160, JOHN M. SMAIL. 
720 feet per hour; the quantities being computed at 228,186 cubic 
feet per hour to 22,477 cubic feet per hour, the size of the sewer 
at water spray being 6’ 10” x 5’ 10” increasing by increments to 
7’ 4” x 6' 4” at limit of effect. The Board have under trial a 
system for ventilating the sewers by means of shafts heated by gas. 
The system is the invention of one of the Chief Sanitary Inspectors 
and may be briefly described as follows : 
A shaft with a base in which is fixed the apparatus for setting 
up the draught. Within the chamber which is the base, is placed a — 
perforated shell, spherical in form, the shell may be made of fire 
clay or other material which will resist the action of intense heat 
its upper part being formed for a lid; a grating or perforated 
false bottom covers the bottom of the interior of the shell forming 
a chamber below the false bottom to receive a gas burner or 
burners. The form of burner used is an “atmospheric blow through 
burner,” the air being supplied either from without or within the 
shaft; the space within the shell between the false bottom and lid is 
loosely packed with lump asbestos. The chamber is provided with 
an opening sufficiently large to introduce or remove shell. This 
opening is also used to apply the light to the burner. The open- 
ing is closed by fire brick or other fire proof material. In order 
to prevent radiation the chamber and shaft are inclosed in three 
inches of fire proof non-conducting material. The working is as 
follows: assuming that all the parts are in position, the gas is 
lighted through the opening which is then closed, the intense heat 
from the burner quickly brings the asbestos contained within the 
shell to an incandescent state, thereby causing a powerful up 
draught to ensue, and thus drawing the foul gases from the sewer. 
As the gases pass through and around the shell, which by this 
time is a ball of fire, they become disintegrated and rendered 
innocuous by the intense heat, and all disease germs therein con- 
sumed, the products of combustion passing up through the shaft 
into the atmosphere in a harmless condition. The inventor claims 
to be able to extract 500,000 cubic feet of air from the sewers in 
twenty-four hours at a cost of one shilling and eightpence. The 
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