the remains of organic animal life; he believed a considerable portion of it was undeleterious vegetable matter, and, so far from the present supply affecting the health of the population, he was informed by the Sanitary Commissioner of Nágpúr that, since the introduction of the new supply, the health of the city had considerably improved. He agreed with Sir George Campbell as to the necessity for the construction of large reservoirs in India, and with General Cotton as to their perfect feasibility. Nor was it from any fault of the engineers in India that they were not constructed. Within the last few years, in a comparatively small district like that of the Central Provinces, he knew of two irrigation projects, both depending for their supply on large irrigation reservoirs. These had been sent up to the Government of India, but they were still unsanctioned. As to the showers recorded in Table II. not being extraordinary, he thought it would be impossible to cite instances in this or any other European country of showers of 3 inches in forty-five minutes, or cases in which there had been a discharge of upwards of 90 per cent. from a drainage area of 6 square miles within three hours after the commencement of the shower. With regard to the yield from the drainage area, taking into account that the average rainfall at Bombay was 76.8 inches, and that the climate was more humid near the sea, he thought the observations of Mr. Russel Aitken, who found the flow from the ground to vary from 50 to 80 per cent., the percentage depending on the amount of the rainfall, fully bore out his observations. For in the exceedingly dry climate of Nágpúr, with an average monsoon rainfall of only 37 inches, he had found from actual gaugings the yield would vary from 15 up to 40 per cent., depending on whether the season's rainfall was 19 or 40 inches. The diagrams with regard to fluctuations of rainfall referred to by Mr. Bateman, of which particulars for Calcutta were given in Fig. 2, p. 56, formed the original basis on which Table VI. was constructed. They were too voluminous for publication in the Proceedings of the Institution, but he would take an early opportunity of presenting them for reference in the library. The subject of rainfall fluctuations formed the most valuable part of the Paper, and he was sorry it was not more discussed, as, in his opinion, Table VI. showed some slight approach to a general law on the subject. With regard to the exceptional character of Madras, it might be explained in this way. Throughout India rains were generally due either to the north-east or the south-west monsoon. In ordinary years Madras received its rain from the north-east monsoon, but occasionally it got a little of the south-west, and sometimes

a large quantity was blown across the continent of India. To that cause he attributed the great fluctuation between the extreme minimum and the extreme maximum which Madras presented when contrasted with other places in India. The subject of evaporation had proved more interesting than he could have expected. The observations recorded in Table V. had been made without any preconcerted theoretical views. The facts were collected in the first five columns, and thus he endeavoured to deduce from them the actual amount of evaporation. The result of the discussion proved how little was known on the subject, and how much the most eminent authorities differed as to the formulæ, and as to the coefficients to be employed. Some gentlemen were able to reconcile the first three of the observations with theory, but failed to do so with regard to the four last, while others said exactly the reverse. All however, were agreed that some great and unexplained force was at work during one of the two periods into which the table could be divided. He did not profess to give all the data on which the theory of the subject depended, but he thought he could explain the matter. From about the middle or the end of March to the commencement of the rains in June, the hot winds blew at Nágpúr continuously, during the day, with a velocity of upwards of 150 miles per day. Their temperature averaged about 98°, and the comparative humidity of the air during that time was considerably under 50, saturation being considered as 1. Of course, in judging of hot winds according to their scientific aspect, personal feeling must be set aside, but the effect on the ordinary senses, when stepping out from a cool room on to a verandah in the open air, was something like that experienced on going in front of a blast furnace. With regard to the apparent discrepancy between the first and last results in Table V., pointed out by Dr. Pole, it might be explained in this way. As stated in the Paper, during the dry season when his observations were taken, there was a fall of 3 inches of rain, which, in order to arrive at the average evaporation per diem, he had distributed over the whole season. Out of that quantity 1 40 inch fell during the period of the last observation, from the 7th of May to the 9th of June. Taking the 1-40 inch, and restricting it purely to that one observation, not distributing it over the whole series, it raised the amount of evaporation during that period from 0157 foot to 019 foot per day. Remembering how many circumstances entered into the consideration of the subject, such as the temperature of the air, the dew point, the force of the wind, the elastic force of vapour,

