HALIFAX WATER WORKS. JOHNSTON. 89 



to such, an extent that men were sent to collect all the specimens 

 that could be found, since which date no more' have been 

 observed. In 1877 a microscopic alga called trichormus flos 

 aqua was 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? appeared hi Chain Lakes, consisting of a 

 galatinous substance forming in detached masses, from the size 

 of a -marble to a large apple, and adhering but slightlv to the 

 soil and sto'ne under water, a light breeze being 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 

 the 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 its starting. 



An analysis of the water from the various lakes was made 

 in 1890 by Mr. Maynard Bowman, with the following results: 



