minutes, or three quarters of an hour. 
 Those persons are deceived, then, who suppose that during 
 a journey they may avail themselves of brief intervals while 
 the carriage slowly mounts a hill, to take views of a country. 
 They also are not less mistaken, who, struck by the curious 
 results sometimes produced by the adhesion of the pages, 
 or the pressure upon the engravings in very old books, have 
 cherished dreams of reproducing and multiplying photo- 
 graphic designs by lithographic impressions. It is not in the 
 moral world alone that the very perfection of certain qualities 
 tends to defects ; the maxim often finds its application in the 
 world of art. To the perfect polish, the incalculable tenuity 
 of the coating upon which M. Daguerre operates, are to be 
 ascribed the finish, the grace, the harmony of these photo- 
 graphic designs ; and to rub, to finger such designs, to sub- 
 ject them to the action of the press or roller, would cause 
 their irreparable destruction. But who ever thought of 
 forcibly pulling a ribbon of lace, or brushing the wing of a 
 butterfly ? 
 
 The academician who has for some months known the 
 secret of the preparations upon which the beautiful designs 
 submitted for our inspection are pencilled, has notyet thought 
 himself entitled to put to account M. Daguerre’s honourable 
 confidence. He has deemed it no more than proper deli- 
 cacy, before entering upon the wide field of research opened 
 
20 
 
 to philosophers by the photographic processes, to wait until 
 a national remuneration shall have placed in the hands of 
 all equal means of investigation. We can do little more, 
 therefore, in speaking of the scientific utility of our country- 
 man’s discovery, than proceed upon conjecture. The facts 
 as to the rest are clear and palpable, removing all fear of our 
 being deceived in their consequences. 
 
 The preparation employed by M. Duguerre is a re-agent 
 much more sensible to the action of light than any other 
 hitherto in use. Never have the rays of the moon, we do 
 not say in a natural state, but even when concentrated by 
 the most powerful lens, or in the focus of the largest reflector, 
 been capable of producing any perceptible physical effect. 
 The plated discs prepared by M. Daguerre, on the contrary, 
 receive impressions from the action of the lunar rays and 
 the succeeding operations to such an extent as permits the 
 hope that we shall be in a situation to make photographic 
 charts of our satellite. In other words, in a few minutes 
 we shall be able to execute one of the longest, most tedious, 
 and most delicate operations of astronomy. 
 
 An important branch of the sciences of experiment and 
 calculation, — that which treats of the intensity of light, or 
 photometry, has hitherto made little progress. The philo- 
 sopher approaches pretty nearly to the determination of the 
 comparative intensities of two luminous sources when near 
 each other, and simultaneously visible ; but the means of 
 ascertaining this relation are imperfect when the condition 
 of simultaneity does not exist — when the question regards a 
 light visible at present, and one which will not be seen till 
 after the first has disappeared. 
 
 The artificial lights, to which as standards of comparison 
 the observer in the case in question is reduced to have recourse, 
 seldom maintain the requisite permanence and steadiness; 
 nor, more particularly as respects the stars, do our artificial 
 lights possess the necessary whiteness. From these causes, 
 
21 
 
 there exist very great discrepancies between the determinations 
 of the comparative intensities of the sun and moon, — of the 
 sun and stars, as given by men of equal scientific acquire- 
 ments. Thence also the sublime inferences deducible from 
 these latter comparisons, in relation to the humble place 
 occupied by our luminary amid the millions of suns with 
 which our firmament is studded, are still veiled in reserve, 
 even in the works of those authors whose least fault is 
 timidity. 
 
 Let us not hesitate, then, to announce the fact; the re-agents 
 discovered by M. Daguerre will speed onwards the progress 
 of those sciences which confer the highest honour on the 
 human mind. By their aid the philosopher will be enabled 
 henceforth to proceed on the principle of absolute intensities ; 
 he will compare lights by their effects. If he find it useful, 
 the same tablet will present him with the impression of the 
 dazzling beams of the sun, and with the pencillings of rays 
 three hundred thousand times fainter than those of the moon 
 — the rays of the stars. These different imprints he will 
 equalize, either by reducing the stronger lights, — through 
 means of excellent methods, the result of recent discoveries, 
 the explanation of which would be here misplaced, — or by 
 allowing the brightest rays to operate, say, only for a second, 
 and continuing according to circumstances the action of the 
 others for half an hour. In short, when observers apply a new 
 instrument to the study of nature, what they expected from 
 it has always proved little indeed compared with the series 
 of discoveries which the instrument originated. In this 
 instance it is upon the unforeseen that we are especially to 
 reckon. Does this sentiment appear paradoxical ? Some 
 references will demonstrate its justness. 
 
 Some children casually attached two glass lenses of diffe- 
 rent focus to the opposite extremities of a tube. They thus 
 produced an instrument which enlarged distant objects, and 
 represented them as if near at hand. Observers of more skill 
 
22 
 
 applied it with the sole — the modest hope — of seeing the stars 
 a little better — stars known from the remotest antiquity, but 
 which till then men had been able to study very imperfectly. 
 Scarcely, however, is this chance gift turned towards the 
 firmament, than myriads of new worlds are discovered. 
 Searching into the constitution of the six planets known to 
 the ancients, these observers find it to be analogous to the 
 earth’s — by mountains whose altitude they measure — by atmo- 
 spheres whose vicissitudes they trace, — by the phenomena of 
 the melting and renewing of polar snows, similar to those of 
 the terrestrial poles, — by rotatory movements corresponding 
 to those which here below regulate the alternations of day 
 and night. Directed to Saturn, the tube of the children of 
 the Middleburgh spectacle-maker disclosed there a pheno- 
 menon the strangeness of which exceeded whatever the most 
 enthusiastic imaginings had been able to realize. 
 
 We mean that ring — or, if the expression be better — that 
 bridge without supports, 71,000 leagues in span, and 
 
 11.000 leagues in breadth, which environs on every side the 
 globe of the planet, without approaching it in any part 
 nearer than 9,000 leagues. Had any one foreseen, that, 
 applied to the observation of Jupiter’s four moons, this tube 
 would enable us to detect the rays of light in their speed of 
 
 80.000 leagues per second, — that attached to graduated in- 
 struments it would serve to demonstrate the existence of no 
 stars whose light comes to us in less than three years — that in 
 short, following out with its assistance certain observations, 
 certain analogies we should have attained within immense 
 probability, — the conclusion that the ray by which at any 
 given instant we descry certain nebulosities has parted on 
 its journey from these regions several millions of years 
 before, — in other terms, that these nebulosities from the suc- 
 cessive propagation of light would be visible from the earth 
 several millions of years after their entire annihilation ! 
 
 The telescope for near objects — the microscope — would fur- 
 
23 
 
 nish subjects of remarkable analogies, for nature is not less 
 admirable in her minuteness than in her immensity. Applied 
 at first to the observation of certain insects whose forms 
 naturalists wished merely to enlarge in order more correctly 
 to reproduce them by the graving tool, the microscope un- 
 veiled, subsequently and unexpectedly, in air, in water, in 
 all liquids those animalcules, those infusories, those strange 
 reproductions in which we may one day hope to grasp the first 
 principles of a rational explanation of the phenomena of life. 
 Recently directed to the minute fragments of different stones 
 hitherto ranked among the hardest, the most compact of which 
 the crust of our globe is composed, the microscope has dis- 
 closed to the eyes of astonished observers the fact that these 
 stones have lived — that they are a compost formed of millions 
 of millions of microscopic animals kneaded together. 
 
 This digression, it will be recollected, was intended to un- 
 deceive those who would wrongfully shut up the scientific 
 applications of M. Daguerre’s processes, within the circuit of 
 what is actually known, the outline of which we have traced. 
 But we hope differently — and do not facts already justify our 
 anticipations ? We might speak, for example, of certain ideas 
 which we entertain of methods of rapid investigation which 
 topography might borrow from photographical principles. 
 I shall attain my object more directly, however, by intro- 
 ducing here a curious remark related to us yesterday by M. 
 Daguerre. According to his observations, the hours of the 
 morning and those of the evening equally distant from mid- 
 day, and consequently corresponding to the same altitudes 
 of the sun above the horizon, are not alike favourable to the 
 production of photographic images. For example, at all sea- 
 sons of the year, and under circumstances of atmospherical 
 influence in appearance the same, images are formed with 
 more rapidity at eleven o’clock in the morning than at five in 
 the afternoon, at eight o’clock than at four, at nine than at 
 three. Let us suppose this result verified, and the meteor- 
 
24 
 
 ologist obtains an additional principle, one element more than 
 he possessed for the construction of his tables. Thus, to 
 former observations on the state of the thermometer, baro- 
 meter, hygrometer, and transparency of the atmosphere, there 
 remains to be added an element not detected by the instru- 
 ments previously in use, — an account must be taken of a par- 
 ticular absorption, which cannot be without influence upon 
 many other phenomena, on those even connected with phy- 
 siology and medicine. 
 
 Gentlemen ; we have thus endeavoured to collect into 
 one view, whatever the discovery of M. Daguerre presents 
 that is most interesting under the four heads of Novelty, 
 Utility to the Arts, Rapidity of Execution, and the valuable 
 resources which it offers to science; we have earnestly laboured 
 to make you participate in our convictions, because these are 
 lively and sincere, — because we have examined all, — studied 
 all with the sacred faithfulness imposed upon us by your 
 suffrages — because, had it been possible to misconceive the 
 importance of the Daguerreotype and the place it is destined 
 to hold in the estimation of men, all our doubts would have 
 ceased on perceiving the eagerness of foreign nations to lay- 
 hold of an erroneous date, of a doubtful fact, of the slightest 
 pretext, in order to stir up questions of priority for the 
 purpose of adding to their own crown of discovery, the 
 beautiful ornament which the photographic inventions will 
 ever form. Let us not forget to proclaim that all discussion 
 on this point is now at an end, and must cease, less from 
 the claims to authentic priority produced by MM. Niepce 
 and Daguerre than by reason of the incredible perfection of 
 the results at which M. Daguerre has arrived.* 
 
 Were it necessary, we could easily produce here the evi- 
 dence of the most eminent men in England and Germany, 
 before whose praise all that we have said in favour of our 
 
 * The Translator had marked this for a long note, but time presses. 
 
25 
 
 countrymen would fade as into nothing. This discovery France 
 has adopted ; from the first moment she has cherished a 
 pride in liberally bestowing it — a gift to the whole world. 
 Still we were far from being surprised at a sentiment almost 
 generally entertained by the public, arising from a passage in 
 the first exposition laid before this House, which, being misap- 
 prehended, seemed to imply that the Administration had 
 trafficked with the inventor — that the pecuniary conditions 
 of the contract now proposed for your sanction were the result 
 of a chaffering. Gentlemen, it is of importance to place 
 these facts in their proper light. 
 
 The member of this Chamber to whom the Ministry gave 
 full powers never bargained with M. Daguerre. Their 
 communications had solely for object to determine whether 
 the recompense so justly due to the accomplished artist 
 should be a pension or a sum paid at once. From the 
 first, M. Daguerre perceived that the payment of a stipu- 
 lated sum might give to the transaction the base character of 
 a sale. The case was different with a pension. By a pen- 
 sion you recompense the warrior who has been wounded 
 in the field, and the magistrate who has grown grey on 
 the Bench ; it is thus that you honour the families of 
 Cuvier — of Jussieu — of Champollion. Reflections like these 
 could not fail to present themselves to a man of his exalted 
 character, and M. Daguerre decided on a pension. All 
 other arrangements were left to the Minister for the Home 
 Department. M. Daguerre himself fixed the amount at 
 
 8.000 frs .* to be divided equally between himself and 
 his partner, M. Niepce, jtinr. The proportion payable to 
 M. Daguerre has since been raised to 6,000 frs. (making 
 
 10.000 in all), both on account of the condition specially 
 imposed upon that artist of publishing the secret of painting 
 and illuminating the Dioramic views, and making known all 
 future improvements with which he may enrich his photo- 
 
 * Three hundred guineas, 
 c 
 
26 
 
 graphic methods.* The importance of this latter engage- 
 ment will certainly not appear doubtful to any person 
 when we inform you, for instance, that a very slight advance 
 beyond his present progress will enable M. Daguerre to 
 apply his processes to executing portraits from life. Far 
 from fearing that M. Daguerre will leave to other ex- 
 periments the care of'adding to his actual success, we have 
 rather sought how to moderate his ardour. Such, and 
 we frankly confess it, was the motive which induced us 
 to desire that you would declare the pension unattachable 
 and unalienable. This amendment, however, we now per- 
 ceive to be unnecessary, an existing law recognising the 
 principle. 
 
