562 
STRENGTH OF FIELD GUN-CARRIAGES. 
The specimens, C, and D, were constructed by simply replacing the 
service straight axle, as in B, by a round bent axle, between angle-irons 
already drilled for the former, and fitting packing pieces between the 
top plate and the axle at the positions of the brackets. The correct form 
of this axle and bed, as proposed by Mr. Butter, Manager R.O.D., is 
shown in the figure, in which there could be no tendency of the angle- 
irons to crack at the lower edges. This construction is far stronger 
A- 5-0 --- 
;<2-s>i 
than that of B, in that it is of deeper section, while the axle is not 
weakened by rivet holes, and is subjected to a purely tensile strain; it 
is also, if damaged, much more easily replaced, being secured by a few 
instead of many rivets, and being of small section, if broken, can be 
rewelded. The solid form, E, in steel, would, after slight damage, 
soon become unserviceable, and if broken could not be rewelded; it 
is also inconvenient for the attachment of axle seats, the necessary 
fittings for which would increase its weight considerably. In a com¬ 
parison of strength to withstand statical pressure, made between the 
forms A , and B, it was found that while the breaking strain of the 
former was 22 5 tons, that of the latter was 54| tons. 
liOYAL AkSENAE, 
October 1876. 
