H. 8S. I. SMAIL. . CXCIII, 
The author had a portable notch board made with crest 
2 feet long. The crest and sides of the notch were of 
wrought iron bevelled on the down stream side. The head 
of water passing over the notch was measured by a hook 
gauge reading to °01 inch and approximating to ‘005 inch; 
this he had made in Sydney. 
The normal flow was first measured at intervals for 24 
hours, to see if any variation took place in the flow. In 
the flows already measured no such variation was observed. 
The bore was next shut down ky the valve till the pressure 
gauge read 25 ibs per sq. in., and the flow again measured. 
It was then shut down till the gauge read 50 Ibs per sq. in., 
and the flow again measured, and so on till the bore was 
entirely shut down when the pressure was again read. The 
bore was kept shut down till the pressure reached its 
maximum, which took some time, a different period for each 
bore. ‘This last pressure is the hydrostatic pressure. After 
the pressure reached its maximum the bore was opened 
full again, and the flow again measured to see whether 
there was any increase, but only in one case was an increase 
observed, viz., at the Wollabra bore, one with a very low 
hydrostatic pressure. 
Tests were also made at the Caryunga and Dolgelly bores, 
only 7 miles apart, to see whether closing down one of 
them had any effect on the flow of the other, but none was 
observed. The temperature of the water of each bore was 
taken. The greatest difficulty in measuring the flow was 
found in fixing the hook of the gauge to the same level as 
the crest of the notch. This was done by means of a 14 
inch dumpy level and a light staff with a target, this was 
checked and rechecked about 10 or 12 times at each bore, 
and the reading on the gauge taken. The author did not fix 
the zero of the gauge to the level of the crest, but had the 
zero somewhat below, and the difference between the read- 
13 -July 20, 1903. 
