379 
On the Construction of Theatres. 
of the axletree. a , fig. 5, is the linchpin detached ; it is 
put through an oblong hole in the axle as usual, but 
there is likewise an additional linchpin &, to make it com- 
plete, which is fixed in a recess cut for it in the axle, and 
turns on a pin (as is shown in the figure) into the hole left 
by removing the linchpin «, when the wheel is to be taken 
off; but if the linchpin a should accidentally get out, this 
additional pin b would effectually keep the wheel on, as 
its hanging position does not at all tend to shut the pin up 
into the axle, but the contrary. The common linchpin a 
is put in downwards, and its weight may also tend to keep 
it in, and is secured in the usual way by a strap, the 
holes for which may be seen in the figures. The whole, 
when in its place, is shown at fig. 4. 
No. yd. 
On the Construction of Theatres , so as to vender them 
secure against Fire . By Mr. B. Cook. 
SIR— In some former letters you did me the favour to 
insert in your Journal, I have recommended the use of 
iron in the place of wood; in my last on that subject I 
pointed out its use and advantages in substituting it for 
wood in buildings, but more particularly in adopting it 
for staircases, as promising a certain eseape in case of 
fire. What I would direct the attention to in this is, the 
great advantage of employing it almost entirely in the 
erection of public buildings, especially theatres ; and al- 
though I am not an admirer and encourager of theatric 
representations, but, on the contrary, think they are inju- 
rious to a state, as contaminating the morals and habits of 
! a people, and consider them as the very seat and emporium 
of vice and immorality, yet as they are permitted, it is a 
Nicholson, vol. 25, p. 301. 
