Description of an improved Rain Gage. 327 
Fig. 4 & 5, Pl. 2. whose top and bottom are, each 10 inc 
This is all that is necessary for occasional experiments, as 
for instance, to determine the quantity of rain, snow or sleet, 
that may fall in winter when the evaporation is incon- 
siderable, or the quantity of rain that falls in a single show- 
er,atany otherseason. But to answer all purposes, it must 
be provided with a cover, in the centre of whichis inserted 
a funnel, whose top has the same area, as that of the top or 
bottom, of the prismatic vessel above. To prevent evapora- 
tion the orifice of the funnel is furnished with a valve against 
which a weak spring, attached to the inside of the cover, 
presses with a force just sufficient to close it, but which is 
overcome by the weight of a few drops of rain. It is evi- 
dent that in a shower the water will open the valve, and af- 
ter it has passed into the body of the gage, the valve will 
close the orifice again, suffering, however, the drainings of 
the funnel to pass along the pendant wire by cohesive at- 
traction. 
This top, with its funnel and appendages, may be fitted 
= the body of the gage, like the lid of a common tea can- 
ister, : 
The water being thus introduced into the gage, the 
method of determining its altitude in inches and decimal 
parts depends upon the following fundamental statements, 
'n connection with the simple operation of weighing the 
water in the gage. 
Fundamental Principle. 
A cubic inch of distilled, or rain water, under a 
medium pressure and temperature weighs 252.525 grains ; 
according to the latest corrections. ow this number, 
multiplied by 100, the area of the funnel, in square 
Inches, or that of the top, or bottom of the body 
ge, gives 252525 grains for the weight of 100 
cubic inches of water. Supposing this quantity of wa- 
