28. Will you state now how the water is drawn from the lower end of the T. Hawksley, Esq, Serpentine, and brought to that point which you have explained?-The water is taken from the lower end of the Serpentine by means of a brick conduit, and that brick conduit is laid at the necessary inclination, to convey something more, I think, than 2,000 gallons per minute, and it carries it directly into the engine-room. 29. What is the depth of the lower part of the Serpentine from whence the water is drawn ?-I think it is 11 feet in mud, and eight feet in water. 30. At what level is the entrance to this conduit?-The entrance to the conduit is brought as near to the surface as is necessary to keep it submerged, so that it will flow with its full volume; but the water can be drawn from any depth. 31. Will you explain that on the plan; the conduit seems to be very near the ordinary level of the upper surface of the water; the entrance of the conduit is near to the top of the water-Yes, and purposely made so. 32. Can it be drawn from any level?-Yes, in exactly the same way that the water is brought up again. There is nothing to be done but to turn the pipe downwards, and the water will rise up that pipe so long as all the pipe is submerged, and it will enable the water to be drawn from any depth-from the bottom, the middle, or the top, just as you please. 33. You would continue the pipe from this conduit ?—No, I would not, because it is not objectionable to do so. The largest quantities of this matter, of which I spoke, are to be found near the surface, and therefore the faster we can draw it from the surface, the more we shall carry away; it will be replaced from the water below.. 34. But what would become of the vegetation below the level where you were drawing?-You cannot skim water off the surface only. It is always being mixed by the difference of its temperature, and as the water is never lying in strata, I could not skim off the surface water; that is impossible. 35. I ask you whether the filaments of the confervæ which are at present near the bottom would rise and enter this conduit to be drawn into the filter beds ?-Certainly; as I mentioned, by merely putting an iron pipe in for this purpose you may draw from any depth, we do it in reservoirs frequently, and put three or four valves on for that purpose. 36. Do you anticipate that there would be a current of water upwards from the bottom?-No; not a current, in the sense of a visible stream, but all the water is being continually mixed, you cannot keep one part stagnant under another. 37. I particularly allude to those things which are held mechanically in suspension, would they be moved upwards by the water, so as to enter it. What guarantee is there that much of this vegetable matter will not always remain beneath the influence of the conduit which is placed at the level of the water ?— Because this vegetable matter is to be found chiefly at the surface, and it is continually rising to the surface, and is always rising in hot weather, that we see in all cases of waterworks, reservoirs-there is great difficulty in consequence of that circumstance in keeping the surface of such reservoirs clean. 38. With regard to the matter which does not rise; how would that be carried off by the conduit?-That which does not rise is fixed. 39. I mean that which is floating on the bottom of the water?—That will always rise; it is always changing its place, and coming to the surface, particle by particle in succession. 40. Will you just explain the action of the engine in drawing this water; how is it drawn from one end of the conduit to the other. In other words, when your steam-engine is drawing the water through this conduit, does it keep the conduit always full, with a perpetual stream, or do you anticipate that only part of the conduit will be filled?-The conduit will be filled, and the water will be drawn in the requisite quantity, as the conduit is made larger than necessary to supply the exact quantity of water which is required to supply the system of filter beds. It commences below the surface of the water, and consequently, the conduit will always be full. 41. What is the size of the conduit?-It is 30 inches in diameter, and the water is brought into this well (pointing to a drawing), and these are the pumps which receive it from the well. This is the top water of the Serpentine, and that will be the level of the water in the well when the engine will be at work (explaining to the Committee by a drawing), the difference being the head which is necessary to give a velocity to the water along the conduit. 42. The fall on the plan is marked as one inch in 100 yards?—Yes; the diameter of the conduit is calculated to that fall. 5 March 1860, T. Hawksley, Esq. 5 March 1860. 43. Will you state what amount of current you expect to be produced through the Serpentine by the abstraction of two millions of gallons daily?--No sensible current; you cannot get a sensible current by putting any quantity of water that you can conceive into the head of the Serpentine; it is quite impossible. 44. You must treat it as a stagnant lake, must you not, even after this alteration has been made? - Lakes of this kind are not properly called stagnant, small lakes are; but these large lakes are always in a state of agitation by the wind and other physical causes, and everything which they contain in the shape of soluble organic matter becomes oxydised and destroyed. That is the reason why large lakes and large ponds are always sweet and pure, and why small ones become foul; you find that the case everywhere; practically, you cannot make any sensible current; neither two millions of gallons nor ten millions of gallons would make a very sensible current in a lake of this magnitude containing sixty millions of gallons. If you put ten millions in, it would move it, if it was of equal depth, just a tenth of its own length in a day; but as it is a mile in length the effect would be, if you were to put ten millions of gallons in it, to move it a tenth of a mile in 24 hours, which, of course, is nothing; and if you could put the whole sixty millions of gallons in, in one day, you could only move it its own length, a mile, and that practically is no stream at all. 45. Lord Fermoy.] I think you stated that the late Chief Commissioner first spoke to you on the 7th of July, and brought this matter under your attention? -He did. 46. Had your attention been called to this subject before?