26 On the Construction of Buildings 
rent passes up, it impinges against a flat board at each aperture, raised 
a short distance above, called a disperser, which throws the air some- 
what horizontally, breaking the upward current. 
‘No less than 300,000 gimlet holes of a conical shape, with the 
Mr. John Sylvester, engineer, presented to the Parliamentary 
Committee a plan very similar in its provisions to that just de- 
scribed. He also proposed to admit fresh air to the House, first 
passing it above a cast iron apparatus heated by steam or hot 
h 
area of the apertures he estimated at about 665 feet, through 
which he supposed the air of the house would be changed six 
times per hour. -He estimated the entire capacity of the house 
at 200,000 cubic feet.+ 
In both these plans some important points are recognized, to 
which we would here direct attention as especially applicable to 
our present subject ;—and, first, the extreme diffusion to which 
the air is subjected as it enters. In the ventilating and warming 
arrangements of our large halls for music and other public purpo- 
is almost invariably transgress- 
two or three points, in large 
Ptr Venaieuierie boa arrangements with diagrams, vide Reid’s Tllus- 
An evidence of the remarkable uniformit of temperature maintained in the 
House of Commons, under this system, will be found in the tabular records in Dr. 
Wyman’s Treatise, 226, 
Report from e select Committee of the House of Commons, on ventilation, 
warming and transmission of sound, with the Minutes of evidence, 18365. 
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