T.ihr^ June 12, 1929 Mr. George v. . Hawley, CiTll Engineer 2409 College -70. flariceloy Dear Mr. Hawley Professor 1. F. Lnngelier hat transmitted to me your gift of the boo* "Filtration of Bivar Waters'* by J. P. Kirfcwood, 1869. This historical volume will be suitably inscribed and placed in the Engineering Library of toe University. We prise tnis accession and thank you for it. With appreciation, Tery truly yours, Dean, College of Civil, . Grand Junction 48 IX. ....West Middlesex " " 56 X. ....New River " " 62 XI. .. .East London 73 xn. ....Leicester " " 82 xrn. ....York " " , 85 XIV. .... Liverpool , 89 XV. ....Edinburgh " " 95 XVI. ....Dublin " " 103 xvn. .Perth Water Works and Filtering Gallery 108 xvm. Berlin " and Filters Ill XIX, . . . Hamburgh " and Reservoirs 116 XX. . Altona " and Filters 120 XXI. Tours " and Filtering Canal 124 XXII. .... Angers " and Filtering Galleries 128 xxm. Nantes " and Filters 133 XXIV. ....Lyons " and Filtering Galleries 137 XXV. Toulouse " and " " 143 XXVI. and XXVU. Marseilles " and Filters 148 xxvm. .... Genoa " and Filtering Galleries 152 XXIX. and XXX. Leghorn " and Cisterns 155 Wakefield " and Filters 159 APPENDIX : Instructions : 165 Table of Equivalents of Measures 167 London Pumping Engines Tabulated 168 Boilers of " ... 174 793286 REPORT. To THE BOARD OF WATER COMMISSIONERS OF THE CITY OF ST. Louis. GEO. K. BUDD, President. GENTLEMEN ; In obedience to instructions received from the Board of ,1 have visited ce there for the . T L ii * 11 these are made The reader will please correct the following errata : Page 70, line 4, for >th>us read about. )rn j n J^ a ]y . o f " 103, " 7, for polltiuons read pollutions. ince . o f g er lj n " 122, " 26, for basin (c) read basin (e). Leicester York " 131, " 22, for (6.50 metres) read (0.50 metres). " 161, " 10, for the Thames or the sea read the Thames or the Lea. filtration in use time than I had _ ^^^ fc all the details and statistics which were desirable, without, a larger expenditure of time and money than your instructions, however liberally construed, would have war- ranted. What may be wanting, however, in the description of one place will generally be found in another. No one but the superintendent or engineer of each work, who had watched the process of filtration from year to year, could give minutely all the experience which each place learns for itself. The process, however, unless where the areas wore incommensurate with the service, was in England everywhere successful. The conditions were simple, well recognized, and easily understood ; and when, as in two instances particularly, they were violated, it was but temporarily the increase of area required being acknowl- edged, and being about to be corrected.* * January, 18G9. At each of these places the enlargement of the filtering area has since been made. REPORT. To THE BOARD OF WATER COMMISSIONERS OF THE CITY OF ST. Louis. GEO. K. BUDD, President. GENTLEMEN : In obedience to instructions received from the Board of Water Commissioners in December, 1865 (see Appendix), I have visited Europe for the purpose of understanding the modes in practice there for the nitration or clarification on a large scale of river waters, where these are made use of for domestic purposes in the supply of cities. To this end I have visited the cities of Genoa, and Leghorn, in Italy ; of Marseilles, Toulouse, Lyons, Tours, Angers, and Nantes in France ; of Berlin, Hamburgh, and Altona in North Germany, and of London, Leicester, York, Liverpool, Edinburgh, Perth, and Dublin in Great Britain. I submit herewith statements descriptive of the modes of filtration in use at each of these places. The obtaining of this information has occupied much more time than I had anticipated. In many places it was found impossible to get at all the details and statistics which were desirable, without a larger expenditure of time and money than your instructions, however liberally construed, would have war- ranted. What may be wanting, however, in the description of one place will generally be found in another. No one but the superintendent or engineer of each work, who had watched the process of filtration from year to year, could give minutely all the experience which each place learns for itself. The process, however, unless where the areas were incommensurate with the service, was in England everywhere successful. The conditions were simple, well recognized, and easily understood ; and when, as in two instances particularly, they were violated, it was but temporarily the increase of area required being acknowl- edged, and being about to be corrected.* * January, 18G9. At each of these places the enlargement of the filtering area has since been made. REPORT ON THE In France, while what is called the natural filter is successful, the arti- ficial filter is usually a failure, for reasons which are sufficiently explained in the descriptions of the several places. In England, where the rivers rarely carry as much sediment as the Missis- . 'sipps,: except in floods, I found the arrangements for filtration very general and ; -.very Jnanageable, and that, so far as my knowledge extends, wherever a city derived its supply from river or stream, unless where large storage reservoirs intervened, filter beds were used as a matter of course, to render the water in every case as unobjectionable and satisfactory to the consumer as might be practicable. In England and France, where the winters are usually mild, the ice seldom forms so thick as to require any extra attention on the filtering basins. I visited Northern Germany, where the climate is as severe as our own, to understand whether the formation of thick ice impeded or interrupted the filtering process. In the description of each place,* while the special object is to give an account of its filtering works, I have noted such other information as incident- ally came within my reach, in order that the general scheme of each place might be understood. Instead of giving a synopsis illustrative of the varying experience of the different places described, it will be more useful probably to explain the prin- ciples in practice, which govern the construction and operation of filter beds in England and elsewhere. The accompanying sketches of a filter bed suitable for St. Louis, will serve to illustrate the details of this practice. It will be obvious, however, that the pertinency of what I may say can- not be judged of without that kind of preliminary information which the state- ments referred to are intended to convey. We are accustomed here to consider the filtering arrangements on Euro- pean works, as having in view simply the removal of the fine sediments which discolor river waters ; but the filter bed equally intercepts and removes the fine vegetable fibres and the minute organisms, vegetable or animal, which in all river waters prevail more or less during certain of the summer months. The removal of this class of impurities is getting to be considered in England, and elsewhere, as of as much importance as the removal of the sedimentary uncleanness which is more apparent. During certain of the summer months, when the rivers usually carry but little sediment, this forms the chief duty of the filter beds. The surface of the sand becomes occasionally as much * Since this report was written, the London journal called "Engineering" has published descriptions of the London Water Works, in which will be found minute descriptions of several of the London pumping engines. The "Encyclopedia Britaunica," " Bourne's Specimens," and "The Engineer," may also be consulted for similar details. FILTRATION OF RIVER WATERS. 7 impeded then with this matter as with the earthy sediments which more usually clog it, and it is of a nature to taint the water under certain condi- tions more ofi'ensively than, the other. The sand filters are therefore con- sidered very important instruments of purification in this relation. They become, indeed, screens of the greatest delicacy, intercepting all material impurities, not the least of which are the very small fish with which all waters are crowded at certain seasons. Most of the European rivers, how- ever, pass through lands where manure is used more extensively, and where a higher state of cultivation prevails than on the lands bordering our West- ern rivers ; and where also a denser population usually exists. Our rivers, therefore, will not probably for a long time carry at any time the same amount of organic matter in suspension. In some of the places visited by me, what is called the natural filter is in successful use ; I will refer to this again, and confine myself first to the artificial filter. The filter bed was designed to get rapidly rid of that very light portion of the sediment carrried by river waters, which takes some time (a fortnight or more) to subside under ordinary circumstances. This clayey discoloration, though trifling in weight, renders the water very objectionable in appearance, very objectionable in its application to any of the arts or manufactures, and no acquisition certainly either as regards health or cleanliness ; although cus- tom, as on the Western rivers, may reconcile persons to its presence, especially when its absence is associated, as there, with the hard and unpalatable waters of the lime-stone springs. That portion of the sediment which, from its greater weight, subsides rapidly, say within twenty-four hours, can be more economically got rid of in subsiding reservoirs. The successful use of the filter bed presupposes the preparation of the water in a subsiding reservoir. Wherever the attempt has been made to use filter beds without that prelimi- nary aid, they have either failed altogether, as in France, or rendered the water but partially clarified, as in one of the London -works. On the London works the aid of subsiding reservoirs is being more and more availed of of late years, both as rendering the filtering process more economical, which they s'iem to have been slow to perceive, and as a necessary auxiliary in time of Hood, to the efficiency of the other. They have become besides, valuable expedients, especially on the Lea, for the storage of water. In some places as at Liverpool, Leicester, Edinburgh, and Dublin, the large valley reservoirs required for compensation and flood storage, perform for the filter beds the functions of a subsiding reservoir. I will refer again to the size and arrangement of these. The materials used for filtration on a large scale are very simple. They are sand, gravel, and broken stone or shingle the depth of the whole varying from 8 REPORT ON THE five to six and one-half feet ; a layer of shells has sometimes been used, placed within the stratum of gravel, but this is not found essential, and is now generally omitted. It will be convenient to consider here the most appropriate size for a filter bed before giving the arrangement and thickness of its materials. The sizes in practice will be found to be very variable, and seemingly to have followed no regular standard. The first filter beds at Chelsea proved inconveniently large, and have since in practice been divided. The new filter beds at Stoke Newing- ton (London), the filter beds at Liverpool, and those now under construction at Dublin, are fair specimens of modern practice, as applied to large cities. For small cities it is found convenient to make the dimensions proportionally smaller. The areas of these are 45,000, 30,000 and 22,550 square feet each, respect- ively. Their forms are rectangular, 300 X 150, 300 X 100, and 205 X 110. At Stoke Newington, with a delivery of 12,000,000 imperial gallons daily, there are 5 filter beds in use now, and two projected, making 7 in all when complete. At Liverpool there are 6 now, for a delivery of 9,000,000 to 12,000,000 imperial gallons. At Dublin, for an assumed delivery of 12,000,000 imperial gallons, there are 7 filter beds in process of construction. Each filter bed, at short intervals varying with the condition of the water, must have the deposit which accumulates on the surface of 1 the sand cleaned off or removed, and while any one is undergoing this cleansing process, the other remaining filters must be competent to deliver the required supply without overstraining their functions. If, then, there are six filters, five of them must be competent to the full duties of the service, and if eight filters, seven of them must be competent to this duty, on the supposition always that not more than one filter will at any time be oft' duty. Should the circumstances in effect render two unserviceable, the remainder must have area enough to meet the require- ments of the case. We see, then, that the smaller the filter beds with the condition, however, that not more than one shall be off duty at a time the smaller will be the total area of filtering surface required for the particular duty. The materials available for construction, and their cost, will also measurably influence the dimensions to be adopted, and it must always be borne in mind that although there may be but one filter off duty, it will frequently happen that another is nearly unserviceable. It is, therefore, found best to give a liberal area of filtering surface, to be prepared for all the contingencies of the service. For a city of the population and pros- pects of St. Louis, I will for the present assume 200 X 150 as convenient dimen- FILTKATION OF RIVER WATERS. 9 sions, giving an effective area of 37,450 square feet for each filter bed. See Plates 1 and 2. The bottom of the filter bed is prepared to suit the circumstances of its position. It must be made practically water-tight. This is sometimes insured by laying concrete on the bottom (a Plate 2), but quite as often by a layer of hard clay puddle 18 to 24 inches thick, over which a flooring of brick is laid ; where the ground is more than usually bad, both the clay and the concrete may be used with advantage ; when concrete is used the brick paving is not essential. Upon this flooring a central drain (b) running lengthwise is laid, with which are con- nected on either side small tubular drains (c) of 6 to 9 inches diameter, pre- pared for this purpose, the sides being pierced with holes to facilitate the entrance of the water. These side drains are laid nearly at right angles to the central drain, and from 8 to 12 feet apart. The central drain referred to as arranged in Plate 2, and as in use on many of the London niters, is a double drain , performing two offices the lower part (b), which is covered, gathering the filtered water, and the upper part (d), which is open, delivering the unfiltered water upon the sand, when refilling a filter bed immediately after cleansing, and in use then only for that special purpose. This central drain is sometimes of brick, and sometimes of stone covered with stone flagging, the side walls of the lowest twelve inches of the drain being in either case laid dry ; the water-way for this size of filter should not be less than 30 inches wide by 15 inches of height. A little reflection will show that the lateral drains can hardly be placed too close together, for it is desirable that the filtered water should flow to the col- lecting drains with as slow a velocity as possible ; and the further these drains are apart, the greater must be the amount of water running through each drain. In the latest constructed filter beds of the New River Works at Stoke Newing- ton, the lateral pipe drains are dispensed with, and over the brick flooring, dry brick are laid instead ; forming a series of small drains not more than six inches apart from centre to centre. The filtered water finds its way into these through the open joints of the bricks. This forms the most perfect arrangement for collection that I have met with ; but it is also, probably, the most expensive. These small drains deliver there into two central drains. This drainage skeleton rests on the base of the filter bed, and becomes the means provided to collect the filtered water and deliver it to the outer passages or wells. Upon the flooring of the filter beds, and covering the gathering drains as well as filling up the intervening spaces, a layer of broken stones is laid, large shingle or quarry spauls (e). The stone should not be larger than will pass through a 4-inch ring, nor less than will pass through a 2-inch ring, and they must be clean and free from earth or quarry rubbish. 10 REPORT ON THE The shingle so called is obtained in England from coarse gravel or beach deposits, and is screened to the size wanted. This layer of broken stone wants to be 24 inches thick to cover efficiently the pipe drains. Upon this layer of stone properly levelled off, from 18 to 24 inches of gravel is laid (/), say 18 inches. This gravel is usually screened into two or three sizes, the larger of walnut size, the next of the size of a hazel nut, and the third between that and pea size. The largest size lies upon the broken stone, the smallest size at the top, the layers six inches thick each. Over this gravel there wants to be laid not less than 30 inches of fine sharp sand (g). The sand to be screened to insure the requisite degree of fineness and uniform- ity. The lower 12 inches may be a little coarser than the upper stratum of 18 inches, but it is important that the two layers should be of uniform fineness and quality throughout, otherwise there will be danger of the water passing through more rapidly at one point than another. The whole depth of these materials amounts to Jive feet eight inches, a depth which will appear at first sight unnecessarily great, since we know that the upper stratum of sand per- forms apparently the whole duty of cleansing the water. The different degrees of fineness in the materials beneath the sand and their several thicknesses, were intended first to prevent the fine sand from following the water down- ward into the drains, and next to insure the presence of such a body of clean water below the surface of the filter, as would penetrate the numerous joints and openings of the drains, and keep them full, without creating anywhere currents or veins of water of any perceptible difference of velocity. With the drains much nearer to the body of the sand, it will be understood that the tendency of the water would be to flow through the filtering material more rapidly just over the pipe than at 5 feet on either side of it. The dis- tance through which it had to travel might be so short as to induce its concen- tration. The low velocity at which the water flows through the filter, the uniformity of fineness in the sand, and the distance of the collecting drains from its surface, all work together to produce that regularity of action over the entire filter bed upon which its perfection depends. The large gravel and the broken stone covering the lateral drains, presents in fact by the voids or spaces existing in such material, an innumerable collection of crooked tubes conveying the water in as many threads to the collecting drains, and rendering as well its concentration impracticable. All the clear water underlying the surface of the earth, from which our springs and wells derive their supplies, has been filtered into the clearness in which it is found, by passing through earthen strata, where the muddy impu- rities which it held on the surface after heavy rains, have been intercepted and separated by a process precisely similar to that of the sand filter, so far as its limpidity is concerned. FILTRATION OP RIVER WATERS. 