the temperature and depth of the water, and other points mentioned during the discussion, he thought the time had arrived when, if the subject was to be thoroughly investigated, it would be necessary to give up observations with small vessels, such as those to which reference had been made; they were too shallow for reliable results as to temperature, too limited in area to allow free play to the wind, and were altogether so small as to be affected by many disturbing causes. He had endeavoured, however imperfectly, to indicate, by the facts given in Table II., how, in his opinion, the observations should in future be conducted, and he believed that his own observations, extending over a water area of 350 acres, were much less liable to small errors and disturbing causes than in the case of the 36 square feet referred to by Mr. Field. No consideration of the subject of rainfall in the present day would be complete without mention of the sun-spot theory; and he was much pleased that so free and full an expression of opinion on the subject had been elicited. The knowledge that, by his remarks, so eminent a man as the Astronomer Royal had been led to consider the relation between solar radiation and rainfall was of itself a sufficient reward for bringing the subject before the Institution. With regard to the duties of engineers in India, he had stated, to the best of his ability, his own personal experience, and what he had himself seen in the case of engineers similarly situated. Mr. Ormiston, at Bombay, was differently circumstanced. He had contractors and a large trained staff, and could obtain easily and cheaply from Europe any materials he might require. If he were removed 500 miles inland, he would be thrown much more upon his own resources. While generally agreeing in the observations as to Cooper's Hill College, yet he had no hesitation in expressing his belief that it was the finest theoretical engineering school he had ever seen, and he believed that Government would in time see the necessity of enlarging the period to be spent by the students on actual works of construction under some eminent civil engineer. Experience was at the very root of the profession, and it could only be properly acquired on actual works under a good master. Personally, he was deeply indebted to Mr. Bateman for the training he had received: without it he never could have brought this Paper properly before the Institution, and he was sure that training could not have been received at any school or college, however good.

Mr. HARRISON, President, said the manner in which Mr. Binnie's observations had been received rendered it unnecessary for him to say a word as to the value of the Paper. It had been the

means of laying before the Institution matters of considerable interest, and had brought among them their Honorary Member, the Astronomer Royal, who had propounded, not exactly a theory, but a striking coincidence in regard to the rainfall going pari passu with the heat of the sun. Although he called it merely a coincidence, he was about to devote his attention to the matter, to see whether there was anything in it that could be reduced to a positive theory. He could not allow the opportunity to pass without making a remark on a further coincidence, in regard to the works constructed by Mr. Binnie. That he should have submitted an estimate for a large work of that kind, and actually completed it within a few pounds of that estimate, was a circumstance that reflected upon him the greatest credit, and he only wished that in the numerous works executed in this country, engineers could lay claim to similar accuracy. He had not himself been engaged in the construction of reservoirs of anything like the magnitude referred to. Immense reservoirs and embankments, however, had been constructed in England, and if it could be shown that such enormous receptacles for water as had been alluded to were a matter of necessity in India, he believed the practical ingenuity, talent, and experience of engineers would not be wanting for carrying them out.

Mr. HENRY F. BLANFORD remarked, through the Secretary, that, in his opinion, India offered a fairer field for investigating the perplexed problem of rainfall, and, indeed, most other meteorological conditions, than any country equally accessible; and he hoped that the steps now being taken by the Indian government to systematise observation and to render the results accessible, would, in the course of a few years, lead to definite conclusions on the subject. He would add a few data to those given by the Author. With respect to Calcutta, the recorded rainfall from 1829 to 1835 was as follows:

and that of 1873, not included in the table, was 45.27 inches. The average of the forty-five years was 65 44 inches, which differed but little from that of thirty-seven years given by the Author. The largest fall recorded within twenty-four hours was 12 inches. That quantity fell on the 11th of May, 1835, and