 Your commission have now only to recommend unani- 
 mously that you adopt simply, and without alteration, the 
 bill proposed by the Government. 
 
 CHAMBER OF PEERS. 
 
 Sitting of the 30th July, 1839. 
 
 Report presented to the Chamber by M. Gay Lussac, in 
 name of a special commission charged with the exami- 
 nation of the Bill relative to the purchase of the 
 process of M. Daguerre for fixing the images of the 
 Camera Obscura.f 
 
 My Lords, 
 
 Whatever conduces to the progress of civilization, to the 
 physical or moral well-being of man, ought to be the con- 
 stant object of the solicitude of a Government alive to the 
 
 * Note 5. 
 
 t The Special Commission was composed of the following Peers : 
 Barons Athalin, Besson, Gay Lussac, the Marquis De Laplace, Vicomte 
 Simeon, Baron Thenard, and the Comte de Noe. 
 
27 
 
 grandeur of those destinies which have been confided to 
 its care ; and they who by happy efforts aid this noble 
 cause, ought to obtain honourable rewards for their success. 
 
 Thus already do the laws, guardians of property in liter- 
 ature and the useful arts, secure to the authors benefits cor- 
 responding to the services rendered to society — a mode of 
 remuneration so much the more just, so much the more 
 honourable, that it resolves itself into a contribution purely 
 voluntary in exchange for services rendered — and that it is 
 independent of the caprices of favour. 
 
 If, however, this mode of encouragement be the best in 
 the majority of instances, there are some cases in which it 
 is impracticable or at least insufficient ; and finally there 
 are others in which great discoveries demand the most 
 splendid and solemn recompenses. 
 
 My lords, the discovery of M. Daguerre appears to us, 
 and such it has been considered both by His Majesty’s Go- 
 vernment who have made it the subject of a Bill now laid before 
 you, and by the Chamber of Deputies, who have already 
 given to the Bill their legislative sanction. 
 
 The discovery of M. Daguerre is known to you by its 
 results submitted to the House ; and by the Report pre- 
 sented to the Chamber of Deputies by the illustrious philoso- 
 pher to whom the secret had been confided. It is the art of 
 fixing the image itself produced by the camera obscura on a 
 metallic surface, and preserving it on the tablet. 
 
 We hasten, however, to explain, without wishing in 
 aught to lessen the merit of this beautiful invention, that 
 the palette of the painter is not very rich in colour — black 
 and white compose the whole. The image in its natural 
 and varied colours may remain long — perhaps for ever — a 
 thing hidden from human sagacity. But let us not rashly 
 circumscribe knowledge within impassable bournes. The suc- 
 cessful efforts of M. Daguerre have disclosed a new order of 
 possibilities. 
 
 c 2 
 
28 
 
 Called to state our opinion of the importance and conse- 
 quences of M. Daguerre’s invention, we have formed that 
 opinion on the perfection of the results — on the report of M. 
 Arago to the Chamber of Deputies — and on fresh commu- 
 nications received both from that philosopher and from the 
 inventor himself. Our conviction then as to the importance 
 of the new process is complete, and we should be happy 
 could we persuade the House to participate in the same per- 
 suasion. 
 
 It is certain that through the discovery in question the 
 Physical Science of the present day has obtained possession 
 of a re-agent sensible in a very extraordinary degree to luminous 
 influences — of a new instrument which will become, for the 
 intensity of light and all the phenomena of luminous bodies, 
 what the microscope is for minute objects — which will 
 supply means for new researches and further discoveries. 
 Already this re-agent has been impressed very distinctly by 
 the feeble light of the moon, and the hope is entertained 
 that a lunar chart may be traced by the Satellite herself. 
 
 My Lords, you have had an opportunity of convincing 
 yourselves by proofs submitted to your inspection, that 
 has reliefs, statues, monuments, in a word, inanimate 
 nature can be rendered, with a degree of perfection un- 
 approachable by the ordinary processes of drawing and 
 painting — a perfection equal to that of nature, since 
 the impressions obtained are in reality a faithful image of 
 nature herself. 
 
 The perspective of a landscape — of every object — is repro- 
 duced with mathematical exactness : no occurrence, no 
 feature — even though unperceived — can escape the eye and 
 pencil of this new painter; and as a few minutes are sufficient 
 for his work, even a field of battle in all its phases may be 
 delineated with a precision unattainable by any other means. 
 
 The arts of industry — for the representation of forms ; 
 linear design — for perfect models of perspective and the 
 
29 
 
 distribution of light and shadow ; the natural sciences — 
 for the study of species and their organization, — all will 
 certainly make numerous applications of the new processes. 
 In fine, the problem of its adaptation to portrait painting 
 is almost resolved, and the difficulties which yet remain to 
 be overcome being ascertained, seem to imply no doubt of 
 success. Nevertheless, it must not be forgotten that 
 coloured objects are not reproduced with their proper 
 tints, and that the different luminous rays acting in the 
 same manner upon M. Daguerre’s re-agent, the harmony 
 of light and shadow in coloured objects is necessarily 
 impaired. This is a line of demarcation traced by Nature 
 herself to the new system. 
 
 Such, my Lords, are the acquisitions already secured 
 by this discovery — such the hopes on the point of being 
 realized. Information, however, was required relative to the 
 practical application of the process, and the Commission 
 thought that it could not be obtained from a surer or 
 more authentic source than the mouth of the honourable 
 Deputy on whom the discoverer had first bestowed his 
 confidence, and at a later period, from the Minister for 
 the Home Department. M. Arago, on the request of the 
 President of your Commission, has, in the other House, 
 confirmed by new details the substance of his previous 
 interesting Report. 
 
 Thus it is certain that the application of Daguerre’s 
 method requires only a very short time, and after the first 
 outlay for the apparatus, about 400 f.* the expense is trifling. 
 After a very few trials every one must succeed without 
 fail in producing the most exquisite specimens of art. 
 M. Arago himself, for instance, after the secret had been 
 disclosed to him, executed, on his first essay, a master-piece, 
 which we should have seen here, had it not perished in 
 the flames when the Diorama was consumed. 
 
 * 12/. sterling. 
 
30 
 
 If additional evidence were needed, your Reporter might 
 add that M. Daguerre has made him also the depository of 
 his secret, and has described to him all its operations. He 
 can assure this House that the process is not expensive, and 
 that it can be easily executed by those unacquainted with 
 drawing, more especially after the instructions which M. 
 Daguerre will be bound to publish. 
 
 Your Reporter will further add, that although he has 
 not, like his honourable friend, M. Arago, repeated the 
 process, he considers it, from description, to be most difficult 
 in the discovery, and as requiring, in order to attain the 
 degree of perfection acquired by M. Daguerre, much time, 
 trials without number, and above all, that indomitable per- 
 severance which failure serves only to stimulate, and which 
 is never found but in great minds. The process in fact is 
 composed of various successive operations, to appearance not 
 necessarily connected, while the final result does not seem 
 progressively to advance after each, becoming visible only 
 when the whole series is concluded. Assuredly, had M. 
 Daguerre wished to keep his process secret, or confine it to 
 a few, its discovery by others was little to be apprehended. 
 But it may now perhaps be asked, and indeed the questions 
 have been urged, — Why, seeing his process is so difficult in the 
 discovery, has not M. Daguerre preferred retaining it ; and 
 why, in the face of so many wise laws, protective of rights 
 such as this, does government propose to purchase the 
 secret, in order to publish it to the world ? We will reply 
 to these two inquiries. 
 
 The principal advantage of Daguerre’s process consists in 
 obtaining quickly and yet with the utmost exactness, repre- 
 sentations of objects, whether to preserve this identical image, 
 or to reproduce it by engraving or lithography. Hence, 
 it is conceived that, limited to the possession of a single indi- 
 vidual, an art like this could not find sufficient exercise. 
 
 On the contrary, given to the public, this process will 
 
31 
 
 receive in the hands of the painter, architect, traveller, natu- 
 ralist, innumerable applications, all more or less useful to 
 mankind. Lastly, as the secret of an individual, the inven- 
 tion itself would long remain stationary, and, perhaps might 
 retrograde ; rendered public it will be extended and improved 
 by a general emulation. 
 
 Thus, from these various considerations, it was thought 
 desirable that this process should become public property. 
 From a different motive it merited the attention of govern- 
 ment, and ought to procure for its author a conspicuous 
 reward. 
 
 To those who are not insensible to national glory, — who 
 know that a people shine with greater splendour among the 
 nations of the earth, only as they have realized a higher 
 advancement in civilization — to those we say, the process of 
 M. Daguerre is a noble discovery. It is the origin of a new 
 art in the midst of an old civilization ; an art which will 
 constitute an era, and be preserved as a title of glory ; 
 And shall it descend to posterity companioned by ingratitude ? 
 Let it rather stand forth a splendid evidence of the protec- 
 tion which the Chambers — the Government of July — the 
 whole country afford to great inventions. 
 
 It is in reality an act of national munificence which con- 
 secrates the Bill in favour of M. Daguerre. We have given 
 it our unanimous assent, yet not without marking how ele- 
 vated and honourable is a reward voted by the country. 
 And this we have done on purpose to remind the nation, — 
 not without some sad remembrances — that France has not 
 always shown herself so grateful, and that too many useful 
 labours — too many works of genius — have often procured for 
 their authors only a barren glory. These are not accusations 
 which we urge, — they are errors which we deplore in order 
 now to avoid a new one. 
 
 My Lords, after having appreciated, to the best of our 
 judgment, the importance of the discovery of M. Daguerre, 
 
32 
 
 we rest convinced that it is new, full of interest, rich in con- 
 sequences, and finally that it is worthy of the distinguished 
 honour of the national remuneration which has already been 
 voted in the Chamber of Deputies. The Commission is 
 unanimous for adopting the Bill simply and without al- 
 teration. 
 
33 
 
 CHAPTER IT. 
 
 So early as 1814, M. Niepce engaged in a series of experi- 
 ments to determine the possibility of fixing the images in 
 the camera obscura ; but more particularly to perfect his 
 methods of copying engravings, applied upon substances sen- 
 sible to the influence of light. 
 
 In 1824, M. Daguerre also was making researches of an 
 analogous description, with this difference, that his experi- 
 ments were directed solely to the fixation of the image 
 obtained by the camera, for he regarded the copying of 
 engravings by these processes as of no importance to art. 
 
 In 1829, M. Daguerre entered into partnership with M 
 Niepce in order that they might prosecute the subject in 
 common. 
 
 M. Niepce had named his discovery Heliography,* and 
 wrote a description of it to be communicated to M. Daguerre. 
 To this account which follows, M. Daguerre now adds a few 
 notes, chiefly including his remarks made to M. Niepce 
 himself. These notes are not produced for the purpose of 
 criticism, but simply with a view to explain the true state 
 of photogenic science when this partnership was formed. 
 From the description of Niepce, his method might other- 
 wise appear to have reached a degree of perfection, which, 
 with all the subsequent improvements even, it is very far 
 from having yet attained. 
 
 * Delineation by the sun. 
 
 c 5 
 
34 
 
 “ DESCRIPTION OF HELIOGRAPHY, BY J. N. NIEPCE. 
 
 The discovery which I have made, and to which I give the 
 name Heliography, consists in reproducing spontaneously by 
 the action of light, with gradations of tints from black to 
 white,* the images received by the camera obscura. 
 
 Fundamental Principle of the Discovery . 
 
