It will be seen by this table, that we had 1.06 inches more rain in 1878 than in 1877, and that we had 11 inches more water in the pond at the close of the year. The greatest variation of water in the pond during the year was 2 feet 4 inches, from the highest to the lowest point.

By reference to the superintendent's report, we find that we pumped in 1877, 960,582,300 gallons, a daily average of 2,631,732 gallons; while in 1878 we pumped 823,874,400 gallons, a daily average of 2,257,190 gallons; showing a gain this year over last year of 136,707,900 gallons less water pumped, a daily average of 374,542 gallons. This difference can be accounted for by various reasons, prominent among them being the excellent condition of our works in regard to leakage and waste. A corresponding saving has been made in the coal consumed during the year, a saving of 222,200 pounds of coal being shown over last year.

Purity of Our Water.

The vegetable growth which troubled us so much last year, and of which we gave extended account in our last report, was very much less this year; showing that for some reason the unusual growth of last year was an abnormal development, and that we need not expect, except at long intervals, such growth as was then manifested.

The water from Fresh Pond has been analyzed many times during the past season, with similar results as have followed former examinations. We send you herewith a letter, and tabular statement, from Professor William R. Nichols, showing the results of seventeen different examinations made by him during the year.

Letter from Professor Nichols of the Mass. Institute of Tech. nology, accompanying the Table of different Analyses in 1878.

GEORGE P. CARTER, ESQ.,

BOSTON, Dec. 14, 1878.

President Cambridge Water Board, Cambridge, Mass.

My dear Sir, I enclose herewith a table containing the results of some of the examinations of Fresh-Pond water, which have been made in my laboratory during the present year.

These samples were taken two feet below the surface at one or the other of two points several hundred feet apart, at the mouth of the

bay from which the conduit issues. I have made other examinations of water taken at different depths at the same time; but, as they form part of an investigation which I am making with reference to some disputed points in the history of pond waters, I do not care to publish the results until I have accumulated more data than I have at present, lest they should give rise to some premature generalizations. If these enclosed results are of any service to you, I should be glad to have you make use of them.

Yours very respectfully,

WM. RIPLEY NICHOLS.

ANALYSES OF FRESH-POND WATER BY PROFESSOR WILLIAM RIPLEY NICHOLS DURING THE SEASON OF 1878.

Several analyses of Fresh-Pond water have been made during

the year by Professor Sharples; and with his table he sends the

results in connection with those of Professor Nichols at the same or about the same time, and also gives what he thinks is the best solution of the fact that our water during the late fall and winter months is not in as good condition as other parts of the year. We submit here with his communication for your more full information, and for future reference.

TO THE CAMBRIDGE WATer-Board:

DEC. 16, 1878.

The analyses of Professor Nichols and myself, made at various times, of the water of Fresh Pond, would seem to indicate, that, while the annual change in the water is but slight, it nevertheless does go through a regular series of changes.

These changes are shown by the ammonia, and more markedly by the free than by the albuminoid. We have now available about thirty determinations of the free and albuminoid ammonia in the water of the pond, besides a few exceptional ones by Professor Nichols made of the water taken from the bottom of the pond last December.

Those made by Professor Nichols may be found in his special report to this Board, and in the last Annual Report of the State Board of Health.

The majority of my analyses are also reported in the same report. I have tabulated all these analyses in Table I. This seems to show that, while the albuminoid ammonia is almost constant, varying only from about.0150 to .0230, with the exception of two or three isolated cases, the free ammonia, on the contrary, is subject to much greater variations. It remains about constant from May to October; then it suddenly rises from about .0050 to .0144, attaining its maximum at about the end of the month, when it reaches .0419: from that time until March and April it seems to gradually sink. Now, while the determinations are far too few to speak with certainty, as they should extend over years of time with constant observations of the temperature and rainfall, and also microscopic observations of the life in the pond, yet I think they are sufficiently numerous to show that there is a law governing the changes, which may be briefly stated thus:

The amount of free ammonia in the water is small so long as plant-life is vigorous and healthy; but so soon as this is checked by the frost in the fall this suddenly rises, from the fact that the plants commence to decay as soon as they are killed; and the amount of ammonia is also, no doubt, increased by the leaves that blow or fall into the pond, and there decay. This ammonia gradually escapes until by about May, or sooner, according to the state of weather, and

according to the fact of the ice covering the pond or not, it has arrived at about its normal state. The round is again repeated the next year. In order to establish this law in regard to the water, and also to ascertain the facts in regard to the remaining water-supply of the city, analyses should be made at least once every two weeks, extending over a space of not less than two years; and these analyses should not only cover the waters of Fresh Pond, but should also include determinations of Little Pond, Spy Pond, Wellington Brook, and the conduit.

With the facts that we now possess, it is very evident that no single isolated determination of any of these waters is very satisfactory as showing whether it is remaining constant in quality, or whether it is deteriorating.

There has been but very little done this year in the extension of the Water-works; and what has been done is so fully set forth in the Superintendent's Report, which we present herewith, that we need say no more on this topic than to refer you to his report for full details of the work done.

The almost annual agitation of the question as to the purity of our water-supply, and what is necessary to preserve its purity, has again come up this year; this time forced upon. public attention by the erection of a large slaughter-house by Niles Brothers, within a short distance of Fresh Pond, and very near our conduit connecting Fresh Pond with our other sources of water-supply.

As soon as it was ascertained that there was an intention to build this slaughtering establishment, all steps at our command were adopted to prevent it. A committee consisting of the Mayor, the City Solicitor, and the President of this Board, was appointed with full power, with instructions to do every thing that could be done to prevent the evil results that must inevitably follow the prosecution of this business as was contemplated.

It was found that the parties building, had not first procured the consent of the Selectmen of Belmont according to the law in regard to erecting slaughter-houses; and application was made to the Supreme Court for an injunction to forbid any further work on the building. At the same time the Board passed a vote, requesting the Selectmen of Belmont to grant us a hearing before giving their permission to have the slaughterhouse erected, which we considered would be of great damage to the city of Cambridge, and, so far as we could see, of little or no benefit to the town of Belmont. A hearing was granted; and the City Solicitor, with Judge Hoar, who had been retained as counsel, and the President of this Board, with other members, appeared before the Board of Selectmen of Belmont, consisting of Messrs. Josiah S. Kendall, Henry Frost, jun., and Converse F. Livermore, and presented the case, showing by expert witnesses, the danger to our water-supply that would result from such a business carried on where it was intended; saying and doing all that could be said or done to induce them to withhold their consent to the erecting of the building. But it was all of no avail, and a permit was given to have the building completed and used as a slaughter-house. We cannot look upon this act on the part of Belmont, except as most unneighborly in an adjoining town, and granted by those who represented the town in utter disregard of the Golden Rule. We think the time will come, not far distant, when the better por