LXXVI. H. G. McKINNEY. 
of information with the minimum amount of work and expense. 
To attain this object, the lines to be levelled and surveyed were 
sketched on the county and sometimes on the parish maps, but 
the surveyors employed were not only permitted, but requested to 
deviate from these lines under certain circumstances which were 
indicated in the instructions. In addition to the instructions 
regarding deviations from the main lines laid down on the maps 
when the natural features proved different to what was anticipated, 
the surveyors were required to run cross sections or other extra 
lines to determine the position and extent of any natural features 
which would have an important bearing on any works for the 
distribution of water. Cross sections of creeks and rivers were 
taken at places where the lines of levels touched their banks, and 
in taking levels of running water both the date and hour of obser- 
vation were in every case noted. The main lines of levels con- 
stituted a series of connected geometrical figures, so that there 
were numerous closes and easy means of checking. The work 
was done by contract, and it is very satisfactory to be able to 
State that, as a general rule, it was highly creditable to the 
surveyors employed. Occasionally it appeared desirable to send 
an officer of the regular staff to check portions of the work, and 
this was easily done by running lines across two or more circuits. 
Tn addition to the checks thus made, surveyors were required to 
connect their levels with those of railway lines and railway trial 
surveys whenever the lines came near work done by the Railway 
Department. This gave many independent checks, and a further 
important check was afforded by the levels taken many years ag0 
along the River Murray by the Department of Harbours and 
Rivers. 
The datum adopted for the water conservation levels throughout 
the Colony is that of{the Railway Department, namely, Sydney 
high water mark, 
The examination of the level books and the apportionment of 
the differences occurring at the end of long closes, was a matter 
requiring much care and labour. The degree of accuracy specified 