 Light, in its state of composition and decomposition, acts 
 chemically upon bodies. It is absorbed, it combines with 
 them, and communicates to them new properties. Thus it 
 augments the natural consistency of some of these bodies: 
 it solidifies them even, and renders them more or less insolu- 
 ble according to the duration or intensity of its action. 
 
 Such, in a few words, is the principle of the discovery. 
 
 Primary Material. — Preparation. 
 
 The substance or primary matter I employ, — that which 
 has succeeded best with me, and which concurs most imme- 
 diately to produce the effect is Asphaltum or Bitumen of 
 Judea, prepared in the following manner. 
 
 I fill a wine-glass about half with this pulverised bitumen. 
 I pour upon it drop by drop the essential oil of lavender till 
 the bitumen can absorb no more, and till it be completely 
 saturated. I afterwards add as much more of the essential 
 oil as causes the whole to stand about three lines above the 
 mixture, which is then covered and submitted to a gentle 
 heat until the whole essential oil be saturated with the colour- 
 ing matter of the bitumen. If this varnish should not yet 
 possess the requisite consistency, it is to be allowed to 
 evaporate atmospherically in a shallow dish, care being taken 
 
 * The clearest tint which is obtained by this process is not white . — 
 M. Daguerre. 
 
35 
 
 to protect it from moisture, by which it is injured, and finally 
 decomposed. If in winter, or during rainy weather, the 
 precaution is doubly necessary. 
 
 A small quantity of this varnish applied cold, with a light 
 roll of very soft skin, to a highly polished tablet of plated 
 silver, will impart to it a fine vermilion colour, and will 
 cover it with a very thin and equal coating ;* the plate is 
 afterwards to be placed upon heated iron, which is wrapped 
 round with several folds of paper, whence by this means all 
 the moisture has previously been expelled. When the var- 
 nish has ceased to simmer, the plate is withdrawn, and left 
 to cool and dry in a gentle temperature, secured against 
 contact with a damp atmosphere. I ought not to omit 
 mentioning that it is principally in applying the varnish that 
 this last precaution is indispensable. In this part of the 
 operation, a light circle of metal, with a handle in the 
 centre, should be held before the mouth in order to condense 
 the moisture of the respiration. 
 
 The plate thus prepared may be immediately submitted in 
 the focus of the camera to the impressions of the luminous 
 fluid. But even, after having been thus exposed, a length 
 of time sufficient for receiving the impressions of external 
 objects, nothing is externally apparent to show that these 
 impressions exist. The forms of the future picture remain 
 still invisible. + The next operation then is to disengage the 
 shrouded imagery, and this is accomplished by a sol- 
 vent. 
 
 * It is impossible by any such means to spread a coating sufficiently 
 equal to obtain in the camera that delicacy required by the modifications 
 of light. — M. Daguerre. 
 
 f If the image were altogether invisible, there could be no result. 
 M. Niepce means that the impression is extremely feeble, but if there 
 be no appearance of action at all, the operation has not succeeded. — 
 M. Daguerre. 
 
36 
 
 Of the Solvent, and Manner of its Preparation. 
 
 As the solvent must be adapted to the purposes for 
 which it is designed, the task is difficult to fix with certainty 
 the proportions of its components ; but in all cases it is 
 better that it be too weak than too strong.* That which I 
 employ in preference, is composed of one part, not by 
 weight but volume, of essential oil of lavender poured upon 
 ten parts, by measure also, of oil of white petroleum. The 
 mixture which is first of a milky consistency, becomes per- 
 fectly clear in two or three days. This compound will act 
 several times in succession. It loses its dissolving power 
 only when it approaches the point of saturation ; this state 
 is readily distinguished by an opaque appearance and dark 
 brown colour. 
 
 The plate or tablet varnished as described, and exposed as 
 directed, having been withdrawn from the camera, a vessel 
 of tinned iron somewhat larger than it, and about an inch 
 deep, is previously prepared and filled with the solvent to 
 a depth sufficient to cover the plate. Into this liquid the 
 tablet is plunged, and the operator, observing it by reflected 
 light, begins to perceive the images of the objects to which 
 it had been exposed, gradually unfolding their forms, though 
 still veiled by the supernatant fluid continually becoming 
 darker from saturation with varnish. The plate is then lifted 
 out and held in a vertical position till as much as possible of 
 the solvent has been allowed to drop away. When the 
 dropping has ceased, we proceed to the last and not least 
 important operation. 
 
 Washing. — Manner of Procedure. 
 
 A very simple apparatus answers for this operation, namely, 
 a board about four feet long, and somewhat broader than 
 
 * These two extremes have their respective inconveniences. In the 
 former the image does not re- appear with sufficient brilliancy; in the 
 latter it is completely destroyed. — M. Daguerre. 
 
37 
 
 the tablet. Along each side of this board runs a ledge or 
 border projecting two inches above its surface. It is fixed 
 to a support by hinges at its upper extremity, in such a 
 manner as permits its angle of inclination to be varied at 
 pleasure, that the water thrown upon it may run off with the 
 requisite velocity. The lower end rests upon the vessel 
 intended to receive the water as it flows down. 
 
 The tablet is carefully placed upon the board thus inclined, 
 and is prevented from slipping down by two little blocks, 
 which ought not to exceed the thickness of plate, that there 
 may be no ripple in the descending stream. Tepid water 
 should be used in a cold day. The water must by no means 
 be poured directly upon the plate, but above it on the 
 board, so that descending in a stream it may clear away 
 all the remaining solvent that may yet adhere to the 
 varnish. 
 
 Now, at length, the picture is completely disengaged, and 
 if the different operations have been carefully performed, the 
 outlines will be found to possess great neatness, especially if 
 the images have been received in a camera with achromatic 
 lenses.* 
 
 When the plate is removed to be dried, which must be 
 done with great care, by a gentle evaporation, it must be 
 kept protected from humidity, and covered up from the 
 action of light. 
 
 Applications of the Heliographic Processes. 
 
 The varnish employed may be applied indifferently to 
 stone, metal, and glass, without any change in the manipu- 
 lation. I shall speak, however, only of its application to 
 plated silver and glass ; as to impressions on copper, I may 
 just state that a small quantity of wax dissolved in essential 
 
 * Here M. Niepce seems to speak hypothetically ; for experience 
 proves that the achromatic camera, though it gives greater purity to the 
 images, does not impart that superior neatness and sharpness to the 
 outlines which were anticipated from its operation. — M. Daguerre. 
 
38 
 
 oil of lavender, may in this case be added with advantage 
 to the varnish already described.* 
 
 Of all substances hitherto tried, silver plated upon copper 
 appears to me to be the best adapted for reproducing images, 
 by reason of its whiteness and structure. One thing is certain, 
 that after the washing, provided the impression has been well 
 dried, the result obtained is already satisfactory. It were, 
 however, to be desired that, by blackening the plate, we 
 could obtain all the gradations of tones from black to white. 
 I have, therefore, turned my attention to this subject, and 
 employed at first liquid sulphate of potassa. But, when 
 concentrated, it attacks the varnish ; and, if reduced with 
 water, it only reddens the metal. This twofold defect obliged 
 me to give it up. The substance which I now employ is 
 iodine, t which possesses the property of evaporating at 
 the temperature of the atmosphere. In order to blacken the 
 plate by this process, we have only to place it upright against 
 one of the sides of a box, open above, and place some grains 
 of iodine in a little groove cut in the bottom, in the direction 
 
 * It is necessary to remark that the “ impressions on copper,” of 
 which M. Niepce here speaks, have reference solely to copies of en- 
 gravings placed above the prepared plate, and thus exposed to the full 
 action of the sun’s light. The application of the wax, as mentioned by 
 him, would have neutralized the effect of the decomposition of the bitu- 
 men in the camera into which the light enters, much weakened. But 
 the presence of this wax was not an obstacle in copying engravings 
 exposed three or four hours to the direct rays of the sun. — 
 M. Daguerre. 
 
 f It is of importance to point out to the reader that the use of iodine 
 here made by M. Niepce only to blacken his plates, proves that he was 
 not acquainted with the property possessed by this substance, when in 
 contact with silver, of being decomposed by light. On the contrary, he 
 used it as a means of fixing his sketches. — M. Daguerre. 
 
 [Daguerre’s own method, as the reader will hereafter understand, 
 depends on this decomposition of iodine. This is the great distinction 
 between the old and new processes — between Niepce’s and Daguerre’s 
 systems — in a word, between the approximation and the real principle. — 
 Translator.] 
 
39 
 
 of the opposite side. The box is then covered with a glass, 
 to judge of the slow but certain effect. The- varnish may 
 then be removed by spirit of wine, and there no longer 
 remains any trace of the original impression. As this 
 process is still quite new to me, I confine my remarks to 
 this simple explanation, waiting till experience shall enable 
 me to enter upon more circumstantial details. 
 
 Two experiments in landscape upon glass, by means of 
 the camera, gave me results which, though very imperfect, 
 appear deserving of notice here, because this species of 
 application may be brought more easily to perfection, and 
 become in the sequel a most interesting department of 
 Heliography. 
 
 In one of these trials, the light having acted with less 
 intensity, removed the varnish in a way which exhibited 
 a more marked gradation of tone, so that, seen by trans- 
 mitted rays, the landscape produced, to a certain extent, 
 the well-known effects of the Diorama.* 
 
 In the second trial, on the contrary, in which the action 
 of the luminous fluid had been more intense, the parts acted 
 upon by the strongest lights, not having been attacked by 
 the solvent, remain transparent, and the difference of tones 
 results entirely from the relative thickness of the coatings 
 of varnish. 
 
 If this landscape be viewed by reflection in a mirror, on 
 
 * M. Daguerre does not see what relation can exist between the effect 
 here described by M. Niepce and the pictures of the Diorama. 
 
 [The reader will find in M. Daguerre’s own description of Dioramic 
 painting, that much of its surprising effect depends upon the transpa- 
 rency of the ground ; both reflected and transmitted illumination 
 throws light up, or, as the case may be, deadens the effect of these 
 pictures. A medium, or (if the expression be allowed) canvas of glass, 
 with a picture sketched in varnishes of different thickness, and, conse- 
 quently, different transparency, as in the case of Niepce’s experiment, 
 would produce the same result, though in a less degree, owing to the 
 absence of colour. — Translator.] 
 
40 
 
 the varnished side, and at a certain angle, the effect is 
 striking, while, seen by transmission, it presents only 
 confused and shapeless imagery ; but what is really sur- 
 prising, in this position the mimic tracery seems to affect 
 the local colours of certain objects.* 
 
 In reflecting upon this remarkable fact, I have sometimes 
 thought that consequences might thence be deduced connect- 
 ed with Newton’s theory of coloured rings. It is sufficient 
 further to suppose that any prismatic ray — the green ray for 
 instance — in acting upon the substance of the varnish and 
 combining with it, imparts the degree of solubility, which, 
 after the double operation of the solvent and the washing, 
 is required to reflect the green colour. But it remains for 
 experiment, which alone can decide, to determine what truth 
 there may be in this theory : but the circumstance appears 
 to me sufficiently interesting to excite new researches, and 
 to merit more profound enquiry. f 
 
 Observations and Additions. 
 
 Although doubtless there be nothing difficult in the pro- 
 cesses just described, yet it must not be expected that one 
 will succeed at once. I am of opinion then that it is better 
 to begin by copying engravings in full daylight, before 
 attempting the camera, and by a very simple procedure, as 
 follows : — 
 
 The engraving must be varnished, but on the back so as 
 to render it quite transparent. When perfectly dry it is 
 applied face upwards to a tablet prepared as already directed, 
 
 * M. Daguerre has often remarked this effect of colour, but could 
 never regard it as the effect of the coloured rays in the camera. 
 
 [M. Daguerre is right ; extremely thin laminae of all transparent 
 substances, as a coating of varnish upon glass, give forth prismatic rays, 
 on an optical principle obvious enough. — Translator.] 
 
 + [The reader will understand the importance attached to these trifling 
 indications of colour, on reflecting that to obtain colour as well as form, 
 is the great desideratum wanted to perfect the photographic process. — 
 Translator.] 
 
