23 
cury, and that degree of vacuum was maintained during 
the experiments. 
The following Table shows the velocity of air flowing 
into a vacuum as deduced from the time and difference of 
pressure for every 51bs. from 1351bs. to 51bs. absolute 
pressure. The velocities of the first column are deduced 
from actual experiment, and in the next column the veloci- 
ties are calculated from the difference of the area of the 
discharging orifice and the vena contracta by applying the 
hydraulic co-efficient *62. 
Table T. 
Discharge into a Vacuum 0*6in. Mercury. 
Barometer 29 ‘42. Thermometer 54° F. 
Absolute 
pressure in lbs. 
per 
square inch. 
Time of 
discharge 
in 
seconds. 
Velocity 
in feet 
per second. 
Velocity 
coefficient 
• 62 . 
135 
7-5 
750 
1210 
130 
7*75 
753 
1214 
125 
8-0 
759 
1225 
120 
8-5 
743 
1198 
115 
9-0 
734 
1184 
110 
9-5 
726 
1171 
105 
10-0 
724 
1168 
100 
10-5 
722 
1165 
95 
no 
725 
1169 
90 
12-0 
703 
1134 
85 
13-0 
688 
1109 
80 
14-0 
678 
1094 
75 
15-0 
675 
1089 
70 
16-5 
657 
1060 
65 
18-0 
650 
1048 
60 
20-0 
632 
1020 
55 
22-0 
628 
1011 
50 
24-5 
620 
1000 
45 
27-0 
624 
1007 
40 
31-0 
613 
989 
35 
36-0 
602 
971 
30 
43-0 
589 
950 
25 
53-0 
573 
924 
20 
69-0 
550 
887 
15 
97-0 
522 
842 
10 
170-0 
446 
720 
