90 
GOODMAN : APPARATUS FOR BORE HOLES. 
nut, which is screwed down on to the stem g and secures the 
needle h to the top of the cone c. The cap portion of the nut k 
is formed on the outside as a hemisphere, having the point of 
the pivot pin d as its centre. 
The base plate e rests on a ledge or flange formed on the inside 
of the enclosing cylinder 6 ; /is the so-called clockwork base plate, 
which is carried from the base plate e by two more pillars m. 
Immediately above the cap nut k and in the central or 
axial line of the apparatus is provided a spindle or plunger n, 
which passes through and is guided by a hole in the boss on 
the underside of the clockwork base plate. The lower end 
of the spindle or plunger is enlarged and made hollow, so that 
when pressed against the hemispherical cap, it bears only with 
its circular rim against the cap ; o is a helical spring surrounding 
the spindle or plunger n, resting with its lower end on the en- 
largement v} and bearing with its upper end against the under- 
side of the clockwork base plate I. The upper part of the plunger 
or spindle n passes through a hole in the lever p, the latter being 
hinged at q. A cross pin r is fitted in the spindle immediately 
above the lever p, so that when the latter is raised the plunger n 
is lifted out of contact with the cap nut k, allowing the pendulum 
cone c to swing free with its base truly horizontal. When the 
lever p is released, the helical spring o pushes the plunger down 
on to the nut cap, fixing the cone and needle in the position 
which they have at the time Avith respect to the apparatus ; 
s, as shown, is a case containing an ordinary alarum clock, which 
is carried on the clockwork base plate. The free end of the lever 
p is cormected to the lower end of a flexible wire or cord t, the 
upper end of which is secured to the projecting end u of the alarum 
spindle, so as to be wrapped round the same when the alarum 
is wound up, thus raising the lever lifting the plunger n and 
allowing the cone and magnet to hang free. The alarum release 
is then set to go off after a certain time interval, and in this 
state the apparatus is lowered into the bore hole. On the lapse 
of said interval, the alarum release goes off and the spindle u 
runs down, unwinding the cord t and freeing the spring o to push 
down the plunger n, which latter fixes the cone and the magnet 
in the position in which they have come to rest. 