41 
 
 and made perfectly smooth and flat by means of a plate of 
 glass, and to diminish the pressure the apparatus is inclined 
 at ao angle of 45°. With two engravings thus prepared, and 
 four small tablets plated on both sides, one may make several 
 experiments in one day, even in the winter or in dull weather, 
 provided the apparatus be protected from the cold and mois- 
 ture which latter, I repeat, so injures the varnish as to detach 
 it in flakes from the plate when plunged into the solvent. 
 This prevents me from making use of the camera during the 
 winter season. By repeating these trials one will soon 
 become quite expert in all the processes of manipulation. 
 
 Respecting the manner of applying the varnish, I observe 
 that it ought to be of such consistence as will form a com 
 pact washing, and should be laid on as thin as possible. The 
 former quality enables it better to resist the solvent ; the 
 latter renders it more sensible to the solar action. With 
 regard to the iodine for blackening heliographic sketches, 
 just as in the case of acid for engraving on copper, it is 
 essential that the varnish after the washing be as described 
 in the second trial on glass, because the lights resist the 
 solvent in the one case, and the vapours of the iodine in the 
 other, that is, the resistance is greatest in those places which 
 are most transparent ;* and it is only on this condition, even 
 with the best apparatus, that one can hope completely to 
 succeed.! 
 
 * The sketch which gave rise to this remark was for a length of 
 time exposed to the action of light in the camera, and although M, 
 Niepce here speaks of iodine to blacken, and acid to engrave, supposing 
 the impression to be on copper, these two operations could have brought 
 out no gradation of tints. In reality the images having been obtained 
 by a greater or less degree of tenuity in the coatings of varnish, accord- 
 ing as it had been more or less acted upon by the light, it is impossible 
 that acid could act upon metal in a manner analogous. Neither 
 did M. Niepce ever make an engraving from a sketch obtained in the 
 camera. — M. Daguerre. 
 
 f The best optical apparatus could not remove the obstacle mentioned 
 in the preceding note. — M. Daugerre. 
 
42 
 
 In speaking of experiments made in open day, and without 
 the camera, I have said nothing of my experiments of this 
 kind on glass. I shall here supply this omission, that I may 
 not forget an improvement peculiar to this description of 
 heliography. It consists simply in placing a black paper 
 under the glass, and interposing a frame of pasteboard 
 between the varnished surface of the glass plate and the 
 engraving, which is previously to be well fixed and stretched 
 upon the frame. By this arrangement heliographic im- 
 pressions appear much more lively than upon a white ground, 
 and the effect is more speedily produced. Secondly, the 
 varnish is not liable to be injured by coming into immediate 
 contact with the back of the engraving, a disadvantage, 
 which otherwise in the case of the metal plate it is difficult 
 to avoid, especially in warm weather, the most favourable 
 season for these experiments. 
 
 But this inconvenience is amply compensated by the 
 superior strength which drawings upon silver plate possess 
 for enduring the process of washing ; while it is rare that 
 this operation does not more or less damage drawings upon 
 glass, a substance to which, from its high polish, the varnish 
 more weakly adheres. It becomes an object, then, how to 
 remedy this defect by giving more unctuosity to the varnish, 
 and this, I believe, I have accomplished, at least so far as I 
 can venture to infer from trials still too recent and too few 
 for perfect conviction. This new varnish is composed of 
 Bitumen from Judea dissolved in animal oil of Dippel, 
 which is allowed to evaporate by atmospheric temperature 
 till of the required consistency. This composition is more 
 unctuous, of greater tenacity, and higher colour than the 
 other, and after being applied it can immediately be sub- 
 mitted to the action of the light, which appears to render it 
 solid more quickly from the greater volatilityof the animal oil.* 
 
 * But this very property diminishes still farther the resources of the 
 process as respects the lights of the drawings thus obtained. — M. 
 Daguerre. 
 
43 
 
 I have retained a copy of this paper, and transmitted the 
 original to M. Daguerre, 5th December, 1829. 
 
 (Signed) J. N. NIEPCE.” 
 
 MODIFICATIONS AND IMPROVEMENTS MADE UPON THE 
 PRECEDING PROCESSES, BY M. DAGUERRE. 
 
 The substance which ought to be used in preference to 
 Bitumen is the residuum obtained by the evaporation of the 
 essential oil of lavender applied in an extremely thin wash 
 by means of dissolution in alcohol. 
 
 Although bituminous and resinous substances without any 
 exception are all endowed with the same property — that of 
 being affected by the influence of light, the preference ought 
 to be given to those which are the most unctuous, because 
 they impart greater adhesion to the drawings. Several 
 essential oils lose this character when they are exposed to 
 too strong a heat. 
 
 It is not, however, from its prompt decomposition, that 
 we are to prefer the essential oil of lavender. There are 
 rosins for instance, which being dissolved in alcohol, 
 and spread upon glass or metal, leave by the evapora- 
 tion of the spirit, a coating very white, and infinitely 
 more sensible to radiation, which is the cause of the de- 
 composition. But this greater sensibility to light caused 
 by a quicker evaporation, renders also the images thus ob- 
 tained more liable to injury from the very same agency 
 which created them. They grow faint, and finally disap- 
 pear altogether, when exposed even but for a few months to 
 the sun. The residuum of the essential oil of lavender, pos- 
 
44 
 
 sesses greater fixity, without, however, being altogether im- 
 pervious to the eroding effects of a direct exposure to the 
 sun’s light. 
 
 To obtain this residuum, the essence is evaporated in a 
 shallow dish by heat, till the residuum acquire such con- 
 sistency, that when cold it rings on being struck with the 
 point of a knife, and flies off in pieces when separated from 
 the dish. A small quantity of this material is afterwards 
 to be dissolved in alcohol, or ether ; the solution ought to be 
 very transparent, and of a citron-yellow colour. The clearer 
 the solution, the more delicate will be the coating on the 
 plate : it must not, however, be too clear, because it could 
 not thicken or spread out into a white coat — requisites indis- 
 pensable for obtaining a good effect in photographic designs. 
 The use of the alcohol in ether is merely to facilitate the ap- 
 plication of the residuum under a form of extreme tenuity 
 and division, for the spirit is entirely evaporated before the 
 light impresses its tracery upon the sketch. 
 
 In order to obtain greater vigour, the metal ought to be 
 burnished : sketches upon glass have more charm, and 
 above all, much greater delicacy. 
 
 Before commencing operations, the experimenter must be 
 careful to have his glass or metal perfectly clean. For this 
 purpose he may use alcohol with emery-powder exceedingly 
 fine, and applied by means of cotton wool ; but this part of 
 the process must always be concluded by dry-polishing, 
 that not a trace of liquid may remain. 
 
 The tablet being thus prepared, in order to supply the 
 wash or coating, the canvas of the future picture, the plate 
 of metal or glass is held in one hand, and with the other 
 pour upon it the solution, (which for this purpose should be 
 contained in a small flask with a wide mouth) so that it may 
 rapidly flow over, and cover the whole surface of the plate. 
 At first it is necessary to hold the plate a little inclined ; 
 but as soon as the solution is poured on, and has ceased to 
 
45 
 
 flow, the plate is raised perpendicularly. The finger is then 
 passed behind and below the plate, in order to draw off a 
 portion of the liquid which, tending always to ascend, would 
 double the thickness of the covering; the finger must be 
 wiped each time, and be passed very rapidly along the 
 whole length of the plate from below, and on the side op- 
 posite the coating. When the liquid has ceased to run, 
 the plate is put aside to dry in the dark, for otherwise the 
 light would destroy the sensibility of the preparation. 
 
 The coating being thus well dried, the plate may be placed 
 in the camera obscura. It is allowed to remain there a 
 sufficient time for the production of photographic images — a 
 space which cannot be determinately fixed, because it 
 depends upon the degree of intensity of the light cast upon 
 the objects to be delineated. However, for a landscape, the 
 time cannot be less than seven or eight hours, and about 
 three hours for single monuments or other objects which are 
 strongly illuminated by the sun, or otherwise very bright in 
 themselves. Still these data are but approximations, for 
 the seasons and the different hours of the day produce very 
 considerable modifications of the principles.* 
 
 When one operates on glass, it is necessary, in order to 
 increase the light, to place it upon a sheet of paper ; but, 
 that this reflection be not confused, we must place the surface 
 opposite the coated side, directly upon the paper, touching it 
 in every point. To accomplish this, we must previously 
 stretch the paper upon a perfectly flat board, having taken 
 care to select a plate, even in its surface, and very white in 
 colour. 
 
 When the sketch has remained the proper time in the 
 camera, it is to be withdrawn, care always being taken to 
 protect it from the light. 
 
 As it very often happens that on being removed from the 
 
 * See page 18, near the bottom. 
 
46 
 
 camera the plate gives no indication of the images traced 
 upon it, our next operation must be to evoke these hidden 
 forms.* 
 
 Provide a vessel of tinned copper or sheet-iron larger than 
 your tablet, and having all round a ledge or border 50 mille- 
 meters in depth. Fill this three-quarters full with oil of 
 petroleum ; fix your tablet by the back to a piece of wood 
 which completely covers the vessel of oil, placing it so that 
 the tablet, face downwards, is over but not touching the oil. 
 In this position the petroleum evaporating, penetrates entirely 
 the coating of the tablet in those places on which the action 
 of the light has been feeble, that is, in the portions of the 
 picture corresponding to the shadows, imparting to them a 
 transparency, as if nothing were there : those points, on the 
 contrary, upon which the light has acted with all its intensity, 
 and which consequently express the lights on the natural 
 objects represented, remain unchanged, because they resist 
 the action of the petroleum. 
 
 In this manner, the whole harmony and gradation of tints 
 are brought out by the varied action of the vapour upon the 
 coating of the tablet, in proportion as that has received the 
 impressions of light. 
 
 The design must be examined from time to time, and 
 withdrawn as soon as a vigorous effect is obtained. For, in 
 urging the action too far, even the strongest lights will be 
 attacked by the vaporization and will disappear, to the ruin 
 of the piece. The picture being finished, a glass is placed 
 over it as a protection against the dust, which is first to be 
 blown away if any has fallen upon the tablet during the 
 operation. Placing the designs under glass will also preserve 
 the silver plating from being injured by the vapours which 
 blacken or corrode the metal. 
 
 * [There seems to be here a contradiction between Daguerre’s 
 remarks on Niepce’s process and the description of his own improve- 
 ments. See M. Daguerre’s note, p. 35.- — Translator.] 
 
47 
 
 Recapitulation. 
 
 It has been remarked above, all bitumens, all resins, and 
 all residua of essential oils are decomposable by light in a 
 very sensible degree : to produce this effect it is only re- 
 quired to spread them in very thin coatings over a proper 
 surface, and to find a solvent which suits them. We may 
 employ as dissolvents oil of petroleum, all the essential oils, 
 alcohol, the ethers, and caloric. 
 
 M. Niepce plunged the tablet, covered with a varnish of 
 bitumen, into a liquid solvent. But such a mode of ap- 
 plying the solvent is rarely in harmony with the diminished 
 intensity of the light in photographic sketches obtained by 
 the camera. 
 
 It ever happens that the dissolvent is too strong or too 
 weak. In the former case the design is destroyed by the 
 entire removal of the varnish ; in the latter, the images are 
 not sufficiently brought out, and the design remains in- 
 distinct. 
 
 The effect of a solvent into which a photographic de- 
 sign is immerged, produces the removal of the varnish in 
 those points where the solar action has been weak, or indeed 
 according to the nature of the solvent, a contrary effect 
 follows, that is to say, the points strongly acted upon by the 
 solar rays, namely, the lights of the picture, are eroded, while 
 the shadows remain untouched. This takes place for 
 instance when alcohol is used instead of an essential oil as a 
 dissolvent. 
 
 Solvents by evaporation or by the effects of caloric are 
 much preferable. Their action can always be arrested at 
 pleasure. But in this case it is indispensable that the ground 
 or coating do not act as a varnish, it must be tough and as 
 white as possible. The vapour of the solvent merely 
 penetrates the coating and destroys its texture, in proportion 
 to the greater or less intensity of the light by which the 
 
48 
 
 design was impressed. This manner of operating gives a 
 gradation of tone altogether impossible to be attained by 
 immersing the design in any solvent. 
 
