_ WATER CONSERVATION SURVEYS OF N.S. Ww. LXXXIX, 
evidence that much mischief was done from the causes described. 
There was, in fact, at the outset a large amount of amateur 
engineering and surveying in connection with the earlier irrigation 
work in America, and he thought that Mr. Haycroft would concur 
in the opinion that in the case of works of any considerable mag- 
nitude, this was an unsafe mode of proceeding. 
Mr. Davis raised an important question regarding the datum 
adopted. There could be no doubt, as Mr. Davis stated, that there 
should be a uniform datum for all levels throughout the Colony. 
That adopted for the Water Conservation Surveys was the most 
Convenient under the circumstances; but he was of opinion that 
a better datum would be mean sea level. However, that is a 
point of less importance than uniformity. In regard to departures 
from uniformity, if he mistook not, the Sewerage Construction 
Branch, which was under the charge of Mr. Davis, was the last to 
adopt a new datum. 
With regard to Mr. Henson’s inquiry, Mr. McKinney pointed 
out that a contour map of Southern Riverina was published in 
1891, the contours being five feet apart vertically. Contour maps 
of the Macquarie, Castlereagh, Namoi, and Gwydir districts have 
also been prepared and parts of them published. 
Tn reply to Mr. Merfield’s inquiries as to how errors in short 
istances were dealt with, it was explained that questions regard- 
ing errors in short distances very seldom arose. When they had 
to be dealt with, they were considered on their merits—if the 
error was materially above the limit the work was done over again 
and if the error was not much above the limit and the general 
character of the work was satisfactory, the short length exceeding 
the limit of error was allowed to pass. 
en many years ago by the Department of Harbours and Rivers 
m Albury to Wentworth were checked in a similar manner— 
& junior officer of the party employed being required to go over 
the lines independently and compare notes as the work proceeded. 
