pela 
VENTILATION OF SEWERS AND DRAINS. 157 
Cubic feet Cubic feet 
per hour. per day. 
3. Cornwall’s Brewery, 6” connection 
utilizing exhaust steam ... eae 108,528 
4. New York and Brooklyn Hobaceo. 
Factory, 6” connection ... Leeann Wie) 310) 168,720 
5. Shaft—Old Engine House, Crown 
Street Reservoir ... ‘ 6,857 164,568 
6. Shaft—New Engine TF see Core 
Street Pumping Station, 6” con- 
nection ... ae ies w.. 4,444 106,656 
@ shattiiyde Park ... on .. O1,424 “1234, 176 
119,932) 2,878,308 
Shafts 1, 2, 5,6 and 7 are connected with the old system, Nos. 
3 and 4 with the new. The ventilating shafts are made of the 
best black iron riveted longitudinally with quarter inch. rivets, 
with one and a half inch pitch, the gauge being for bottom lengths 
16 B.W. gauge and for top lengths 20 B.W.G. The sheets are 
first passed through a steam power squaring and cutting machine 
by which all the sides are cut true to pattern, they are next passed 
through a multiple punching machine and punched on both sides 
perfectly true, they are then passed through a roller and rolled 
into shape, riveted, and all seams laid perfectly close. The faucets 
are now formed and ground out to a standard size, the pipes are 
afterwards placed in pickling tanks to prepare them for the gal- 
vanizing process, (these tanks contain sulphuric acid sp. gr. 1°845) 
when they have been sufficiently operated upon they are cleaned 
and passed through other tanks containing hydrochloric acid (sp. 
gr. 1-284) then heated very carefully in an oven, after which they 
are immersed in a bath of pure zinc—the surface of this bath is 
covered all over with a thick coating of hydrochlorate of ammonia. 
This ensures a complete and uniform covering. The pipes are 
afterwards washed and dried and having partially lost their 
cylindrical form they are put through various other machines 
until they regain their proper shape, no hammering is permitted, 
as it would disfigure or break the joints. The tubes are finished 
