92 GOODMAN : APPARATUS FOR BORE HOLES. 
The upper end of the hollow cylinder h is hermetically 
closed by the cover or cap piece w. 
The means above set forth for freeing the magnet and cone 
and for securing them in any position in which they may have 
come to rest are not limited, as other means both mechanical 
and electrical suitable for effecting this purpose are well known 
or will readily suggest themselves. 
The rim of the cone is graduated all round in degrees as 
shown on the righthand side of the cone, the magnet being 
secured so that its centre line lies in the central plane of the cone 
passing through the zero and 180° mark. The angle of incHna- 
tion of the cone is most readily ascertained by finding by means 
of a gauge or cathetometer the highest and lowest points respec- 
tively of the base rim of the cone from the base plate e. The 
difference between these heights divided by the diameter of the 
base of the cone will give the sine of the angle of deviation of 
the bore hole from the vertical. 4 are scratchers or scrapers of 
steel, diamonds, or the like, secured on the inner side of the 
tube h close to the lower end of the same, so that by raising 
and lowering the bottom of the tube in the annular space sur- 
rounding the core, scratches or marks can be made on the sides 
of the cone, so that when this portion of the core is afterwards 
broken off and brought to the surface, if the lines of bedding 
can be traced, the dip and direction of the dip of the strata, as 
shown by the core, can be deduced. To facilitate the marking 
of the core, the scratchers may be formed on or attached to a 
flat spring or springs 5, secured to the lower end of the tube. 
