[7] WATER SUPPLY AT WOOD's HOLL. 221 



more than 800,000 gallons since. The well G, close to salt water, started- 

 witli more salt than either of the others, but was closed and has not 

 been since examined. 



Now, this quantity of salt (01 grains in 70,000) is not sufficient to be 

 injurious to health, and falls a little within the limit at which * (accord- 

 ing to De Ohaumont's experiments) salt becomes i)erce])tible to the 

 sense of taste. It is a rather siguilicant fact, liowever, that the more 

 water there is pumi)ed the more salt it is found to contain, and the ques- 

 tions, whence the water comes originally, and where it gets its salt 

 from, become of interest as relating to the probiible continuance of the 

 increase in salt hereafter, until it shall exceed the limit of potability. 



Good water, similar to that in the spring already mentioned (whicli 



stands at about the same level as the water in the Fish Commission 



wells), is found all along the land lying to the north and east of tlie 



' Eel Pond (see map), while attempts to get at the same supply by bov- 



I ing in the laud to the westward have not thus far been successful, it 



seems probable, therefore, although we have no exact data bearing upon 



the subject, that this supply comes from the hills to the north and east 



of the pond, and that it is retained at or below the depth of 10 feet be- 



\ low mean low water by the lower of the two strata of clay above noted. 



I A fault or break in thechiy would account for the i)resence of the sjuing 



j above noted, and the large admixture of rain and surface water which 



< it must receive, being an excavated well of considcnil)le extent, and 



j situated in a depression in the land, would account for the less quantity 



j of salt it contains. 



( The increase in salt, after prolonged ]>umi)ing, in tJie Fish Oonunis- 



sion wells, may be due to the near neighborhood of Eel Tend, which 



I is salt water, and to the fact that long pum[)ing from wcIIk of lliis kind 



tends to produce a considerable cavity around the lower end of the pipe, 



into wdiich water Hows from neigliboiing ])arts of the soil. 



There is nothing in the cluiracter of the stratum in wliieli this water 



is found to a(;count for the presence of salt, gra\el being considered 



the best possible soil fi'om which to <lraw ;i, water sni)ply, and there is 



I therefore, 1 thiidi, reason to api)rehend that after continued pumping 



I the ])roportionate <]uantity of salt will continue to increase. 



Considering all the facts, I think that it will be judicious to i)ump no 

 longer and no oftener than may be necessary for the needs of the Com- 

 mission, and, when opportunity offers, to make another drive to a 

 greater depth, in the liope of finding a still lowei- stratum of clay, be- 

 low the level of the bottom of Eel Pond, beneath whicli water may be 

 j found which will be unallected by its neighborhood. 

 Wood's Holl, Mass., September in, 1884. 



Seventy grains to tUe imperial gallon. 



