284 Scientific Proceedings, Royal Dublin Society. 
the rain-water. It delivers its catchment into separate bottles for 
the most part (if the rainfall is at all considerable); and by simply 
varying the dimensions of these bottles, they may be arranged to 
receive the rain in various fractional parts. Thus the first one- 
tenth inch of rainfall may be automatically delivered into the first 
bottle, the second tenth into a second bottle, and so on. Or the 
second bottle may be of such dimensions as to receive the subse- 
quent two-tenths of an inch or three-tenths, and, in short, any one 
of the receiving bottles arranged to take up any desired number 
of tenths of an inch rainfall. Again, the basis of the fractionation 
may be one-twentieth of an inch rainfall, and any number of 
successive twentieths arranged to collect in each bottle or in any 
one of the bottles. 
How this is effected will be seen by reference to the accompany- 
ing diagram. The catchment basin or funnel of the rain-gauge is 
lettered c, and appears at the top of the gauge. This discharges 
through a narrow tubulure into the wider tube ¢, which, in turn, 
communicates with the receiving reservoir a. In the figure this 
reservoir is shown as provided with two siphons only. It will 
presently be seen that this suffices to effect, in general, a three-fold 
division of the rainfall received. 
Two other vertical tubes, ¢’, ¢’, support the siphons, which are 
shown dipping to the bottom of the bottles 1 and 2 placed beneath. 
The bend or turn-over of the one siphon (that communicating 
with bottle 1) is at a lower level than that of the other. The only 
peculiarity in the construction of these siphons is the use of a 
wide-mouthed bell-shaped or thistle funnel suspended on a short 
length of rubber tubing, to form the shorter leg of the siphon. 
The rubber tubing hangs vertically within the tubes /’, and may 
be about five or six inches in length. 
The action is as follows:—As the rain collects in the reservoir, 
it at length fills this, and rises in the siphons and in the central 
tube till the lower siphon comes into action and runs the whole 
contents of the reservoir in bottle 1. If the reservoir is of such 
dimensions as to fill when one-tenth of an inch rainfall has been 
received in the funnel above, evidently this first bottle receives the 
first tenth of an inch rainfall. 
The reservoir being now empty, and assuming for the present 
that the siphon, which has just operated, is again completely filled 
