O14 > Seientifie Proceedings, Royal Dublin Society. 
mately vertical pull now withdraws the drill, retaining within it 
the excavated rock. It is evident that the saws will retain the 
final dotted position shown in the plan. When, in fact, the current 
is stopped, the spring pulling the drill upwards maintains. the 
vanes pressed against the base-plate above them and so fixes them 
in their position of extreme deflection. In this position the saws 
meet across the opening of the drill-shaft, and the loss oe the 
specimen is impossible. 
In place of cutting-saws, a cutting wire or r chain may be used. 
This wire may be lodged in a horizontal groove within the drill. 
at its lower extremity. When the drill has attained its lowest. 
position, the release of the fans effects the rotation of a loose collar 
which carries the fans, rotates on the drill-shaft, and is attached 
to one extremity of the cutting wire by means of a rigid extension. 
extending downwards in the inside of the drill-shaft. The rota- 
tion of the collar is thus accompanied by the gradual pulling of. 
the cutting wire into the diametral position. When this position. 
is attained the horizontal cut is complete. This form has the. 
advantage of requiring a drill of less thickness in the walls than 
the first form, but experiment alone will show how far it may be 
relied upon in the case of a hard rock. 
In many cases the rock beneath the sea is probably eovered 
with but a shallow thickuess of mud or sand. In such cases it- 
would be possible to modify the apparatus so as to enable it to 
bore through this covering.. Experience will probably show that. 
the electrical measurements and observation of the duration of- 
drilling will, at any rate, after a single trial of the rock, enable a 
a sufficient estimate to be made, by those at the surface, of the 
depth to which the drill has penetrated. An electrical release 
may then be employed to stop the vertical cut and liberate the 
vanes, and so commence the horizontal cut or simply reversion of 
the direction of rotation of the drill might be used to stop the 
vertical cut, and at the same time call the vanes and saws into. | 
operation. ‘I'he mechanism would be of the simplest kind. 
. But trial of the form first described, upon ground where bare 
rock is assured, will at once be a test of all such modifications so: 
far as their essential features are concerned. . 