11 From the ends of the pipe drains referred to, as well as from the end of the central drain, small cast-iron pipes (A), of 4 inches diameter, rise to the surface of the ground to enable the air to escape while the water is being first let on upon the filter bed. In England the sides are usually paved with brick or stone to slopes of from 1 to 1 to 2 to 1. In this climate as in North Germany the side walls would have to be vertical on account of ice (see Plate 2), and the depth of the water over the filter beds should not be less than 4 feet. With vertical walls as at Berlin and Altona, the attendant, with proper tools, readily keeps the ice separated from the walls, and although it frequently forms 18 inches thick, and occasionally 24 inches, it does not interfere with the filtration, nor has it dam- aged the side walls, to which the floating cake of ice is never allowed to become attached. The water of the river Spree at Berlin, and of the Elbe at Altona, is usually clearer in winter than in summer. The filter beds on that account will operate for a longer period during the winter months than at other times without being uncovered. At Berlin and Altona, as I was informed, the filtering had never been interrupted in winter nor had the works been damaged by the ice. In our Western rivers the winter waters usually present the same character of greater clearness during the winter than during the summer months. But some winters are exceptional in this respect, and during such winters it would be desirable and might be necessary to uncover and clean off, as in summer, any filter that should become, from an accumulation of sediment, unserviceable. The proposed roofing in of the filter beds, to defend them from the hot suns of midsummer, would come into play here to defend the beds on occasion from frost, and admit of their being uncovered for cleansing. Practice would speedily indicate how best to meet any exceptional difficulty of this kind ; and what had succeeded so well in the severe climate of Northern Germany, would not probably fail here from want of the required ingenuity or intelligence to meet the case. In the worst stages of the English rivers a filter bed has to be cleansed once a week, rarely oftener. The stuff, whether sediment or otherwise, intercepted by the filter, is found collected on the surface of the sand ; in the process of its removal, a thin paring of sand is necessarily taken with it, not exceeding from half an inch to three-quarters of an inch in thickness. The impurities carried by the water are not found to have penetrated the sand. The paring of sand is usually cleansed and laid aside for future use, except when fresh sand can be procured at less cost than the washing of the old sand. The thickness of the sand bed is allowed to be reduced by these repeated parings from 8 to 12 inches before it is renewed. The original thickness of 30 inches of sand becomes then but 18 or 22 12 REPORT ON THE inches before it is replaced and brought up to the original lines. The renewal is usually made once in six months, sometimes but once a year, as the conve- vcnience of the service may permit. At each cleansing of the filter bed the sand is loosened by forks for some 6 to 8 inches in depth, and afterwards raked smoothly over. The sand is liable to pack close if the cleansing is too long delayed. . In such case the weight of the water is felt upon the sand ; in the usual state of the filter it is not so felt. The filter bed is usually filled with water from above by flowing it slowly upon the sand either from one point in connection with an overflow drain (as in Plate 2) or from several points on the side of the filter. It would be safer and more convenient as regards getting rid of the air, to fill it from below by means of the drains there ; but if this were done with the uncleaned water it would distribute its impurities all through the filter. The filtered water may, however, by suitable arrangements, be made available for this service. When the filter has been once filled it is not necessary to empty it entirely at each cleansing of its surface. The lowering of the water 12 to 18 inches below that surface will after- wards be sufficient to admit of the workmen removing the crust of sediment col- lected upon it. To insure the perfect cleansing of the water by the filters as well as to pre- vent any disarrangement of the materials of which they are composed, the velocity of movement of the water must be very slow. There is but little difference of opinion among English engineers as to the best average rate, although in some places that rate is exceeded, the consumption of water having in such cases increased more rapidly than was anticipated , and the works fallen temporarily behind the necessities of the service. Mr. Charles Greaves, Engineer of the East London Water Works, limits this rate to an average of one-half gallon per minute for each square yard of sand surface, which is equal to 3s gallons per hour for each square foot of sand ai-ea of the filter bed. Mr. James Simpson, Engineer of the Lambeth and Chel- sea Water Works, who may be said to be the originator of the method of filter- ing now in such general use in England, gave me as his opinion that the filtering surface should be predicated on a rate of 72 gallons per diem for each square foot of sand, which is equal to 3 gallons per hour per square foot. Mr. Henry Gill, Engineer of the Berlin Water Works, considered that the rate should not exceed half a cubic foot of water (31 gallons) per hour per square foot of sand. Mr. Thomas Duncan, Engineer of the Liverpool Water Works, who is a close observer, gave me his opinion that the works should have in view a rate of filtration of from half a cubic foot (3s gallons) to one-third cubic foot (2 T \r gallons) per hour per square foot of sand. FILTRATION OF RIVER WATERS. 13 The gallons mentioned above are imperial gallons. It will be convenient to give all the measures in feet, the various gallon measures differing considerably. Referred to feet, the opinions'of these engineers appear as follows : RATE OF FILTRATION CUBIC FEET OK WATKR, PER SlIUiRB FOOT OF SiND SURFACE. Per Hour. Per Diem. 0.533 0.480 0*50 0.50 12.79 11.52 12.00 12.00 Mr Henry Gill Mr. Thos. Duncan I will assume half a cubic foot of water per hour per square foot of the sand floor as a fair exponent of the best English practice, and as a rate which with the usual attention will be certain to insure satisfactory results. This rate is equivalent to 75 imperial gallons, or 891 United States gallons, per foot square per diem. When the flow of water through the system of filters during the 24 hours cannot be made uniform, that is to say, when, as is sometimes the case (in the absence of an intermediate clear water basin), it varies with the consumption, being greater during the day hours than during the night hours, the combined area of the filter beds in that case should be made to meet the maximum or daylight consumption of the service per hour. The average rate of half a cubic foot per hour pre-supposes a maximum and a minimum rate, both of which have their working limits. When the filter is clean the water is allowed to pass through more rapidly than the average velocity of six inches per hour, and when it becomes clogged with sediment it cannot be made to pass through it at that rate. So far as I can judge, the rate should not exceed 8.8 inches per hour (110 imperial gallons per square foot) when the water is clean, nor get below 3.2 inches per hour (40 imperial gallons per square foot) when it becomes obstructed by the deposit. Mr. Hack, of the West Middlesex Water Works, stated that it varied on their filter beds from 11 \ inches to 2.9 inches per hour ; but these appear to me to be extremes, rather to be avoided than copied. The objection to the very low velocity of 2.9 inches per hour may not be apparent without explanation. The most obvious objection refers to the work done ; the delivery at that rate is trifling and incommensurate with the cost of the machine ; but the low velocity indicates another source of danger growing out of the compression or packing induced upon the sand by the sealing of 2 14 REPORT ON THE its surface, and the risk of this almost impervious coating being of unequal thickness, and of the water venting itself unequally at the thinner spots. The filtered water from each filter bed" should be delivered into a small well (as at m, Plate 2), whence it escapes into the proper conduit, and is carried either to a common clear water basin, or directly to the pumps. The sluices at this well can be so arranged, by operating downwards instead of upwards, as to adjust the head of water actually in action upon the filter bed. When the filter is clean, nine inches of head will produce the required flow through the filtering material ; according as the sediment becomes deposited on its surface, this head has to be increased to 2 or 1\ feet, varying a little with the character of the sand. If the head be allowed to exceed 3 feet, it is because the surface is being rapidly closed ; the weight of the water comes then into play upon the sand, induces the packing already referred to, and leads to the labor of loosening up the material during the process of cleansing. Sometimes when this amount of head is exceeded, the pressure leads the water to break through at points where some slight difference in the material gives it opportunity. It will then flow through in veins, damaging the filter bed. Such overstraining of the filters is rare. I observed but one instance of it, but the effect can readily be brought about by overworking the filters. The English filters are all deficient as regards any arrangement for meas- uring the precise flow from each filter, or the precise head of water on each filter while it is in action. A simple arrangement, involving very little cost, admits, as our sketch shows, of this knowledge being rendered certain where it is now guessed at. In London, where the service of each company is effected by steam power, the daily or hourly delivery of the pumps forms the measure of the amount of water passing through the filters. The engineer knows by this means when the filtering area is too small, because in that case the pumps are insufficiently supplied ; and he would know if the water was passed through the filters too rapidly, by its want of that perfect clearness which an efficient filtration always produces. But of the separate action of each individual filter bed he is ignorant, except by guess. The attendant can see when the filter bed has ceased to operate, by its ceasing to pass the water thrown upon it, and he can see when it passes the usual amount too rapidly, and can check this ten- dency by lowering his stopcocks and allowing the water to lower upon the filter bed ; but his judgment may frequently be in fault in both cases, and there ought to be something more than the instincts of an intelligent laborer to regu- late points of so much practical bearing on- the proper working of these filter beds, as the varying amount of water delivered upon them, and the constantly varying head required to pass that water under the changing conditions of the sand bed. The small well at the terminus of the centre gathering drain, with the iron FILTRATION OF RIVER WATERS. 15 sluice shown there (Plates 2 and 3) operating downwards, will enable the attend- ant to know at any time the head in action upon each filter, and the amount of water passing, for the top of the sluice becomes then a weir. He will thus learn, without guessing, when the delivery of any filter is so low as to render cleansing essential, and will throw it out of action and have it cleansed accordingly, and he will learn precisely, as the sand bed becomes gradually clogged, the head of water under which it will continue to deliver sufficiently beyond which amount of head it is needless, and it might be dangerous to go ; and he can always at the sluice regulate precisely the amount drawn from the filter per hour, so that the flow through it shall never be too rapid, nor the water permitted to be imperfectly cleansed. He will learn by this means, in fine, what the safe maxi- mum flow really is ; and as it becomes less and less notwithstanding the increased head produced by his lowering of the sluice, he will ascertain the least flow under which it is advisable to work it, and will know exactly when to throw it off and prepare it for cleansing. The best size of filter bed for such a city as St. Louis has been assumed to be 260 X 150, giving a sand area of 37,440 square feet. This area, at the rate of one-half cubic foot of water per hour per square foot of bed, gives a filtration 18,720 cubic feet of water per hour, which is equivalent to 449.280 cubic feet, or 3,360,847 United States gallons in twenty-four hours. To filter twelve millions of gallons daily, five filters of this size would be necessary, on the supposition that the flow of water through four of them is continuous through the twenty-four hours. To insure this condition the clear water basin should be large enough to receive the water passing through the filters during the night hours, accumulating it there for the day service. This clear water basin need not be large. The ability to store up one- third of the calculated daily consumption would meet the case. I have very little information in regard to the precise cost of filtration in England, no separate account being ordinarily kept of its particular expenses. At the Chelsea Water Works, London, the extra charge for filtering, Mr. Simp- son informed me, averaged 4 shillings and 6 pence per annum per tenement. If each tenant consumed 300 imperial gallons per diem, this charge would' be equal to one cent (specie) for each 1,314 United States gallons. The charge probably includes some profit. At Liverpool, Mr. Duncan found the cost of filtering (exclusive I presume of the capital invested in it) to average nearly 100 sterling per annum for a million imperial gallons filtered daily, or for each 365,000,000 imperial gallons. This is equal to 1.14 mills per thousand United States gallons or $1.14 (specie) per million United States gallons. For a delivery of 12,000,000 United States gallons daily, this would make 16 REPORT ON THE the cost of attendance, repairs, and maintenance, equal to $4,997 (specie) per annum. Mr. Hack, the Engineer of the West Middlesex Water Works, London, stated the cost of filtering as about 10 shillings, ($2.40 specie) per million impe- rial gallons. These works are very economically managed, and this amount includes the capital invested. On the supposition, as before, that each tenement used 300 imperial gallons per diem, or 109,500 per annum, equal to 131,435 United States gallons, the cost per tenement is in this case but 13 pence, equal to 26 cents (specie). The first cost of such works varies with the nature of the ground, the cost of material at the particular place, and the character of the construction. We can- not therefore infer from any one place, except in very general terms, the expend- itures to be encountered at another for the same extent of water supply. I have already said that the use of settling basins forms a necessary and an economical preliminary to the use of the filter bed in all cases, and especially during those months of the year when the water is very turbid. In a temperate climate, such as England, it is of little consequence how large these settling basins are made, provided that the depth of water is not less than 8 or 10 feet, and that it is not held unchanged for any great length of time. But in our warm climate it will be advantageous to have the settling basins as small as practicable consistent with the due preparation of the water for the filters. This preparation, our experiments upon the Mississippi water have shown, can be secured in 24 hours, Within that time, in still water, the heavier portion of the sediment in suspension sinks to the bottom, leaving the water thoroughly discolored still, but holding, as respects weight, a very small part of the original matter. This part, which even in still water settles and disappears very slowly, is intercepted and separated readily and speedily by the sand filter, leaving the water invariably clear and limpid. Under this arrangement we have the water but 24 hours still ; during the rest of the time it is in motion. To make the arrangement efficient under all circumstances there should be four settling basins, each of capacity to hold 12 millions of gallons with not less than 12 feet in depth of water when full. When a greater capacity is required the walls could be carried up, and a greater depth of water Obtained. With the four basins, there would be one filling, one in which the water was still undergoing settlement, one in which the water was being drawn off', and one upon which the process of removing the stuff deposited on the bottom could be going on without interrupting the duty required of the others. Waste pipes from each settling basin to the river would enable the attend- FILTRATION OP RIVER WATERS. 17 r ants to scour or flush off at intervals the lowest three feet of the water, and by some manipulation to pass off with it more or less of the accumulated sediment. It never was supposed that this deposit would flow off without this kind of assist- ance, and it can only be determined by experience whether it will be cheaper to run it out by wheelbarrows or to carry it off by mixing it with water. If it should be desired to use settling basins without filters, they ought to be much larger than indicated above to secure approximately the same results. They would not be so economical in first cost if of sufficient size, but they might be more economical in attendance ; but it is to be remembered that in this connection, having in view their probable dimensions, they would be an experiment which it might be interesting to have made, but which could not be advised, that I know of, on the faith of its having succeeded elsewhere. Even where very large gathering reservoirs have been available, as at Liverpool and at Dublin, filter beds have been constructed on the usual scale, to get rid of that slight discoloration which frequently remains in large bodies of water, and to meet the turbid character of such water when the reservoir is low, as well as to intercept the organic impurities referred to elsewhere. It remains to speak of the natural filter, of which we have specimens at Genoa, Toulouse, Lyons, Angers, and Perth. The descriptions of the works at these places will show that this mode of obtaining a supply of clear water has been eminently successful, as regards the quality, if not always as regards the quantity. The character of the water at the places referred to is indeed unobjectionable, the slight increase of hardness at Lyons as compared with the Rhone water being too small to be of any moment. The water, indeed, in this case, is not made clear and pure by any artificial process ; it is received from the underground flow as from springs, and has not been exposed to light or to surface contamination of any kind. Bordering upon all rivers there are found at intervals narrow plains of gravel or sand brought down and deposited there by the river under the varying positions of its channel way. When these beds of gravel extend to a dep'th below the bottom of the neighboring stream, they will always be found saturated with water mainly derived from that stream, and however turbid the water of the river, this underground flow will always be found clear, provided that we tap it at a reasonable distance from the channel way. The cities referred to derive their supplies of water from gravel accumulation of this kind Genoa at a considerable distance from the city, but the other places in the immediate vicinity of the several cities. Covered galleries have been carried through these beds of gravel at depths sufficiently below the channel of the neighboring stream to insure a supply of water within the gallery during the lowest stages of its water. The water in these gravel beds rises and falls with the height of the water in the river, and 18 REPORT ON THE unless the galleries were placed below its lowest water they would obviously become dry and would cease to deliver at its lowest stage. These galleries are of various sizes and of various widths, eight to thirty feet in width being the latest practice. But the experience of one place will seldom be applicable to another. The character of the neighboring stream and the fineness or coarse- ness of the gravel or sand in which the galleries are placed, influence impor- tantly the rate of supply. As regards St. Louis, although I have already in a former report, expressed an unfavorable opinion in regard to the applicability of this method here, it seems to me important that an experiment should be made upon the river plain above Bissell's Point, to ascertain whether the material of that bottom is sufficiently open and gravelly to secure a supply of water in this way, what length of gallery would probably be necessary there, and whether the water would be of the same character as the Mississippi water.* If clear water could be obtained there by underground galleries at a rea- sonable cost, it would be more satisfactory to the inhabitants probably, than if the river water were rendered equally pure to them by filtering or settling reservoirs operating above ground. The experiment should be on a sufficiently large scale to give some confidence as to the ultimate results. Although the filtering galleries of the Genoa Water Works give larger results than any others that I am acquainted with, no conclusion can be drawn from them which would be applicable to our case, the circumstances being so very different. At Toulouse, Lyons, Angers, and Perth, the circumstances bear a closer resemblance to our own, though I fear that the materials of the plain above Bissell's Point may prove finer and closer than the sand and gravel deposits of the places above mentioned. These galleries are all of stone masonry, open at bottom.. The water in all these cases enters principally from the bottom, and the estimated rate of delivery in these galleries is generally referred to the area of the bottom. The flow into them must be at a velocity which shall not carry sand or any kind of material with the water. There is, therefore, no danger of under- mining the side walls. The first galleries built at Toulouse and Lyons were two small in size to give the best results there. The latest galleries have been made larger. At Toulouse Ik feet wide, at Lyons 33 feet wide. The galleries at Angers and Perth are too small for your purpose. * This recommendation was not carrried into effect, the Commissioners not feeling warranted, from such information as they could obtain, in risking the delay which a sufficient experiment would necessarily entail. FILTRATION OF RIVER WATERS. 