 Numerous experiments made by the author prove that light 
 cannot fall upon a body without leaving traces of decompo- 
 sition on the surface upon which it impinges. But these 
 experiments have also demonstrated to him that these same 
 bodies possess the power of restoring and renewing in a 
 great measure their previous loss in darkness, provided the 
 light has not effected a total decomposition.* 
 
 Any one may be convinced of this, by taking two plates, 
 prepared as already described, and exposing them to photogra- 
 phic influences of exactly the same kind and duration. When 
 it is judged that the light has produced its effects, and that 
 both are impressed with the same, or nearly the same 
 
 * [Instances of the truth of these remarks will occur to every reader. 
 How often are interesting remains, as coins, utensils, bones, and even 
 manuscripts, dug up in dry situations, protected from light, and seem- 
 ingly in good preservation ? A short exposure to daylight, dissolves the 
 charm with the substances themselves. I had once the good fortune to 
 be present at the opening of the grave of an ancient British chief, whose 
 remains had slumbered in undisturbed repose for eighteen centuries. A 
 rude urn, a well-formed battle-axe of stone, and a bronze dagger, were 
 apparently in excellent condition. The dagger was particularly beautiful ; 
 its ivory handle, even to the ornamented tassel of white bristles, all 
 seemed perfect as when grasped by the wearer. But while we looked, — 
 like the air-drawn dagger of Macbeth, — it melted away on exposure to 
 photogenic, or rather phototheiric process of exposure to day-light, 
 leaving behind only regret — and a fragment of the corroded blade. The 
 state of the atmosphere, particularly as to its humidity or dryness, has 
 doubtless a very considerable share in such changes as Daguerre refers 
 to. Still his principles are exceedingly valuable, and if followed out 
 might lead to important results in physiology. Why, for instance, the 
 beautiful skies of his own France are so rapidly destructive of youthful 
 beauty in one sex — the complexion and form of the human being in dif- 
 ferent climates — the different qualities of vegetable productions, varying 
 with the light of the regions in which they grow — the plumage of birds, 
 —following to a certain extent the same principle, &c. &c. — are often 
 illustrations of the same principle. — Translator.] 
 
49 
 
 imagery, let both be withdrawn from the camera. Let one 
 be now exposed to the immediate action of the dissolvent, 
 but let the other be preserved carefully in the dark for some 
 days, after which let it be subjected also to the solvent. 
 It will be seen that the result obtained from the second does 
 not resemble the effects on the first plate. 
 
 It may thence be concluded that a large portion of bodies, 
 and without any doubt all varnishes, would perish much 
 more rapidly, but for this property which they possess of 
 renewing in the shade the waste produced in them by the 
 action of light. 
 
 It has already been explained in the note prefixed to N. 
 Niepce’s description of his process, that a provisional act of 
 association was entered into between him and M. Daguerre in 
 the month of December, 1829. In that act M. Daguerre be- 
 came bound to perfect the system of M. Niepce, and to com- 
 municate to him all the information regarding the adaptations 
 which he had made in the applications of the camera obscura. 
 M. Daguerre has judged it necessary to insert here an extract 
 from the correspondence of M. Niepce, in order to prove that 
 the latter had no part in the discovery of the Daguerreotype, 
 properly so called, or true method of photogenic delineation. 
 
 In fact, it will be seen from the correspondence of M. 
 Niepce that M. Daguerre had pointed out to him the effects 
 of light upon iodine, when in contact with silver, in a letter 
 dated the 21st May, 1824, of which M. Niepce acknowledges 
 the reception in his letter of the 24th June following. In 
 that letter M. Daguerre urged M. Niepce to turn his attention 
 to this new method. M. Niepce did in fact in several 
 instances return to the subject, and always at the request of 
 M. Daguerre. But these experiments of M. Niepce had 
 always been unsuccessful ; he even regretted the time which 
 M. Daguerre had caused him to lose in a process which he 
 
 D 
 
50 
 
 regarded as impossible. It is true that at this period there 
 remained to be resolved the two most important problems. 
 The first was, to obtain the lights in the natural state ; the 
 second consisted in discovering the means of fixing the images. 
 
 These two problems M. Daguerre has since completely 
 resolved by the application of mercury. 
 
 M. Niepce died July 5th, 1833. 
 
 On the 13th June, 1837, a definite agreement was entered 
 into between M. Daguerre and M. Isidore Niepce, jun. as 
 heir of M. Joseph Nicephore Niepce, by which act M. 
 Isidore Niepce admitted that M. Daguerre had explained to 
 him his new process. It is also specified in this deed that 
 the process shall bear the name of M. Daguerre, he alone 
 having been in reality the sole inventor. 
 
 These facts will appear from the following extracts of 
 correspondence.* 
 
 FROM M. NIEPCE, SEN. TO M. DAGUERRE. 
 
 81, Loup de Varennes, 24th June, 1831. 
 
 Sir, and dear partner, 
 
 I had long expected to hear from you with too much im- 
 patience not to receive and read with the greatest pleasure 
 your letters of the 10th and 21st of last May. I shall con- 
 fine myself in this reply to yours of the 21st, because having 
 been engaged ever since it reached me in your experiments 
 on iodine, I hasten to communicate to you the results which 
 I have obtained. I had given my attention to similar re- 
 searches previous to our connexion, but without hope of 
 success, from the impossibility or nearly so, in my opinion, of 
 fixing in any durable manner the images received on iodine, 
 even supposing the difficulty surmounted, of replacing the 
 
 * All these published letters are authenticated in the original by the 
 signature of M. Arago, who compared them with the autographs. 
 
51 
 
 lights and shadows in their natural order. My results in this 
 respect have been entirely similar to those which the oxide of 
 silver gave me ; and promptitude of operation was the sole 
 advantage which these two substances appeared to offer. 
 Nevertheless, last year, after you left this, I subjected iodine 
 to new trials, but by a different mode of application : I in- 
 formed you of the results, and your answer, not at all encou- 
 raging, decided me to carry these experiments no farther. 
 It appears that you have since viewed the question under a 
 less desperate aspect, and I do not hesitate to reply to the 
 appeal which you have made. 
 
 (Signed) I. N. NIEPCE. 
 
 FROM THE SAME TO THE SAME. 
 
 8th Nov. 1831. 
 
 Sir, and dear partner, 
 
 In terms of my letter of the 24th June, in answer to yours of 
 the 2 1st May, I have completed a long series of experiments 
 on iodine in contact with polished silver, without however 
 attaining any result which can make me hope to succeed in 
 deoxydizing the metal. I have fruitlessly varied my pro- 
 cesses and combined them in numerous ways. I have not 
 been more fortunate on that account. I now admit, once for 
 all, the impossibility, — at least in my opinion, — of re- 
 ducing to their natural state the inverted order of the lights, 
 and also of obtaining any other than an evanescent image of 
 objects. Besides, sir, this failure is in exact conformity 
 with what all my former researches on metallic oxides had 
 previously led me to expect, — a disappointment which had 
 induced me to resolve on abandoning them. Finally, I tried 
 iodine in contact with tinned iron ; this process seemed to 
 me at first to augur well. I remarked with surprise only, 
 d 2 
 
52 
 
 however, in one instance while operating- with this preparation 
 in the camera, that the light acted with marked influence on 
 the iodine, in a way so that the tints, or to speak more cor- 
 rectly, the lights and shadows were produced in their natural 
 order. I know not how or why this effect took place, without 
 my having ever again been able to produce it, though ope- 
 rating in exactly the same manner. But even this mode of 
 application, as respects the permanency of the image ob- 
 tained proved not less defective than the others. Thus after 
 several other trials, I find myself just where I was, bitterly 
 regretting, I confess it, having so long pursued a wrong path, 
 and what is worse, so fruitlessly, &c. &c. 
 
 (Signed) I. N. NIEPCE. 
 
 FROM THE SAME TO THE SAME. 
 
 29th January, 1832. 
 
 Sir, and dear partner, 
 
 To the substances which, according to your letter, act upon 
 silver in the same way as iodine, you may add decoction of 
 thlaspi,* fumes of phosphorus, and particularly of sulphur, 
 for it is principally to their presence in these bodies that the 
 similarity of results obtained is to be ascribed. I have 
 remarked also that caloric produced the same effe.ct, by the 
 oxydizing of the metal, for from this cause proceeded in all 
 these instances this extreme sensibility to light ; but this, 
 unfortunately, tends in no degree to the solution of the 
 question which engages your attention. 
 
 For my part, I no longer employ iodine in my experi- 
 ments, except as a means of comparing the relative quick- 
 ness of their results. It is true that for the last two 
 
 * That called Shepherd’s purse. 
 
53 
 
 months the weather has been so unfavourable that I have 
 been able to do little. As to the subject of iodine, may I 
 intreat you to tell me, at your earliest convenience, how 
 you employ it ? Whether it is in the solid form, or in 
 a state of solution in a liquid ?* for in these two cases 
 the evaporation could not certainly act in the same manner 
 as regards promptitude of effect, &c. &c. 
 
 FROM THE SAME TO THE SAME. 
 
 3rd March, 1832. 
 
 My DEAR ASSOCIATE, 
 
 Since the date of my last letter, I have confined myself, 
 with few exceptions, to new researches in iodine, which have 
 produced me nothing that is satisfactory, and which I resumed 
 only because you appeared to attach a certain importance to 
 them, and because, on the other hand, I should have been 
 very happy to satisfy myself as to the application of iodine 
 to tinned iron. But, I repeat it, Sir, I do not see that we 
 can hope to derive any advantage from this process, more 
 than from any other method which depends upon the use of 
 metallic oxides, &c. &c. 
 
 (Signed) I. N. NIEPCE. 
 
 * Note by M. Daguerre . — These expressions of M. Niepce’s will, I 
 hope, convince the most prejudiced that it was I who first pointed out 
 iodine, not as a means of darkening certain portions of a design already 
 produced by photographic processes, but as the sensitive coating upon 
 which the image was to be created photogenically. The italics are in the 
 original, in all instances. 
 
54 
 
 FROM M. ISIDORE NIEPCE, JUNR. TO M. DAGUERRE. 
 
 Luz, 1st November, 1837. 
 
 My dear Daguerre, 
 
 You will doubtless, my dear friend, have been more for- 
 tunate than I, and, very probably, your portfolio is by this 
 time enriched with the most beautiful designs ! What 
 a difference also between the method which you employ 
 and the one by which I toil on ! While I require almost 
 a whole day to make one design, you — you ask only four 
 minutes ! What an enormous advantage ! It is so great, 
 indeed, that no person, knowing both methods, would 
 employ the old one. 
 
 This reflection makes me feel less painfully my own want 
 of success. For, though the old system might be described 
 as the result of my father’s labours, to the perfection of 
 which you equally contributed, it is certain that it could not 
 become the exclusive object of a subscription.* Therefore, 
 I think we should content ourselves with simply mentioning 
 it, in order to make both methods known, for of the two 
 yours alone will obtain the preference ! &c. &c. 
 
 (Signed) ISIDORE NIEPCE. 
 
 * At this date we were thinking of publishing the process by sub- 
 scription. In the original this extract is inscribed : “ Extract of a 
 
 letter from M. Isidore Niepce, junr., who was endeavouring to make a 
 collection of designs by his father’s methods as perfected by M. Da- 
 guerre.” The internal evidence of priority in these letters is conclusive 
 in favour of Daguerre. 
 
55 
 
 CHAPTER III. 
 
 The designs are executed upon thin plates of silver, plated on 
 copper. Although the copper serves principally to support 
 the silver foil, the combination of the two metals tends to 
 the perfection of the effect. The silver must be the purest 
 that can be procured. As to the copper, its thickness ought 
 to be sufficient to maintain the perfect smoothness and flat- 
 ness of the plate, so that the images may not be distorted by 
 the warping of the tablet ; but unnecessary thickness beyond 
 this is to be avoided on account of the weight. The thick- 
 ness of the two metals united ought not to exceed that of a 
 stout card. 
 
