Town annual reports of the several departments for the fiscal year ending December 31, 1875, Part 25

Author: Worcester (Mass.)
Publication date: 1875
Publisher: The City
Number of Pages: 490


USA > Massachusetts > Worcester County > Worcester > Town annual reports of the several departments for the fiscal year ending December 31, 1875 > Part 25


Note: The text from this book was generated using artificial intelligence so there may be some errors. The full pages can be found on Archive.org (link on the Part 1 page).


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3.116


May, .


4.86


42.8


2.080


7.38


44.8


3.308


4.78


46.7


2.233


5.97


50.6


3.023 10.18


56.4


5.745


5.21


49.4


2.576


June,


3.41


18.6


0.634|


5.71 28.1


1.603


3.90


56.6


2.209


6.19


67.4


4.172 5.76


53.3


3.071


2.51


46.1


1.156


July, .


2.37


8.5


0.201|


8.12 19.3


1.571


4.45


16.4


0.729


29.6


1.555 3.37


28.9


0.974


2.31


23.4


0.540


August,


6.90


8.4


0.577


3.05


17.4


0.530


6.11


16.1


0.984


9.21


42.2


3.885


8.63


21.7


1.877


2.30


10.9


0.252


September,


4.68


10.2


0.475


2.23


10.8


0.240


6.20


18.1


1.123


2.51


92.0


2.310 13.35 38.4


5.132


2.85


11.1


0.315


October, .


3.94


23.9


0.940


4.56


7.6


0.346 5.08


21.9


1.114


4.51


38.1


1.717 0.74 366.5


2.712


8.74


28.8


2.518


November,.


3.48


54.6


1.901


3.15


36.3


1.142


3.48


94.1


3.273


3.09


64.6


1.996 5.36


69.9


3.744


4.39


42.9


1.884


December, .


2.73


62.1


1.795


3.87


47.2


1.825


3.76


74.7


2.810


1.86


94.5


1.757


2.51


55.2


1.385


6.86


39.0


2.675


Totals, .


40.80


36.5|14.892 52.43


39.2 20.563 48.57


51 9 25.208 48.88


62.7 30.649 60.87


57.2 34.804 52.21


48.9 25.553


inches.


Croton Dam.


inches.


Croton Dam.


inches.


inches.


Croton Dam.


inches.


Croton Dam.


CITY DOCUMENT .- No. 30.


Total Rainfall for six years, 303-76 inches ; average yearly rainfall 50-62 inches ; percentage flowing to dam for six years, 50; average yearly quantity flowing to dam, 251% inches.


Percentage flowing to


Croton Dam.


5.25


TABLE II.


TABLE SHOWING THE MONTHLY RAINFALLS ON THE COCHITUATE WATER-SHED FOR NINE (9) YEARS, AND THE PERCENTAGE OF THE SAME THAT REACHED THE LAKE.


1863.


1864.


1865.


1866.


1867.


1868.


1869.


1870.


1871.


MONTHS.


Rainfall in inches.


Per cent. rec'd in Lake.


Inches collectable.


Rainfall in inches.


Per cent. rec'd in Lake.


Inches collectable.


Rainfall in inches.


Per cent. rec'd in Lake.


Inches collectable.


Rainfall in inches.


Per cent. rec'd in Lake.


Inches collectable.


Rainfall in inches.


Per cent. rec'd in Lake.


Inches collectable.


Rainfall in inches.


Per cent. rec'd in Lake.


Inches collectable.


Rainfall in inches.


Per cent. rec'd in Lake.


Inches collectable.


Rainfall in inches.


Per cent. rec'd in Lake.


Inches collectable.


Rainfall in inchies.


Inches collectable.


January,


4.10'


47


1.93


3.37| 71


2.39


4.99


43


2.15


1.4451


0.73 2.76


1.10


3.70


33


1.22


3.71,49


1.82 7.85,60


4.71


1.31 79


1.03


February


4.38 71


3.11


0.98 159


1.56


4.45


39


1.74


3.92,45


1.94,84


1.63


2.43|118 2.87


5.61 62


3.48


2.57 97


2.49 2.20


8.81 78


6.87


2.29 57|


1.31


May,


2.66


54


1.44


2.84


57


1.62


8.25 57


4.70


6.46 20


1.29


6.46


2.95


22


0.65


2.95


54


1.59


3.68 29|


1.07 4.05 24


0.97


5.96 9


0.54


July,


14.12.


