422 REPORTS ON THE STATE OF SCIENCE, ETC. 
2. SITE SURVEY AND WATER LEVEL GAUGE INSTALLATION.. 
Assume that a suitable site has been selected. 
A careful survey of the river bed and banks should be made above and 
below the gauging section. The zero for levels and the zero and direction 
of the gauging section should be fixed, for all time, by permanent stations 
on the banks which are included in the survey. 
The sites of the water level recording points have then to be settled. One 
of these will have to be the final station for the continuous records of water 
level. Another will have to be on the gauging site in order to give the depths 
of water during the gaugings. ‘This will have to be a permanent gauge if 
the water slopes are found to differ on the rising and falling river. 
The water level apparatus requires special consideration according to 
the nature of the site, but automatic recorders and gauge posts are necessary. 
When sufficient funds are available there is little difficulty in setting up 
permanent stations with float gauges; but in the moreordinary circum- 
stances it is best to follow the bank up with short gauge posts: or with a 
series of pipe-wells for the use of a hook-gauge. ‘The automatic takes the 
form of an air box in the lower well connected by a small diameter pipe to 
the clock-driven chart on the bank top. 
The site may now be considered as equipped with the necessary water 
level apparatus for the flow measurements and for the permanent records. 
3- FLow GauGING APPARATUS, ITS SETTING-UP AND USE. 
On rivers of any considerable width where floods are to be measured, the 
apparatus is the boat or punt or double-punt, with a cross river ropeway ; 
the velocities being measured by current meters on wire or rod. The 
writer and others have used the bos’n’s chair on a ropeway, and it is not satis- 
factory. A portable bridge with trestle piers on the lower part of the bank 
may prove best on narrower rivers. 
In the writer’s experience, accuracy of current meter observations is 
dependent principally on the use of a rod which holds the current meter 
steady to the point and depth ; readings then become uniform, even in the 
presence of considerable turbulence. 
The writer’s apparatus has been developed gradually. It is founded on 
a secure ropeway across the river which remains unchanged throughout the 
whole period of gauging work. It is easily transported, and is adaptable to 
most sites. The head lines of the double-punt are attached to a small 
trolley which is made to travel along the ropeway by means of an endless 
rope worked from a winch on the bank. The double-punt is steadied and 
held in position by another light wire rope across the river. ‘This rope 
passes round a drum fixed at the base of the frame which holds the gauging 
rod, and the strain on therope is regulated from the bank. An independent 
tally line marked at each 5 ft. is permanently stretched across the river 
about 2 ft. upstream of the actual gauging section. 
The double-punt used by the writer is very completely equipped for 
control from a small cabin. The operations are :— 
(1) Adjustment up and down stream on the head lines. 
(2) Adjustment to the tally line mark by revolving the drum. of the 
straining rope. 
(3) Adjustment of the current meter dan by raising or lowering the rod. 
Each punt is in two parts for ease of transport and launching. 
The principal point to emphasise is the use of the streamlined rod, which 
