BY JAMES TOLSON, ESQ. 69 
The following table is calculated from this rule :— 
‘Table 6.—Showing the loss of heat by contact of cold air by vertical 
cylinders in units per square foot per hour fora difference 
ofr? Kah. 
VALUE oF A FOR VERTICAL CYLINDERS. 
Loss of Heat in Units per Pe Foot for 1° Reoocs 
Diameter 3 WR hae 
in Height of the Cylinder in Inches. 
Inches. ! - 
12 24 | 36 48 60 
2 lees "6835 | 6474 6199 | 6046 
4 | “7213 | 6378 | “6038 | “5789 | +5639 
Cr ie O80" |sbosm "5738" (5402 414 5353 
12 "6683 | "5906 | °5594 | 5355 | 5224 | 
18 6550 S700 -5AGs BoA a | 
24 6471 S7ro) || bar ||) 15168) | 5058 
36 OST be esse S38. St IZM rages 
In removing the heat from a body by means of cold air, 
care must be taken to obtain a free circulation, otherwise 
the temperature of the air will rise until it approaches that 
of the body, its passage along the surface of the heated 
body will be rendered slower, and, consequently, the 
removal of the heat greatly checked. To attain the best 
results it would seem to be necessary to admit the cold air 
Jelow the radiant, and to withdraw the air that has passed 
over the hot surface from above. By this arrangement no 
obstacle is placed in the way of a free circulation. 
Let fig. 4, plate II., represent a case where the surface, 
S, of a heated body, say, meat, loses heat simultaneously 
by radiation and contact of cold air. Here W W, the walls, 
are ata temperature of 15°04 F., the air is at 14° F. and the 
body, P, at a temperature of 80° F. 
Here the surface, S, is radiating heat to the walls, W, at a 
ratio by Table 2, for a difference of 65° (80° — 15°) of 
102. The value of R, or the radiative power of meat, 
being taken at, say, 1°25 (by Table 1) units per square 
foot per hour, the heat emitted at the commencement of the 
