1864. ] 
being swung round the columns, 
and with the cylinder it can swing 
round sideways at any angle in 
front of the columns. Each of these 
movements is effected by a hand- 
wheel, and each set of gear is pro- 
Notes and Correspondence. 
ATT OD nA nm 
583 
vided with a tightening break, so 
as to render the whole perfectly 
steady whilst in operation. ‘The 
working parts are covered to pro- 
tect them from the rock-dust and 
débris. 
Fie. 3. 
Figure 3 shows the cylinder and 
boring-machine and tool in detail. 
The chief peculiarities of these are, 
the shortness of the whole, the fixed 
cylinder, with telescopic tool, cen- 
tral screw, and parts completely 
covered. The screw which propels 
the tool in progress of boring (ac- 
tuated by a diagonal slot attached 
to the cylinder by a roller-ratchet 
wheel) goes up inside the piston- 
rod, receiving the percussion blows 
centrally, and thus obviating any 
danger of the tool leaning to either 
side. 
It will be observed that the 
cylinder is, as remarked, stationary, 
the tool and screw being propelled 
from it in course of boring, instead 
of a motion being imparted to the 
cylinder itself. This arrangement 
allows of wil the working parts of 
the cylinder and boring motion 
being completely covered from rock- 
dust, wet, &c., which have been 
found so destructive to boring-ma- 
chines. 
The tool is arranged so that it 
travels (self-acting) at any rate that 
may be requisite, proportioned to 
the hardness of the rock, this being 
regulated by the position of the 
