46 
MINUTES OF PEOCEEDINGS OF 
is fired when the limiting value of R is reached and the axle and bed 
break, can be deduced, thus :— 
R x EF = P Y x HF + W x qF, 
■pY _ R x EF — W x qF 
_ 13*13 x 77*5 - 1*0076 x 70*4* 
1 78*75 
But P = 
sin of z of elevation = 
11*98 tons. 
P Y 
sin of z of elevation 5 
11*98 
43*74 
= *27396; 
.*. z of elevation = 15° 54'. 
Now, in carriages of this construction, as a fact, the axletree and bed 
would not stand the gun being fired at so high an elevation. To 
reduce, therefore, the calculated angle, either the value of P Y —or, 
what is the same thing, of R —must be diminished, or that of P in¬ 
creased. The latter is inadmissible; for it would amount to saying 
that a carriage of the latest construction would not stand when the 
gun was fired at an elevation of 30°, which elevation, as before said, is 
really under the mark. Ifc therefore remains that the value of P Y —or 
rather of R , from which it is obtained—is too high ; and this, no doubt, 
is the true case. In fact, it is not fair to take the total strength of the 
axletree and bed combined as the sum of their separate strength; for 
the elasticity of the wooden bed is greater than that of its iron axle, 
and consequently the latter is broken before the full strength of the 
former has come into play. 
June, 1874. 
* The weight and distances vary slightly from those of the latest pattern carriage. 