19 The minimum deliveries of these underground galleries per diem per square foot of their bottom areas is as follows : CUBIC FEET. U. S. GALLONS. Toulouse, the new gallery 38.50 288 19.64 147 Angers, the latest gallery 40.10 300 Perth 24.32 182 The lower the gallery can be carried below the lowest stage of the river the more safe and abundant it is said will be the supply. If we suppose the galleries to be 20 feet in width, and that a rate of 200 United States gallons per square foot of bottom could be obtained from them at low water of the Mississippi, the length of gallery required to give 1,000,000 gallons daily would be 250 feet, and for a supply of 12,000,000 it would require a length of 3,000 feet. In other words, the bottom area, to produce this last quantity, would be 60,000 square feet. The filtering galleries and basins at Lyons have an aggre- gate of 57,706 square feet, giving, at low water of the Rhone, a daily delivery of about six millions U. S. gallons, but the galleries of the other cities give much higher results, as you have seen, than the Lyons galleries. The river water which finds its way into the deposit of sand or gravel where the galleries are placed, must have deposited somewhere the sediment held by it in suspension while in the river channel. I could not learn, however, that the filtering galleries became unserviceable from any such cause. The deposit which takes place upon the river bottom in the ordinary and in the low stage of its water is removed, it is asserted, in time of floods, when the bottom is scoured of all its light matter, and the coarser earths composing -it become in this way periodically exposed. This, and the fact that the water drawn from a gravel bed of this description percolates into it from a very extended face as compared with any artificial filter, may account for the continued regularity of flow into the natural filtering galleries. In the accompanying descriptions there will be found some other modes of filtering in practical use, but I refrain from alluding to them here, as they are not applicable to your case, nor can they be recomnlended for similar works. The two modes of sand and gravel filtration to which your attention has been specially directed the natural filter and the artificial sand filter have each of them met the test of long and successful use ; and when the natural filter is not available, the artificial filter may always be safely depended on in connec- 20 REPORT ON THE tion with subsiding reservoirs as competent to render any river water, however turbid, entirely limpid and satisfactory in that respect for domestic use. Respectfully submitted by JAMES P. KIRKWOOD. NOTE. April, 1869. New works for the supply of the city of St. Louis with water are now in the course of construction under the charge of Mr. Thomas J. Whitman as chief engineer, the undersigned being connected with them only as consulting engineer. These works include settling reservoirs, but the public mind of St. Louis, so far as it has been expressed, does not yet seem to consider filtration important I will take advantage of this note to mention the works now under construction (May, 18G9), for supplying the city of Newark with water, as presenting the only instance in the United States that I know of where provision is made for the filtration of the river water from which the supply is derived. In this case two basins, 350 feet by 150 feet each, have been constructed alongside of the Passaic river, above the village of Belleville. They have eight feet depth of water in them now. The flat or bottom land on which the basins are placed is understood to consist of sand and gravel, resting on a sandstone rock. The river is distant about 200 feet from the basins. The water which fills them is evidently dependent mainly on the river as its source of supply, not drawn exclusively from that part of the river immediately bordering the basins, but as well from the plain above and below, which mast be saturated with the same water. These basins collect the water on the same principle as the filtering galleries at Lyons and Toulouse. They are, however, open basins, while the French filtering galleries are all covered. The basins are bordered by vertical stone walls of excellent masonry, very neat and substantial in character. Mr. Bailey is the engineer of the works. At the Hamilton Water Works, in Canada, built after the designs of Mr. Keefer, another instance occurs of this kind of surface filtration. The water there is not drawn directly from the hike, but from an artificial pond bordering the lake. The lake water finds its way into this pond through the intervening beach of gravel which acts as a filtering medium. The pond, however, is not so elaborately finished as the Newark basins. J. P. K. FILTKATION OF KIVBU WATERS. 21 DESCRIPTIONS OF THE FILTERING WORKS REFERRED TO IN THE REPORT. LONDON, June, 1866. The metropolis of London derives its supply of water at present from the Thames, the river Lea with certain springs in the valley of the Lea, and from a series of chalk wells in the valley of the Ravensbourne, sunk on the upper side of a fault which occurs in the chalk basin there, in the neighborhood of Deptford. The proportions are nearly as follows : From the Thames 49 parts of the whole. From the Lea 44 " From Chalk Wells in the Ravensbourne Valley 7 " 100 The present condition of the supply is in a measure due to the legislation which followed the visitation of the cholera in 1849, and the result when com- pared with what was tolerated before that time must be admitted to be very satisfactory. The past history of the waters delivered to, and submissively endured by, the populations of London and Paris, may be studied as instances of how much discomfort and filth in this direction communities will suffer before being roused to insist upon the remedial measures within their reach. Previous to 1852, when the Parliamentary investigations following 1849 ended in a bill to provide for and insure the improvement of the water supplied to the city, the Thames Companies drew their supplies from the river within the city lines, where the water, besides being turbid more or less at all times, was contaminated by the sewerage of the largest city population in Europe. After 1852 the Thames Companies were required to get their water from a point on the Thames above the city influences and above the tidal flow ; they were also all required to filter the water intended for domestic use, including in this term all water except that used for street or fire purposes ; but as thi i 19,380,739 -*" rH oi rH IO S g i rH rH IO CM CM t- I 1 CM t- oo" rH oo" rH 6 tf * g | 22,898,769 18,536,804 CO r-1 Oo" CO d o" i CO O CM g CO oo co" W o r-J 9,317,255 \ o CO of IO CO IO O> rH o 8 10" o 8 oo" CO CM CO o co" CM CO CO oo oT SOCTHWARK am VAUXUAI.L. o IO of \ : 9,425,288 CO IO IO CO oi rH of CO CO O i CM 1 CO rH co" 00 rH j ' | oo" j 1 10 IO CO IO CO ~' rH 1 IO I-H" CO 00 CO CO O o co" CM CO CO CO to oo CO oo" i ; S- | oT IO IO 00 IO t- 00 o cf o CO (M CM CM CO CO CO O o 1 of g co -o< o t* 8 o CO E2 . . oo * 1 1 i" S" 1 g s : : I CO : i CM OS 00 g I I on 1 DO ^ QC O s E 3 a CD oo rH tb 1 g .9 _a CC g 01 1 s "3 a ,0 1 1 f J & ft So a & ft CD OO rH t _fl rH ,0 CO OO rH -0 1 : Average total consumption per di Ions I 1 rH of 8 .s co- co oo 1 cS 1 A From Springs in the chalk, 1866, ir Quantity for house supply daily, in Hardness as given by Dr. Letheby, Hardness after boiling, by Dr. Let grees Hardness as given by Dr. Frankla In each case 1 degree = 1 part c 100,000 parts of the water. Aggregate areas of the filter basins Aggregate areas of settling basins. 1 '3. S | Is "S .a CO i & d" ci I I Number of houses, 1866, excluding premises and public buildings. . Bate per house per diem Daily average per year, 1868 24 LONDON. If we take the given population supplied at three millions, and the aver- age daily delivery at ninety-seven million gallons, we have a rate of daily con- sumption per head of 32s imperial gallons, this amount being inclusive of all water used for manufactories, shipping, fires, streets, and other purposes. The Thames, at an unusually low stage of the river, in August, 1868, as measured by Mr. Hamilton N. Fulton, near Tottenham Lock, was delivering 256,000,000 gallons in 24 hours. In 1867, its lowest state was mentioned by Mr. Simpson as being at no time less than 300,000,000 gallons per diem. The water companies, it will be seen farther on, withdrew a little over one-fifth of the lowest of 1858, or 57,900,000 imperial gallons. The drainage area of the Thames above Hampton is stated to include 2,352,640 acres, or 3,676 square miles. The drainage area of the river Lea at Fields Weir, near to where it is tapped by the New River Company, is stated to measure 444 square miles, and the en- tire drainage of the river at the point above Lea Bridge where the river is tapped by the East London Water Works Company, I estimate as equal to 640 square miles. I find it difficult to get at the minimum flow of this river, but it seems plain that it has more than once fallen below the amount which the two water companies are entitled to draw from it, making a recourse to storage reservoirs therefore indispensable. I visited the works of all the Metropolitan Water Companies, and, although my object was to obtain the required information in regard to their filtering processes especially, I was permitted at the same time to take notes of the general dimensions of their pumping engines. The information thus collected, however, is necessarily incomplete. Neither the time at my own disposal nor the time of the officials, to say no more, permitted me to acquire that fulness of detail that was desirable. Such as it is, however, it may prove to others, as it has done to myself, useful as a basis of reference.* All of the water delivered to London undergoes a process of filtration through beds of sand and gravel, with the exception of a portion of the water used for fire purposes and for street washing, and with the exception of the water delivered by the Kent Water Company. This last water is obtained from wells sunk in the chalk, and does not re- quire filtration. Allowing for these deductions, the amount of water filtered daily must reach about eighty million gallons. The aggregate area of the filter beds at the works of the seven companies herein described amounts to 2,239,010 square feet, or 51.10 acres. If we take six-sevenths (f) of this area as in daily use, the other seventh being under repair, it would give, as compared with the eighty million gallons filtered, an average rate of 41 2 imperial gallons per * See Appendix. UNIVERSITY OF OF CIVIL. ENGINEERING BERKELEY. CALIFORNIA LONDON. 25 square foot of sand area per diem ; but at least three-fourths of the London supply is delivered during the day hours (6 A. M. to 6 P. M.), and for a certain portion of the mid-day hours in summer, the consumption may be taken at double the average which refers to the diem of 24 hours. The rate of filtration, therefore, during the day may at times reach an average rate of 83 gallons per square foot a rate which exceeds by 11 gallons the average (72) which the best authorities recommend as the proper limit. All the companies deriving their supplies from the Thames are required by law to take the water from the river above Teddington Lock ; in other words, above tidal influence, and above the influence of the sewerage of London, Ted- dington Lock being the first lock on the river above its tidal flow. The law also requires that all storage reservoirs for filtered water situated within five miles of the centre of London (St. Paul's), shall be covered. All of them are, therefore, arched over. The storage reservoirs, probably on account of the great expense attending their construction and the cost of property within the city, are most of them comparatively small, and, while they assist to meet any extraordinary increase of consumption, as in the case of fires to which the pumping engines of the night service might not be able to respond at once, they are rarely sufficient to enable the entire engine power of any company to be at rest during the night hours, far less to admit of one or more days' inter- mission of the pumping operations to meet any extraordinary emergency.* August, 1868. Since the above introductory remarks were written and this report presented to the Board, a short visit to England, in July, 1868, has per- mitted me to visit again most of the pumping stations of the different London water companies. Since my former visit in 1866, the Chelsea Company has added a new set- tling reservoir at Thames Ditton, and is now constructing two additional filter beds there; the Lambeth Company has more than doubled its filtering area, and has provided for three settling reservoirs in connection with these, one of which is finished and the other two under construction. The Grand Junction Company is constructing three new filter beds and an additional settling reservoir at Hampton, aad has also under construction an additional storage reservoir at Camden Hill ; and the New River Company has constructed two new filter beds at Stoke Newington. I crave leave, therefore, * The Metropolitan water acts prescribe as follows : From and after 31st August, 18G5, no company to take any water from the Thames below Teddington Lock, except the Chelsea Company. From and after the 31st August, 1856, no water to be taken by the Chelsea Company below Teddington Lock. From and after 31st August, 1855, every reservoir within a distance in a straight line of five miles from St. Paul's Cathedral shall be roofed or otherwise covered over, except storage reservoirs for collecting the water before nitration, and except reservoirs for water used for street cleaning or fires, and not for domestic use. From and after the 31st December, 1855, every company shall effectually filter all the water supplied by them within the metropolis for domestic use, excepting any water which may be pumped from wells into a covered re- servoir or aqueduct without exposure to the atmosphere. 26 LONDON. to revise that part of my report which referred to the London Works so as to meet more nearly the present condition of things there, and with the permission of the Board of Water Commissioners, the changes and improvements referred to are now incorporated accordingly. To appreciate the present situation of the London water supply in a sani- tary point of view, the report of Dr. Parr on the cholera epidemic of 1866 should be read. The sewerage of the many villages within the valleys of the Thames and the Lea finds its way into these streams now. When the rivers are as low as they have been this season, this cannot but affect the purity of the water, which, while it can be clarified and made perfectly limpid by sand filtra- tion, cannot by that process be dispossessed of any noxious gases which it may have from such sources absorbed, nor of some of the very minute organisms due to such causes. A law passed recently for the defence of river waters against such sources of contamination, will, to some extent, it is hoped, correct the evil referred to, though it cannot entirely remove it. In this place it may be well to keep in mind that the water which will satisfy a chemist will not always be a safe water for public use. Chemistry can- not always detect the nicer shades of impurity which should render a water objectionable to the consumer. Impurities which the sense of smell or of taste can detect, the researches of chemistry fail to expose, and for that reason are apt to ignore. Dr. Letheby, the Professor of Chemistry in the London Hospital, and Medical Officer of the city, has acknowledged " that we have not at the present time any absolute test for discovering organic matters in water, much less the nature of those organic matters." " We cannot distinguish absolutely vegetable from ani- mal substances in water unless they are in so large a quantity as to be able to show us their marked properties, when they can be tested ; but under common every-day circumstances of organic matter in water, we cannot say whether it is vegetable or animal organic matter." The General Board of Health in their .report of 1850, speaking of the Thames river, makes the following remarks to the same effect : " High up the river the water is so transparent that the bottom is visible more than eight feet deep. As the examiner proceeds down- wards the transparency diminishes, and the water becomes turbid until it reaches the metropolis, where nothing is to be seen within a few inches beneath the surface. It was the task of Dr. Angus Smith to follow the river and ascer- tain by analysis more closely than had hitherto been done, the nature and quantities of these variable additions. This he has done carefully with all the aid which chemistry is capable of affording. But as yet chemistry has failed to determine the qualities of much animal and vegetable, and above all, gaseous matter, that is perceptible and offensive both to the taste and to the smell." The works will now be described as shortly as practicable, in the order in which they were visited. THE CHELSEA WATER WORKS. 27 THE CHELSEA WATER WORKS The water supplied by this company is derived from the river Thames. The filtering works are situated on the right bank of the Thames, close to the river at Seething Wells, near Thames Ditton. The original works of the company were situated at Chelsea ; they were removed in 1852, to Seething Wells. The accompanying sketch will explain the form of these works (Plate 4). The narrowness of the strip of ground available, controlled the arrangement here, and has obliged the engineer to place the engine-houses rather inconve- niently away from the filter beds. There are three settling reservoirs and two filter beds. The settling reservoirs have each a water area of about one and a half acres. The filter beds have each a sand area of about one acre or very nearly 44,000 superficial feet. Two new filter beds were being constructed during the summer of 1868, of the same capacities very nearly with those now in use. The settling basins have a depth of water in them of six to ten feet, vary- ing with the water in the Thames. The first and second from the filters, are each 272 feet long by 226 feet wide at the top of the banks, with inside slopes of 1 to 1. The third has about the same water area, but is a little differently shaped, to meet the situation of the ground. The water passes into each freely from the Thames through a sluice-way, and stands at the same level as the river water. In the sluice-way there are screens. At the side of each reservoir oppo- site to the sluice-way, the water passes to the filter beds by means of a 24-inch pipe controlled by a stopcock. A rough semicircular filter of gravel and small stones, shown on the sketch, intervenes between the pipe mouth and the water of the basin, and intercepts any floating grasses or other impurities that may have passed the screens. The condition of things here does not admit of the water remaining at absolute rest in either basin. It enters at one side in each case and passes slowly through to the other side, the movement being more rapid during the day than during the night. 28 THE CHELSEA WATER WORKS. This slow passage admits of a sufficient amount of deposition in the pres- ent state of the Thames (June, 1866), when its water is but very slightly turbid ; but when the river is in flood and carrying much sediment, the preparation here for the filter bed must be insufficient. The settling basins are said to be cleaned out twice a year. To effect this the water is drawn off through an 18-inch pipe into a silt well, whence it is pumped off by two small pumping engines appropriated to this service, the mud at the bottom of the settling basin being stirred up during the process of pumping, so that the greater part of it flows with the water into the drain-well of the pump. The dirty water and slush pass into a sewer which has its outlet on the Thames, about half a mile below the works. The pipe (24-inch) which takes the water from the settling basins to the filter beds, passes round to the extreme side of the beds, and delivers the water upon each bed by 6 branch pipes, of 6 inches diameter each. After a filter bed has been cleaned, and while its surface of sand is bare, the covering it again with water is an operation requiring considerable circum- spection. The sand will be rutted into channels if the water is let on rapidly, or blown, if the process is not effected so slowly as to admit of the escape of what air may be lodged within the filter bed. After the filter is well covered and in use, the water may be delivered upon it as rapidly as it can use it. The branch pipes above mentioned do not deliver the water directly upon the sand surface, but they deliver it into wooden troughs 10 feet long, 12 inches wide inside, and twelve inches deep. From these troughs, which are imbedded in the sand, the water flows over their edges upon the filter beds without dis- turbing the sand. When a filter bed is bare here, it is filled from the surface, and the attendant says that he finds no difficulty in effecting this and getting rid of the air, except that the operation must be begun slowly. There are air pipes along the two ends of each filter bed, connected with the clear water drains, but these air pipes can be of little service, except when the water is entirely drawn off from the filtering materials, which seems rarely to be the case. Usually the water when drawn off is not lowered more than two feet below the surface of the sand. I saw one of the filters bare in February, 1866. At the time of my last visit they were both covered. The depth of water in each was 82 feet. The water delivered into London from these works in June, 1868, was reported to average daily 9,333,900 imperial gallons, and in July, 1868, 9,748,100 imperial gallons. Assuming 550,000 gallons to consist of the unfilterod water delivered for street and fire purposes, there remains say 9,200,000 of filtered water delivered per THE CHELSEA WATER WORKS. 