98 HALIFAX WATE1{ WORKS. JOHNSTON. 



ooiiduit. rebiiilr in 1S<S(!, is 1,.'5()0 feet long, 3^ feet wide and 4^ 

 feet high, huilt nf 4-int'li liy 4-iu('h heiidock deal, with four 

 manholes thruiighnut its lengtli. its npper end is at an (d(n'a- 

 tion of 196.20, Avith a fall to Chain Lake of six inches. 



Id'. 



The ('X))erien('e with the tm-iiiatidn of a'.ichor ice has heeii 

 siniihir to tliat of other ])la('('s. With a slieet of Oj^eii water at a 

 teiiij)eratnre of -'52 degrees F., and the teniperatnrc of tlie air 

 \arving from 5 degrees to 20 degrees above zero, and a high 

 wi'nd blowing, the ice forms in small detached needles or crys- 

 tals. Thin ])ortioiis of it accnmnlate in spongy masses and float 

 along at or b(dow the snrface, their specific gravity differing 

 bnt little from tliat of water. They adhere readily to all solid 

 bodies Avitli A\liich they come in contact, and grow i-a])i(lly when 

 once they have secured a centre of crystallization. It will not 

 form in bright sunshine — on the contrary, it rises to the sur- 

 face in spongy masses, and when the surface freezes over it 

 lets go its grip. The lee side of a reservoir gets most of its 

 anchor ice, and whenever we have been troubled with it the 

 wind has always been from a north-westerly direction, between 

 1S83 and 1S93 'ao trouble was had from ice, and it is thought 

 that this was due to the fact that a screen of stout pickets 

 driven into the bottom, capped on top with a boom rising a'rid 

 falling with the level of tlie water, was l)laced in front of the 

 gate houses. In 1892 this was removed, and on the 11th 

 December of tKat year ice closed the sluice gate at the south 

 gate-house cutting off the supply to the 24-inch nuiin, and con- 

 tinued until four o'clock i'n the morning, when the wind sub- 

 sided, and the ice stopped running. In 189S the filter wall 

 already referred to was built in front of the south gate-lious>3, 

 but ice formed inside the wall, and there was danger that the 

 gate-house would freeze up solid, so the screens were removed 

 until the danger had passed. This is the last time there has 

 been any trouble from it. 