21


2.97


1.06


39


0.41


3.10


15


0.46 13.35 9


1.20


5.36


11


0.59


2.16


21


0.45


2.63 28


0.74


3.10 17


0.53


2.20,22


0.48


August,


5.61


27


1.51


3.56


19


0.68


3.36


14


0.47


3.98 16


0.64 12.36


17


2.10


7.38


2.34 25


2.03 20


0.41


3.56 26


0.93


Sept.,


3.39


29


0.98


1.52


32


0.49


1.66


27


0.45


8.36 16


1.34


1.08


29


0.31


7.69


1.85


8.49 13


0.64|13


0.08


1.46 39


0.59


October,


4.56 29


1.32


6.50


22


1.43


6.99


10


0.70


3.4327


0.93


7.27


14


1.02


1.19


0.95


9.50 25


2.37


7.96 14|


1.11


5.38 18


0.97


Nov.,


8.54


31


2.65


5.45


23


1.25


4.78


21


1.00


4.52 22


0.99


2.63


42


1.10


6.77 29


1.96


3.26,40


1.30


4.40 20


0.88


7.01 23


1.61


Dec.,


5.05


43


2.17


4.28


31 1.33


3.31


34


1.13


4.32 36


1.56


1.90


59


1.12


0.45 261


1.17


5.98,53 3.17 3.19 24


0.77 3.2438


1.23


Totals. 69.30


39 26.88 42.60


43 18.38 49.46


42 20.50 62.32 26 16.01 56.25


39 21.80 50.06 50 24.98 64.34 34 21.99 55.89 45 25.30 45.39 32 14.68


40|


5.80.49 2.84 5.40 97 5:24 1.18 95


3.50


2.51 153


3.84 7.52 44


3.31 6.04 56


3.38


5.02 45


2.26


April,


11.34


39


4.42


4.02


66


2.65


2.18|124


2.70


1.76 5.65


62


34. 2.20


8.12 76


6.17


7.59 29


3.14 53


1.66


5.66 26


1.47


June,


1.98


34


0.67


0.58


84


0.49


0.91 37


0.34


4.80 23


1.10


Total Rainfall for nine (9) years, 495.61 inches. Average, 55.07. Percentage received into the Lake during nine (9) years, 38}. Average yearly depth of rain received into the Lake, 21.2 inches.


363


ADDITIONAL SUPPLY OF WATER.


1.12 7.07 26 1.84


4:68 84


3.93


2.3099


2.28


March,


3.57 104


3.71


8.44 48


4.05


5.48


85


4.66


| Per cent. rec'd in Lake.


16 24


1.18|


0.58 1.10


80


364


CITY DOCUMENT .- No. 30


Mr. Davis, in estimating for a supply from the Shawshine, for Boston, says :-


" The Cochituate tables show that in 1871, with a rainfall of 45-39 inches, only 1468, inches found their way into the Lake, the rest of the fall having been lost by evaporation. The rain tables published in the Report of the Water Board for 1871 show that frequently the yearly rainfall is considerably less than 45-3% inches. Thus, in 1849, the fall at Lake Cochituate was 34-69 inches ; in 1852, 38,58 100 inches ; in 1855, 39-57 inches ; in 1860, 38-2% inches ; in 1864, 36-83 inches. The fall in 1846 at Lowell was 282307 inches only, and since 1842 there have been nine years when the fall was less than 40 inches. At Boston, in 1846, the fall was only 29,95% inches, and since 1842 there have been three years when it was less than 40 inches. At Cambridge, the fall in 1846 was 30-37 inches, and since 1842 there have been two years when it was less than 40 inches, and four years when it was between 40 and 41 inches. Should any of these low rainfalls occur with condi- tions favorable for a high rate of evaporation from the ground surface, the figures for 1871 show us that, at such time, the amount of water reaching the streams would not much, if at all, exceed 12 inches upon the area of the water shed. Gaugings taken at the outlet of Long Pond or Lake Cochituate, from June 27, 1837, to July 27, 1838, show that only 1176 inches of the rainfall passed through the Lake during that year. In stating the available capacity the yield of the year of drought should be given, as that yield determines the real value of the source."


