HALIFAX WATER WORKS. — JOHNSTON. 89 



to sucli an extent that men were sent to collect all tlie specimens 

 that could he found, since which date no more have heen 

 obseiwed. In 1877 a microscopic alga called tricJiormus flos 

 oqua Avas found in Spruce Hill Lake, which had the effect of 

 giving the surface of the water, especially near the shore, a 

 brilliant green color. This is not known to be injurious, but 

 is regarded as an indication of water being stagnant or con- 

 taining organic matter. It has not reappeared, and was prob- 

 ably removed by clearing the lakes of vegetable matter. In 1885 

 new forms of alga' ap])eare(:l iu Cliain Lakes, consisting of a 

 galatinoU'S substance forming in detached masses, from the size 

 of a marl:)le to a large ap[)le, and adhering but slightlv to the 

 soil and sto'ae under water, a licht breeze beina' sufficient to 

 detach quantities of this substance and carry it to the screens in 

 the pipe-house where, if allowed to collect, it would soon cut off 

 tlie supply to the city. Lime scattered along the shores of the 

 lakes seems to kill this growth, and a certain amount is depos- 

 ited yearly to prevent irs starting. 



An analysis of the water from the various lakes was made 

 in 1890 bv ]\rr. ^favnard Bowman, with the followino- results: 