29 diem in July. Had this been an ordinary year as regards temperature, the delivery of filtered water would not probably have exceeded a per diem of 8,000,000. This Company, as well as each of the other four Thames Water Companies, has a right to take from the river twenty millions imperial gallons per diem. At this date the five companies take a little exceeding fifty million gallons daily from the stream. To avoid to some extent the excess of duty thrown upon one of these filter beds by the disuse of the other (during the process of cleansing), a low earthen bank has been run across each of the filters, dividing each into two, and making practically four filter beds. This earthen division being but a make -shift of not more than 2 2 feet in height, the water is partially drawn down when it is brought into play. The effect, however, is to secure the use approximately of three-fourths of the entire filtering surface, leaving but one-fourth necessarily in disuse. The two filter beds have a joint area of 88,000 square feet. Assuming three-fourths of this to be always in service, there are 60,000 square feet of sand area to filter ordinarily 80,000,000 gallons of water. But although the larger portion of this amount is pumped during the day hours, the day rate of filtration cannot be more than 393,000 gallons per hour, because two pairs of engines cannot deliver above this rate. This is equal to 6 gallons per square foot of filter per hour, or 144 gallons per square foot per diem ; with the whole filtering area in use, the flow is reduced to 107 gallons per square foot per diem. Both of these very much exceed the rate which the Engineer considers best, a rate namely of about 72 gallons per square foot per diem, but the increase of the population of the district has exceeded the anticipations of the Company, and the filtering works have fallen behind the necessities of the service. When the new filter beds are completed, this condition of things will be entirely corrected. The outer walls of the filter beds are slope walls of brick on edge laid at an inclination of 1 to 1. On two sides of each filter bed, appearing at the top of the slope walls, are rows of 3-inch cast-iron air pipes, communicating with the drains on the bot- tom of the filter beds. The pumping power at work during the day is about double of what is at work during the night. The additional charge made for filtration, Mr. Simpson stated to be about four shillings and sixpence (one dollar) per house per annum on the average. The materials of these filters consist of sand, gravel, shells, and small stones, in the following proportions : 4 30 THE CHELSEA WATER WORKS. Fine sand 30 inches. Coarse sand 6 inches. Shells 4 inches. Fine gravel 6 inches. Large gravel 24 inches. 70 inches. Perforated clay pipes are imb edded in the large gravel. The thin layer of shells was intended to intercept any sand which might follow the water. On the bottom there is a central drain, into which the water is collected by these earthenware perforated pipes, branching from it across the bottom on either side. These drain pipes were given me as of 9, 8, and 6 inches in diam- eter on each branch, the smallest being placed furthest from the central drain. A circular well of about 12 feet diameter receives the filtered water ; it is trans- mitted thence by a cast-iron pipe to the pumping engines, which are situated on the opposite side of the Kingston road, as shown on the sketch. At the time of my last visit, the water in the well (at noon) stood 3 feet below the water on the filter beds, both of which were then in full use. The water in the well varies from 2 to 4 feet below the level of the water on the filters, according to the condition of the beds. The filter beds are cleaned off from once in six to once in twenty days each, according to the condition of the river. The amount of sand taken off does not exceed half an inch, and this is washed and used over again. A cir- cular sieve (kept in motion by one of the small engines) into which the water is poured from perforated iron pipes, is used for cleansing the sand. The position of the engine-house is shown on the sketch. There are six double-cylinder rotative beam engines here, working in pairs, having one fly-wheel to each pair. The engines, however, can be uncoupled and worked separately. Of these engines the first and second pairs are known as the "A. B." and " C. D." engines ; the third pair, furnished in 1867, as the " E. F." engines. Each pair is given as of 300-horse power, or 150-horse power for each engine. The steam cylinders of each are : the small or high-pressure cylinder, 28 inches diameter, and 5 feet 6 inches stroke ; the large cylinder, 46 inches diam- eter, and 8 feet stroke. The pump is in each case a plunger and bucket pump ; the barrel 24-inch diameter, the plunger 17^-inch, and the stroke 7 ft. 1 inch. The delivery pipes of the pumps unite on one pipe main. There are two air vessels to each pair of engines, connected with the delivering pipes. Any dimensions or details given by me of engines in this report, were de- THE CHELSEA WATER WORKS. 31 rived from the foreman or the engineman in charge. The precise forms and plans of these pumping engines must be sought for in other works. The gen- eral characteristics only are aimed to be given here. These engines cut off on the small cylinder at half stroke steam 38 to 40 Ibs. The engines make 12 to 14 revolutions per minute, varying with the city consumption. The pumps were stated to deliver 120 to 126 gallons per double stroke. The beam of each engine is double, composed of two flitches, 32 feet in length between end centres, and five feet in depth at its bearings. The first built engines were not precisely balanced. To remedy this in the pair just built, the beam is made heavier on the side towards the steam cylinders than on the other side. The beams of the other engines are having balance plates added to them inside, at the same end, to perfect their adjustments. The one fly-wheel to each pair has a diameter of 18 feet, weight 14 tons. The suction valve of the pump is a two-ring valve. It is in fact a four-beat valve of the same character as the Harvey & West valve, except that in this case the beats are upon the same plane, and the facilities of emission for the water are therefore not so good ; the two rings are not connected, but act inde- pendently of each other. The delivery valve is a flap valve, consisting of two, and sometimes three, inclined iron flaps, hinged at the upper end, and beating on leather linings. For the first two pair of engines (A. B. and C. D.) there are 13 boilers in one house. One of these pairs was at work to-day with six of these boilers un- der steam. The steam carried varied from 40 to 42 Ibs. pressure. The boilers are all of the Cornish type, single-flued, the shell 5 feet 10 inches diameter, the flue 39 inches, length 30 feet. Ten boilers are used when both pairs of engines are at work. The steam pipe connecting all these boilers, and running into the engine- house, was of 14 inches diameter. The fuel used is the slack of Newcastle coal (bituminous). The last built pair of engines (E. F.) has a battery of seven boilers. Five of these were in use to-day. They are Cornish boilers, single flue. Shell 5 feet 10 inches diameter, flue 38 inches ; length 32 feet, carrying 42 Ibs. steam. There are two large square chimneys here of 110 feet in height ; I was not able to ascertain the sizes of the flues. This class of engine has now been long and well tried at these works, and its performance, so far as duty trials are comparative evidence, has proved to be at least equal to that of the best Cornish engines. At the time of my visit two pairs of engines were at work (A. B. and E. F.) pumping into the same rising main, which is of 30-inch diameter, and con- veys the water to the Putney reservoir, distant six miles. It is not considered 32 THE CHELSEA WATER WORKS. safe to work the three pairs of engines into the same main, and until a second main is laid, one pair of engines will always be at rest. The Company is laying a second 30-inch main at this time. The filtered water is all pumped into the Putney reservoir, with the excep- tion of a small portion which is drawn from the rising main to supply the inter- vening villages. From the Putney reservoir, the City district pertaining to the Company is supplied by gravitation. The Putney reservoir stands 181 feet above the pump well ; at the time of iny visit the gauge in the engine-houses showed a pressure of 220 feet. The A. B. engines were making 14 to 14^ revolutions per minute, and the E. F. engines, 12 revolutions. Both pairs of engines were stated to be working continuously through the 24 hours, and every day of the week. It has been usual for two pairs to work during the day, and one pair at night, but the in- creased demand for water this season must lower the Putney reservoir during the day much more than heretofore. Under any circumstances the water in the rising main is never supposed to come to a state of rest, but the rate of flow during the day is generally much more rapid than during the night. During the night hours the supply of water is cut off from the city tene- ments, with the exception of factories or other works, where the necessary supply of water cannot be continuously maintained by cisterns. The main pipes must, therefore, be always charged. The Putney reservoir, which is covered, has a capacity of 8,300,000 gal- lons. There is a small open reservoir near it for unfiltered water, with a capacity of about 1,250,000 gallons. The water for fire purposes, and for street-washing, is not filtered. Two small engines deliver this water into the small open reservoir above mentioned, whence it is passed into the city by a separate system of distributing pipes. The engines for this service are single cylinder rotative engines, with a fly- wheel to each. They are arranged, however, so as to be coupled, and generally work in connection. The steam cylinder of these engines is 20 inches diameter, with a stroke of 36 inches. The pumps are plunger and bucket pumps. The pump barrel is Ilk inches diameter, with 30-inch stroke. The delivery of unfiltered water is very light in winter, but may sometimes reach 500,000 gallons per diem in summer. The pipe main conveying the unfiltered water to the Putney open reservoir, is of 15 inches diameter, and 51 miles in length. There are a pair of small engines (15-horse power) for the drainage service that is, for pumping off the low refuse water, when required, from the THE CHELSEA WASTER WORKS. 33 settling basins, and we presume, also, for draining off the water from the sand of the filter beds, when they require cleansing. These works have been constructed from the designs and directions of Mr. James Simpson, Civil Engineer, under whose charge they continue now. Mr. Simpson is understood to be the originator of the very simple and manageable sand filter which has been so successfuly used at the London Works and else- where. 34 LAMBETH WATER WORKS. LAMBETH WATER WORKS. The Lambeth Works are situated on the right bank of the Thames, imme- diately above the Chelsea Water Works. They are under the charge of the same engineer, Mr. James Simpson. There are four filter beds here, each of the same size and form, as may be seen in the accompanying sketch (Plate 5), where they are marked a 1 , a 2 , a 3 , a 4 . The outer walls of these filter beds are vertical brick walls, thrown into the curved forms for strength. The central wall, which appears to divide each, is a buttress wall, built to receive the thrust of the horizontal arch walls, and arranged so as not to inter- fere with the free passage of water from the one half to the other. These filter beds have been doubled in size within the last two years. The sand area of each filter bed is 16,500 square feet, now making for the four beds an aggregate of 66,000 square feet. These works were reported in July, 1868, to be delivering that month an average of 11,210,400 per diem), the whole of this water passing through the filter beds. Two pairs of engines were at work on the day of my visit, making 15 revolutions per minute. At this rate I calculate their delivery to be about 453,000 gallons per hour, which, applied to the filtering surface, gives a flow through the filters of 6.86 gallons per square foot per hour, when the four beds are in use, and in a ser- viceable state. The average, as already stated, should not exceed 3.12 gallons (2 cubic foot) per square foot per hour. The rate here is therefore more than double the usual velocity, but this defect is to a certain extent compensated by an auxiliary filtration which the water undergoes at the settling reservoirs. These works, which at my previous visit in 1866, possessed no settling reservoirs, have now one settling reservoir in use, and two under construction. The three when finished will have a water surface of 3.1 acres. The sub- joined plan (Plate 5) will show the position of these, and of the filter beds. To remedy the inadequate surface area of the latter, a vertical filter of fine gravel, designated on the plan as "rough filter," is constructed across the lower end of LAMBETH WATER WORKS. 35 each settling reservoir. This gravel is held in place by two brick walls, bolted together at intervals. The walls are 4 feet apart, and the screen of gravel is, therefore, 4 feet thick, by about 15 feet in height, and 150 feet in length. The bricks are laid slightly apart at the joints, to permit the water to reach the gravel and to escape from it on the other side. The arrangement will be understood on inspection of the plan. That this rough filter was operating to some purpose seemed evident from the fact that the water stood 18 inches lower on the one side of this filtering wall than on the other. Doors are arranged on the upper side for drawing off the gravel at intervals and cleaning it. The bottom of each settling reservoir consisted of a layer of concrete resting on clay, over which was a paving of brick on edge, laid in mortar. The side slopes were 1 to 1, laid in the same way. The water is drawn directly from the river into these settling reservoirs, at the upper end of each, passing through the whole length in each case, before reaching the filtering walls. There are screens and sluices in the entrances from the river. Three of the filter beds were in use at the time of my visit (7th August, 1868), the fourth had just been cleansed. One f-of the filters was said to be cleaned every ten days. There was 4 feet of water on the beds. The materials of the filters are the same as on the Chelsea bed, and the re- lative arrangement the same, but the mode of collecting the clean water is different. On the floor of the new portions of the Lambeth filter bed a series of small brick arches is built, as shown on the cross section (Plate 5). These arches have vertical openings in them across the axis of each, of 1 inch in width on every 27 inches in length of each arch. This allows the water to pass through, without drawing with it any of the shingle. The water has thus but a short distance to travel, to reach a collecting drain. These small drains deliver into a larger drain communicating with the out- side conduit to the pump wells. On the original portions of these beds (the halves on the river side) small square drains are in use, covered with slabs of slate 3 feet long, 8 inches wide, and 3 inches thick. The slabs are kept an inch apart and covered with large shingle. These drains, as in the other case, deliver the water into the central collecting drain. Some fine sand, I was informed, would occasionally get through the shingle into the collecting drains, before the enlargement of these filter beds, probably caused by the unusual rapidity of flow through the filtering materials, which prevailed then. The depth of water on these filters, which formerly varied with the stage 36 LAMBETH WATER WORKS. of the river, can now be controlled from the settling reservoirs, and made uniform or otherwise at discretion. The sand removed from the surface of the filter-bed (2 to * inch in thick- ness) during the process of cleansing, is washed and replaced at intervals. The washing here is done by using hose connected with a pipe, from the rising main. Eight per cent of the sand is said to be lost by the washing process. Twenty-four inches of sand is taken off in twelve months, by the various cleans- ings. It is ordinarily replaced but once a year. The labor of attendance and cleansing of the filters was stated (1866), to be nearly 1,000 per annum. There are six double-cylinder rotative pumping engines working in pairs (3 pairs), with one fly-wheel to each pair. The third pair was added in 1866-7. The engine-houses are situated about 600 feet from the filter beds. The water is conducted by a, conduit to the pump wells. The engines are all represented to be of the same dimensions, viz. : The small steam cylinder, 28 in. diameter, with 5' 6" stroke. The large " " 46 in. " 8 feet " The pumps are plunger and bucket pumps ; the pump barrel 24 in. diam- eter, with 6' 11" stroke ; the pump plunger 17! inches diameter. There are two air chambers to each pair of engines, 10 feet high, by 38 inches diameter, of cast-iron ; they are connected at the top. There is no stand pipe here. The beams are all double. The length between end centres on the new engines, was 26 feet ; the depth of the beam at the gudgeon, 5' 6"; diameter of gudgeon 15 inches. These last beams were made heaviest at the steam end, sufficiently so to balance the engine. The diameter of the fly-wheel is 21 feet, 4 feet cranks, weight 15 tons. The engine was cutting off at one half on the small cylinder, and making 15 revolutions per minute. The suction valves are 4-beat valves, in two rings ; these valves are weighted to make them work well. The valves of the new engines were striking hard, and were said to be out of adjustment as regards weight. The delivery valves were flap valves in two parts. For the six engines there is provided a battery of 19 boilers, all connected. Twelve boilers were in use to-day for the four engines at work. There are never more than four engines at work at present, but when the second force main is laid, the three pairs of engines will be able to work simul- taneously, if necessary ; the second main, also of 30-inch diameter, is now being laid. LAMBETH WATER WORKS. 37 The boilers are all Cornish boilers, each 6 feet diameter of shell, and 31 feet long, with one flue 39 inches diameter. The fire grates 6 feet in length. Every boiler has a large drum 51 feet high, and 39 inches diameter. The steam pipe runs over the drums, and is 15-inch diameter. The chimney is a large square chimney, 100 feet in height, and apparently 8 feet square inside. The coal used is Newcastle slack. Four engines were at work during my visit, and work at present continu- ously, I was informed, night and day. They all pump into the Brixton reser- voir, through a rising main of 30 inches diameter, and 10i miles in length. The Brixton reservoir is situated 103 feet above the pump well. The gauge showed a pressure against the engines of 190 to 192 feet. At night the pressure shows 200 to 210 feet, the difference arising from the relief afforded by two or three branches from the rising main, delivering into the country dis- trict, which are not in operation during the night. From the Brixton reservoir the water is distributed to that portion of the district which it controls, the remainder being pumped up from that point to meet the requirements of the higher grounds within the district. The reservoir is covered and has a capacity of 15,000,000 gallons, with 12 feet depth of water. The reservoir falls during the day hours, showing the consumption of water to exceed the ordinary rate of the pumping power. It is filled up by the pumping engines during the night hours. At this reservoir there are three sets of supplementary pumping engines moving portions of the water received here from the river engines to higher altitudes. The first set, consisting of two engines, pumps the required supply for the Streatham reservoir, situated 82 feet above their pump well, and also into Salthurst reservoir, situated 103 feet above their pump well. An 18-inch main connects the pumps with both reservoirs, the length to the Streatham reservoir being about one mile, and to the Salthurst reservoir about 5 miles. The Streat- ham reservoir has a capacity of 3,672,000 gallons ; the Salthurst reservoir, of 3,400,000. The two engines are each double-cylinder rotative engines, but the large cylinder is annular, enveloping the small one, and the length of stroke is the same for both. The dimensions were given me as follows : Small cylinder 16 in. diameter and 5' 6" stroke Annular" 41 in. " " 5' 6" " The pump is a plunger and bucket pump, the barrel 17 is inches diameter, plunger 12ss, stroke 4 feet 7g inches. 