OF THE IRK, LOCOMOTIVE ENGINE. 511 
af 2m (108.4 $-) Bs at = nas; 
4, ig 3 — a3 
& 64/2 dt = a ath tig hao 
(tog. ae (108) ) 
Let log —= z*, then er, hyp. log. e = 1; and let 
— = =p, and then, » dt = —2 dz. dommes 
By Sk Hea ut = — 22 +e=—2 (108. —) : +e 
= log. +c; but, when }=D, ¢ =o; therefore, 
D 
pt — log.—- 
& pt = com. log ( 2} 
nearly. 
"4342 y 
10. When, as in the last article, the steam issues 
through a given aperture, in the top of the fire- 
box, and when, as in Barker’s mill, the steam, by 
its re-action, presses upon that part of the top of 
the boiler, which is opposite to the aperture, and, 
by this means, causes the Locomotive Engine to 
revolve about its centre of gravity ; it is required 
to find the angle, through which the Engine will 
