396 REPORTS ON THE STATE OF SCIENCE, ETC. 
CONCLUSION. 
From the foregoing notes it will be seen that the demand for records of 
underground water and river gaugings is general and persistent for purposes 
of water supply. The onus of providing these data must in the first place 
fall upon the water authorities for whose benefit they are primarily required, 
as, for instance, in the matter of compensation water, and whose works 
create the liabilities such as have given rise to the Reservoirs (Safety 
Provisions) Act. Further, it is on their property that the observations must 
be made, and their staff are on the spot to make the records. Water 
authorities, however, with few exceptions, have proved slow to realise that 
the slight expense involved would be for the advantage of their individual 
undertakings, as well as contributing to the wider knowledge essential for 
such bodies as regional water committees, and contributing also to the 
science of water engineering on which all such undertakings intimately 
depend. 
It is highly desirable, therefore, that convincing efforts should be made 
to enlist the co-operation of the water authorities. 
When this is secured, water engineers should have no difficulty in estab- 
lishing some appropriate body of experts to give any advice that may be 
desired as to the methods of observing and recording, and to compile the 
results and draw conclusions of value to all concerned. 
APPENDIX D (1) (a). 
RECORDS OF WATER SUPPLY AUTHORITIES 
(GRAVITATION SUPPLIES). 
By C. CLEMESHA SMITH. 
It is probable that many of the stream-flow records, etc., kept by water 
supply authorities are not in a form which would be serviceable to others 
than themselves. 
The regulating effects of impounding reservoirs, the existence of catch- 
waters, tunnels, and conduits which convey the whole or a portion of the 
yield of one catchment area to another, the delivery of compensation water 
either intermittently or continuously, the drawing at irregular rates of supply, 
all render it necessary that adjustments should be made if the yield of a given 
catchment area is to be arrived at. 
The records may be used in two distinct ways :— 
(a) To show the actual yield of the catchment area in such a form that 
it may be compared with the rainfall for stated periods, and, by subtraction, 
show the losses by evaporation and absorption. 
(6) The quantity which passes down the stream as compensation water 
and as unstored flood water. 
Water undertakings reasonably organised should generally be able to 
furnish the following data in respect of their catchment area :— 
Rainfall—The average rainfall over the area for each year, for each 
month, and for specific dry or wet periods. (Note.—Automatic recording 
gauges are fixed on a few catchment areas. An extension of their use is 
desirable.) 