5 38 LAMBETH WATER WORKS. But one engine was at work. During the night the two engines are at work, filling the reservoirs. The engine at work during the day is pumping directly into the appropriate portion, of the district, the reservoirs delivering then into the same distribution pipes. There is no delivery of water to the district during the night except for fires, and for any manufacturing works that may require a continuous delivery. The day delivery is intermittent, the turnkey letting on the water so many hours to one portion of the district, and so many hours to another. The same practice prevails in the Chelsea district. Two smaller engines, 16 years old, deliver into the Kockhill reservoir, which controls and supplies the highest portion of the district. The Rockhill reservoir (covered) has a capacity of 1,250,000 gallons. Its water, when full, stands 247 feet above the pump wells of the engines which supply it (or above the Brixton reservoir). An iron tank is built within the grounds of the Rockhill reservoir, raised 18 feet above its level, and with a capacity of 120,000 gallons. To supply a small portion of the district situated above both of these last- mentioned reservoirs, there is a stand-pipe on the Rockhill grounds, which, when in use, carries the water 50 feet above the Rockhill reservoir. The water is pumped over this stand-pipe by the Brixton pumps so many hours every day. The engines referred to are rotative beam engines, usually working couplet, but capable of working independently. There is a fly-wheel to each. But one of the engines was at work at the time of my visit. The steam cylinder is 21 , on the sketch. On the left bank of the Lea there are six filter beds, grouped also round a central well ; they are marked q, q, q, q, q, q. The filter beds were all covered, at the time of my visit, with from 4 to 5 feet of water, except one, which was bare, undergoing the process of cleansing. The materials of the filters are sand and gravel 4^ feet deep ; the depth of fine sand varying from 18 to 30 inches, according to the time which has inter- vened since the last renewing. The gravel is screened and arranged with the largest size at the bottom. The bottom is of concrete, upon which are laid the drains and earthenware pipes, which collect the filtered water and carry it to the central well. I was not able to get the particular size and arrangement of these pipes in this case, but they are of the same general character as those used at the other works. 76 EAST LONDON WATEE WORKS. In the worst state of the river a filter bed is cleaned once a week, but usually it suffices to clean them once in three to four weeks. The Engineer informed me that the aggregate filtering area cleaned off during the year averaged 160 acres. This is equal to 3.08 acres cleaned off per week. The entire sand areas of the filters amount to 12 acres, which would give an average of three filter beds cleaned each week, which would again give an average for each filter bed of a cleaning off every four weeks. About half an inch of sand is taken off in the process of cleansing. The foul sand is washed and used over again. The sand is not replaced upon each bed oftener than once in from 6 to 8 months. These filter beds are not bounded by vertical walls, but by steep slope- walls, paved with brick. The air pipes come to the surface at the top of the slope. In the filter bed, which was bare, there were three pipes visible at the foot of the slope-wall of one of the sides, for refilling and supplying it with water. Each of these pipes delivered its water into a small semicircular basin, the walls of which were flush with the surface of the sand. In commencing the refilling, the water overflows from these basins slowly upon the filter bed. There being 12 acres of filtering area here, I will suppose 10 acres of it to be always available for service. The water supplied averages 20 millions per diem, but of this we may consider 15 millions as passing through the filters during the 12 hours of day, the filtered water reservoir at Old Ford not being large enough to equalize the rate of filtration through the 24 hours. This gives a rate during the day of about 70 gallons per square foot. With all the filter beds in service, the rate would be 57 gallons per square foot per diem. The height of the water in the central well which receives the filtered water, as compared with its height or level on the filter beds, shows the head required to produce the flow through the filtering material. This head will vary with the rate of that flow, the extent of the filtering area in use, and the condition of the sand surface (whether it be recently cleaned or nearly closed). The well belonging to the set of filters on the left bank of the Lea, stood at the time of my visit 3 feet 9 inches below the level of the water upon the cor- responding filter beds. Although the mode of filtration adopted on the London works was origi- nally prepared with a view simply of depriving the river water of the sediment which discolors it after heavy rains, it is now conceded that the process of filtra- tion is quite as desirable in summer, to deprive such water of the floating vegetable fibres and certain animalcules which it carries in suspension. During certain of the summer months, this intercepted matter rapidly gums up the surface of the filter beds and induces vegetation there. At these EAST LONDON WATER WORKS. 77 seasons of the year the filter beds require to be cleaned off, in consequence of this coating of organic matters, about as frequently as when the river is in flood. In these filter beds, for instance (as related by Mr. Maine, one of the Company's Managers) during the month of July of every year, the slimy matter very rapidly deposits upon the sand, interrupting the filtration. In the month of August this slimy matter vegetates, producing green confervoid fibres, and spreading itself like a green carpet over the surface of the sand. Doubt- less, the other London Companies could testify to the same kind of experience. There is one Cornish beam engine (1866) at this station. Steam cylinder, 100 inches diameter ; stroke 11 feet. Plunger, 50 " " " 11 " The engine was at work, making 7 to 8 strokes per minute, and deliver- ing, I was told, 150 cubic feet per stroke. It works through a single-legged stand-pipe directly into the city main. There is also an air chamber on the main. It has a battery of eight boilers ; six at work, two at rest. Diameter of boiler 5 feet 9 inches each, by 30 feet in length. The flue 3 feet 6 inches diameter. Chimney 148 feet high. The engine has been working since 1854 day and night. During this period it has had no repairs other than such light work as could be done at the smithy on the premises. Although this engine frequently makes 10,000 strokes in 24 hours, yet the ordinary week's work, I was informed by the Engineer, seldom exceeds 62 to 64 million imperial gallons for seven days. Its work, therefore, averages 9 million gallons per diem at present. The night service of the district is per- formed by this engine alone, the engines at Old Ford being then at rest. Since my visit to Lea Bridge in 1866, two new engines have been erected there, each with a steam cylinder of 84 inches ; the other particulars of these I am not able to give. The 100-inch engine above mentioned seemed to be, on the whole, the most satisfactory specimen of the Cornish pumping engine to be seen in London. The cost of such an engine now (1866), I was informed, would probably be about 15,000, complete in all respects. There are two small water-wheels at this place whose pumps work into the local service pipes. OLD FOED. The 48-inch pipe main already mentioned, which conveys the filtered water from the filtering works to the Old Ford Works, is two miles in length. 10 78 EAST LONDON WATER WORKS. At Old Ford, it delivers the water into a covered clear water basin. This basin, or low storage reservoir for filtered water, has an area of 2s acres, with a depth of water when full of 12 feet. I calculate it to hold about seven mil- lion gallons of water. The filtered water is running into this basin night and day. The pumping engines at Old Ford draw down this basin during the day hours when they are at work, and at night, when they are not at work, the un- interrupted flow from the filters fills it. The basin, however, is not large enough to make the rate of flow, and therefore of filtration, uniform during the day and night hours. From this basin the water has free access to the different pumping engines by a conduit with suitable sluices. The 48-inch main has a lateral connection with the wells of the pumping engines, independent of the covered basin referred to, in order that, when that basin requires repairs or cleansing, the flow of filtered water to the pumps may not be interrupted. At this station there are also two open reservoirs, kept full of unfiltered water from the Company's canal. They are not, however, in use, although they have been permitted to remain, as a measure of precaution against unforeseen emergencies. There are four single-acting beam engines here, of the Cornish variety. The general characteristics are as follows : No. I.' 1 Hercules." Steam cylinder, 85 inches diameter ; stroke, 10 feet, cutting off at one-third. SOlbs. steam shown by gauge in engine-room, making 8 to 9 strokes per minute. Double beam length, 29 feet c. c. depth at centre, 6 feet. Plunger, 43-inch diameter ; stroke, 9 feet. One stand-pipe to the four engines, with a single leg 135 feet in height and 5 feet diameter. For suction valves, two double-beat valves. Delivery valve, one double-beat valve. The outer beat is 55 inches diameter ; the inner beat 43 inches. The beats are level, and metal to metal. The engine works into the City main, not through the stand-pipe, but the main is connected with the stand-pipe. The engine has a battery of 4 Cornish boilers, three of which were in use, the fourth in reserve. Diameter of shell, 69 inches ; length, 30 feet. Length of fire-place, 6 feet. There is but one chimney here for the four batteries of the four engines, height 175 feet. EAST LONDON WATER WORKS. 79 No. 2. *' Cornish." Steam cylinder, 80 inches ; stroke, 10 feet, making eight strokes per minute. Plunger, 41 inches diameter ; stroke, 9 feet. This engine works directly into the stand-pipe. The gauge in the engine- room showed a pressure of 95 feet. Suction valve, a double-beat valve. Delivery valve, the game. Four boilers, carrying 35 Ibs, steam ; shell of boiler, 69 inches ; length, 30 feet. Diameter of flue, 42 inches. No. S. "Ajax." Steam cylinder, 72 inches ; stroke, 10 feet, making 8 to nine strokes per minute. Double beam, cast-iron; length, 30 feet c. c. ; depth at centre, 6 feet. The flitches 8 inches apart. Plunger, 36 inches diameter ; stroke, 10 feet. The suction valve is a double-beat valve. The delivery valve is one of Austin's patent cone valves, with horizontal india-rubber rings. This valve is considered good for delivery valves, but the other valve is preferred here for suction valves. The delivery main is connected with the stand-pipe. The gauge in the engine-room showed a pressure of 85 feet. Four Cornish boilers shell, 69 inches ; length, 30 feet ; flue, 42 inches. No. 4. "WicJcsteed," 184:7. Steam cylinder, 90 inches ; stroke, 11 feet ; 30 Ibs. steam in engine-room. Cutting off at one-fourth, 8j strokes per minute. Double beam, cast-iron ; length, 36 feet c. c.; depth at centre, 7feet 6 inches ; weight, 35 tons ; gudgeon, 16-inch diameter. Plunger, 44 inches diameter ; stroke, 11 feet ; 40-inch main from engine to stand-pipe. Suction valve, double beat. Delivery valve, double beat. The pump was stated to be delivering at the rate of 5,700 imperial gallons per minute. The gauge in the engine-room showed a varying pressure of 84 to 88 feet with each stroke. 80 EAST LONDON WATES WORKS. This engine, like the other, has a battery of four Cornish boilers, of same dimensions each as those already given. The steam-pipe from the boilers was of 15 inches diameter, and cased. All of the four engines have steam jackets. In this engine and in the Hercules there is also a steam cover. The actual stroke made is usually from 2 to 4 inches below the lengths here given. These four engines were all at work (1866). They are all kept at work during the day and all at rest during the night. I judged them, from their dimensions, to be delivering about 12 million gallons in 12 hours. (On my visit to the works, on 4th August, 1868, there were but three en- gines at work, No. 3 being at rest ; but the river supply had been deficient that season, and the Company found it difficult to meet besides, the increased consumption produced by the great heat of the summer. On this day the water in the adjoining covered reservoirs stood 5 feet below its ordinary level.) All the engines work directly into the mains, either through or connected with the single-legged stand-pipe, against not exceeding a hundred feet of head. Each engine is connected with an air chamber. Of the four boilers connected with each engine, three are in use in each case and one in reserve. The engines were making 8 to 9 strokes per minute. There are two small rotative beam engines at this station, serving generally a special high corner of the district. The East Twin and the West Twin. These engines are sixty years old. The East Twin working, the other at rest. Steam cylinder, 36 inches ; stroke, 8 feet. Crank and fly-wheel inside of the pump. Crank, 2 gravel bottom . . j 4,368 1,000 46,956 10,750 Total filtering area at this date 5368 57706 LYONS WATER WORKS. 141 This extent of area for 22,000 cubic metres which is the filtering capacity at low water of the river, is equivalent to 100.7 U. S. gallons per diem per square foot of open bottom. But as the shape which the filtering excavations have taken here is probably not the best for a maximum delivery, it will be better to take the new gallery by itself as a fairer measure of the amount of pure water obtain- able from this particular deposit by underground galleries. An experiment made to test the water capability of the new gallery gave, we were informed, a result of 6,000 cubic metres in 24 hours. The bottom area being 1,000 metres square, this is equivalent to 147 U. S. gallons per square foot of bottom. This rate of delivery is very much less than that of the new filtering gallery at Toulouse. The velocity of the stream at Toulouse, held baek by the dam below, did not exceed from one to Is miles an hour, while here it appears to be from 2i to 3 miles an hour. This would not sufficiently account for the differ- ence, which must be influenced by some difference in the character of the filter- ing material, and in the extent and volume of the underground flow. For the measures of the water capacities of such works, I am necessarily dependent on the officials in charge, and although the data have undoubtedly been communicated with much frankness and good faith, it is not in the nature of such things that the experiments on which they are founded, hurriedly as these must often have been made, should always be correct. The delivery per lineal foot of this gallery is by the same experiment 4,833 U. S. gallons in 24 hours. This contrasts less dtsadvantageously with the result of the new Toulouse gallery. At the lowest stage of the river the water in the filtering galleries and basins is reduced 2 feet below its present level, and it becomes troublesome then to work the pumping engines, except by intermitting their action and allowing the water to accumulate in the basins and rise to a convenient height in the pump wells. Mr. Dumont states in his book that, of the two elements required in certain proportions for a free delivery of water in a filtering gallery, area and depth, the last is very much the most important. But by the last he meant, more particu- larly, head, or difference of level between the surface water of the underflow in its natural state and that water when drawn down in basins, or otherwise, by artificial means. This will be readily admitted ; but it is at the same time con- ceded that the velocity upwards or sideways through the gravel deposit must not be so great as to carry with it sand into the basin, or, if near a river, it must not be so great as to draw water from that river in a turbid condition. The velocity into the filter basin must be very moderate to insure safety to the works, and an unvaried purity of supply. With the view of increasing the supply here without extending the filter basins, and of testing, too, the effect of drawing down the water in the filter basins below the level necessary for the action of the original pumps, a small 18 UNIVERSITY OF C*f EttPARTMENT OF CIVIL ENGINEER!?* BERKELEY. CALIFORNIA* 142 LYONS WATER WORKS. engine was built at the suggestion of the Engineer, and the original pump wells being cut off from the filter works, these wells were temporarily sup- plied by this new engine. By this action the water in the filter beds was reduced below its ordinary level, the head of the inflow was correspondingly increased, and the rate of delivery sensibly augmented. But Ihis increase in velocity of the inflow through the gravel proved in this case to be in excess of what the circumstances admitted of. The water concentrated itself in springs, and brought with it sand in sufficient quantity to risk the under- mining of the vault foundations. The maximum for the situation had been overreached. The use of the new machine was therefore stopped, and the works restored to their old regime. The engine is now used as an auxiliary to furnish water directly from the river to the reservoir in the Jardin des Plantes, at such very low stages of the river as inconveniently reduce the sup- ply from the filters. The frank statement of this result, which I have gathered from Mr. Dumont's report, is very honorable to the Engineer, and very valu- able to the profession. TOULOUSE WATER WORKS. 143 THE FILTERING GALLERIES AT TOULOUSE, NATURAL FILTERS. The population of Toulouse is stated to amount to 100.000 souls at this date (March, 1866). The water is derived from the Garonne, indirectly, by means of subter- ranean galleries situated in a bank of gravel on the left bank of the river. The sources of the Garonne are found on the slopes of the Pyrenees chain of mountains, in the department of Ariege. The velocity of the river at Tou- louse was stated to me to average ordinarily 1 metre per second, or about 2k miles an hour. Immediately opposite the filtering ground tha velocity dees not ex- ceed 2 miles an hour, the dam erected a short distance below having modified importantly the current there. The bank of gravel and sand in which the galleries have been constructed lies within the city limits, but in what may be called the suburbs ; the dense portion of the city lies below this point as regards the river, and upon its oppo- site bank. The annexed sketch (Plate XXV.) will show the position of the filtering gal- leries, and of the pump-house (Chateau d'Eau), upon which the galleries all con- centrate. It is important to understand the relation of this gravel bank to the lowest stage of the Garonne, and to its flood waters. The surface water of the Garonne at its lowest stage is recorded to have stood 433 feet (132.09 metres) above the level of the sea. The surface of the gravel bank referred to is on an average (136 metres) 446 feet above the same level, or about 13 feet above the lowest stage of the river. The river floods rarely cover this bank ; in long intervals, however, extreme floods set over it, and the one of 1832 rose to 451 2 feet (137.69) above the sea, covering this gravel meadow, therefore, with some 5i feet of water. . The rise of the river in ordinary floods may be taken at 8 to 10 feet. In the highest flood on record referred to it rose to 18 feet above the lowest water of the river opposite to the present pumping engines. " In the pump-house there are two breast wheels (163 feet diameter each, 144 TOULOUSE WATER WORKS. exclusive of the buckets, and 5 feet wide each). Each wheel works four plunger pumps of 10$ inches (0.27) diameter each, and 3.80 feet stroke. All the pumps were at work both days that I visited the pump-house, and according to their velocity at that time they would deliver into the city about 4,500 cubic metres per 24 hours. The delivery was stated to me to average 5,000 cubic metres per diem (176,585 cubic feet), equivalent to 13^ U. S. gallons per head of. the popu- lation. Each set of four pumps delivers its water into a vertical pipe of 10 inches diameter, which is carried up the pump-house tower to a height of 66 feet above ordinary water of the river. At this height the waters of the two rising mains are delivered into -two city mains of the same diameter, and the head thus acquired enables the numerous fountains to be well supplied, and admits of the lower stories or ground floors of many of the houses receiving the water into the house. In this last respect, Toulouse is at present very imperfectly accom- modated. There is no reservoir connected with the pumps, which are, there- fore, necessarily kept perpetually at work, except as one wheel must be occa- sionally intermitted for repairs. These pumps have be'en in use since 1839. The new pump-house and engines now under construction, and nearly completed, are upon a scale to admit of a delivery of water into the city equivalent to a rate of 50 U. S. gal- lons per head. The old pumping machines will be altered and made auxiliary to the new. The new works include a sufficient reservoir to defend the city against ac- cidents to the works, and to admit of their more leisurely repair and examina- tion. They are so arranged as to admit of the water being received into the highest stories of all the buildings. These new works are being constructed in all respects most substantially and thorough!