upon its quality for use by the towns situated lower down on the stream, and such statements as the following, which appears in the Waltham Water Report (1872), are to be regarded as depreciating, although perhaps unintentionally, a matter which is really of great importance. "The question of sewage is not at present of immediate importance to us [inhabitants of Waltham] in its effect upon the quality of the water; undoubtedly, in time, as population increases upon its banks, some comprehensive system will have to be adopted; in a growing country like ours, we cannot provide for too great a distance in the future."

Waltham derives its water-supply in theory from Charles River, but the water is not taken from the river directly. Use, in this case, is made of what is called a filter-basin. This basin was constructed at the side of the stream, partly by making an excavation into the knoll, at the foot of which the basin is situated, and partly, on three sides in fact, by inclosing a portion of the river by a gravel embankment some thirty or forty feet wide. This embankment slopes outward on the river-side, but is walled perpendicularly on the side towards the basin. The idea at first was, that the river-water should filter through this gravel embankment, and the filtered-water should then be pumped into the reservoir and distributed for domestic use. Practically, it seems, however, that the basin draws the main part of its supply, not from the river, but from springs, from the underground flow towards the river. Various circumstances point to this conclusion. In the first place it was noticed, before the construction of the basin, that in winter there was generally open water at this point in the river, or when ice did form in extreme cold weather, that it was thinner than on the river itself, indicating the entrance of warmer water from the land. Further, during the construction of the basin it was found that water came into it so rapidly from springs, that it was necessary to pump at the rate of 4,000 gallons per minute in order to remove the water that the work might go on; moreover, the water sometimes stands higher in the basin than in the river, and the temperature is quite uniformly 49° or 50° F. The pumps are now working from six to twelve hours per day, Sunday excepted. On Monday morning, when the weather is cold, the water-which

TABLE VIII.-Examination of Filtering Scheme at Waltham. [Results expressed in Parts per 100,000.]

1 These results were obtained from a mixture of equal parts of Nos. 193, 194, 195.

See No. 194 above.

Nov. 17,
Dec. 16,

1 These results were obtained from a mixture of equal parts of Nos. 193, 194, 195.

2 See No. 194 above.

Ꭰ Ꭺ Ꭲ Ꭼ .

LOCALITY.

had then stood in the basin some thirty-six hours-is found to be skimmed over with ice, having acquired at the surface a low temperature; but, during the week, as the water is constantly renewed and constantly supplied, it is found that the temperature varies but slightly.

Chemical examination of water from the river and from the basin also leads to the same conclusion,-the water of the basin being harder, and containing less organic matter, as we should expect if the water indeed comes in considerable measure from the underground flow. The water for examination was obtained through the kindness of Dr. R. S. Warren, of Waltham, who attended personally to its collection, and the results of the chemical examination are incorporated in Tables VIII. and VIII a.

From the filter-basin the water is pumped through a castiron pipe, 2,950 feet long, into a reservoir situated at an elevation of some 130 feet above the main street; from this reservoir it is distributed through cement-lined pipes.

NOTE.

Since this Report was presented to the Board of Health, I have made a further comparison of the water in the filter-basin at Waltham, and that in the river, by determining the amount of oxygen held in solution in each case. The determinations were made on the morning of Saturday, February 7, 1874, on the spot. The temperature of the air at the outer portion of the filter-basin and on the river was -7° C. (19.4° F); at the inner portion of the filter-basin under the shelter of the engine-house the temperature was about -3° C. (26.6° F.), and while the river was completely frozen over the filterbasin was entirely free from ice.

The specimens examined were as follows:

No. 213, from the river some ten feet from the embankment, taken six feet below the surface.

No. 214, from the river at the surface just under the ice. No. 215, from that side of the filter-basin nearest the river, taken just below the surface.

No. 216, from that side of the filter-basin nearest the engine-house, taken from the bottom.

Number.

No. 217, from the faucet in the house of the engineer. This house is situated on the hill above the engine-house, and is supplied by a pipe from the force-main, not from the reservoir.

The results of the examination are as follows:

LOCALITY.

In connection with the facts already mentioned, these results would seem to confirm the idea that the water comes in considerable measure from springs. This comparative deficiency in oxygen cannot be offered as an objection to the use of the water for drinking, as the absolute amount is not small, and by exposure in the reservoir it, no doubt, absorbs oxygen; even just after it enters the force-main we see (No. 217) it is found already to contain rather more than in the basin. Moreover, a sample of water taken from the filter-basin in a (clean) wooden pail, the water being somewhat agitated by the operation, after being exposed to the air a short time, was found to contain 9.58 c.c. to the liter (2.21 cubic inches to the gallon). That in respect to the dissolved oxygen there should not be as marked a difference as was observed at Lowell, is not strange, when we consider the large surface which the Waltham basin exposes to the air; it is possible, also, that determinations made later in the day-after the water which had remained in the basin for some time had been pumped out-would have shown a greater difference. It is proposed to make further examinations with reference to this matter.