-Frequently. 47. Then you stated that you sent in your report on the 15th? Yes. 48. Between the 7th and the 15th, or previously, what steps did you take to ascertain the features of this lake?-I made personal examinations between the 9th and the 15th. Of course I was very well acquainted with the Serpentine previously, and I knew also all that had been said about it; and of course, in walking along the banks of the Serpentine, I could not avoid, being constantly engaged in hydraulic questions, of this kind, comparing the state of the Serpentine with the statements made with regard to it, so that I was pretty well prepared on that subject, although I had come to no conclusions and made no examination. But when this matter was brought before me in this form, I immediately instituted, not only personal examinations, but I got Mr. Spencer, a gentleman who is particularly well versed in questions of this kind, as to chemistry and the organic contents, and also with regard to vegetation, and the animalcula which abound in water of this description. I took the precaution to take him with me, and upon several occasions we made our examinations together, and I asked him to report to me the actual facts as he found them; and although it was an inquiry of my own, I thought it my duty to append his report to mine, and that I think appears in the printed document before the Chairman. 49. I think you said that you had made soundings?-No; when Mr. Fitzroy pressed me for my report I told him that it was impossible to make a report in the short time that he wished, as the data were not supplied, and I supposed they did not exist; he then said that he had them, and he sent them to me, and here they are. 50. You have considered the question of the depth of the mud, I have no doubt ? -Yes; I have not only considered the depth of the mud, but I have considered that which was most important of all-the question of the character of the mud. If I bad found the mud undergoing decomposition, I should have recommended in all probability some other and more expensive steps, but I found that the mud was not undergoing decomposition, but that it had passed through that state, and instead of making the whole impure, it had a perfectly neutral effect, just like the mud at the bottom of any gentleman's lake. It does no harm, it is black, carbonaceous, and looks inky, and under certain circumstances has a peculiar smella sort of mawkish smell-but there is nothing as long as it is kept at the bottom of the water to affect the water in the least degree. 51. Can you give the Committee any idea as to what the depth of the mud is?-Yes; it is enormous. The quantity of the mud in the Serpentine is very nearly 200,000 cubic yards; it is 160,000, I think, below the bridge. 52. Could you state it to the Committee in depth ?—Yes; it is all marked on these drawings (the same being produced). This shows the state of the mud at the bottom of the Serpentine; they are most elaborate sections, and the black matter is the mud. The natural mud is indicated by a brown line, and the quantity of water is indicated by the light blue. 53. Are 53. Are the figures in feet and inches ?-Yes. 54. I see eight feet six inches black, and eight feet nine inches blue, on the same line?-The blue is the water and the black is the mud. 55. I see eight feet to a great extent in black figures, and eight feet six? Yes; you will find more in some places. 56. Do you state, assuming that the lake has got eight feet of that mud at the bottom, and that the depth of water is somewhere about eight feet over it, running to nothing at all at the edges, that that eight feet of mud can have no deleterious effect upon the water ?-Yes, on the water it does not. I do not lay that down as a general proposition, because I have already said that the mud while undergoing decomposition has a deleterious effect, but after that decomposition has taken place it has none, it is merely inert matter. 57. I will assume that at the bottom of the Serpentine the mud is eight feet deep and the water is eight feet over it in the centre, and runs to nothing at the edges, and my question is, in this particular case of the Serpentine, are you of opinion that that mud has no effect in injuring the quality of the water?-Certainly no perceptible effect. 58. I think you have stated that your filters will pass two millions of gallons per day?--Yes. 59. Does the water which has been once passed through your filters ever become impure again?-Yes, just the same as pumping clear water or allowing a clean stream to run into the Serpentine, just in the same degree. 60. Can you form any estimate as to how long the water, after being filtered and again passed into the lake, will take to become impure? That depends entirely upon the intensity of the light and the heat; it will begin as a matter of course to become impure, as I have already said, in a very few days, and it goes on increasing in impurity, and the object of this process is to keep removing the water as it does become impure, and re-purifying it; one of my objects was, to ensure that all the water of the Serpentine should be practically renewed (because it is a practical renewal of the water itself) once in every month during the hot weather, the whole of the contents. 61. Do you mean to say that your filters filtering two millions of gallons every day will pass all the Serpentine water through in a month ?-Yes, there is a little over 60,000,000 of gallons of water in the Serpentine. 62. Have you not been able to form a notion of what state the first two millions of gallons will be in by the time you have finished the filtering the last two million gallons-I have never been called upon to make any estimate of that kind; I know the practical operation which we employ in waterworks occasionally for these purposes. 63. With regard to waterworks, you send the water away do you not, nearly as you filter it, for consumption ?-Nearly always, not invariably, but nearly always; sometimes we filter from one reservoir into another, but not very commonly 64. Have you ever estimated what the result will be while you are making it pure at one end of the lake, and how fast it will make itself impure at the other end?