The following extracts from the Report of the Royal Commission of 1867 on Water Supply show conclusively the fallacy of estimating the available yield from averages of rainfalls, volumes of flow, etc. The term " gravitation schemes " refers to sources of supply derived from small rivers and brooks, improved by storage reservoirs, similar to Lynde, Kettle, and Tatnuck Brook schemes, the water from which is delivered by gravity, in distinction to supplies derived directly from large rivers, without artificial storage, and which generally requires pumping :-


" During the sittings of the Commission the gravitation plans throughout the country have been subjected to a severe test by the occurrence of an unusually long drought in 1868. Although the rain- fall of the whole year was above the average, yet it was very unequally distributed ; as from the end of April to the end of September, a period of five months, there was scarcely any rain. Hence the capacities of the catchment reservoirs were severely tested, the towns having to depend entirely on the stores in them, without any feeding supply, except that of perennial springs.


In Manchester, it appears that after official notices had been pub- lished, cautioning the inhabitants against waste, and urging them to


365


ADDITIONAL SUPPLY OF WATER.


economize their supplies, the corporation, on the 3rd of August, limited the supply to the city to twelve hours of the day, stopped the street watering, and diminished the trade supplies by one-half. They also made an arrangement with the mill-owners for reducing by one-half the quantity given to the mills on the line of the river, and made com- pensation in money for the deficiency. In the middle of September the general supply to the town was further limited to eight hours per day, and the quantity for trade also diminished. Many persons were prosecuted for waste or nndue use of water. The eight hours supply lasted seven days, and the twelve hours supply 76 days.


" At Rochdale, as early as the 25th June, the supply was limited to four hours per day for 15 weeks ; but, with this precaution, during the second week in October, the store became entirely exhausted, and the town would have been almost without water, but that recourse was had to pumping from a colliery in the neighborhood.


"At Bury, the store ran so low towards the end of August that it was reserved entirely for compensation to the mills, and the company obtained a supply of seven gallons per head from neighboring works ; for baths, and for the numerous manufacturing and trade uses in the town there was none. This continued for five weeks."


The Report mentions the following towns depending upon storage schemes as having derived, during seasons of drought, a much less supply than had originally been estimated : Liverpool, Newcastle-on-Tyne, Bristol, Preston, Kendall, Bradford, Halifax, Sheffield, Stockport, Bolton, Ashton, Stalybridge, Oldham, Dewsbury, Warrington, Black- burn and others.


"The causes of this difficulty may lie either in an over-estimate of the available rainfall, or in an insufficient provision of storage. The sufficiency of water-collecting plaus in these respects must be tested both by the concurrence of several consecutive dry years, and by occasional droughts of long duration; and to obtain the necessary data on these points for any particular district, must require special observations on that district, extended over a considerable time.


" In so variable a climate, and with a rainfall in different parts of the kingdom ranging, in round numbers, from 20 to .00 inches, it is of primary importance to have the most complete information as to the rainfall; and, as the annual variation is also great, the average fall for a term of years cannot be determined without observations extended over a long period .. Less than 20 years would probably not suffice. But the question with reference to a water supply, has to deal not with the average rainfall of a long term of years, but with a short term depending on the capacity of storage. In no case yet contem- plated would it be prudent to rely on more than an average of three years, and under certain conditions it is doubtful whether two years would not be a safer term.


366


CITY DOCUMENT .- No. 30.


"The question of storage room involves complicated considerations, which have been especially dwelt upon by Mr. Hawkesly. On account of the irregularity of the rainfall, particularly in mountainous districts, it is impracticable to construct reservoirs large enough to store the. entire quantity received, so that all large floods occurring when the reservoirs are full must pass away and be lost. Hence the available average attainable from reservoirs must fall much short of that deduced simply from the fall of rain."


Evidence of Robert Rawlinson, Esq., Civil Engineer :-


" Are we to understand that the object of the remarks which you have made with regard to the average of rainfall is to guard against the supposition that any scheme which professes to supply the inhabit- ants of any given town with water should not be calculated upon the average, but that there must be a deduction ; and of, in your judgment, one third from that average as a proper deduction to make that quantity safe ? "


"I think so ; the same as I say is exemplified in Liverpool; they have been landed in a very grievous mistake, because they relied upon the supposed average."


Evidence of Rev. J. C. Clutterbuck :-


" Does there appear in your judgment any serious objection, apart from the question of cost, to the schemes which have been generally considered ? "


"One of the objections which struck me with regard to the scheme proposed by Mr. Bateman was, that he had not sufficiently shown that the water shed there would yield the amount of water that he calculates upon. In the first place, he has not sufficient information with reference to the average quantity of rainfall ; not that I attach much importance to the average of rainfall. I think that all rainfall with reference to the areas which are to supply water to London, must be considered with regard to the minimum of rainfall, and what shall be the possible duration of drouth which may deprive you of water at a certain time. The objection as it appears to me to Mr. Bateman's plan is that you have no certainty that you shall not at some period be deprived of water."