}', and we looked over their details with much interest and satisfaction. The form and size of the gravel bed in which the filtering galleries are situated will be best understood by reference to the annexed sketch. In this sketch the filtering ground is colored brown to enable the reader to understand its extent, but upon the surface it is covered with grass. The deposit consists of gravel and sand of different degrees of fineness its surface, however, covered with a thick bed of rich soil. The whole rests upon' a compact tufa or marl, and as will be seen by an examination of the sketch, the depth at which any filtering galleries can be laid is limited by this impervious base. The surface of the marl is situated here about 12 feet below the low water of the river. The river water at the time of my visit did not carry much weight of sedi- ment, but it carried sufficient to give the stream a dirty, muddy color. The body of sand and gravel referred to above, so much of it as lies below the level of the water in the river, it is superfluous to say, is saturated with water, and this water, although evidently derived from the river and its afflu- TOULOUSE WATER WORKS. 145 cuts, has passed through such a width or depth of material at a very slow velo- city, on the wide plains above, as to have deprived it entirely of the matter which gives the muddy hue to the stream. In the filtering galleries, therefore, it is found colorless and limpid. Immediately under the bed of the stream, or in too close proximity to it. this result would not probably have place. The first filter gallery or drain (C D on the sketch) was laid at a distance of about 60 metres (197 feet) from the bank. The bottom is situated only about 4 feet below the lowest water of the river. The form is square, the interior width 1 foot 8 inches, the height 3 feet. The side walls were of brick laid dry, with a flagging stone for the cover, and with no paving on the bottom. The bricks were laid dry and the bottom left uncovered, that the water might have free access to the culvert. The inside of this culvert was filled up with small stones, probably to , prevent the side walls, which were not in mortar, from being pressed inwards. The trench in which the culvert was laid was filled up again with the materials taken from it. A coarse gravel was found at the bottom of the trench mixed with flints. The gravel became finer as the depth lessened from the surface, and ended in a fine river sand, covered at present with from 2 to 3 feet of soil. The length of this first filtering culvert is 056 feet ; it is said to have deliv- ered at all times clear water ; but the quantity was soon found to be insufficient for the demands of the city. To increase the supply, a second filtering arrange- ment was projected and built, differing somewhat in character frooi the first. In this second case eleven wells were sunk along the margin of the river, covering a distance of 300 feet (g h on the plan). They were carried to the same depth as the culvert, and steined up with dry brick. The wells were connected together by iron pipes, and from their lower terminus a connection was made with the pump well of the pump-house. The water from this second filter turned out bad, and it has consequently been for some time in disuse. A third filtering culvert was constructed on the same plan as the first, but larger. In the lower part of its course it is situated farther from the river than the first culvert, and in the upper part nearer to the river (c ef on the sketch) ; the length was given me as 1,476 feet (450 metres). Like the first, it has always produced good and clear water. The total length of these old filtering galleries (excluding the wells in disuse) is 2,132 feet. The growing wants of the city and the increase of its population rendered necessary a further and more liberal supply of water, and a new filter- ing gallery has been constructed within the last two years in the same bank of gravel. It will be convenient to note here the water capacity of the old galleries so far as I am able correctly to understand it. This capacity has been given me as equal to 5,000 cubic metres per diem, and I judge this from other circumstances to be its maximum. ;jj^ gives a rate per foot per diem of (2.345 metres cubic) 620 140 TOULOUSE WATER WORKS. U. S. gallons, or 82.82 cubic feet. The new filtering gallery is of larger dimen- sions than the others, and it is laid lower in the bed of gravel, and, consequently, has a greater capacity of drainage from the underground reservoir of the neigh- boring plain, of which the particular gravel bank of these works may be said to form a part. It difi'ers in other respects importantly from the old filtering conduits. Its contour is of mortared masonry (in this case beton) of sufficient strength to defend it from the outer thrust of the material in which it is imbedded, and its inte- rior is not filled with stones, but void forming thus in itself a considerable re- servoir of water. The water finds its way into the conduit from the gravel deposit in which it lies, in part by small earthenware tubes placed on both sides of the gallery, but mainly through the bottom, which is left (six-sevenths) uu- paved for that purpose, and where the clear water rises, therefore, from the coarse gravel which has place there. At every seventh metre a buttress is thrown across of one metre in width, and to this extent (1-7) the bottom is impermeable. The surfaces of these but- tresses, which are intended to defend the side walls against movement from the back thrust, do not rise above the prescribed level of the bottom of the conduit. The interior height of the new conduit is 8 feet 8 inches (2.65 metres), the width 7 feet 6 inches (2.30 metres). Its form and position is shown on the annexed sketches. The bottom is placed at 129.45 metres (424.6 feet) above the sea, or 8 feet 7 inches below the lowest stage of the river. It is therefore 4^ feet below the bottom level of the old galleries. The present length of the new gallery is 1,180 feet (360 metres) ; but the intention is to extend it gradu- ally to double this length, or more, according as the requirements of the city may demand it. An experiment made by the Engineer of the new works, Mons. Hepp, indicated, as I am informed, its capacity of delivery at the low water of the river to equal (10.000 cubic metres) 2,642.000. U. S. gallons per diem. Its extension will, it is supposed, double this rate of delivery. The capacity of this new gallery at low water is therefore equal to ( 2C T 4 o 2 73 00 ) 2,462. U. S. gallons per foot of its length, while that of the small conduits was but 620 gallons per foot, an improvement due to its position and mode of construction combined. It will be observed that the new gallery is not based on the marl or tufa ypon which the gravel bed rests, but is kept from 2 to 3 feet above it. This has been done to permit the water to percolate easily into the gallery from the bottom, where it is expected that the mass of the water will enter it, rather than from the side tubes. With the present rate of delivery into the city (5,000 cubic metres per diem), 1,320,900 U. S. gallons, the water stands now in the new gallery (131.60 metres) 2i feet below the ordinary river water. During the experiment refer- red to, when the draft from the gallery was at the rate of 10,000 cubic metres, TOULOUSE WATER WORKS. 147 2,G41,180. U. S. gallons, it stood in this gallery, according to my notes, at (128.15 metres) 4 feet below the lowest stage of the river water. When the new pumps are completed and the city is supplied with a. better head of water, the capacity of the now gallery will be more thoroughly tested. I have given above the experimental rate of delivery of the new gallery per lineal foot. -It would be preferable to give its rate per square foot of the open bottom; but in this case the proportional effect of the side pipes is difficult to appreciate. If we take the whole width and length of the gallery, as including a sufficient allowance for the side pipes, and to that add the bottom area of the small auxiliary galleries, we shall have a rate of delivery at low water of 228 U. S. gallons per square foot of open bottom. The delivery is elsewhere given in a pamphlet published at Marseilles, as equal to 27. 6 metres cubic per metre courant, or 2,223. U. S. gallons per lineal foot. The dam in the river below the present pump-house, produces compara- tively still water opposite to the filter ground, and must encourage that kind of sedimentary deposit there, which the natural current of these rapid mountain streams does not admit of, except in eddies, and then only until the scouring operation of a heavy flood clears the channel of such accumulations. But when the underground material of the plain, for some distance above, consists of an equally open gravel, it can be of little consequence that the river bottom, within the influence of the dam, should become comparatively water-tight. The water will, in any case, reach the filter galleries from above, and from a some- what greater distance, arid the only effect would be to reduce the rate of delivery somewhat, and perhaps render a greater length of gallery necessary. 148 MARSEILLES WATER WORKS. MARSEILLES WATER WORKS. MARCH, 18G6. The supply of water to the city of Marseilles is especially noted for its abundance, the amount at present passed through the city reaching frequently, as I was informed by the Engineer, a rate of (550 litres) 145 U. S. gallons per head per diem ; but a large portion of this water, as he stated, is flushed into the harbor to carry off the sediment which would otherwise accumulate in and choke the pipes. The water passes at present into the city in its natural state, and without filtration. The reasons for this state of affairs will appear here- after. The population of Marseilles is given as 250,000 in 18G4 ; Mr. Pascalcs, the Engineer, stated it at 300,000 at this date, 18G6, and I find it elsewhere stated at the same figures. The water is derived from the river Durance, and the boldness of the pro- ject will be admitted when it is stated that the point of derivation is distant 62 miles from Marseilles. The river Durance in its upper reaches is a rapid moun- tain stream, flowing over a stony, gravelly bed. The sources of the river are widely spread upon the eastern slopes of the lower Alps. The canal of supply commences on the Durance near the bridge of Pertuis. In the construction of the canal the city had two purposes in view the supply of the city with water, and the improvement of the lands in the vicinity of Marseilles by irrigation. The amount of water which can be drawn from the river Durance at the lowest stage of its water is limited to 5.75 cubic metres (203 cubic feet) per second; but the ordinary flow into the canal reaches 7 metres per second (159 1 millions U. S. gallons in 24 hours). Of this amount li cubic metres per second (34,240,320. U. S. gallons) is considered as applicable to the city, although that amount is not used there at present. The rest is available for irrigation and water power, and in this respect has been a source of great benefit to the intermediate country. The Engineer estimates one-seventh of the water to be lost by evaporation and filtration. The canal has a fall of 6 inches to the mile, very nearly (0.30 metre per kilometre), and its dimensions are adapted to the required flow mentioned above. MARSEILLES WATER WORKS. 149 There is no navigation upon it. It is open throughout, except at the tunnels, which are numerous. The main canal is carried to the sea below Marseilles, delivering its surplus waters there. The city is supplied by a branch 3i miles in length. The distance from the Durance river to the Marseilles branch is 682 miles, and to the filtering works at Longchamps, as already stated, 62 miles. The waste water from the fountains, which are numerous, and from the flushing of the pipes, passes into the harbor through the sewers, which are thus effectually scoured. The health of the city is said to be very much improved since the introduction of this supply. The Durance river is represented as carrying an unusual amount of sediment, and as presenting in this respect greater difficulties, as regards filtration, than any other river in France. The average amount of sediment is given as equal to T-J-ir of its volume, but this is probably an exaggeration ; Mons. Bernard, Engineer at Aries, gives ^^ as the result of his experiments for one year. In all arrangements for filtering turbid river water by artificial means, that portion of the sediment which will settle in comparatively still water within 24 hours is always supposed to be got rid off before placing the water upon the artificial filter. The means provided upon this canal for. clarify ing the very turbid waters of the Durance were as follows : A filter bed was constructed at Longchamps, in the upper part of the city, the surface of which is (72 metres) 236 feet above tide in the harbor. This filter bed is of very costly construction, as will be seen by examination of the accompanying plan and section. (Plates XXVI. and XXVII.) The filtering materials rest on arches, a vaulted chamber of like dimensions with the filter bed being constructed below it for the reception of the filtered water. This chamber or reservoir will hold about 540,000. U. S. gallons. The filter proper is composed of sand, gravel, and stones, in about the fol- lowing proportions, as shown on the accompanying sketch : 1. A layer of small stones over the arches, about 8 inches thick at the top of the arch 8 inches. 2. Broken stone 3 " 3. Small gravel 4 " 4. Coarse sand from river 8 " 5. Ordinary sand of " Goudet " 3 " 6. Fine sand of " Montredon " 12 " Total 38 inches. 19 150 MARSEILLES WATER WORKS. In other words, the filter is composed of two feet of sand, resting on gravel and broken stone. This filter is said to have operated well and satisfactorily while the water that was passed upon it had been prepared for filtration ; when this ceased to be the case, it became rapidly unserviceable. When I saw it there was from 3 to 4 inches of compact mud over the surface of the sand, and it had not been used, except as a reservoir for water, for two years. It is vaulted over throughout, and therefore not very conveniently acces- sible for cleansing or renewal. The filter bed is in two divisions, which can be used together or separately, as may be desired. -The areas are as follows, excluding the pillars upon which the arches rest : Division No. 1 47,613 square feet. " 2 44,753 " Total . 92,366 square feet. Filtering at the rate of 90 U. S. gallons (72 gallons imperial) to the square foot, these filters would be competent to clarify 8,312,940 U. S. gallons in 24 hours, or half this quantity with but one in use. The population supplied from them did not probably exceed 230,000 when they were in use, which would give a rate of 36 U. S. gallons per head with both filters in operation, or of 18 with but one. I have been informed that this filter will be used again when the means proposed to be provided for the preparatory removal of the grosser parts of the sediment by settlement shall be completed ; but it is obvious that for a population of 300,000, increasing from year to year, more extended arrangements somewhat in unison with the general project would be required. When these filter beds were in use they were cleansed at intervals by reversing the movement of the water and forcing it upwards through the filtering material. While this upward movement was in progress the surface sand of the filter was raked and disturbed by laborers with suitable tools, to facilitate the removal of the sedimentary deposit. The turbid water thus produced was run off into a sewer. The water used for this purpose must have been the clear water of the reservoir below. When water is in such abundance as in this case, the amount used in this way may be of little moment. If it had all to be raised by steam power, it would make this mode of cleansing the filters a very costly one. To get rid of the mass of the sediment of the river by settlement, and suf- ficiently prepare the water for filtration, five reservoirs or settling basins were constructed on the line of the canal, in certain of the small valleys which it crossed, where their application was convenient and economical. Dams were MARSEILLES WATER WORKS. 151 constructed across the valleys indicated, sufficiently high to bring the water up to the canal level, and through these dams, pipes and sluices were provided for flushing off the sedimentary deposits. The water of the canal was made to flow into one end of each of these reservoirs, and passing slowly through it, the reservoirs being deep, it parted with a portion of its sediment and left the reservoir at the other end in a less turbid state, returning to the main channel there. These reservoirs, or settling basins, for such was their use and intention, were : 1. The Ponseret reservoir. 2. The Garenne 3. The Vallonbiere " 4. The Realtort 5. The St.Marthe " With the five in use, a superficial area of 220 acres of water was available for settlement, which, including the effect of the canal itself, must have been abundantly sufficient to prepare the water for the filter beds at that time. But from some defect in the construction of the Realtort dam, this reservoir, much the largest (185 acres), does not appear to have been long in use. Of the others, the Ponseret basin (No. 1) is the only one now serviceable, and this has a surface area of but 2% acres. The other three, for reasons growing out of the difficulty of, or neglect in, withdrawing the sediment, have been allowed to fill up, and are now entirely unserviceable. A considerable quantity of sediment is deposited in the canal itself, which is cleansed out twice a year ; but the velo- city of the water in the canal maintains that water in a very turbid state, and it consequently reaches the filter beds now in a condition which makes their application impracticable. The water passes into the pipes of the city, at present in its dirty, muddy state, to the great dissatisfaction of the inhabitants. Should the large reservoir of the Realtort be brought into use again, with the means of scouring it proposed by the Engineer, Mr. Pascales, the water may again be rendered fit for filtration. Many of the citizens advocate the applica- tion of the natural filter, by the construction of subaqueous galleries, on the banks of the Durance, and it remains still somewhat uncertain what process will be adopted to render the water tolerable. Under any circumstances, its condition, in summer, after being exposed for 62 miles to the sun, cannot be very pala- table. 152 GENOA WATER WORKS. GENOA WATER WORKS, GENOA, March, 1866. NATURAL FILTER. The city of Genoa is supplied with water from two separate quarters, the oldest supply being derived from the south side of the maritime Alps ; the modern works, from the north side. The first is still in charge of the city authorities ; the second was constructed by, and is operated by, the Nicolay Water Company, under a special concession or charter. The construction of the old works was completed in 1729. The water in this case is derived from the river Bisagno, at Stigliera, by damming the main stream there and two of its branches ; at low summer water the amount available does not exceed from 80 to 100 litres (say 3 cubic feet) per second. The water is conducted to the city in a small masonry conduit, 22 kilometres in length (13.6 miles). The width of the conduit is 0.80 metres (2k feet) ; its depth varies. About half of it is stated to be covered, the rest uncovered. The water is used at one place outside of the city for mill-power, and a portion of it in the same way inside of the city. It passes through the city as a covered conduit, deliver- ing its water on either side, but not under pressure. There are no filtering arrangements connected with this branch of the water supply. The population of Genoa is variously stated at from 150,000 to 165,000. The new works of the Nicolay Company derive their water from the valley of the river Scrivia, near Busallo, at a point distant (26 kilometres) 16 miles from Genoa. The river Scrivia has its source in the northern slopes of the maritime Alps. It is a rapid mountain stream, the channel at Busallo evidencing, by the coarse- ness of the gravel or shingle composing it, the rapidity of the current. The water is gathered from underground galleries in the valley of the Scrivia, is con- veyed thence by cast-iron pipes to Genoa without exposure anywhere, and is introduced into the city under pressure by a net-work of pipes, whence it can be carried into the highest stories of all the city buildings. In all respects the scheme is more complete in its parts, and more liberal in its dimensions and preparation for the growth of this thriving seaport, than usually obtains in con- tinental cities. , GENOA WATER WORKS. 