WATER CONSERVATION SURVEYS OF N.S.W. LXXVII. 
was that the errors in large circuits should not exceed a foot in a 
hundred miles, and this limit was not allowed to be departed from 
except in a few cases where creeks or ridges were numerous, or 
where there were other conditions unfavourable to great accuracy. 
Tn addition to the checks already described, it occurred to the 
author that it would be interesting to combine the outlines of a 
series of circuits and thus to obtain one great circuit for an entire 
district or a river basin. The results for a number of such circuits 
were prepared by Mr. D. R. Alderton, Licensed Surveyor, of the 
office staff, and from these the following may be cited :— 
(1) Commencing at Albury and carrying levels through Jeril- 
derie, Conargo, Wanganilla, Moulamein, Euston, and Gol Gol to 
Wentworth, the levels taken by the Water Conservation Branch 
close with those taken by the Harbours and Rivers Department 
along the River Murray with a difference of only 1:56 feet. The 
circuit includes eight hundred and fifty miles of levelling by the 
Department of Harbours and Rivers, and four hundred and fifty 
miles by the Water Conservation Branch. 
(2) Commencing at Wagga Wagga and levelling along the north 
Side of the Murrumbidgee to close at Hay, the distance by the 
water conservation survey being two hundred and three miles, 
and that by railway one hundred and eighty-nine miles, or a 
total of three hundred and ninety-two miles, the difference at 
the close was 0°54. 
(3) Commencing at Hay and following lines through Oxley, 
Balranald, Euston, and Gol Gol to Wentworth, the difference at 
the close was only 0:50. The circuit here included eight hundred 
and fifty miles by the Harbours and Rivers Department, two 
hundred and sixty-four miles by railway, and two hundred and 
eighty miles by the water conservation surveys, or a total of 
1,394 miles, 
(4) Commencing at Hay and following lines through Oxley, 
along the north side of the River Lachlan through Booligal, 
Hillston, Euabalong, Condobolin, and Forbes to Cowra, the closing 