"Then your objection would be taking an average at all ?" " Decidedly.


" And for the sake of safety you would take the minimum fall, and all plus that would be gain ? "


" The only thing to set against that would be the natural or artificial storage of water in those lakes, but when you speak of that as a sup- ply of water which you are to depend upon you must take the mini- mum, as it appears to me."


367


ADDITIONAL SUPPLY OF WATER.


Evidence of Thomas Duncan, Esq., Engineer of the Liverpool Water Works :-


"I think the calculations for the supply of towns should be upon minimums and not means. "


Evidence of Thomas Hawksley, Esq., Hydraulic Engineer :-


" In order to furnish that supply to London, what amount of rainfall would you consider to be necessary ?"


" I should first explain that the 45 inches of rain is only the quantity which on an average descends from the Heavens, and that quantity is subject to two deductions. In the first place, we know as a matter of absolute fact that we cannot by any system of reservoirs which it is prac ticable to construct (I will not say with a reasonable but with a large amount of capital) deal with more than the average of three consecu- tive years of minimum fall. We know as a matter of experience- and this important fact is verified by large and long-continued rain tables-that in those three years the average fall of rain is almost precisely one-sixth part less than the general average, and I could refer the Commission to any number of long-continued rain tables to establish that fact; but we know also, as engineers, that prac- tically that is the case. If we take from the 45 inches a sixth of that quantity, that will be 72 inches, and that would leave 372 inches as the quantity of rainfall due to the three minimum years. Then from that we have to take the evaporation. Now the evaporation over a district like that, part of which is low land and part of which is high land, will be about 132 inches," (the evaporation and losses in the Eastern States of this country are from 75 to 100 per cent. greater than in England), "and if that be deducted there is the residual quantity of 24 inches, and that may be deemed to be the available quantity. That is the way in which we now make all our calculations for undertakings of this kind. I am not shifting or moving the calculation in any way. This system has been tested by actual results in a great many cases, and is known to be as accurate as anything dependent upon the eventu- alities of the seasons can possibly be. It is as near the truth as we can in practice obtain anything. "


"You stated, did you not, that you allowed from the 372 inches 132 inches for evaporation ?" "Yes 132 inches." "That would give you an available rainfall of 24 inches ?" "Yes, upon which you might, in my opinion, safely rely, providing your reservoirs were made large enough to deal with that quantity."


" What sized reservoirs should you think would be large enough to deal with that quantity ? " "The reservoirs to deal with that quantity should be of a magnitude to store 170 days supply."


Extract from a Report to the Commission, by John Taylor, Esq., Civil Engineer, on Gravitation Water Supplies to large towns :-


" The general conclusions to be drawn from the data I have given in the preceding pages respecting the largest gravitation water supplies


368


CITY DOCUMENT .- No. 30.


in this country, are as follows :- "That none of the works alluded to have completely fulfilled the anticipated results.


"Manchester and Glasgow are favorable examples of gravitation works, but exhibit signs of deficiency when tested for cycles of dry years ; and of the five large towns alluded to, four have already erected, or are erecting, pumping works in aid of the gravitation supplies. Thus, it appears that, basing calculations on average falls of rain is erro- neous ; the minimum quantities only should be depended upon ; but, as I have before stated, there is yet no experience sufficient to show what are the minimum falls in a given district, nor what propor- tion of such falls would be available.


"The question of storage is, of course, an important element in gravitation works, and from past experience it is plain that complete security against want of water, in exceptionally dry years, could only be attained by storing all the flood water, of two or three successive winters, or, in other words, providing storage for 300 to 400 days sup- ply to the district.


"This matter was well explained by Mr. Homersham, C. E., in a re- port on the supply of water to Manchester in 1848, in which he states generally that if the whole quantity of water collected in wet years be not used, then the quantity of water that could be regularly yielded by the reservoirs would depend upon the depth of rain falling on the gathering ground and flowing off it in the average of years, since the water falling in wet years would be stored from wet to dry years. The size of such reservoirs must, however, be very large, as they must be sufficient to contain the superabundance of a succession of wet years, in order to compensate for the deficiency of a succession of dry ones.


" The axiom in mechanics that the strength of a beam is the strength only of its weakest part applies also to gravitation water works, their real strength or power of supply being only the minimum quantity they may be reduced to."


