844 NEW YORK STATE MUSEUM 



The following shows the more important results of the weekly 

 biological examinations of Hemlock lake water which have taken 

 place from 1896-1902, inclusive. These determinations have been 

 made by Prof. Charles Wright Dodge, of the University of Roch- 

 ester, using for the plant and animal organisms, exclusive of bac- 

 teria, amount of amorphous matter, average number of moulds, 

 etc. the Sedgwick-Rafter method. 1 The determinations of bac- 

 teria have been made by standard bacteriological methods. 





1896 



1S97 



1898 



1899 



1900 



1901 



1902 



(1) 





"liT 





(5) 







(8) 



Average number of plant and animal 

















organisms (exclusive of bacteria) per 

















cubic centimeter of unfiltered water. 

















i. water as it comes from the tap. . . 



135.95 



83.26 



62.8? 



74.94 



56.88 



88.07 



141.69 



Average amount of amorphous matter, 

















i. e., iron rust from the pipes, earthy 

















matter, etc., in standard units per 

















cubic centimeter of unfiltered water. . 



74.41 



48.84 



43.0 



41.37 



37.71 



38.59 



41.87 



Average number of bacteria per cubic 

















centimeter of unfiltered water 



334.0 



101.0 



91.0 



51.0 



52.2 



103.75 



102.70 



Average number of moulds per cubic 

















centimeter of unfiltered water 



3.8 



10.6 



11.4 



8.4 



8.9 



16.0 



16.45 



Average number of genera of organisms 













6.1 



5.14 





M 



8.2 



M 



7.5 



5.6 



The following eighteen sources were considered: Gates bored 

 well ; driven or bored -wells in the bottom lands south of Mount 

 Hope reservoir ; Irondequoit creek and its tributaries ; Red creek ; 

 Little Black creek; springs and well at Coldwater; Snow 

 springs; Hubbard springs; Black creek; Oatka creek; Caledonia 

 springs; Mendon ponds; pond near Bushnell Basin; Ironde- 

 quoit bay; Lake Ontario; Erie canal; Honeoye creek at East 

 Rush, and Genesee river. The following is a brief description 

 of these several sources as mostly taken from the reports of the 

 Executive Board of Rochester. 



The Gates well. This well is situated about one mile west of 

 the Rochester city line. The surface of the ground at the well is 

 27.5 feet above the Erie canal aqueduct, or 96.5 feet below the nor- 

 mal water surface in Mount Hope reservoir. A test of the quantity 

 of water to be obtained from this well was made by the writer in 

 the latter part of May, 1890, and a full report of the results of 



ir rhis method of biological Analysis is described in The Microscopical 

 Examination of Potable Water, by Geo. W. Rafter. See also The Microscopy 

 of Drinking Water, by Geo. C. Whipple. 



