418 REPORTS ON THE STATE OF SCIENCE, ETC. 
according'to rainfall and season. ‘This intermittent stream forms the upper 
reaches of the River Ems. 
Weekly water levels are available from 1893 to 1930, and the record is 
still being maintained (February 1933); there are, however, gaps in the 
record prior to 1898. Also, prior to 1903, the measurements were made 
at another well in the near vicinity. 
Rainfall records at the same site are available for the whole period ; also, 
since 1920, a percolation gauge, recording percolation through 3 ft. of chalk, 
has been maintained. 
An examination of the well-record shows that during dry periods there 
is, at any given level, a maximum rate at which that level falls, and that this 
maximum rate decreases as the level itself decreases. By piecing together 
these maximum rates a ‘ dry weather depletion curve’ can be established > 
when the observed rate of depletion is less than that shown by the curve, 
or if the level is actually rising, the difference is ascribed to percolation : 
The curve, therefore, can be used to analyse the record into two components, 
(1) depletion by underflow, and (2) replenishment by percolation. It is: 
also found that there is a direct relation between the vertical displacement 
of the ground-water level and the effective percolation, by means of which 
the fluctuations can be converted into rainfall units. 
The water levels are normally lowest in the late autumn, when percolation 
is negligible. If the record is divided into periods of nine to fifteen months, 
according to the date of recommencement of the annual percolation cycle, 
it is found that the percolation figures, as measured by the subsoil gauge 
and as calculated from the water levels, are in close agreement. It is also 
found that the annual evaporation loss, after excluding the effect of ground- 
storage, is nearly constant. 
APPENDIX £ (6). 
THE SOUTH STAFFORDSHIRE WATERWORKS COMPANY. 
DESCRIPTION OF METHODS FOR OBTAINING WATER LEVELS IN 
WELLS AND BOREHOLES. 
By F. J. Drxon. 
In the case of shallow wells the water level is usually obtained by direct 
measurement with a wooden float and cord, or if permanant apparatus is 
desired then a copper float with a flexible metallic cord working through 
either pulleys or geared reducing apparatus indicates the water level. 
The actual indication at the surface can be shown on a graduated gauge 
board or a dial, but if a permanent record is desired then.a recorder in 
which the movement of the chart is synchronised with a clock is the best. 
Usually these recorders are made to give a seven-day record, but a shorter 
or longer period chart can be used if the recorder gears are arranged to suit. 
For deep wells float gears are not so suitable and in boreholes their use 
is impracticable. 'The two most suitable methods are the direct measure- 
ment method by galvanometer and the pneumatic system reading either on 
a gauge or recorder, 
The galvanometer consists of a rubber-covered single or double core 
cable on a drum fitted with handle for winding up the cable. At the loose 
end of the cable is a sinker with brass contact, which is connected to the 
cable and covered with a vulcanite sheath, having a hole in the bottom and 
a small vent hole at the level of the contact.’ In the case of the double-core 