Extract from a Report of John Taylor, Esq., on the drought of 1868, as regards its effect on gravitation water supplies to large towns :-


" The general result has been that nearly all gravitation supplies of water, obtained from drainage grounds, have failed in a manner hitherto unprecedented within the known experience of such works, proving that the data on which they have been based have been falla- cious, and that the storage reservoir and gathering grounds of such works must be greatly increased to meet the demands of years like the present. "


The question now arises, what amount of water can be relied upon as available from the Lynde Brook sheds. The area of the water-shed is, including the water surface of the reservoir, 1870 acres. The water surface of the Reservoir, at the present height of the rollway, is 132 acres, and as the evaporation from water surfaces in our climate is


369


ADDITIONAL SUPPLY OF WATER.


greater than the rainfall, this area at least should be deducted, which leaves an effective shed of 1738 acres. Table 3 is a Rec- ord of the rainfall kept at the Worcester Lunatic Hospital from 1841 to 1870 inclusive. From the preceding evidence and experience we have had it is evident that our calculations should be based on the mini- mum fall of rain for two or three consecutive years, and not on the average. The next point is, what percentage of the rainfall shall be taken as available ? By consulting table 1 it will be seen that in 1864, on the Croton shed, the rainfall amounted to 401% inches, of which but 36} per cent. or 14 892 1000 inches reached the dam; in 1865 the rain- fall was 5043% inches, 39% per cent. or 201563 inches reaching the dam, and the average rainfall for six years was 50-62 To6 inches, 50 per cent. of which was collected.


48


370


CITY DOCUMENT .- No. 30.


TABLE III.


RECORD OF RAINFALL IN INCHES, KEPT AT THE WORCESTER LUNATIC HOSPITAL, FROM 1841 TO 1870.


YEAR.


Januray.


'February.


March.


April.


May.


June.


July.


August.


September.


October.


November.


December.


TOTAL.