 The process is divided into five operations. 
 
 1. The first consists in polishing and cleaning the plate, 
 in order to prepare it for receiving the sensitive coating, upon 
 which the light traces the design. 
 
 2. The second is to apply this coating. 
 
 3. The third is the placing the prepared plate properly in 
 the camera obscura to the action of light, for the purpose of 
 receiving the image of Nature. 
 
 4. The fourth brings out this image, which at first is not 
 visible on the plate being withdrawn from the camera 
 obscura. 
 
 5. The fifth and last operation has for its object to remove 
 the sensitive coating on which the design is first impressed, 
 because this coating would continue to be affected by the 
 rays of light, a property which would necessarily and quickly 
 destroy the picture. 
 
56 
 
 First Operation. 
 
 Preparing the Plate . 
 
 The requisites for this operation are : — 
 
 A small phial containing olive oil. 
 
 Some very finely carded cotton. 
 
 A small quantity of very fine pumice powder, ground with 
 the utmost care, tied up in a bag of muslin sufficiently thin to 
 allow the powder to pass through when the bag is shaken. 
 
 A phial of nitric acid diluted with water in the proportion 
 of one pint of acid to sixteen pints of distilled water. These 
 proportions express volume, not weight. 
 
 A frame of iron wire upon which to place the plate in 
 order that it may be heated by means of a spirit lamp. 
 
 Lastly, a small spirit lamp. 
 
 As already stated, these photographic delineations are 
 executed upon silver plated on copper. The size of the plate 
 will depend of course on the dimensions of the camera. We 
 must begin by polishing it carefully. To accomplish this 
 the surface of the silver is powdered all over with the 
 pumice, by shaking the bag without touching the plate. 
 
 Next, with some cotton dipped in a little olive oil, the operator 
 rubs the plate gently, rounding his strokes, as represented, 
 Plate I. Fig. 2. beginning from C. During this operation, 
 the plate must be laid flat upon several folds of paper, care 
 being taken to renew these from time to time that the tablet 
 be not twisted from any inequality in the support. 
 
 The pumice must be renewed and the cotton changed 
 several times. The mortar employed for preparing the pumice 
 must be of porphyry. The powder is afterwards finished by 
 grinding upon polished glass with a glass muller and very pure 
 water. And lastly, it must be perfectly dried. It will be readily 
 apprehended of what importance it is to attend to these 
 directions, since upon the high polish of the silver depends 
 in a great measure the beauty of the future design. When 
 the plate is well polished, it must next be cleaned by pow- 
 
57 
 
 dering it all over once more with pumice, and rubbing with dry 
 cotton, always rounding and crossing the strokes, for it is im- 
 possible to obtain a true surface by any other motion of the 
 hand. A little pledget of cotton is now rolled up and moistened 
 with the diluted acid already mentioned, by applying the 
 cotton to the mouth of the phial and inverting it, pressing 
 gently, so that the centre only of the cotton may be wetted 
 and but slightly, care being taken not to allow any acid to 
 touch the fingers. The surface of the plate is now rubbed 
 equalhj all over with the acid applied by the pledget of 
 cotton. Change the cotton and keep rubbing, rounding as 
 before, that the acid may be equally spread, yet in so small a 
 quantity as just to skim the surface so to speak. If, as fre- 
 quently happens, the acid run into small drops from the 
 high polish, change the cotton repeatedly and break down 
 the globules as quickly as possible, but always by gently 
 rubbing, for if allowed to rest or to run upon the plate they 
 will leave stains. It will be seen when the acid has been 
 properly diffused, from the appearance of a thin veil spread 
 regularly over the whole surface of the plate. Once more 
 powder over pumice, and clean it with fresh cotton, rubbing 
 as before, but very slightly. 
 
 The plate is now to be subjected to a strong heat. It is 
 placed upon the wire frame (Plate Fig. 1, both views), the 
 silver upwards. The spirit lamp is applied below the 
 hand, moving it round, the flame touching and playing upon 
 the copper. This operation being continued at least five mi- 
 nutes, a white strong coating is formed all over the surface of 
 the silver, if the lamp has been made to traverse with pro- 
 per regularity; the lamp is now withdrawn. A fire of 
 charcoal may be used instead of the lamp, and is perhaps 
 preferable, the operation being sooner completed. In this 
 latter case the wire frame is unnecessary, because the plate 
 may be held by one corner with pincers, and so held over the 
 fire, moving it at the same time till all is equally heated, and 
 
 d 5 
 
53 
 
 the veil appear as before described. The plate is now to be 
 cooled suddenly, by placing it on a cold substance, such as 
 a mass of metal or stone, or best of all a marble table. 
 When perfectly cold, it is to be again polished, an operation 
 speedily performed, since the gummy appearance merely has 
 to be removed, which is done by the dry pumice and cot- 
 ton repeated several times, changing the cotton frequently. 
 The polishing being thus completed, the operation of the 
 acid is to be repeated three different times, dry pumice being 
 powdered over the plate, each time, and polished off very 
 gently with the cotton, which must be very clean, care 
 being taken not to breathe upon the plate or to touch it with 
 the fingers, or even with the cotton upon which the fingers 
 have rested, for the slightest stain upon the 'Surface will be 
 a defect in the drawing. 
 
 When the plate is not intended for immediate use, the last 
 operation of the acid is not performed. This allows any 
 number of plates to be kept prepared up to the last slight ope- 
 ration, and they may be purchased in this state if required. 
 It is, however, indispensable that a last operation by acid as 
 described, be performed on every plate, immediately before, 
 it be placed in the camera. Lastly, every particle of dust 
 is removed by gently cleaning the whole edges and back also 
 with cotton. 
 
 Second Operation. 
 
 Coating the Plate. 
 
 For this operation, we require, 
 
 The box represented, Plate II. Figs. 1 and 2. 
 
 The small board, Plate I. Fig. 3. 
 
 Four small metallic bands, the same substance as the 
 plates. 
 
 A small handle, Plate I. Fig. 5. and a box of small tacks. 
 A phial of iodine. 
 
 The plate is first to be fixed upon the board by means of 
 
59 
 
 the metallic bands with their small catches and tacks, as 
 represented Plate I. Fig. 3. The iodine is now put into the 
 little dish, D, at the bottom of the box, Plate II. Figs. 1 and 
 2. It is necessary to divide the iodine into pieces, in order 
 to render the exhalation the more extensively and more 
 equally diffused, otherwise it would form circles in the centre 
 of the plate, which would destroy this essential requisite. 
 The board is now fitted into its position, the plate face down- 
 wards, the whole being supported by small brackets project- 
 ing from the four corners of the box, the lid of which G is 
 then closed. In this position the apparatus remains till the 
 vaporization of the iodine which is condensed upon the plate, 
 has covered its surface with a fine coating of a yellow gold 
 colour. If this operation be protracted, the gold colour 
 passes into violet, which must be avoided, because in this 
 state the coating is not so sensitive to the impressions of light. 
 On the contrary, if the coating be too pale, the image of 
 nature in the camera will be too faint to produce a good 
 picture. A decided gold colour — nothing more — nothing 
 less — is the only assurance that the ground of the future 
 picture is duly prepared. The time for this cannot be deter- 
 mined, because it depends upon several circumstances. Of 
 these the two principal are the temperature of the apartment, 
 and the state of the apparatus. The operation should be left 
 entirely to spontaneous evaporation of the iodine — or at all 
 events, no other heat should be used than what can be applied 
 through the temperature of the room in which the operation 
 takes place. It is also very important that the temperature 
 of the inside of the box be equal to that of the air outside, 
 for otherwise, a deposition of moisture takes place upon the 
 plate, a circumstance most injurious to the final result. 
 Secondly, as respects the state of the apparatus ; the oftener 
 it has been used, the less time is required, because in this 
 case, the interior of the box being penetrated with the 
 vapours of iodine, these arise from all sides, condensing thus 
 
60 
 
 more equally and more rapidly upon the surface of the plate, 
 a very important advantage. Hence it is of consequence to 
 leave always a small quantity of iodine in the cup, and to 
 protect this latter from damp. Hence, likewise, it is obvious 
 that an apparatus of this kind which has been some time in 
 use, is preferable to a new box, for in the former the opera- 
 tion is always more expeditiously performed. 
 
 Since from these causes the time cannot be fixed, a 
 ■priori, and may vary from five minutes to half an hour, rarely 
 more, unless the weather be too cold, means must be 
 adopted for examining the plate from time to time. In 
 these examinations it is important not to allow the light to 
 fall directly upon the plate. Also, if it appear that the 
 colour is deeper on one side of the plate than the other, to 
 equalize the coating the board must be replaced, not exactly 
 in its former position, but turned one quarter round at each 
 inspection. In order to accomplish these repeated examina- 
 tions without injuring the sensibility of the ground or coat- 
 ing, the process must be conducted in a darkened apart- 
 ment into which the light is admitted side-ways, never from 
 the roof — the door left a little ajar answers best. When the 
 operator would inspect the plate, he raises the lid of the 
 box, and lifting the board with both hands, turns up the 
 plate quickly, and very little light suffices to shew him the 
 true colour of the coating. If too pale, the plate must be 
 instantly replaced, till it attain the proper gold tone ; but if 
 this tint be passed, the coating is useless, and the operations 
 must be repeated from the commencement of the first. 
 
 From description this operation may perhaps seem dif- 
 ficult, but with a little practice one comes to know pretty 
 nearly the precise interval necessary to produce the true 
 tone of colour, and also to inspect the plate with great ra- 
 pidity, so as not to allow time for the light to act. 
 
 When the coating has reached the proper tone of yellow, 
 the plate with the board to which it is fixed, is slipped into 
 
61 
 
 the frame (Plate III., Fig. 4.) and thus adjusted at once in 
 the camera. In this transference care must be taken to pro- 
 tect the plate from the light; a taper should be used, and 
 even with this precaution, the operation ought to be performed 
 as quickly as possible, for a taper will leave traces of its 
 action if continued for any length of time. 
 
 We pass now to the third operation, that of the camera. 
 If possible the one should immediately succeed the other, 
 the longest interval between the second and third ought not 
 to exceed an hour. Beyond this space the action of the 
 iodine and silver no longer possesses the requisite photogenic 
 properties. 
 
 Observanda . — Before making use of the box, the operator 
 should clean it thoroughly, turning it bottom upwards, in 
 order to empty it of all the particles of iodine which may 
 have escaped from the cup, avoiding at the same time 
 touching the iodine with the fingers. During the operation 
 of coating, the cup ought to be covered with a piece of gauze 
 stretched on a ring. The gauze regulates the evaporation of 
 the iodine, and also prevents the compression of the air on 
 the lid being shut from scattering the particles of iodine, 
 some of which reaching the plate, would leave large stains 
 on the coating. For the same reason the top should always 
 be let down with the greatest gentleness, not to raise the 
 dust in the inside, the particles of which being changed 
 with the vapour of the iodine, would certainly reach and 
 damage the plate. 
 
 Third Operation. 
 
 The Camera. 
 
 The apparatus required in this operation, is limited to the 
 camera obscura. (Plate IV. figs. 1 & 2.) 
 
 This third operation is that in which by means of light, 
 acting through the camera, nature impresses an image 
 
62 
 
 of herself on the photographic plate, enlightened by the 
 sun, for then the operation is more speedy. It is easy to 
 conceive that this operation, being accomplished only through 
 the agency of light, will be the more rapid in proportion as 
 the objects, whose photographic images are to be delineated, 
 stand exposed to a strong illumination, or in their own 
 nature present bright lines and surfaces. 
 
