44 Mr James Straton on the Rain-Gauge. 



gauges. But the shape has also much to do in the matter 

 as well as the size of the receiver ; and this is the next par- 

 ticular we will glance at. 



Shape or Form. — If we take a number of vessels of different 

 shapes and sizes — say a soup plate and a flat one, a tea cup and 

 saucer, a wash-hand basin, a washing-tub of the largest size, 

 a strong ale-glass, and a lady's thimble — if we take these and 

 arrange them level, a foot or two from the ground, in the 

 field or open plain where wind has free scope every way, we 

 may test the question of efficient size and shape of the rain- 

 gauge to any extent. When the drops of rain and the snow 

 float gently down in the calm, all are equally efficient, all re- 

 gister quantity in proportion to the area or surface expan- 

 sion ; but when the wind, " blowing great guns," drives the 

 dry snow over the plain, all are equally useless, excepting 

 the ale-glass and thimble. 



This needs only to be considered for a little to be assented 

 to and appreciated. The plates will remain empty, and the 

 saucer nearly so (the particles being blown out as fast as 

 they are blown in), the basin will not be so full as the cup, 

 and the washing-tub will have little more in proportion to 

 its size than either the basin or saucer. The whirl which 

 carries the particles from the crested bank to the next one, 

 some 50 or 100 yards off, is about as efficient in emptying the 

 tub as the plate, but the limited opening of the glass or the 

 thimble annihilates the whirl of the wind as effectually as 

 the cage arrests the gambols of the imprisoned elephant ; all 

 the particles that enter the orifice drop quietly down, and 

 render their account when called on. 



Of the various shapes of gauges in use — square, round, 

 and oblong — I much prefer the round. I have not indeed 

 tested the square forms in every variety to be able to pro- 

 nounce definitely on their merits, but all of them seem to be 

 peculiarly objectionable, from the amount of commotion or 

 deflection caused in the passing stream of air, compared with 

 that caused by a round, or cylinder of the same diameter. 



I have already shewn the noxious effects of commotion in 

 and about the gauge so fully as to have demonstrated, I pre- 

 sume, that the form and size of instrument which creates 