-In this degree; at the lower end it will become sensibly tinged with the green colour; not as it is now, but sensibly. 65. At the end of a month, when you have passed the periodical sixty millions of gallons through, you will not have got the whole lake ?-No; neither is it possible to make the whole lake pure. Suppose you were to admit from a well a pure stream that had never seen the light, in the same quantity (two millions of gallons per diem), at the upper end, and you allowed it to occupy a month in running down to the lower end, which it would occupy, because there are sixty thousand millions of gallons in the lake, excepting in so far as the wind agitates the water, then the result would be, that that water which I have already described as being more prone to vegetation than the water filtered in this manner, would be green at the lower end, in at least the same degree as this water will be green, but then the discoloration is slight; I wish to state the thing fairly; that is the sort of thing I mean; it will be perceptible at the end, not foul. 66. I understood you to say, that you consider that eight feet of mud do not injure the water?--No, not perceptibly; I have described the state of the water, and there are about, even in its present unpurified state, only 2 or 2 grains of organic matter in a gallon. 67. Did you consider in your estimate, or in devising this plan, the question at all of sewerage; that is the overflow ?—Yes. T. Hawksley, Esq. 5 March 1860. T. Hawksley, Esq. 5 March 1860. 68. Which you spoke of as coming from the Ranelagh sewer?-Yes. 69. Are you able to state to what extent it was every day deteriorating the water?-It does not discharge into the river more than three times in the course of a year, and then only perhaps for a couple or three hours at a time, and probably for not more than half an hour. There is a great mistake in that subject. The circumstances under which the sewer discharges into the Serpentine are simply these the clear stream which formerly ran through the bed of the Serpentine became in process of time very much fouled, and a sewer was then made along the Uxbridge Road to divert it; when buildings became erected to an extent larger than that sewer was capable of carrying the water from, especially in heavy storms of rain when the water is shot very violently from roofs and paved courts, and streets, many houses were flooded; and then a weir was constructed, by means of which the overflow could be allowed to go into the Serpentine. When heavy storms came, the overflow did go into the Serpentine; then it was found to be a great nuisance, and an enlargement of the sewer took place; but the weir was still kept up to provide against extraordinary floods; there was one of these in July last which the enlargement of the sewer was not capable of conveying; and the consequence was, that for a short time it overflowed into the Serpentine. I suppose that three occasions in the course of a year are about as many as now take place of overflowing from the Ranelagh sewer. 70. Are you aware that there is no other sewerage coming into the lake, except this back-water from the Ranelagh sewer?-There is no other. I may mention that that objectionable state of circumstances is not to continue, because the Board of Works are about to make the Middle Level Sewer, which will take the water to a large extent eastward. And besides that, there is another sewer to be made through the Park itself; and then as a matter of course, the inlets to the Serpentine will be blocked up, and there will be no more of it. These two works are going to be done directly. 71. Did you inquire where these eight feet of mud have come from ?-Yes. 72. Will you be good enough to state that to the Committee?-Yes. The Serpentine was the natural valley of the Ranelagh brook, and was formed in the reign of William and Mary, by the blocking up of the lower end of the stream, where it issues from the Park; but afterwards greatly enlarged in the reign of George the 2d. The valley was closed in by an embankment; and as a matter of course, a great deal of vegetable matter came down the brook, and also some mud. The two together are deposited at the bottom of theSerpentine, and that deposit has been going on until within, I suppose, the last twenty years, more or less. I think the first sewer which diverted a portion of this matter, was made as far back as 1810; but from the time as I am informed of the first formation of the lake to the present time, it has never been completely cleansed, never emptied. Then as the district about Paddington became largely occupied by buildings, after the houses were constructed, there was not only the vegetable matter and the clay of the district coming in, but a great deal of water-closet filth and water fouled by domestic use; and it made large deposits especially at the upper end. 73. Are you aware of the fact, or is it a fact, that the water of the Serpentine has of late years become fouler than it was in former times ?-No, of late years it has not; of late years it has been better than it formerly was; some years ago it was very much fouler than it is now. Previously to that time and up to 1810 it was not so foul; the water was then mere brook water which came through the fields, and of course was in the ordinary condition of a country rivulet. 74. I understand you that subsequently to 1810, and up to this time the water has been fouled by the sewerage?—No, not up to the present time, except under the circumstances I have related, in very occasional instances. 75. You have spoken of the conduit which is to convey the water from the bottom to the top of the Serpentine; how do you get the water through it?-It is laid to an inclination and it terminates in a sort of well or cistern, which, being partially exhausted by the action of an engine, creates a difference of level, and the water flows from the higher level to the lower level. 76. Then the engine works pumps?—Yes. 77. Have you estimated the yearly or the weekly cost of those engines and pumps?—Yes; the total cost will be something under 300 l. a year, including the filters and the coal and the other materials. 78. How |