how at the Inventions Exhibition, London, a light portable rock-boring
machine for prospecting for minerals, water, etc. It is capable of
sinking holes from 2 in. to 5 in. in diameter, and to a depth of 400 ft.
The screwed boring spindle, which is in front of the machine, is actuated
by miter gearing driven by a six horse power engine; the speed of driving
is 400 revolutions a minute. The pump shown on the left-hand side of the
engraving is used to deliver a constant stream of water through the
boring bar, the connection being made by a flexible hose. Suitable
winding gear for raising or lowering the lining tubes, boring rods, etc.,
is also mounted on the same frame. The drill is automatic in its action,
and the speed can be regulated by friction gearing. The front part of the
carriage is arranged so that it can be swung clear of the drill to raise
and lower the bore rods, etc.

* * * * *

AUTOMATIC SAFETY GEAR.

Among the safety appliances which are to be found in the Mining Section
of the Inventions Exhibition is a model of an ingenious contrivance for
the prevention of overwinding, the joint patent of Mr. W.T. Lewis,
Aberdare, lead mineral agent to the Marquis of Bute, and W.H. Massey,
electric light engineer to the Queen. Both these gentlemen, having been
members of jury, were not allowed to compete for an award. The invention,
says _Engineering_, seems to possess considerable merit, and it should
prove of practical utility in collieries where enginemen are usually kept
winding for many hours at a stretch, and where the slightest mistake on
the part of the driver may lead to an accident.

Safety hooks are often fitted to winding ropes, and although the damage
to life and property is greatly reduced by the use of them, they do not
protect a descending cage from injury in a case of overwinding; besides
which, they are almost useless when a wild run takes place, an accident
which, strange to say, has already occurred many times after engines and
boilers have been laid off for repairs. Stop valves are left open, the
reversing lever is not fixed in mid-gear, steam is got up in the boilers
at a time when no one is in the engine house, and the engines run away.

[Illustration: LEWIS & MASSEY'S AUTOMATIC SAFETY GEAR.]

Various devices have been suggested and tried as a preventive, but their
application has either caused as much mischief as a bad accident, or it
has depended upon t