408  mbbaien  on  the  EESISTANCE  OE  TEEES  to  COllAPSE. 
and  by  an  obvious  transformation,  we  have 
P= 
820 
L.D 
The  following  Table  will  show  how  nearly  formula  (6.)  represents  the  results  of  the 

D.  1 
Diameter. 
inches. 
L. 
Length. 
feet. 
k. 
Thickness. 
inches. 
P. 
By  experiment  j. 
in  lbs. 
4 
•043  1 
137 
4 
5 
•043 
43 
6 
H 
•043 
55 
8 
H 
•043 
32 
10 
•043 
19 
12 
5 
•043 
12-5 
18| 
•250 
420 
9 
•140 
378 
14| 
5 
•125 
125  1 
p. 
130 
41 
54-7 
31*6 
19-7 
13*6 
407 
392 
116 
Proportional 
error  bv 
formula 
"ih 
“T2 
"TOO 
1 
•To 
•4- TO' 
■t-TT 
1 
T2 
+rr 
So  far  as  regards  practical  purposes,  lO-inch  tubes  pre- 
° . ,•  4-nrv  of  the  experiments, -siz.-— 
sent  the  greatest  aevrduuu.  ' . r. 
° if.  thp  results  of  the  experiments,  iiz.-— 
a still  closer  approximation  to  tiie  lesuits  p 
P=806,300x 
It  is  highly  desirable  that  we  should  ^rify 
variation  of  pressure  as  regards  and  diameter  pressure  when 
Let  P be  the  pressure  of  collapse  of  a tube  k inches  thick,  and  r P 
the  tube  is  •!  inch  thick ; then 
P 
P' 
:=(t)“ 
/ 1 p 
P'=Px(^10Aj  ""(10A-)“’ 
and 
log  P'=  log  P--2-19  log  {lOIc). 