153 The Engineer of the project was Guilio Sardi ; the Constructing Engineer, Aleso. Moschini, and the President of the Company, Paulo An. Nicolay, to whom I am under great obligations for the facilities which he afforded me toward obtaining access to the galleries. The accompanying sketch will explain the position of these galleries with reference to the river. (Plate XXVIII.) The wide bottom of gravel over which the river flows here is, as well as I could learn, 40 to 50 feet in depth, except in the immediate channel of the river, where the depth does not exceed 30 feet. It rests upon an irregular bed of compact rock, and the underground flow of filtered water is held up by this rock. This underground flow is doubtless moving down the valley, which has a considerable fall here, but at a very slow velocity as compared with the river, its movement being impeded by the body of sand and gravel through which it percolates. The side walls of the galleries, which tap this underground flow, are carried down to the rock above mentioned, as will be seen by the cross-sections given in the accompanying sketch. The underground flow cannot, therefore, pass under the gallery. Referring particularly to that portion of the gallery which underlies the bed of the river at right angles to its course, the underground flow is dammed to a certain extent by the position of this gallery, and must rise over the top of its arch in its course down stream. The galleries are built of hydraulic masonry, and the water enters them by pipes built in the side walls of the up-stream side. There are no pipes on the heavy side walls of the down- stream side of the galleries. The effect of this damming process must be to increase the head of the underground flow at this point, and to that extent to increase the volume of water delivering through the side pipes into the gal- leries. At the points m, n, and q on the sketch, there are large man-holes, with stairs for descending into the galleries. These man-holes had houses over them. When I descended, in March, 1866, the galleries were full, and the water stood some feet above the soffit of the gallery arch. It was perfectly clear and limpid, and reached the city through the pipes in the same state. At the point n there are sluices established in the gallery, by which that part of it from n to r can be separated and its waters cut off from the portion south of n. In high stages of the river these sluices are closed, the water from the portion of the gallery south of n (580 feet in length) being then sufficient for the city supply. The shutting of the sluices at such times is said to relieve the lower southern part of the gallery, situated alongside of the railroad tunnel there ; from the superfluous pressure of the flood waters, and from any risk of leakage into that tunnel. The galleries are five feet in width, by seven to eight feet in height, in 154 GENOA AVATER WORKS. English measures. The amount of water derivable from these galleries much exceeds the amount required by the city of Genoa now, and the works are, therefore, in a condition to meet liberally the growth of the city for some time to come. The water consumption of Genoa from the Nicolay Works was stated by Mr. Nicolay to average 500 ounces daily, the ounce being equivalent to 800 litres (28.25 cubic feet) per hour. This gives a rate per diem of about 10,000 metres, strictly 9,600, which is equal to 2,536,128. U. S. gallons. If we take the population at 160,000, and allow three-fourths of it to be supplied from the Nicolay Works, it will be found equal to 15.8 U. S. gallons per head of the population supplied. An experiment made during a very low stage of the river in- 1865, to ascertain the minimum capacity of the filtering galleries, gave a delivery then of 500 litres per second (1,765. c. feet), which is equal to 11,413,440. U. S. gallons in 24 hours. This minimum rate will admit of a delivery to the city of over four times its present consumption. But the ordinary delivering capacities of these galleries must approach to double its minimum rate, and when it shall become necessary, the minimum rate can be largely supplemented by providing storage reservoirs for accumulating the surplus water of the more abundant months. The galleries being 1,780 feet in length, the minimum capacity is equal to (Li^l3>^o)= = 6,412. U. S. gallons per lineal foot of this length. This is a greater rate of delivery than the Toulouse or the Lyons galleries indicated, and may be referred, in part at least, to the peculiar mode of construction across the channel of the stream. Two cast-iron pipes, of 171 inches (45 centimetres) diameter each, convey the water from the south terminus of the filtering gallery, along the line of the Turin Railway to Genoa. The altitude of the Scrivia at Busallo is (360 metres) 1,181 feet above the Mediterranean, but this is reduced within a mile of the Scrivia by a safety-valve to (280 metres) 918 feet. At Genoa the pipe distribution is divided into a high-service and a low-service. The pressure at the terminus of the main at Genoa, used for the high-service, indicated 320 feet and at the terminus of the low-service main 203 feet. Both pipes reached Genoa under the same pressure, but for the low-service a safety-valve, wasting a certain amount of water, reduced the pressure as indicated. The vault in which these gauges were situated was estimated to be about 30 feet above the sea. There are, doubtless, contrivances along the line for relieving the pipes of their super- abundant head, and reducing it to the manageable pressure which we find exist- ing, as above stated, at their entrance to the city. The length of these pipe conduits has been already stated to be each (26 kilometres) 16.15 miles. A small fraction of the water delivered by these pipes is applied in the city to mill- ing purposes ; but this is understood to be in addition to the city consumption proper, as given above. LEGHORN WATER WORKS. 155 LEGHORN WATER WORKS. LEOHOBN, March, 1866. FILTERING CISTERNS. Leghorn is supplied with water from a number of springs on the slopes of the- low mountain range of Maggiore and Corbolone, where the head waters of a branch of the river Tora take their rise. The springs are brought together and conducted to the filter-house or cis- tern of " Pian di Rota" by a small covered conduit of masonry. The length of this conduit was given us as (14.05 kilometres) 8.73 miles. The water space in the conduit is but 12 inches in width and 17 inches deep (see Plate XXIX). It is conducted over the valleys upon neat bridges of masonry, and through some ridges by roomy tunnels. The amount of water flowing through the aqueduct (10th March, 1866). as measured that day in one of the tunnels, was 568,760. U. S. gallons in 24 hours. In low summer water, according to the Superintend- ing Engineer, it has been reduced (June, 1864) to 276,000. U. S. gallons per diem. The population in 1848 was 72,400; it is stated at 80,000 in 1861, and may be safely taken at 82,000 now. This, for the amount of water delivered by the aqueduct at this date, which was considered an average of the spring months, is equal to but about 7 U. S. gallons per head. During the hot summer months the supply is very inadequate to the requirements of the population, and its increase is under consideration. Leghorn is a seaport, and there is very little irregularity in the level of the streets, which are generally from 10 to 15 feet above the water of the Mediter- ranean. The altitude of the springs above the sea is (256 metres) 840 feet. The altitude of the filtering-house or cistern mentioned above is (48 metres) 157 feet above the sea. From this filter-house the water is conveyed by a 9-inch pipe main to a larger cistern-house within the city, which had also apparently a process of filtering in contemplation, and is curiously divided up towards that end ; no filtration, however, is attempted there now. Both of these cistern-houses are tasteful and monumental, as specimens of architecture, but costly for the engineering duties required of them. 156 LEGHORN WATER WORKS. The length of the pipe main, or the distance of the two cisterns apart, is (3,309 metres) 10,856 feet. The water in the city cistern stands ordinarily about 28 feet above the sea. The pipe mains deliver the water freely into the city cistern, unchecked or throttled by a stopcock, so that the pressure due to the altitude of the outside or country filter-house is not applied to the city, the small amount of water at present available probably making such an application impracticable. From the city cistern, water is distributed by pipes to the numerous foun- tains, and it is to these fountains that the inhabitants go or send for water. A supplementary covered cistern in another part of the city acts as an aid to the city cistern above alluded to, in increasing the small provision made for the storage of the water flowing on through the aqueduct and pipe main during the night hours. We have, then, as a summary of the works, the pipes and fountains ex- cepted : 1st. The cluster of springs situated (17.36 kilometres) 10.78 miles north- easterly from the city. 2d. The aqueduct from the springs to the water filter-house. 3d. The principal filter-house or cistern, situated (3,309 metres) 2.05 miles from the city. (Plate XXIX.) 4th. The large cistern or covered reservoir within the city (Plate XXX.), auxiliary to which is the smaller cistern in the city, increasing simply the reserve of water in store. The Leghorn Water Works have been spoken of as possessing very simple and efficient arrangements for the filtration and purification of the water, and it was therefore that I was desired to visit them. I will endeavor to describe what these arrangements are. The principal filter-house (Pian di Rota), which is outside of the city, may be called the outer filter-house. The water chamber of this house (see the accompanying Plate) is divided into seven divisions. The bottom of the first five divisions is covered with a filtering material composed of gravel and charcoal in the following proportions : 1. A layer of coarse gravel 8 inches. 2. A layer of wood charcoal 12 " 3. A layer of coarse gravel 8 " 4. A layer of fine gravel 12 " Total thickness . 40 inches. LEGHORN WATER WORKS. 157 No sand is used, and the charcoal is not laid in the shape of powder, but, as described to me. is broken to about the size of very large gravel and so laid ; much of it, however, must get broken up smaller during the manipulation of laying and covering it. In the sixth chamber, the material is simply gravel, without charcoal. In the seventh chamber, which forms the receptacb for the water after passing through the others, there is no filtering material on the bottom. The first division, marked a in the Figure, receives the water from the aqueduct. The water cannot pass from a into the second division b, except by the small holes provided for that purpose at the bottom of the division wall, and to reach those holes it must pass downwards through more or less of the filtering material in a, and after passing through the holes it must pass upwards through more or less of the filtering material in b, to fill the division b. Thence the water can only reach to fill the division c by flowing over the top of the wall dividing b from c, there being no holes in that wall. Having got thus into c, the same process is repeated between c and d, the water after passing through holes at the bottom of the wall dividing c from d, flowing there- . after over the top of the wall dividing d from e. Thence it finds its way through the bottom of the wall dividing e from/, and after filling the division/, overflows into the final division g. At the time of my visit the water from the aqueduct flowed into the first division, perfectly clear. There were fourteen feet in depth of water in all the divisions, and we could see the gravel bottom of the first six, and the paved bottom of the seventh, quite distinctly. Two American Engineers accompanied me in my visit to these works, Mr. W. H. Talcott and Mr. L. B. Ward, and they assisted me in my examination of the water, and the measurement already referred to of the flow. A tumbler of water taken from the aqueduct where it flows into the first division a, was compared with a tumbler of water from the last division g, and we could not distinguish any difference. The water entered the filter-house clear, and there was consequently no duty thrown on the filter beds. We were informed by the attendant in charge, that the filtering material was cleansed or changed once in two or three years ; the last cleansing was after an interval of two years. This account was corroborated by the Engineer in charge. We were further informed, that when the aqueduct water came down turbid, which was very rare, it was wasted, by means shown us, into the neighboring valley, and not passed through the filter-house. There were means provided, besides, for connecting it with the city main, without passing it through the filter-house. As two and a-half feet of open gravel could evidently be of no use in ren- dering turbid water clear, the material relied on for that purpose must have been the charcoal, the gravel being used only to keep the charcoal in place. 20 158 LEGHORN WATER WORKS. How far the charcoal would have answered the purpose had the water been turbid, and how frequently it would have required, in that case, to be un- covered, and more or less renewed, cannot be gathered from the experience of these works, for we were informed that turbid water was not allowed to be passed into the filter-house, and that indeed the aqueduct water, coming from a collection of springs, and not from the channel of a stream, was rarely otherwise than clear. The works were not considered, by those in charge, as valuable, or as necessary for nitration, but simply as monumental cisterns, admitting of the storage of a certain amount of water. The area or superficies of the filtering material in the six divisions referred to is about 7,450 square feet. The city cistern or reservoir (Plate XXX.) is in plan divided into four spaces. Into two of these, m and n. the main pipe from the country reservoir delivers its water. The floors of divisions m and n are covered with about 12 inches of gravel, as is the bottom of the small square division p. From m and n the water reaches p by holes along the bottoms of the respective division walls, passing through the gravel to reach these holes, and to fill the division p. From p the water overflows into the large space q, and thence communicates with the city fountains by a system of cast-iron pipes. There is no charcoal used with the gravel in this house, and although the divisions indicate a provision for filtration in case it should have been necessary, no operation of this kind is necessary now, and no adequate materials for that purpose are therefore provided. The house, therefore, is only of use as a storage cistern. The Engineer in charge, Mons. A. Delia Valle, and his aid, Mons. Francesco Pelligrini, very obligingly gave us access to the works, and permitted us to copy the drawings of the reservoir houses. The Engineer of the project, Mons. Paschal Poccianti, of Florence, who enjoyed a high reputation as an architect, has been some time dead. WAKEFIELD WATEll WORKS. 159 WAKEFIELD WATER WORKS, ME. THOMAS SPENCER'S PROCESS. I visited Wakeficld in August, 1868, for the purpose of seeing in operation the process of Mr. Thomas Spencer, of London, for the purification of objection- able water. Although this special application of Mr. Spencer is not requisite upon any of our Western rivers now, a report on nitration would be incomplete without some allusion to it. The population of Wakefield was given me at 25,000. The supply of water is in the hands of a Water Company. It is a con- stant supply, and not intermittent. The water is taken from the river Calder, at a point about a mile below the city. This river rises in the high moor lands, west of Halifax, which divide Yorkshire from Lancashire. In its course it receives the sewerage of Halifax and many small places, and it has received the sewer- age of Wakefield before reaching the point whence the water is taken by the Water Company ; it is also contaminated by the refuse waters of various dyeing establishments and other factories situated on the river. On the other hand, the river receives at Wakefield the lockage water of a canal which has not been subject to the same extent of pollution. At this date (13th August, 1868) the long season of drought and the low state of the stream made the water unusually objectionable. A tumblerful taken from the river at the connection of the Company's conduit was of a dark, inky hue, and slightly offensive to the smell. When the Company established its works here some twenty-three years back, the river water was comparatively pure ; but the increase of the population resi- dent on the river since that time, and the growth of factories, has rendered it entirely unfit for domestic use in its natural state. This condition of things in- duced the Company four years ago to try the application of Mr. Thos. Spencer's mode of filtering and purifying such waters, and the r.esult has been wonderfully satisfactory. As my only object is to give an idea of the materials and arrangement of this filter, I will refer very briefly to the general arrangement of the works: On the left bank of the river, at a point about a mile below Wakeneld, there are two settling reservoirs, having a water surface of six acres. The water is pumped into one of these, and. passes thence through openings in the division ICO WAKEFIELD WATER WORKS. wall into the other, whence it is drawn by a conduit to the pumps, which lift it to the high grounds at Fieldhead where the filter beds are situated. The water, in its course through these two settling reservoirs, has deposited the greater portion of any sedimentary matter held in suspension. There are two pumping engines for this service, each of them operating both a low-service and high-ser- vice pump at the same time. The high land at Fieldhead, on which the filter beds and storage reservoirs are placed, commands by at least fifty feet the highest ground in the city. It is situated, as given me, 150 feet above the pumps already mentioned. From the pumping engines two mains, of 10 and 15 inches diameter respectively, convey the water to the filters. There are four filter beds at Fieldhead, and two small storage reservoirs. The floor of the filter bed is concrete, resting on a layer of clay puddle. Upon this floor is laid a series of small drains ; in the case of the first two filters, of brick in the case of the two last, of square clay pipes, not perforated all over, but with one hole in the centre of each, over which a cup is placed, perforated with a dozen small holes of about 3-1 6th inch opening. These square pipes are in three-feet lengths, the size inside being not quite 4 by 5 inches ; they have sockets, and when laid constitute a series of collecting drains about five feet apart, c, c; their ends on either side opening into large collecting con- duits, whence the filtered water is delivered into storage reservoirs in communi- cation with the city mains. Each of the clay pipe drains is connected with a vertical air pipe. Between and over the series of clay pipe drains gravel is placed, the depth of gravel not being carried to more than three inches over the pipes. Upon this is laid 17 inches of the carbide of iron mixed with fine sand, about half and half. This carbide of iron forms the purifying material of the filter. Over the layer of carbide of iron there is a layer of fine sand, of from 15 to 18 inches in thickness. The sand, as I understand the process, is mainly depended on to clarify the water from anything held in mechanical suspension, so to say, but the carbide of iron destroys the noxious gases and offensive coloring belonging to any water contaminated as this is with a large proportion of sewerage and of the refuse of factories ; and this it is said to do usually very thoroughly, for the water after passing through the filters presents nothing offensive to the taste or smell, and is used unstintingly by the citizens ; but at the time of my visit the discoloration was not perfect. The amount of water used in this hot season, and its abnormal character in the river as regards appearance, had evidently taxed the filters beyond their capacity. Of the four filter beds, one has to be cleansed off every day, removing about 'I inch of sand, which is washed and cleansed for renewal. There are, therefore, during a large portion of the 24 hours, but three filter beds' in use. WAKEFIELD WATER WORKS. 