MUNICIPAL WATERWORKS LABORATORIES. 177 



in the basement contains all the necessary apparatus for testing cement, 

 analyzing sand, etc. The laboratory force consists of one biologist and 

 director, one chemist, one assistant chemist and three assistants. 



The routine work of the laboratory consists of the regular examina- 

 tion of samples of water from all parts of the watershed and distribution 

 system, i. e., from the driven wells, streams, ponds, aqueducts, reser- 

 voirs and service taps. The complicated and varied character of the 

 water supply requires the examination of an unusually large number of 

 samples, and it is safe to say that no water supply in this country is 

 examined more thoroughly and minutely than that of Brooklyn. Dur- 

 ing the three years that the laboratory has been in operation over eight 

 thousand samples have been analyzed. 



The problems of the Brooklyn supply are very different from those 

 met with in Boston. The supply is drawn, not from a few storage reser- 

 voirs of large size, but from a large number of small supply ponds, sup- 

 plemented by an almost equal amount of water from deep and shallow 

 driven wells. There are no extensive swamp areas, but the watershed is 

 sandy and serves as a natural filtering medium. The entire supply, 

 therefore, partakes largely of the character of ground water. The stor- 

 age of ground water in an open reservoir has been almost always at- 

 tended with troubles due to growths of microscopic organisms, and the 

 Brooklyn supply has proved no exception to the rule. The mingling 

 of surface water, seeded with plant life, and ground water, laden with 

 plant food, has resulted in the enormous development of microscopic 

 organisms in the distribution reservoirs. During the summer and au- 

 tumn of 1896 the condition of the water in the city caused general com- 

 plaint because of its bad odor. An examination, made by Dr. Albert R. 

 Leeds, showed that the diatom asterionella was responsible for the 

 trouble, and that the fishy odor was caused by an oil-like substance 

 secreted by this microscopic plant. Since 1896 growths of asterionella 

 and other odor-producing organisms have recurred regularly in the dis- 

 tribution reservoirs, but by the use of the new by-pass, through which 

 water may be pumped around the reservoirs direct from the aqueduct 

 to the distribution pipes, the water in the city has been kept compara- 

 tively free from them. The organisms appear and disappear according 

 to laws that are now beginning to be understood, and while their growth 

 in the Brooklyn reservoirs cannot be wholly prevented under present 

 conditions, the laboratory is doing an important service by constantly 

 noting their condition of growth and by forecasting their effect on the 

 city supply for the guidance of the engineer in his manipulation of 

 the reservoirs. The chief service of the laboratory, however, is in con- 

 nection with the sanitary condition of the watershed, and upon this 

 most of the bacteriological and chemical work is concentrated. The 

 laboratory was- installed and equipped under the direction of Mr. I. M. 



VOL. LVIII.— 12 



