and its Discharge hy Drains. 
147 
simple. It consists of an open-top cylinder or rain-receiver sunk 
vertically in the earth level witli its surface, having a false bottom 
perforated with holes, like a cullender, which supports three feet 
depth of soil within the cylinder, through which, and through the 
cullender, the excess of the rain — or the portion not evaporated 
— filtrates to the close bottom of the vessel ; and this commu- 
nicates, by means of a small pipe, with a vertical tube, whose 
diameter bears some definite proportion to that of the receiver, 
and is sunk so much lower in the earth as to have its top nearly 
on a level with the bottom of the receiver. Thus, all the water 
which permeates the soil contained within the rain-receiver flows 
into the tube, and is measured by a float carrying a divided stem, 
and indicating, in parts of xo^o^th of an inch, the quantity of rain 
which has entered it. The measuring tube has a cock at the 
bottom for evacuating its contents from time to time, and bring- 
ing the scale to zero. 
Mr. Dickinson's rain-receiver has a diameter of 12 inches, and 
is 36 inches deep to the false bottom ; it was originally filled with 
the soil of the country, a sandy gravelly loam, and has constantly 
had grass growing on it. The contents of the receiver, therefore, 
represent fairly the natural state of such soil ; whilst the gauge 
indicates the quantity of water which a drain, at a depth of 3 feet, 
would have to convey away. The proportion which this quantity 
bears to the rain is obtained by comparison with the rain-gauge ; 
and their difference gives the quantity evaporated, assisted by the 
action of the succulent grasses. We may, however, for the present 
purpose, consider the whole of this last quantity under the term 
evaporation. 
It will be interesting and useful to agriculturists to learn Mr. 
Dickinson's object, as a manufacturer, in ascertaining and regis- 
tering phenomena of this nature. Having several mills on the 
river Colne or its tributaries, it was a matter of importance to him 
to be able to calculate the power of water on which he might 
depend for use at different periods of the year ; and having noticed 
that a considerable period elapsed after rain, owing to the extent 
and stratification of the country, before the springs were affected 
by it, he fixed a rain and Dalton gauge to assist his judgment in 
forming an estimate of the amount and duration of their flow ac- 
cording to the varying seasons, and the proportionable water- 
power on which he might count. These registers, combined with 
observation, liave since enabled him to regulate his manufac- 
turing oj)erations, and to foresee what dependence he could place 
on the mill-streams, and to what extent he should require the aid 
of steam-power for fulfilling his contracts and engagements. This 
is a very remarkable and honourable instance of the application 
of meteorological " science to practice." 
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