196 
Proceedings of the Royal Society 
those of M. Poiseuille. ls£, Our tubes had a much wider diameter — 
those used by the French observer varied in diameter from 
0 mm T949-0 mm, 256, whilst our tubes were from 0 mm, 845-l mra *259. 
2 dly, By our tubes being much longer than those of Poiseuille ; 
and, 3 dly, By the liquids being allowed to flow, not into water, but 
into empty vessels placed in the partially exhausted receiver. 
I. — Influence of the Shape of the Tubes employed on the Rate of Flow. 
It was considered advisable to determine, in the first place, 
whether bends in the tubes through which the liquids were made 
to flow w r ould exert any influence on the rate. Accordingly, a 
tube 1129 millemetres long was bent twice at right angles; one 
end was connected by means of a tightly fitting cork with the 
Table I. 
Time of 
No. of 
Diame- 
Length 
Temper- 
ature. 
Pres- 
Flow of 
Experi- 
Fluid used. 
ter of 
of 
lOOCubic 
ments. 
Tube. 
Tube. 
sure. 
Cents, in 
Seconds. 
mm. 
mm. 
mm. 
Tube bent 
twice 
1-5 
Water, . . 
0-845 
1129-8 
13 ? 0 C 
708-59 
126-4 
at right angles, 
5-8 
Common Sul- 
phuric Acid, 
!" 
13-5 
» 
2978-0 
thus, 
f 
8-9 
Water, . . 
” 
” 
13-5 
588-5 
158-0 
10-11 
Water, . . 
0-845 
1129-8 
13-5 
588-5 
159-8 
Tube bent four 
times at right an- 
gles in the same 
plane, thu; 
A 
s, 
11-12 
Water, . . 
0-845 
1129-8 
11-5 
588.5 
157-4 
Tube bent 
four 
times at right an- 
gles; at one point 
bent at an angle 
of about 135° to 
its former plane. 
13-14 
Water, . . 
0-845 
1129-8 
11-4 
588-5 
161 
Tube again 
. bent 
as in experiments 
15-17 
Water, . . 
0-845 
1129-8 
33-0 C 
588-5 
108 
10 and 11. 
