Laterally loaded St puts and Tie-rods. 711 
disturbing the relation of temperature and density at any 
point of the mass. 
Equations (59) and (60) show that in spherical gaseous 
nebulas for whose gaseous stuff k=d the total internal 
energy, and the gravitational work, corresponding to each 
equilibrium distribution of gas, has the same value, whatever 
be the central temperature or total mass, provided tempera- 
ture and density at each point within the mass are related to 
each other in accordance with the same value of theadiabatic 
constant in each case. 
[To "be continued.] 
LXIY. Laterally loaded Struts and Tie-rods. By Arthur 
Morley, M.Sc, Professor of Mechanical Engineering at 
University College, Nottingham *. 
THE frequent occurrence of laterally loaded struts and 
ties iu structures and machines makes the subject one 
of some importance. Every horizontal strut or tie-rod carries 
a lateral load in its own weight, every vertical stanchion 
which carries a horizontal wind load, every beam which is 
not horizontal, and the coupling-rods of locomotives loaded 
transversely by their own centrifugal force, are common 
examples. The increase in the maximum intensity of stress 
due to a small transverse load on a strut which has a 
considerable axial thrust is very marked in long struts. 
Prof. Perry f has given a method of finding the stresses 
in such cases, his solution embracing conditions of the most 
general kind. 
Three methods are in common use for the determination of 
the maximum intensity of stress in such cases. In each 
of these the resultant intensity of stress is found by taking 
the algebraic sum of that due to the axial thrust or pull 
and the intensity of bending stress. The methods differ in 
the calculation of the bending stress only ; the usual as- 
sumptions are made and the simple Bernoulli-Euler theory 
employed; but the calculation of the maximum bending 
moment differs in the three methods as follows : — 
(a) The maximum bending moment is taken as that due 
to the transverse loads only. This will evidently be nearly 
correct in a very short stiff beam having a small thrust 
or pull. 
(6) To the bending moment which the lateral loads would 
* Communicated bv the Author. 
t Phil. Mag. March 1892. 
3B2 