1841


4.78


0.83


3.43


6.54


3.46


0.92


2.94


2.97


4.27


3.84


4.17


4.77


42.92


1842


1.35


4.13


2.24


2.82


3.24


4.93


1.96


7.12


3.50


0.83


3.36


5.30


40.78


1843


5.05


4.45


5.23


3.13


1.73


4.15


3.39


9.19


1.25


5.19


3.63


2.28|


48.67


1844


3.14


1.44


3.80


0.35


3.67


1.92


3.50


3.39


3.68


7.34


3.06


2.56


37.85


1845


4.17


2.61


3.29


1.61


3.23


3.14


2.91


2.36


2.57


4.44


6.77


5.39


42.49


1846


2.92


2.50


3.33


1.34


5.85


2.37


3.81


2.44


0.90


2.19


4.08


2.87


34.60


1847


4.66


4.08


3.89


1.67


3.52


5.29


4.86


4.20


7.17


2.36


5.75


1.94


3.93


38.53


1849


0.98


1.30


4.75


1:95


3.56


1.25


1.60


4.28


2.49


6.45


4.11


3 12


35.84


1850


4.79


2.23


3.67


5.53


7.50


3.25


3.75


6.05


7.92


3.37


2.14


4.19


55.39


1851


2.07


4.01


1.40


6.76


4.73


3.16


2.17


1.97


2.59


7.04


5.68


2.30


43.88


1852


5.44


2.46


3.42 10.77


3.15


3.53


3.42 11.38


3.36


3 89


5.88


4.78


61.48


1853


3.04


8.09


3.60


4.92


5.45


1.01


3.29 10.71


5.26


6.20


5.30


3.79


60.66


1854


2.82


6.62


3.45


6.69


6.78


3.05


5.68


0.35


5.53


5.03


9.82


3.34


59.16


1855


8.11


4.48


0.23


5.39


1.64


4.19


9.40


4.06


0.20


8.17


5.85


6.90


4.08


46.94


1857


4.48


2.24


2.80


8.77


4.56


3.44


3.80


5.75


4.92


3.93


3.12


6.11


53.92


1858


3.06


1.10


3.67


7.71


2.90


3.65


5.17


1.26


5.45


4.00


2.46


3.00


4.55


49.57


1860


1.34


2.77


2.26


1.36


2.66


6.65


7.91


5.76


6.02


2.47


4.38


5.05


48.63


1861


4.33


1.60


2.85


5.71


3.50


2.46


5.29


3.99


3.11


3.38


3.93


1.81


41.96


1862


4.47


2.44


3.51


2.34


1.87


7.44


6.10


2.64


2.14


3.22


5.35


2.50


44.02


1863


4.09


3.42


5.78


5.28


1.76


1.18


8.87


3.96


2.56


4.85


4.77


4.41


50.93


1864


4.54


1.74


3.90


5.66


5.96


2.40


1.68


3.11


2.93


4.29


4.81


3.67


44.69


1865


3.92


3.26


4.72


2.51


5.33


1.72


3.37


3.39


0.68


0.51


2.36


2.75


34.52


1866


2.56


5.27


3.18


2.09


5.33


3.40


3.78


3.22


4.77


1.97


3.79


2.19


2.07


48.88


1867


5.16


4.42


4.40


2.50


4.91


3.32


3.08


1.08


3.57


8.60


1.14


4.24


1.85


44.66


1869


2.82


5.49


4.83


2.52


5.77


3.08


1.40


2.21


4.74


9.81


2.43


5.25


50.35


1870


6.34


3.04


2.34


6.03


2.40


2.09


2.39


1.74


1.40


5.89


3.48


4.10


41.24


1856


4.60


1.35


1.69


3.34


6.55


1.44


4.13


5.16


4.18


4.00


5.70


3.09


1.69


3.19


41.73


1859


5.75


1.61


3.89


1.52


6.82


1.31


3.13


3.19


2.87


3.75


4.93


50.89


1848


3.08


3.27


1.53


2.82


5.18


8.30


Average for 30 years


46.53 inches. Minimum for three successive years


38.31


2.51


3.73


42.21


3.36 10.79


1868


2.68 13.14


3.39


2.65


2.03


58.62


2.29


4.14


2.37


371


ADDITIONAL SUPPLY OF WATER.


Table 2 shows that from 1863 to 1871 inclusive but 382 per cent. of the rainfall on the Cochituate shed reached the lake, while in 1866 but 26 per cent. of a fall of 62-3 inches, or 16-2% inches was col- lected. 50 per cent. of the rainfall, as available, is as much as we can safely base an estimate upon, and that is used in considering all the sources surveyed. By an examination of Table 3, it will be seen that,


In 1844 the rainfall in Worcester was 37185% inches, in 1845 it was 4249% inches, and in 1846, 34166 inches, an average for three consecu- tive years of but 38-31 To6 inches. This would give on a shed of 1,738 acres, with 50 per cent. collected, in round numbers, 904,000,000 gal- lons. The present consumption of water in Worcester is fully 3,750,- 000 gallons per day, so we should have averaged for each of those three years but 241 days supply, and have had a deficiency of 372 days supply at the end of three years, against which we should have the amount stored at the commencement of the first year. It will be sup- posed that the reservoir was raised to its proposed additional height of 5 feet, and that it was full, containing 895,300,000 gallons, or 238 days supply, which is the most favorable condition possible ; deducting from 372, 238 and we still have a deficiency of 134 days, during which we should have had a water famine. Again, in 1848 the fall was 38-53 inches, and in 1849 35-84, inches, the mean being 37-185. o's inches for two consecutive years, which would have given but about eight months supply for each year, and we should have had a deficiency of about one month's supply, supposing the reservoir to have started under the same conditions of storage as in the first case.


Still again, in 1864 the fall was 446% inches, in 1865 3415% inches, and in 1866 42,2% inches, an average of but 4017% inches, which would again have placed us in great danger. But our present condi- tion is, perhaps, the strongest proof that can be produced to convince the most casual observer that our only safety lies in an additional and independent source of supply.


The following plan was adopted in estimating the value of each source .. The total water-shed, including water surfaces, was first ob- tained. The area of water surfaces was then deducted, the evapora- tion rendering them worthless for collection, and the remaining area taken as the effective water-shed. The average rainfall, as observed for the years 1844, 1845 and 1846, was taken as a basis for calculation on the minimum amount to be relied upon in cycles of dry years, and therefore the true value of the source, and 50 per cent. of that rainfall taken as available. Kettle Brook will first be considered as a source of supply.


372


CITY DOCUMENT .- No. 30.


KETTLE BROOK.


The project of diverting the waters from Kettle Brook at Kent's Mill into the Lynde Brook Reservoir, will first be considered. The total area of the water-shed at Kent's Mill is 3,200 acres ; deducting the area of water surface of Kent's Pond and the reservoirs above, and we have an effective shed of 2,937 acres, which, with adequate storage capacity, will insure a supply of 4,184,000 gallons daily.


While the execution of this scheme would relieve us speedily from danger of a water famine, at a very moderate outlay for construction, there are objections to its adoption as a permanent source of supply.




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