Tidal Phenomena at Inland Boreholes near Cradock. 
73 
The apparatus consisted of a large metal float firraly fixed to a vertical 
brass rod, the upper end of which was connected by a hinge joint to a 
horizontal brass arm lever of the first order about 19 inches long. At the 
end of the lever remote from the float was fixed a pencil, recording its 
vertical movement on the drum, which revolved on a vertical axis once 
a day. 
The fulcrum support was placed near the middle of the lever. The 
pencil-point was found to be, as nearly as one could measure, 9 inches from 
the point of support, so that the pencil moved in an arc of a circle of 
^- 9" yo" > 
f wl C 
Clock 
Dri/m 
1 ' 
^y///y////^////^Wf''/'^^^'!f'^f'/ //////////^ //////^/^ 
U/ater Lev^el. 
Fig. 3. 
9 inches radius. The top of the float rod was found to be 10 inches from 
the point of support of the lever. Thus the actual vertical movement of 
the float was reduced on the record by about -^-^ of its amount. As thus 
arranged an upward movement of the float was recorded by a downward 
movement of the pencil. The essential dimensions and general arrange- 
^ment of the parts of the apparatus are exhibited in Diagram 3. The 
whole apparatus, with the exception of the float and part of the upright 
rod, was enclosed in a stout wooden box fitted with a plate-glass lid. A 
hole in the bottom of the box vertically under the hinge joint was fitted 
?LOhl 