161 The walls of the filters are vertical, or nearly so. In the absence of a correct diagram of these, which I could not obtain, my notes give the ap- proximate area of the four filters as equal to 16,400 square feet; three of them, therefore, would contain about 12,300 square feet. The consumption during the day of 24 hours was stated to average gene- rally 750,000 imperial gallons. Taking the average day rate at 50,000 gallons per hour, we have a flow through the filters of four gallons per square foot per hour, which would not be considered extreme on the London filters ; but we are to consider, that a very slow rate of filtration may be necessary here as compared with the Thames or the sea, to enable the material specially pro- vided in this case to produce its effect upon a water so very much more objec- tionable than these others as regards discoloration and exposure to offensive contaminations. The carbide of iron, which forms the purifying element of Mr. Spencer's patent process of filtration, was described to me by Dr. Statter as being pre- pared from red hematite iron ore, by mixing that ore with sawdust in equal portions and roasting it in an iron retort. The result is crushed to the size of fine gravel, pea size, and mixed for use with equal parts of fine sand. It costs, de- livered at the works, five pounds sterling per ton. On the two first filters, it has been in use without change or addition four years, and is said not to be in any way deteriorated. The filtered water is drawn into two small stor- age reservoirs, having a joint capacity of 2,750,000 imperial gallons. It is thence delivered to the city by two pipe mains of 12 and 15 inches diameter respectively, I am indebted to Dr. Statter, the Chairman of the Water Company, for permission to visit the works. I learned from Mr. Filliter, the Engineer of the Leeds Water Works, that the process of Mr. Spencer was in use at Southport, and also at Wisbeach, ap- plied to waters that are not contaminated with sewerage, but objectionable in color from other causes. At Wisbeach, the water comes from a moor tract of country, and is discolored by peat ; at Southport, the water, which is drawn from wells, is tainted with iron rust. In both cases, the action of the new process was said to be successful in removing the objectionable features. UNIVERSITY' OF CALIFORNIA BP!AKT1VENT OF CIVIL BERKELEY, CALIFORNIA 1 APPENDIX APPENDIX. OF INSTRUCTIONS. OFFICE OF BOARD OP WATEB COMMISSIONEES, ST. Loois, Dec. Uth, 1865. JAMES P. KIRKWOOD, Esq., Chief Engineer. DEAR SIR, At a meeting held this da} 7 at the rooms of the Commissioners, there were present His Hon. the Mayor, J. S. Thomas ; Philip Wiegel, and Dwight Durkee, President. Mayor Thomas offered the following resolution, to wit : ''Resolved, That James P. Kirkwood, Esq., our Chief Engineer, be re- quested to proceed at once to Europe, and there inform himself in regard to the best process in use for the clarifying river waters used for the supply of cities, whether by deposition alone, or by deposition and filtration combined, making such an examination in each instance as will enable him to report to this Board the general dimensions and special characteristics of the specific works visited by him, so that this Board may be able to appreciate how far the same mechanisms, and the same or similar combinations of materials, are likely to be adaptable to the purifying of the Mississippi water at St. Louis. The following cities which are supplied by river water, and which possess works for the cleansing of that water when turbid, are indicated as points to be visited, to wit : In England London, Norwich, Preston, Nottingham, and Southampton ; Scotland Paisley and Perth ; in Ireland Dublin ; in France Lyons, Tours, Toulouse. Marseilles ; in Germany Berlin, Hamburgh, Brunswick ; in Italy- Leghorn ; and that such other cities not above mentioned as may be ascertained to possess works of this class, deserving of examination, be visited also. Pro- vided, however, that Mr. Kirkwood shall so arrange his movements as to return to St. Louis by the first day of May, 1866, at the furthest. 21 166 APPENDIX. " Resolved, That Mr. Kirkwood be, and he is hereby, empowered to employ such assistance or interpreter when in Europe, and particularly where foreign languages are spoken, as may be necessary to enable him to get all the infor- mation needed." Above I hand you copy of resolutions, and, to enable you to carry them out, I enclose herein my individual check, No. 30,009, on National Bank of North America, New York, for $2,700, which, I trust, will be sufficient for the whole trip. I have to request that you will advise me of the receipt of this, also what day you sail, and any other particulars you choose ; and, further, that you will report your arrival on the other side, with such observations as your time and inclination will permit. With the hope that an overruling Providence will guide and protect you, I remain very truly yours, (Signed) DWIGHT DURKEE, President. APPENDIX. 167 Table of Equivalents of certain Measures mentioned in the preceding Descriptions. NAME OF ITS : EQUIVALENT IN . MEASURE. U.S. Gallons. Imp. Gallons. Litres. Cubic Feet. Cubic Metres. Cubic Inches. Pounds Avoirdupois. 1 U. S. Gallon 1. .833111 3.785203 .133681 .0037852 231. 8 3388822 1 Imp. Gallon . . 1.20032 1. 4.543457 .160459 0045434 277 274 10 .2641866 .220097 1. .035317 001 61 0271 2 204737 1 Cub. Foot 7.480152 6.232102 28.315289 1. 028315 1728 62 37916 1 Cub. Metre 264.18657 220.096714 1000. 35.316609 1. 61027 0963 2204 737 1 Cub. Inch 036099 Weight of a cubic inch of water, English standard, .036065 Ibs. avoir. ; U. S. standard, .036099 Ibs. avoir. ; French standard, .036127 Ibs. avoir. The "Ordnance Manual of the U. S. Army, 1861," and the "Engineer's Pocket-Book," by C. H. Haswell, give 8.3388822 Ibs. avoirdupois as the weight (U. S. standard) of a gallon of water, from which, in the above table, the weight of a cubic foot and a cubic inch are calculated. The same works give 61.0270963 cubic inches in a litre, and 2.204737 Ibs. avoirdupois as the weight (French standard) of the same. The "Engineer's Pocket-Book," London, 1869, and "Beardmore's Manual of Hydrology," give 61.028 cubic inches in a litre, and a weight of 2.2055 Ibs. avoirdupois for the same. "Beardmore's Manual of Hydrology" gives 10.003 Ibs. avoirdupois as the weight of an imperial gallon. "Agenda Opperman," Paris, 1869, gives 4.543458 litres in an imperial gallon. All of the above works give 277.274 cubic inches in an imperial gallon, as also does Francis, in his " Lowell Hydraulic Experiments." 168 APPENDIX. LONDON PUMPING ENGINES, I will here condense in a tabular form some of the information in regard to pumping engines which is scattered over the descriptions of the London Works. These works afford fair specimens of the different kinds of pumping engines and pumps in use in England and elsewhere. The greater number of them are found to give very satisfactory results, whether as regards economy, endurance, or ease of action, and of some of these engines it may safely be said that they have not been anywhere surpassed in these respects. Two types of pumping engines are more especially esteemed by the generality of English Hydraulic Engineers, opinions being much divided as to which should have the preference. These are : the single-acting engine with the plunger pump, usually called the Cornish engine ; and the two-cylinder double-acting engine, with the plunger and bucket pump, which may be called the Simpson engine. The fuel economy of the one has proved to be as good as that of the other ; but the cost of maintenance, the wear and tear, we have no means of comparing. The current expenses of some of the Cornish engines have been very faithfully given by the Engineers of the East London Water Works, but the corresponding expenses of the double-cylinder engines have not been made public. We are rather left to infer, therefore, that the cost of main- tenance and repairs is in favor of the Cornish engine. The double-cylinder engine is a safer engine, the crank controlling and limiting the stroke, which in the Cornish engine is loose, and dependent to some extent on the watchfulness of the engine-man. The double-cylinder engine admits of a higher degree of expansion being used than on the other, with much less strain or harshness of action on the machine. In this respect it has the advantage of any descrip- tion of single-cylinder engine, an advantage which renders the double-cylinder engine specially valuable as a pumping machine. The following are the results of test trials made on these two classes of engines, to ascertain the rate of expenditure of fuel, or the "duty," so called. The " duty " in England for pumping engines means the Ibs. of work or Ibs. of load raised one foot high by one cwt. of coal (112 Ibs.). In the LTnited States it has been referred to the simpler measure of APPENDIX. 109 100 Ibs. The English results have, therefore, been reduced to meet this last unit. Ibs., raised 1 foot high. The four double-cylinder engines at Lambeth were tested by Mr. Joshua Field during 24 hours without stopping, and for every 100 Ibs. of coal consumed gave a duty in foot Ibs. of 86,665,075 The fuel was Welsh coal of good average quality. The New River engines (double-cylinder), tested soon after com- pletion, gave a result on an eight hours' run of 100,892,847 Using Welsh coal, we presume of best quality. The Chelsea (double-cylinder) engines, tested by Mr. Field during 24 hours, gave a result of 92,765,972 Using Welsh coal. The Chelsea engines, under a four days' trial by Mr. Cowper (llth to 15th June, 1861), gave a result of 77,796,656 The three tests first given above, and all short tests, are of little account, except as affording some indication of the capability of the engine, when compared with other tests of about the same duration. The last-mentioned test of four days approximates more nearly to the ordi- nary work of these engines throughout the year, as stated by Mr. Simpson, the Engineer of the Chelsea and Lambeth Companies. The "duty" statistics of work of the Cornish engines are for longer periods, and therefore more satisfactory. Ibs., raised 1 foot high. During a five days' trial of the 80-inch Cornish engine at Old Ford, by Mr. Wicksteed, using the best small Newcastle coal, the result was 86,737,739 During 11 3 years' work of the same engine, using ordinary small Newcastle coal, the steam cut off at 1, the duty was 69,093,852 With the best Newcastle coal, according to Mr. Wicksteed, it would have been 82,637,205 The Wicksteed engine (90-inch) at Old Ford, during three years work, 1848, 1849, and 1850, steam cut off at I, gave a result of 73,079,032 Mr. Greaves, the Engineer of the work, stated that, using the "commonest coal that could be bought in 1862," the East London Cornish engines gave a duty result of 62,500,000 Mr. Morris, the Engineer of the Kent Water Works, where, how- ever, the single-acting engine uses a different form of pump from the Cornish plunger, stated as the result of 14 years' ex- 170 APPENDIX. Ibs., raised 1 loot high. perience, using the best coal at 25 shillings per ton, that these engines had shown a duty of 75,892,222 At present (1'863), using inferior coal, at ten shillings per ton, he got a duty of but 66,964,000 At the Kew Bridge station of the Grand Junction Water Works, there are five Cornish engines. Mr. Fraser states that the usual duty maintained there " throughout the year," using small coal, costing 13 shillings per ton, is 65,178,477 The above statements show sufficiently that the double-cylinder crank and fly-wheel engine can be relied on to afford as good an economy of fuel as the Cornish engine ; the short trials given above show indeed a higher ' ' duty " for the double-cylinder engine than for the Cornish engines ; but I assume that for a long period of time, and using the same quality of fuel, they would not exceed the Cornish rates. The following table brings together the leading engines of the London Works (the Kent Works excepted), with the view of indicating the relation of the pump load to that of the cylinder. This is a mere blocking out, so to say, of the question, for the friction of the engine is not added, as it should be, to give the actual work done at the steam end ; but the results are significant, nevertheless, and of value, we think, so far as they go. The addition for fric- tion would have been in most cases a guess which the reader can as well make for himself. The data on which the table is founded are not given as severely correct, though all received at the several stations from the persons in charge there, and from personal observation. They will most of them be found, I trust, to be near approximations. Some errors have evidently crept in, and the publication of the table may lead to their correction. APPENDIX. 171 CO I! a 1C CO CD CD rH 10 rH 3- 1 ?? i 1 OS CO CO CO d CO b t* Ci t~ "^ 1-1 rH 1 rH CO 1 S3 CO CO j -i s'fei-S a aj " 5 OS CM ** 00 rH O t- OO OS t- CO CO d rH oo OS d oo 1C 00 1 1 t- OS 1C oo OS (M01 S . OS rH 1 (M 00 CO CO ' ^ *i It * 1C 1A CD t- rH rH IO CD rH OO d 8 CO 1C t- rH c rH i-H rH (M ss i 1 rH : g rH rH 1 irj 00 : j O OS O CO CO rH CD o rH rH OS CO OS CO OS CO CO--H rH 1^- CO rH r- 5 OS CO rH b- S5 ioSi l- f 1C CO IO CD OO OS 1C 00 CO rH I CO (M s d rH t- CO -^ -* rH ic 10 d CO t- o ^t* CD iC CDd II III (3 * s ' 9 GO CO rH 3 1 t rH T j 1 S CD S * rH O rH rH o 00 00 rH 00 CO 00 00 ^ 00 CO o rH OS 00 33 00 CO Q a CO O CO 1C s *4n rH CO rH S CM 3 0$ O -O d rH s CO CM US rH 22 S2 CHARACTER OF PUMPS. fo JS d G, CO ^g 3 | d d 1=1 h GO 00 ^ ^^ OO *^ r ^ O r ^ -*" -* _o 1 1 Ji - ^H S t-i OiOOi-iOOOOOOOO o o o r- i m T-l t-fi-tr-ti-Hi-HiHrHt-HTHiH 1-1 ^^ H i-*. ' i I S 41 Vf * " ^ ^ ^Y^ i i i : i : : : i : : : : : ^ : : : : : : - d d d d d d d : . . . : ^ s *-< b S I |fifi| d 6 cJ a S OS -OO Ob-CD -QO^-ti-HCOCO CN OO 01 * 0> C* V -OOCOCOb-CD SC-3 CM b- Ci CS Oi O T-nOiOOOOS lOOSCiCOCS i-H*'i 1 Cl rH 1 i ( fH *H Oi CO CO (M -l i-l ft 3 a CD e S. o i-i -OOO^-lOOOOOOOO O O O ICQO < O CO i-( *-l rH 11 I I S-^IOOG^O O CD O OOOOO 00 OO OO b- O5 b" CD CD b" CD CD b- t^ 8 S S ^ : : : js,g> : 1 i 1 i i I 3) Sfe 3 o (JJ 5g S n-g a o. Bh O j 3 d d d d ^ d d d o o d d G> ' * "8 | 4 ' 4 ""!> S 1 a-S S> j j .S 1 CO EC d o o > || Q 4J [S ^ ^ *- 'SB. Bu O S Q) , . . . -*J -4-3 . -IJ -*J 3 5iO ....c8fl3>rtci | 'O n3 ,*. -S hrt - al : a " a .1 * C c5 03 ' 43 j d d d d d||I|l|ll I d d d j Q fl Q w||||||l| a ft Q Do. do. West Middlesex, at Hampton Do. do. Chelsea, at Thames Ditton. . s ,1 Hi M EH W APPENDIX. 173 "3 -o _: i 3 QO CO O t H IH -1 SB'S i [L ' ' ^ o 1 .? . ^ CB E? o C" ^g ^- o.^ ^ Q o ^rd^o oo ^ " ^|2* S ^2 s n"l2 ^ 1 ^ h ]| h -1j ^ I t, ns a s "a s "Pi's ;3 '-fflSag s c 5 |4l Q oQ Q H 1 ^ i ^ 1 as CD 0) CD CD 1 III g 02 05 CO s 1 4J Ci rt " ri* 1) CJ 03 S .fc fl . ^ . f r3 r? ^ [Z; 22 174 APPENDIX. The following table in regard to boilers was prepared hi the hope that it would expose some uniformity of opinion and practice among the London Engineers, as respects the boiler capacity which should be provided for a given capacity or area of steam piston. The batteries of all the engines indicated in this table are composed of Cornish boilers. They are all of very nearly the same general dimensions, and they are all worked under about the same pres- sure of steam. The engines too are mostly single-acting Cornish engines ; the rotary engines given in the table are served by the same class of boilers, and worked under very nearly the same average of load per square inch of piston. Their action is more rapid in the proportion say of 8 to 12, and they would therefore use more steam per minute for any unit agreed upon, than the other class of engines. By referring to the first table given above, the reader can make such correction for variations in velocity as his judgment may dictate. I prefer to give this table in its crude state, without attempting the nicety of correction due to the various modifying influences of each case. The capacity of boiler understood here refers to the gross size of the boiler without deduction for fire space or flues ; these last bear about the same pro- portion to each other in each case, and have 'therefore been disregarded. The unit at the steam cylinder to which the boiler capacity is applied, has been taken as one square foot of the area of the steam piston. This unit would correctly represent the case, were the velocities of the pistons of the different engines the same ; these velocities, however, vary even in the same class of engines, and to that extent the proportionate boiler capacities given in the table will be felt to be unsatisfactory. But as the variations in velocity are variations of practice rather than of principle, and each Cornish pumping engine is probably designed with reference to a conventional velocity for that class of machine, the capacity of boilers provided should in reality bear some uniform relation to the engine as it may be supposed to have been designed, rather than as it happens to be actuated. This kind of uniformity, however, is not found to exist. The boiler power varies considerably, as will be perceived at the different sta- tions, and to an extent that is not easily explainable. The table indicates a provision of boiler of from 100 to 140 cubic feet of boiler space to 1 square foot of piston area for the single-acting Cornish engines; and for the rotary engines, a provision of from 200 to 250 cubic feet of boiler space for each square foot of the steam piston area. The rotary en- gine, in other words, should have at least double the boiler capacity per square foot of its piston area, which would be requisite in the single-acting engine ; the steam in the rotary engine being used on both sides of the piston and the velocity of motion being usually greater. The first Belleville engine (Cornish) of the Jersey Water Works was pro- APPENDIX. 175 vided with a boiler capacity (4) in gross, equivalent to 150 cubic feet of boiler space to each square foot of piston area, and it was usually worked from a boiler capacity (3) equivalent to 112 cubic feet of boiler space to the square foot of piston area. At this time, 1869, there are six Cornish boilers to two engines, and the relations of these give 112s cubic feet of boiler provided for each square foot of piston, and yet, when but one engine is in use it is usually served now by four boilers. This is sufficiently accounted for by the rate at which the engine is worked since the erection of a stand-pipe, 9 and 10 strokes per minute, as compared with the old rate of 6 and 7 strokes per minute. 176 APPENDIX. 8 S s g O 3 H H I ...1 f 1 2 - . g a^ggi o ^ i*> ca j b g THCdOO U5 -^(OOT-^COOO IO 30t-M QOIOt-CDO T-I f-H i 1 t* t- CTS h- O -^ OOOfMOSOS -^1 t- -l OS * CO OOit* Olr-ICN f-t i-l i-H?H(M 5 ^J IO Citr--* t-CQiOi-HQO l> CS O -t. W 1 5 2 ^ I ,0 3 osot-**-^ -i oo i co' -^ cs r---i*o ^Ht-i 1COO -^lOCO^OlO i 1 i (h-O ooc-c^ toosdeo^o o w> d t- -*-*O5O?o tot-io^m co OU3QO rH rH rH | g . I k fl h 9 rjrJ OIOIMC3O r>rHl>COQO Oi (MCOO rH (N i-t r-l rH CC "A O a IS ITd III J_W 1 SOOCOiMt- t-M^OOlO rH t^-^Ci Or-trHO (M d -^ O C-l OS (MW^ COCOOO1O CirHCO-^QO ^ Cs^CO (M -cDCOCOlO-rHlO CO COiO-^ rH rH rH a a- i _rt-djajaj3ja_3jt 1 ri rl f|l *3 oo ^to to oS aft ^bD^bbt,!^ ^ 1 a i 1*1 5| X a a o I 1 1 s s 'g e 1 l c -s & c .a | g -a taaa3aaa' s i- s 8aa CO CDcOCD(MtMlO(MClCO CT COrH-^ 1 | M I 1 ! ' | ' 1 - | i . ! : M p E < I 1 ! lit . 4 ' & M ^ '3 35 M H fl a i ajj3 1 1 & 5- < rO.a OO'ti'g is g 1 atelaa o- Jfi H 08 o> 3 03 oS 'O S P5 PEJ ft 1 tqWoHW 1 LEADING ENG * [2 .O3fl3 PLATE FILTERING RESERVOIR i SI :. fe$*!MM(*&;iM9&(<*i' . ? lianbeth. _ 5 Viniti'fuill J D" Gnijul ,Ju7ictum 8 11 West mdMe-Sfj: 9 f> Snr Ki-cr JO T>" East loruitm Jt SCALl. n 040 H 1DJ JQ) FILTER BEDS PLATE IV UNIVERSITY OF or CIVK- BERKELEY, CALIFORNIA II AfM1fR^f?"TrfWi WM'TFtf'f 5 ? LLiiniLMJ lEJiSi J Lnl Vv^iu liLRi RESERVOIRS AND FILTERS AT DITTON 1668 PLATE V. of filter- fTiroit/jfh ^A fr&r.f are- in -3 iftjji&s earfb ttrul tAwr* F*V a aen/fftaa. <=* *. Ml O s ^ I 1-1 < o l*ipe, from new settanff RIVER THAMES -f, .; < o_ Ml s LO Mil SO JtW X MEW Wfl feet FILTER BEDS AT . Nl'Wi JV7 HELIO_ ENGR.8. Pftl PLATE X ff 3 Form a/' rim/ pr/y drains OF CIVIL BERKELEY. CALIFORNIA LONDON PLAN OF FILTER BEDS AT LEA BRIDGE HELlO. ENGR.& PRtt PLATE XI M)fle of ' de7i,i'Pring the water .retf/rita mserrmrv at WaJffiam <%/ . 135 W_ 25TH.ST. N.Y. ftpe, io t/ir aafy SKETCH OF FILTER BEDS AND RESERVOIRS PLATE XII ONIVERSITV or OF CIVIL EN Fret PLAN AND LONGI HE P3G If Section, on- lin \ ; ^'fjfri--' ' PLATE XV. MAL SECTION QF IS 20 25 30 feet FILTER BEDS PLATE XVI. "* 1 I ^ V NATURAL FILT a q> MELIO. ENC^. PLATE X . Perth 1 ^^^^^^^^^^^^^^J llHBh' J ! i 135 W_ 25 TM. ST. M.Y_ . .'3s,- ~ FILTER BEDS J 7 ! s - : /:;^-* !Ls *jr^yW'^ Section on line* Clean, water ri' C of Sfl . tOO iv/////V/ IfRt^vl ';- v'l^fl sS /".TZ HELIOGRAPHIC ENGR. 4 PLATE XVi'll f) Section, G. CD. 135 YI.25T.i-ST.N-Y. f* .if * *-..* 4 SETTLING RES 1866. HELIQ.ENCR.*- PRINT PLATE XIX. )IRS 35 W.25 T ." ST N.Y- SETTLING BASINS AND FILTER BEDS Ml 300 PLATE XX .100 {'** -'--''- Section of .Basins JWFett. * -i "^ ' PLATE XXL #?>"<; .v -_ ..- . ~.^^*>' rr i*f - _f > :~C- SectioTi t>fma&n, gallery o JO feet PLATE XXII. Cross section of Gti&rj C FILTERING GALLERIES * -v. *. ..-*. UNIVERSITY OF C*t.1>RNIA QttPARTMENT OF CIVTL ENOJNEERIN 1 BERKEUEY. CALIFORNIA SETTLING BASINS & FILTERS 4ELIO. ENGR.& PRI J.I35 W. 25 rn ST.N_Y_ > (ran/an V;r :^v^'--::^v-.^S^'-' PLATE > FILTERING GALLERIES AND BASINS fjl/tl/fH Gallery $? 4 t filtering GaZZ&ri&s of flie G a^ronns^ Section, A B HELIO.ENOR.i PR PLATE XXV. e a/'./fuw 4W 7."~. :''.~ : :'- 'V'/'-l : "*". >" ' '...;:-'.; T^'-' -^- r '- : -^.; Cross W sertw~n of the 2>rtint'7if-s n f ne-w IARSE1B.L1 CO ^^s ' ~ ~ on- A fi C of PLATE xxvi. D FILTERS OF SCMASflP SrnaJS gravel '.-,';/. ',-'.'/:/8 "->'', BM . . ... . . . ' '. ' % %'/ . . '. ' . '. .;/./ ;>. '. '. 'A '/'/; PLATE XXVHI. SECTIONS OF TMt ., -Jg^p, ""-r:*4fc. "i**..-- , ~ POSITION OF FILTERING GALLERIES AT THE RIVER SCRIViA BUSALLA ON FILTER HOUSE OF THE PL Alt: XXIX ////u//f/// ///e centre PLATE XXX. LEGHORN CITY CISTERN .50 joafeet 77tf ///r//;r.v .flitiw thf Hii the wiitrr thrmfflh 1/ie riittm 7931286 UNIVERSITY OF CALIFORNIA LIBRARY