 After having placed the camera in front of the landscape, 
 or facing any other object of which it may be desirable to 
 obtain a representation, the first essential is a perfect adjust- 
 ment of the focus, that is to say, making your arrangements 
 so as to obtain the outlines of the subject with great neatness. 
 This is accomplished by advancing or withdrawing the 
 frame of the obscured glass which receives the images of 
 natural objects. The adjustment being made with satisfac- 
 tory precision, the moveable part of the camera is fixed by 
 the proper means, and the obscured glass being withdrawn, 
 its place is supplied by the apparatus, with the plate attached 
 as already described, and the whole secured by small brass 
 screws. The light is of course all this time excluded by the 
 inner doors; these are now opened by means of two semi-circles 
 (see Plate) and the plate is disposed ready to receive its proper 
 impressions. It remains only to open the aperture of the 
 camera, and to consult a watch. 
 
 This latter is a task of some nicety, because as nothing is 
 visible, and as it is quite impossible to determine the time 
 necessary for producing a design, this depending entirely 
 on the intensity of the light on the objects, the imagery of 
 which is to be reproduced. At Paris, for example, this 
 varies from three to thirty minutes. 
 
 It is likewise to be remarked, that the seasons, as well as 
 the hour of the day, exert considerable influence on the 
 celerity of the operation. The most favourable time is from 
 seven to three o’clock ; and a drawing which, in the months 
 of June and July at Paris, may be taken in three or four 
 
63 
 
 minutes, will require five or six in May or August, seven or 
 eight in April and September, and so on in proportion to. the 
 progress of the season. These are only general data for very 
 bright or strongly illuminated objects, for it often happens 
 that twenty minutes are necessary in the most favourable 
 months, when the objects are entirely in shadow. 
 
 After what has just been said, it will readily occur to the 
 reader that it is impossible to specify with precision the 
 exact length of time necessary to obtain photographic 
 designs ; practice is the only sure guide, and with this 
 advantage, one soon comes to appreciate the required 
 time very correctly. The latitude is of course a fixed 
 element in this calculation. In the south of France, for 
 example, and generally in all those countries in which light 
 has great intensity, as Spain, Italy, &c., we can easily 
 understand that these designs must be obtained with greater 
 promptitude than in more northern regions. It is, however, 
 very important not to exceed the time necessary, in different 
 circumstances, for producing a design, because, in that case, 
 the lights in the drawing will not be clear, but will be 
 blackened by a too-prolonged solarizatiou. If, on the 
 contrary, the time has been too short, the sketch will be 
 very vague, and without the proper details. 
 
 Supposing that he has failed in a first trial, by withdraw- 
 ing the tablet too soon, or by leaving it too long exposed, 
 the operator, in either case, should commence with another 
 plate immediately ; the second trial, being corrected by the 
 first, almost insures success. It is even useful, in order to 
 acquire experience, to make some essays of this kind. 
 
 In this stage of the process, it is the same as for the 
 coating ; we must hasten to the next operation. When the 
 plate is withdrawn from the camera, it should immediately 
 be subjected to the subsequent process ; there ought at 
 most not to be a longer interval than an hour between the 
 third and fourth operations ; but one is always surest of 
 
64 
 
 disengaging the images when no space has been allowed to 
 intervene. 
 
 Fourth Operation. 
 
 Mercurial or Disengaging Process. 
 
 Here are required : 
 
 A phial of mercury, containing at least 3 oz. 
 
 A lamp with spirit of wine. 
 
 The apparatus represented in Plate V., Figs. 1 , 2, and 3. 
 
 A glass funnel with a long neck. 
 
 By means of the funnel the mercury is poured into the 
 cup c at the bottom of the larger vessel. The quantity must 
 be sufficient to cover the bulb of a thermometer F. After- 
 wards, and throughout the remaining operations, no light 
 save a taper can be used. 
 
 The board with the plate affixed is now to be withdrawn 
 from the frame already described as adapted to the camera, 
 and figured PI. III., Fig. 4. Theboard and plate are placed 
 within the ledges of the black iron vessel PI. V. Fig. 1 , at an 
 angle of 45°, the tablet with sketch downwards, so that it 
 can be seen through the glass G. The top A is then gently 
 put down, so as not to raise up particles of the mercury. 
 
 When all things are thus disposed, the spirit lamp is 
 lighted, and placed under the cup containing mercury. 
 The operation of the lamp is allowed to continue till the 
 thermometer, the bulb of which is covered by the mercury, 
 indicates a temperature of 60° centigrade. The lamp is 
 then immediately withdrawn ; if the thermometer has risen 
 rapidly, it will continue to rise without the aid of the lamp, 
 but this elevation ought not to exceed 75° centigrade. 
 
 The impress of the image of Nature exists upon the plate, 
 but it is invisible. It is not till after the lapse of several 
 minutes that the faint tracery of objects begins to appear, of 
 which the operator assures himself by looking through the 
 
65 
 
 glass, G, by the light of a taper, using it cautiously that its 
 rays may not fall upon, and injure the nascent images 
 of the sketch. The operation is continued till the thermo- 
 meter} sink to 45° centigrade; the plate is then withdrawn, 
 and this operation completed. 
 
 When the objects have been strongly illuminated, or when 
 the action in the camera has been continued rather too long, 
 it happens that this fourth operation is completed before the 
 thermometer has fallen even to 55° centigrade. One may 
 always know this, however, by observing the sketch through 
 the glass. 
 
 It is necessary after each operation to clean the inside of 
 the apparatus carefully to remove the slight coating of mer- 
 cury adhering to it. When the apparatus has to be packed 
 for the purpose of removal, the mercury is withdrawn by the 
 small cock E, inclining the vessel to that side. 
 
 One may now examine the sketch by a feeble light in 
 order to be certain that the processes hitherto have suc- 
 ceeded. The plate is now detached from the board, and the 
 little bands of metal which held it there are carefully cleaned 
 with pumice and water after each experiment, a precaution 
 rendered necessary from the coating both of iodine and mer- 
 cury which they have acquired. The plate is now deposited 
 in the grooved box (Plate II. Fig. 3.), until it undergoes the 
 fifth and last operation. This may be deferred if not conve- 
 nient ; for the sketch may now be kept for months in its 
 present state without alteration, provided it be not too fre- 
 quently inspected by the full daylight. 
 
 Fifth Operations 
 Fixing the Impression. 
 
 The object of this final process is to remove from the 
 tablet the coating of iodine, which continuing to decompose 
 by light would otherwise speedily destroy the design when 
 too long exposed. For this operation the requisites are— 
 
66 
 
 A saturated solution of common salt, or a weak solution of 
 hyposulphite of pure soda. 
 
 The apparatus represented Plate VI. Fig. 4. first and 
 second views. 
 
 Two square troughs, sheet copper, Plate VI. Fig. 2. both 
 views. 
 
 A vessel for distilled water, Plate VI. Fig. 5. 
 
 In order to remove the coating of iodine, common salt is 
 put into a bottle with a wide mouth, which is filled one- 
 fourth with salt and three-fourths with pure water. To dis- 
 solve the salt shake the bottle, and when the whole forms a 
 saturated solution, filter through paper. This solution is 
 prepared in large quantities before-hand, and kept in corked 
 bottles. 
 
 Into one of the square troughs pour the solution, filling it 
 to the height of an inch ; into the other pour in like 
 manner your water. The solution of salt may be replaced 
 by one of hyposulphate of soda, which is even preferable, 
 because it removes the iodine entirely, which the saline solu- 
 tion does not always accomplish, especially when the 
 sketches have been laid aside for some time between the 
 fourth and fifth operations. It does not require to be 
 warmed, and a less quantity is required. 
 
 First, the plate is placed in common water, poured into a 
 trough, plunging and withdrawing it immediately — the sur- 
 face merely requiring to be moistened — then plunge it into 
 the saline solution, which latter would act upon the drawing 
 if not previously hardened by the washing in pure water. 
 To assist the effect of the saline solutions, the plate is moved 
 about in them by means of a little hoop of copper wire, 
 Plate VI. Fig. 3. When the yellow colour has quite dis- 
 appeared, the plate is lifted up with both hands, care being 
 taken not to touch the drawing, and plunged again into the 
 first trough of pure water. 
 
 Next, the apparatus, Plate VI. Fig. 4, two views, and the 
 
67 
 
 bottle Fig. 5, having been previously prepared, made very 
 clean, and the bottle filled with distilled water. The plate is 
 withdrawn from the trough, and being instantly placed upon 
 the inclined plane, Plate VI, Fig. 4, distilled water, hot but 
 not boiling, is made to flow in a stream over its whole sur- 
 face, carrying away every remaining portion of the saline 
 wash.* 
 
 Not less than a quart of distilled water is required when the 
 design is of the dimensions indicated in the engraving 8^ by 
 6^ inches. The drops of water remaining on the plate must be 
 removed by forcibly blowing upon it, for otherwise in dryingthey 
 would leave stains on the drawing. Hence also will appear 
 the necessity of using very pure water, for if in this last wash- 
 ing, the liquid contain any admixture of foreign substances, 
 they will be deposited on the plate, leaving behind numerous 
 and permanent stains. To be assured of the purity of the 
 water, let a drop fall upon a piece of polished metal ; evaporate 
 by heat, and if no stain be left the water is pure. Distilled 
 water is always sufficiently pure without this trial. 
 
 After this washing the drawing is finished, it remains only 
 to preserve it from the dust, and from the vapours that 
 might tarnish the silver. The mercury, by the action of 
 which the images are rendered visible, is partially decom- 
 posed ; it resists washing, by adhesion to the silver, but 
 cannot endure the slightest rubbing. 
 
 To preserve these sketches then, place them in squares of 
 strong pasteboard, with a glass over them, and frame the 
 whole in wood. They are thenceforth unalterable even by 
 the sun’s light. 
 
 In travelling, the collector may preserve his sketches in a 
 box similarto the one Plate II, Fig. 3, and for greater security 
 may close the joints of the lid f with a collar of paper. 
 
 * If hyposulphite has been used, the distilled water need not be so 
 hot as when common salt has been employed. 
 
 t The author made attempts to preserve his sketches by means of 
 
68 
 
 It is necessary to state that the same plate may be em- 
 ployed for several successive trials, provided the silver be 
 not polished through to the copper. But it is very important 
 after each trial to remove the mercury immediately by using 
 the pumice powder with oil, and changing the cotton fre- 
 quently during the operation. If this be neglected, the 
 mercury finally adheres to the silver, and fine drawings can- 
 not be obtained if this amalgam be present. They always 
 in this case want firmness, neatness, and vigour of outline 
 and general effect. 
 
 different varnishes obtained from succinum, copal, Indian rubber, wax, 
 and various resins ; but he has observed, that by the application of any 
 varnish whatsoever, the lights in these sketches were considerably weak- 
 ened, and at the same time the deeper tones were hidden. To this dis- 
 advantage, was added the still greater injury from the decomposition of 
 the mercury by all the varnishes tried ; this effect, which did not become 
 apparent till after the lapse of two or three months, terminated in a 
 total destruction of the forms of the objects represented. Even had this 
 not been the case, the author would have deemed it a sufficient reason 
 for rejecting all varnishes, that they injured the vigour and clearness of 
 the lights. The quality most to be desired in the new art is this inten - 
 sity of tone in the contrast of the lights and shadows. 
 
69 
 
 CHAPTER IV. 
 
 OF THE DIORAMA. 
 
 Tiie principles of this new art have been most admired, or per- 
 haps rather most fully developed, in the following pictures : — 
 The Midnight Mass — Landslip in the Valley of Goldau — • 
 The Temple of Solomon — and The Cathedral of Sainte 
 Marie de Montreal. Each of these paintings has been ex- 
 hibited with the alternate effects of night and day gradually 
 stealing over them. To these effects of light were added 
 others, arising from the decomposition of form , by means of 
 which, as for example, in the Midnight Mass, figures ap- 
 peared where the spectators had just beheld seats, altars, 
 &c. ; or, again, as in The Valley of Goldau, in which rocks 
 tumbling from the mountains replaced the prospect of a 
 smiling valley. 
 
 1. Pictorial Processes. 
 
 The canvas is painted on both sides. In this case, 
 therefore, whether the subjects be illuminated by reflected 
 or refracted light, one indispensable essential is, to employ a 
 medium or canvas which is exceedingly transparent, and the 
 texture of which is as equal as possibly can be obtained. 
 Either lawn or calico may be used. It is also necessary to 
 choose those stuffs of the greatest width that is manu- 
 factured, to avoid seams, which are always difficult to con- 
 ceal, especially in the principal lights of a picture. 
 
