80 ROCHESTER ACADEMY OF SCIENCE. Junewes 
Referring to Dr. Ernst’s report on the bacteriological examinations, 
we find that sample No. 3, from Lime-Kiln Gull creek at Advent 
church, contained 800 colonies of bacteria per c. c., while the examina- 
tion of sample No. 11, from same stream at north end of village, gave 
1,000 colonies perc. c. 
At the time of taking the samples from which these determinations. 
were made the Lime-Kiln Gull creek was a vigorous stream of at least 
three or four million gallons daily flow. By studying the rainfall record 
as kept at the foot of Hemlock lake, it is found that there 
occurred on October 26th and early on the 27th a rainfall of 1.27 
inches in 27 hours. Appreciable quantities of rain fell later in the day 
on the 27th, and also on the 29th and 31st, and on November 2nd there 
were appreciable rainfalls. The samples submitted to Dr. Harrington 
were taken on November 4th, and we must conclude from the preced- 
ing analysis of the rainfall record that on that date the stream was not 
carrying excessive quantities of organic matter, due to sudden heavy 
rainfall after long contmued dry weather, but that on the contrary the 
previous sequence of the rainfall had been such as to leave no other 
alternative than to conclude that the increased contamination appearing 
at that time was the ordinary, every-day increase, due not merely to the 
flow of the Lime-Kiln Gull creek through the village of Springwater, 
but principally to the material accretions which it received in the course 
of such flow from the polluted ground water of that village. 
With our present understanding of the conditions prevailing, we 
believe it would be desirable to have the general question here raised 
somewhat carefully studied, such study to include a series of analysis. 
of samples taken at different times and places, and under such condi- 
tions as to preclude the possibility of error. We make this suggestion 
because we are aware that it is unsafe to reason to absolutely definite 
conclusions from a single series of analyses, and we believe the question 
is of enough practical importance to the city of Rochester, as a guide 
in determining just what remedy to apply to the existing conditions, 
to justify moderate expenditure in the direction indicated in this 
discussion. 
Plate 8, is a profile of Mill street, directly across the Springwater 
valley from east to west, and shows the elevation of ground water on 
that section, as found by actual measurement in the wells on January 
8, 1890. Studying it, we easily perceive that not only is the ground 
water at times very near the surface, but that its relation here to the 
bottom of the main creek channel is such as to indicate a flow from the 
higher ground at each side of the creek. It also appears that the bottom 
