ARMOUR AND ITS ATTACK BY ORDNANCE. 103 
Fig. 26. 
sisting of a travelling crane made by an erection of fir poles in the 
form of a sorb of gyn, with four feet striding on to two trucks, which 
moved on parallel lines of rails. A differential pulley was suspended 
to lift the pieces of the mounting. The heaviest lift is 1900 kilogs. 
(1*87 tons), being the hood or cupola roof pieces, of which there are 
two, the hood being in this case made in two thicknesses. The entire 
weight of the mounting is 17,000 kilogs. (16*73 tons). Six men 
performed the entire work. They commenced at 9.42, and completed 
it by 11.30, having occupied 1 hour and 48 minutes. 
The main questions in all these designs are the ease of working and 
the strength of mounting. The large turret for the two 15 ctn guns, 
revolved once, when its momentum was overcome in 11 seconds, but 
generally slower, from 22 to 42 seconds. The 21 cm mounting, two 
revolutions in 20 seconds. 
The following remarks suggest themselves on the whole trial and Gruson 
exhibition of Gruson w.ateriel. First as to the turrets and heavy generally. 
shielded mountings. The mechanism is excellent. The ease with 
which the heavy shielded mountings are worked is only to be under¬ 
stood when it is borne in mind tnat they revolve on a central pillar, so 
that there is a great leverage against friction. Their behaviour under 
fire appears to be very good. There is a space between the edge of 
the hood, or cupola top, and the glacis plate or ring round it varying 
from about 1J inch in the large turret for the two 15 cm guns down 
