ME.  EAIEBAIEN  ON  THE  EESISTANCE  OE  TUBES  TO  COLLAPSE. 
399 
function  of  the  length ; and  it  is  important  to  observe,  that  we  cannot  in  practice  intro- 
duce long  tubes  into  constructions  exposed  to  external  pressure,  without  making  very 
considerable  allowance  for  their  loss  of  strength. 
In  the  earher  experiments  the  tubes  were  made  of  thin  wrought-iron  plates ; but  con- 
cemng  that  it  would  be  of  interest  to  examine  how  far  the  laws,  which  were  found  to 
prevail  with  them,  apphed  also  to  tubes  of  other  materials,  three  tubes  were  made 
of  the  following  dimensions : — 
GG.  Iron  flue,  15  inches  in  diameter: — 
Plates  ’125  inch  thick. 
Web  [a  a)  ‘25  inch  thick. 
Eivets  inch,  at  1|-  inch  apart. 
k _ A 
r 1 
S Af! J 
\ 
K 
!?•  ; 
r 1 
i 
a.  a -M  Collagse^ 
HH.  Steel  flue,  diameters  15 and  15|-  inches : — 
Plates  '125  inch  thick. 
Web  {bV)  '25  inch  thick. 
Eivets  J inch,  at  1|-  inch  apart. 
JJ.  Iron  flue,  with  overlap  joints;  diameters  14^  and  inches: 
Plates  '125  inch  thick. 
Ends  '25  inch  thick. 
Length  5 feet. 
Eivets  ^ inch,  at  1|-  inch  apart. 
5.0% 
JS  Colla^sz. 
Table  IX.  Eesistance  of  Steel  and  Iron  Flues. 
Mark. 
No. 
Diameters. 
inches. 
Length. 
inches. 
Thickness. 
inch. 
Pressure  of 
collapse, 
lbs.  per  sq.  in. 
Remarks. 
GG. 
HH. 
31 
15 
15^X151 
21 
•125 
150 
Each  had  an  internal  longitudinal  stay  between 
32 
17 
•125 
220 
the  ends. 
J.I. 
33 
141x1411 
60 
•125 
125 
The  experiments  on  these  tubes  do  not  at  first  sight  appear  to  yield  very  satisfactory 
results.  The  first,  GG,  gave  way  with  a pressure  of  150  lbs.  on  the  square  inch,  when 
it  began  to  leak  so  much  as  to  cause  its  removal  from  the  vessel,  to  replace  some  of  the 
rivets  which  were  imperfect.  After  the  necessary  repairs,  it  was  again  subjected  to 
experiment,  when  it  gave  way  with  a force  of  146  lbs.,  showing  how  much  it  had  been 
injured  by  the  previous  pressure.  On  comparing  it  with  the  mean  results  of  all  the 
other  experiments,  we  find  that  it  should  have  borne  about  300  lbs. : it  eGdently  failed 
at  the  rivets,  and  cannot  be  relied  upon. 
MDCCCLVIIl.  3 H 
