448
Molesworth’s pocket-book
Ventilation in Collieries.
(‘ Trans. Inst. Civ. Engrs.,’ vol. vi.)
t = temperature of air in downcast shaft.
T = temperature of air in upcast shaft.
D = depths of the shaft in feet.
m = the periphery of the transverse section of
the air-course in feet.
s = the area of the section in feet.
= the length traversed by the current in feet.
v = the velocity of the current in ft. per second.
n T + 448 '
v = 9ß\/ — - „ «■
V m I + 368 s
Ventilation in Collieries.
(‘ Trans. Inst. Civ. Engrs.,’ vol. x.)
C = length, of downcast column.
c = length of upcast ditto.
T =± number of degrees in excess of 32° F. in C.
t = number of degrees in excess of 32° F. in c.
/ 480 + t \
C = ° \480 + Tz '
Winding Engines with Flat Ropes coiled
on Drum.
To find the place of meeting for ascending and
descending skips.
t = thickness of rope in inches.
n = number of revolutions of the drum.
x = the distance below half the depth of tho
pit at which the skips will meet in yards.
x = -0218n8t