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no further comment, as it must meet with the condemnation of all sanitarians.

The better class of dug wells are either lined with cemented bricks or iron cylinders, and if they exclude contamination through the sides are very costly, especially if the digging has to be made through a large body of contaminated water. Such wells are also liable to contamination by the introduction of objectionable matter from the top. It will be remembered that the Caterham dug well, which caused an outbreak of typhoid fever in the district that it supplied, was polluted in a particularly disgusting and dangerous way by workmen employed in it, who used the well buckets for an improper purpose.

The well that is made by boring alone may be sanitarily good or the reverse, according to the method in which it is carried out. To deal first with the objectionable method,

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which is shown in Fig. 1, the lining tubes are what is called "telescoped," that is, one tier of pipes is dropped within the other without any proper connection between the different sizes

of pipe, and hence every point of junction is a possible source of contamination. The metal in the pipes is also thin, little better than sheet iron, and the joints are what are known as braize and collar, which is frequently not an efficient air-tight joint. Owing to their weakness, such pipes cannot be driven forcibly through the strata, and hence they fit the bore hole more or less loosely, thus allowing surface water to run down the annular space outside them. Such pipes cannot be placed in air-tight connection with the pumps. There are, therefore, four dangers in a well of such construction: contamination may get to the source of the supply outside the pipes, and through the imperfect joints, and at the point of junction between the different tiers of pipes, or actually through the iron, which is so thin that it offers very short resistance to the action of corrosion.

The combination of digging and boring affords a much safer means of obtaining a water supply if the bore pipe be properly constructed, and attached by air-tight connections to the suction of the pumps. Should this precaution not be adopted, the danger of contamination is exactly the same as in the dug well pure and simple.

The bored well that complies with sanitary principles is shown in illustration, Fig. 2.

It will be seen that the tubes are much thicker; the joints are screwed and fitted with great accuracy, so as to be not only water-tight but air-tight. A continuous tier of tubes goes from the pure spring to the surface. The outer and larger pipes are simply used as tools for obtaining this result, and only those that serve a useful purpose in excluding objectionable water remain permanently in the ground. The stoutness of the tubes enables them to be driven very tightly into the bore hole. Tubes of this construction are frequently subjected to 100 blows with a 1200 lb. monkey to drive them a single inch without any injury to pipes or screw threads, as the pipes accurately butt in the centre of the socket, and leave no exposed thread. The connection to the pump from the tube is air-tight, so that the spring is effectually sealed from all sources of contamination, and is delivered just as it comes in its natural state from the spring. This last mentioned method is known as the "Artesian Bored Tube Well" system. It is a development of the "Abyssinian" Tube Well system, and became necessary when strata were met with that could not be penetrated without the removal of cores. The "Abyssinian " Tube Well system is so widely known as merely to require passing mention. A pointed tube is driven forcibly into the ground until it meets with the desired water supply. The water is then drawn into

the tubes through the perforated bottom length by a pump in air-tight connection with them. This simple means is available in cases where the soil can be penetrated by mere displacement, or by fracture and displacement, without any removal of cores. As a rapid and economical means of obtaining water supplies free from surface contamination it is the most efficient known. It was awarded the Medal of the Sanitary Institute, and the Gold Medal at the Health Exhibition. At the recent water famine at Swansea it was largely brought into requisition, and by its means water was found at a depth of 40 ft. in less than two hours, which was pronounced by the public analyst to be the purest water in Swansea. The greatest depth that an "Abyssinian" Tube Well has been driven within the knowledge of the author was 157 ft., at Norwich. The largest supply of water obtained from "Abyssinian" Tube Wells is probably at Burton-on-Trent, where the large breweries draw about two million gallons daily from a number of tubes coupled to one receiver, and pumped by steam power. The time at disposal will not permit of a description of the method of pumping from a tube when the water is far below the surface, but it may be mentioned that water is drawn from a depth of from 100 to 200 ft. through tubes 4 in. and upwards in diameter.

[This discussion applies to the two preceding papers by Mr. STEPHEN TERRY and Mr. ROBERT SUTCLIFF.]

Professor T. HAYTER LEWIS, F.S.A. (London), explained that he had allowed these papers to be read consecutively, because they were so closely allied that it would save time to discuss them together.

