BROOKLYN PARK COMMISSIONERS. 21 



agitation of the water, floats upon the surface, and being blown 

 into the inlets and bays of the lake often present an unsightly 

 and disagreeable feature to the eye of the visitor. 



Professor Sillirnan, after an examination of a body of water 

 similarly affected in a reservoir in Massachusetts, reports that 

 this fungus is common even to the purest water, under certain 

 conditions of temperature and depth, and unless it is subjected 

 to decomposition in large quantities, exerts no serious influence 

 upon the healthfulness of a neighborhood, and is often a source 

 of purification in the water itself. 



Many people visit the park at night, when the atmospheric 

 precipitation of moisture in the vicinity of the lake tends to 

 abnormally cool the surrounding air. Failure to adapt one's 

 clothing to this change of temperature in the park or else- 

 where, as in summer resorts contiguous to water, subjects a 

 person to influences from which ailments ambiguously attrib- 

 uted to malarial conditions often arise. The whole park con- 

 stitutes one of the most thoroughly drained areas in this 

 vicinity. Our keepers and laborers, boatmen and others, who 

 have been employed upon and about the park waters for years, 

 have been subjected to no special illness attributable to this 

 cause. The water supply to the lake is derived fi'om surface 

 water from storms, and melting of snow over a given area sur- 

 . rounding the lake, -and an intermittent supply from the well. 

 At rare intervals only has the level of the water in the lake 

 reached the height originally established for the summer or 

 maximum point, and there being no constant supply to the 

 lake, such as would come from a living stream, there is no 

 occasion for an overflow, the purpose of which would be simply 

 to waste the surplus inflow above a certain level. 



No material quantity of impure water finds its way into the 

 lake, and during most portions of the year it is pure enough to 

 use for potable purposes. One considerable source of purifica- 

 tion alone is the extensive evaporation which occurs during the 

 warmer seasons of the year. This evaporation on warm days 

 in summer amounts to nearly 500,000 gallons. 



