Tidal Phenomena at Inland Boreholes near Cradock. 77 
During these years I observed no change in the temperatures of the 
waters. 
Towards the end of 1907 Messrs. Eayner and Eoberts informed me 
that j they had made arrangements which would probably allow of a long 
record of several months' duration being taken during the early half of 
1908. 
The arrangement for the delivery of the water from No. V. well, how- 
ever, had now been entirely altered, and the old recording instrument 
could no longer be applied in the new conditions. On visiting the farm I 
found the altered state of affairs to be as follows. (See Diagram No. 5.) 
The old small tank A had been removed, and a few feet of iron piping p 
had been added to the former top of the 6-inch lining of the borehole. 
The top of this new pipe projected a few feet above the level of the ground. 
A new exit pipe s, lying almost horizontally, pierced the borehole lining at 
T about 7 feet below the former top of the borehole, and led the water 
directly into the bottom of the great tank B. The level of the water 
standing in the vertical pipe was always a few inches above the top of the 
horizontal exit pipe. The water flowed out of the tank B through the old 
opening at W, and so away down to the dam as before. 
Measurements by means of a plumb-line showed that the water surface 
in the borehole was about 16|- feet beneath the top of the pipe P. I came 
to the conclusion that this water surface was probably still near enough 
to the potential level to allow of fluctuations being recorded, and a new 
recording machine was designed to fit the new conditions. (See Diagram 
No. 6.) 
A recording drum of about 3*7 inch diameter was obtained from a baro- 
graph instrument. The clock in this drum caused one revolution per 
week An 18-inch brass rod lever was supported on a fulcrum pivot 
placed 7 inches from the writing end. Fixed to the end of the long arm 
of the lever was a length of silk fishing-line, which ran upwards, and after 
passing over two brass pulleys fixed to the top of the borehole pipe P, 
descended vertically within the pipe to the water-level, where it was 
attached to the float. It was found necessary to fix a small weight near 
the end of the long arm of the lever to ensure that the silk line should be 
always taut. Attached to the lower surface of the float by means of a few 
inches of brass chain was another metal weight, whose purpose was to 
steady the float and keep it in a position towards the centre of the hori- 
zontal section of the borehole. 
It will be observed that a rise of the float was recorded by a rise of the 
pen on the drum record sheet. The whole instrument, except the silk 
line and float, was enclosed in a stout teak box with plate-glass lid, secured 
by means of a lock. 
The silk cord emerged from the box by a small hole drilled in the wood 