Mr. ROGERS FIELD, M.Inst.C.E. (London), observed that he had often been struck in considering the question of water supply, that such little use was made of the windmill. Of course one could well understand that in the case of supplying a town of any considerable size it would not be advisable or economical to use wind power. The question was, however, altogether different in the case of a small village, or even a moderate sized town. The great disadvantage of a windmill was of course its uncertainty; for some time they would get a considerable amount of wind, and then for days or weeks

perhaps they would get none at all. But this was capable of being entirely met in the case of the water supply of small towns, for all they had to do was to construct a reservoir of sufficient size to hold a supply large enough to meet the demand until such time as the windmill could be got to work again, when they had at once a power for raising water which worked practically at a nominal expense. Some time ago he had to look into this question, and was anxious to see what was the necessary size of the reservoir; but he found that there was hardly any reliable information at all on the subject. He had therefore investigated the question to a certain extent for himself. The first point to ascertain was the length of time they might have to wait in this country without the wind blowing with sufficient force to work the pumping engine. In order to gain accurate information on this point he got the records of the velocity of the wind as recorded in the quarterly weather report of the Meteorological Council, and he took five different places of which there was a continuous record, and which he thought would fairly represent the difference found in the climatic conditions of the several parts of the country. Of course anyone who had paid attention to the subject knew that the velocity of the wind and the extent of calms would differ very much in different parts of the country. He took Stonyhurst, Kew, Glasgow, Greenwich, and Aberdeen. At Stonyhurst there was the least amount of wind and the greatest amount of calm, at Aberdeen there was the greatest amount of wind and the fewest calms. Before using these data he had to determine another point, about which there was the greatest possible uncertainty-viz., what is the velocity of wind which will work a windmill effectively; there was hardly anything definite known about this, but as far as he could ascertain the velocity seemed to lay between five and eight miles per hour. Dealing with these data in the best way he could, the result he arrived at was as follows: taking an ordinary case, such as that represented by Stonyhurst or Kew, they might have twenty days, or from that to thirty days, in which the windmill would practically do them no good, and therefore they might want twenty or thirty days' storage capacity. Taking on the other hand a favourable case, such as that represented by Greenwich or Aberdeen, they probably would not require more than a fortnight's storage capacity. Terry stated that in America storage capacity for a week's supply had given satisfaction, but he did not think that would meet the wants in England. If they only made a reservoir capable of holding a week's supply, they would soon find themselves running short; but if they provided a fortnight's or a month's storage capacity, then it seemed to him that wind power might be used with the greatest possible advantage in country places. There were numbers of places which could be supplied from springs or wells at a low level if the water were elevated by this means. He knew of one or two cases where large mansions were supplied in that way, and when the reservoirs were made sufficiently large the results had been advantageous. He wished also to emphasize the point made by the writer when he called attention to the necessity of having waterworks


properly designed; he knew cases where land agents and others who had no practical knowledge on the subject essayed the task of planning waterworks with the idea that money would thus be saved, whereas it was generally not so. Often a spring was chosen without any sufficient research as to what was the yield of the spring in dry weather, and a large outlay was thus incurred to very little advantage. He could instance the case of a small village where iron pipes had been laid to convey water from a spring which had not been properly investigated, and then directly a drought came they were short of water. Now no engineer would dream of going to work until he had some reliable data as to how much water could be depended upon in dry weather.

Mr. H. LAW, M.INST.C.E. (London), endorsed what had been said by Mr. Field. It was a very important matter that really healthy supplies should be obtained for the villages, but it was also important that they should bear in mind that the villages were often so small that they could not bear a large expenditure; which difficulty however might be overcome, as was pointed out in the paper, by the amalgamation of districts. But this was often a difficult matter from conflicting interests and jealousies, and therefore any practical suggestion which enabled the village to provide for its own wants in some inexpensive manner was well worthy of being considered by the profession. He felt very sure that if proper reservoirs, which could now be very cheaply constructed of concrete, were provided, the windmill pumping would in many cases form an easy and economical solution of this important question.

Mr. PAGE considered Mr. Terry would have done well to have added some information upon the collection and purification of roof water. In the country districts where dwellings were isolated, rain water formed a very important feature in cheap water supply; and he thought the paper would have been rendered a great deal more valuable had the storage of water from the roofs been mentioned, and some means of purifying it indicated. In travelling in country villages and districts, they must all have seen what a number of dwellings there were without any provision in the way of water supply; it was only the other day that he was investigating a rural district, and he found people actually fetching their water in buckets from a stream nearly a mile distant, of very doubtful purity. He thought some legislation ought to be carried into effect to render it absolutely necessary for owners to provide a water supply to their property. Roof water might be collected and purified cheaply in many cases.

Mr. H. LAW, M.INST.C.E. (London), observed that in the large and important city of Buenos Ayres, in South America, the people depended almost entirely for their water supply upon a large underground tank, which was constructed in the centre of the court of most of their residences, and it was hardly ever known to fail. He knew cases in the neighbourhood of London where water for drinking

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