 When the canvas thus selected is stretched, it is necessary 
 to prime it, on both sides, with at least two coats of parch- 
 ment size. 
 
70 
 
 First Effect . 
 
 The first effect, which ought to be the clearer of the two, 
 is executed on the right side of the canvas. The sketch is 
 first made in black-lead, taking care not to sully the canvas, 
 the whiteness of which is the sole resource possessed by the 
 artist for bringing out the lights of the picture ; for white 
 cannot be used in executing the first effect. The colours 
 which I use are ground in oil, but laid upon the canvas with 
 turpentine, to which sometimes I add a little animal oil, but 
 only for deep shadows, and these latter may be varnished 
 without injury. The manipulation is exactly the same as in 
 water-colour painting, with this difference only, that the 
 colours are prepared with oil instead of gum, and applied 
 with turpentine instead of water. It will readily occur to 
 the artist that he can employ neither white nor any opaque 
 colour whatsoever by coats, which in the second effect would 
 occasion spots more or less tinted, according to the greater 
 or less degree of opacity. It must be the endeavour of the 
 artist to bring out effects at a stroke — at once ; going over 
 an effect injures the transparency of the canvas. 
 
 Second Effect. 
 
 The second effect is painted on the wrong side of the can- 
 vas. The artist in executing this part of his work must 
 employ no other light than that which comes from the 
 front of the picture through the canvas. By this means 
 the transparent forms of the first effect are seen ; these 
 forms must either be preserved, or painted over, according 
 to the effect intended. 
 
 First of all, a wash of some transparent blue is put over 
 the whole canvas. This coating, like the other colours, is 
 prepared in oil, and laid on in essence of turpentine. The 
 marks of the brush are effaced by a huge tool of badger’s skin. 
 
71 
 
 By means of this coating the seams also are concealed to a 
 certain extent, by taking care to lay it on thin along the 
 selvedges, which have always less transparency than the rest 
 of the canvas. When this coating is dry, the alterations in- 
 tended to be made on the first effect, are sketched out. 
 
 In executing this second effect, the artist has nothing to 
 do beyond modelling in light and shadow, without reference 
 to local colour or to the colours of the first picture, which are 
 seen by transmitted light as transparencies. This part is 
 executed by means of a tint of which white is the base, with 
 which lamp-black is mixed in order to obtain a grey, 
 the strength of which is ascertained by applying it to the 
 wash of blue on the wrong side, and then viewing it from the 
 right side of the picture, from which position it will not be 
 at all perceptible if of the proper strength. The gradation 
 of tones is produced by the greater or less opacity in this 
 tint. It may happen that the shadows of the first effect 
 interfere with the execution of the second. To remedy this 
 inconvenience, and to conceal these shadows, we can har- 
 monize their force, by using the gray of a corresponding 
 opacity according to strength of the shadows which it is 
 the intention to destroy. 
 
 It will occur to the artist, that it is necessary to urge this 
 second effect to its utmost power. 
 
 When this general effect of light and shadow is finished on 
 these principles, and the desired effect obtained, the picture 
 may be coloured, the artist using only the most transparent 
 tints prepared in oil. It is still a water colour that is to be 
 executed; but less turpentine must be used in these glazings, 
 which produce a powerful effect only in proportion as they 
 are repeated several times, and with more of oil than essence. 
 However, for slight effects of colour, turpentine is sufficient. 
 
 The Eclairage or Lighting up the Pictures. 
 
 The first effect painted on the right or front of the canvas is 
 
72 
 
 lighted by reflection, that is to say, only by a light which comes 
 from the front, while the second effect — that painted on the 
 wrong side receives its light by refraction ; that is, from be- 
 hind only. In both effects we may employ both lights at once, 
 in order to modify certain portions of the picture. 
 
 The light which gives effect to the painting in front 
 should come from above. The illumination which falls upon 
 the second effect — that painted behind, should come from 
 vertical openings, it being always understood that these are 
 to be completely closed when the first effect only is to be seen. 
 
 If it happen to be necessary- to modifiy a part in the first 
 effect or picture by a light belonging to the second, that is, 
 coming from behind, then this light must be inclosed so as 
 not to fall, except on the proper place. The windows or 
 openings ought to be distant from the paintings at least two 
 metres,* in order to give a power of modifying the light by 
 transmitting it through coloured media, as the exigencies of 
 desired effects may demand. The same means are requisite 
 for the first effect or front picture. 
 
 It is admitted that the colours which appear on objects 
 generally are produced only by the arrangement of the mole- 
 cules of these objects. Consequently all those substances 
 used in painting are colourless : they only possess the 
 power of reflecting such or such a ray of light which in itself 
 co - tains all the colours. The more pure these substances 
 are, the more decidedly do they reflect the simple colours, 
 never, however by an absolute or independent property, which 
 by the way, it is not necessary they should do in order to 
 represent the effects of nature. 
 
 To explain then the principles upon which Dioramic paint- 
 ings are executed and lighted up, take as an example the 
 effect produced when light is decomposed; that is to say, 
 when a portion of its component rays is intercepted. 
 
 Put upon a canvas two colours — the brightest possible — 
 the one red, the other green, both as near as may be of the 
 * Between 7 and 8 feet English. 
 
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73 
 
 same intensity. Now, interposa a red medium, as a coloured 
 e;lass, in the stream of light which falls upon them — what 
 happens ? The red colour reflects the rays which belong to 
 it ; the green remains black. Reverse the experiment by 
 interposing a green glass — the effect also is reversed ; the 
 green colour gives forth its proper reflection ; the red is rtow 
 black. The effects, indeed, are not perfect unless the inter- 
 posed media completely exclude all rays but their own, a 
 condition not easily obtained, for coloured media have rarely 
 the power of excluding all but one ray. The general effect, 
 however, is sufficiently determined. 
 
 To apply this principle to dioramic paintings, though in 
 these paintings there are only two effects represented, one of 
 day in front, one of night behind. These effects not passing 
 the one unto the other without a complicated combination of 
 the media which the light had to traverse, produce an 
 infinity of other effects similar to those which nature presents 
 in her transitions from morning to night, and the reverse. 
 It must not be imagined that it is necessary to employ media 
 of very intense hues in order to obtain striking modifica- 
 tions of colour, for often a slight shade in the medium suffices 
 to operate a very great change in the effect. 
 
 It will be understood from these principles of dioramic art 
 in which striking results are obtained by a single decomposi- 
 tion of light, how important it is to observe the aspect of the 
 sky when we would appreciate the tone of a picture, whose 
 colouring matters are thus subject to decompositions so great. 
 The best light for this purpose, is that from a pale sky ; for 
 where the sky is blue, it is the blue tone of the picture also, 
 and consequently its cold tone which comes out most power- 
 fully, while its warm tones remain inactive. Their media are 
 not present, and they are cast comparatively back into neutral 
 tints by the blue medium of the sky— so favourable to the 
 cold tones of the picture. It happens,' on the contrary, 
 when the sky is coloured, that the warm tones of the picture 
 
 F. 
 
74 
 
 — its reds and yellows — come forth too vigorously, and, 
 overpowering its colder tones, injure its harmony, or, it may 
 be, give it quite a different character — a warm instead of a 
 cold tone of colour. 
 
 It is easy to understand from these observations that the 
 uniform intensity of colours cannot be maintained from 
 morning to evening. We may even venture to assert it to be 
 physically demonstrated that a picture cannot be the same 
 at all hours of the day. This, perhaps, is one of the causes 
 which contribute to render good painting so difficult to 
 execute, and so difficult to appreciate. Painters, led into 
 error by the changes which take place between morning and 
 evening in the appearance of their pictures, falsely attribute 
 these alterations to a variation in their manner of seeing, and 
 colour falsely, while, in reality, the change is in the medium 
 — in the light. 
 
NOTES . 
 
 (1) M. Daguerre is a professional man, member of the French 
 Academy of Fine Arts, of the Academy of St. Luke, & c. His works 
 as an artist are of great excellence, and from these his reputation 
 among his countrymen stood high long before the photographic disco- 
 veries gave him a European fame. He is a man of extreme modesty 
 and great personal worth. On the 19th August, when the secret of 
 the process was to be for the first time publicly announced in the 
 Institut, M. Arago began his admirable address on this occasion by 
 apologizing for his taking apparently the place of another : “I have to 
 express my regret that the inventor of this most ingenious apparatus 
 has not himself undertaken to explain all its properties. This morning 
 even I begged — I intreated the able artist to yield to a wish which I 
 well knew is universal ; but a bad sore throat — fear of not being able 
 to render himself intelligible without the aid of plates — in short,” added 
 the philosopher, with admirable feeling, “ a little too much modesty — a 
 burthen that the woild bears so lightly — proved obstacles which I 
 have not been fortunate enough to surmount. I hope, then, I shall be 
 pardoned the appearance which I am this day proud to make before 
 this assembly.” M. Arago’s explanations were delivered without notes ; 
 his eloquence, so admirably adapted to the subject, could only be 
 exceeded by the reverential attention with which bis explanations 
 were heard by probably the largest meeting that had ever assembled 
 in the halls of the Institut. M. Daguerre is ardently devoted to 
 his profession ; and, on looking at some of his pictures, it is hardly 
 possible not to believe that he has taken lessons from his own secret, in 
 a most skilful management of the lights which they exhibit. A pleasing 
 proof of his simple love of art appears in his title-page, which thus 
 announces the author — “by Daguerre, Painter,” &c. 
 
 (2) The agreement between the Government and the discoverers of 
 Photography, runs in these terms : — ■ 
 
 Between the undersigned, M. Duchatel, Secretary of State for 
 the Home Department, on the one part ; and 
 
 MM. Daguerre (Louis Jacques Maude) and Niepce, junr. (Joseph 
 Isidore), on the other ; 
 
76 
 
 It lias been agreed— as follows : 
 
 Art. 1. — MM. Daguerre and Niepce, junr. make over to the Minister 
 for the Home Department, acting for the State, the process of M. Niepce, 
 senr., with its improvements by M. Daguerre, and also of the last 
 process of M. Daguerre for fixing the images of the camera obscura. 
 They bind themselves to place in the hands of the Minister for the 
 Home Department a sealed packet, containing the history and descrip- 
 tion, exact and complete, of the said processes. 
 
 Art. 2. — M. Arago, Member of the Chamber of Deputies and of the 
 Academy of Sciences, who has already knowledge of the said processes, 
 shall verify previously all the writings in said deposit, and shall certify 
 their correctness. 
 
 Art. 3. — The deposit shall not be opened, nor the description of the 
 processes given to the public, till after the adoption of the bill already 
 mentioned ; then M. Daguerre shall, if required, operate in presence of 
 a Commission named by the Secretary for the Home Department. 
 
 Art. 4. — M. Daguerre makes over, in addition, and engages to give, in 
 like manner, information in the processes of painting and optic which 
 distinguish his invention of the Diorama. 
 
 Art. 5. — He shall be held bound to publish all the improvements 
 which from time to time he may make in each and all of these 
 inventions. 
 
 As the price of these rights given up, the Minister for the Home 
 Department engages to demand from the Chambers, for M. Daguerre, 
 who accepts an annual pension for life of six thousand francs. 
 
 For M. Niepce, who likewise accepts an annual pension for life of 
 four thousand francs. 
 
 Art. 7. — In case the Chambers should not pass, during the present 
 Session, the Bill granting these pensions, the present agreement shall 
 become null and void, and MM. Daguerre and Niepce shall be returned 
 their communication unopened. 
 
 Art. 8.— The present agreement shall be registered on payment of one 
 franc. 
 
 Made triple, at Paris, 14th June, 1839. 
 
 Signed by the contracting parties, &c. 
 
 STEWART AND Ml'llIlAV, PRINTERS, Oil) KAI1EY 
 

 
 
 
 
 
 
 
 
 

 
 
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