V. RAIN GAUGES. 697 



V. RAIN GAUGES. 



2847. Rain Gauge. In use at meteorological stations belong- 

 ing to the Norway Meteorological Institute. 



Prof. H. Mohn, Christiania. 



Square surface, 15x15 centimetres, height 50 centimetres, for catching 

 snow ; the lower part protected against evaporation. The rain (or melted 

 snow) water is to be poured out of the gauge through one of its upper 

 corners, into a measuring cylindrical glass, divided to show the height of fallen 

 rain in millimetres. The gauge is made of plate iron, after design made hy 

 Professor H. Mohn. The measuring glass was calibrated at the Meteorological 

 Institute, in Christiania. 



2848. Bain Gauge, No. I. Scottish Meteorological Society. 



Designed to obviate errors due to out-splashing and in-splashing of rain 

 drops. Designed by Thomas Stevenson, C.E., F.R.S.E., Honorary Secretary, 

 and described in the Edinburgh Philosophical Journal, 1842. 



2849. Jagga's Bain Gauge, No. II. 



Scottish Meteorological Society, 



The principle of this gauge consists in making the diameter of the funnel 

 equal to 4 '637 inches, so that a fluid ounce of the rain-water collected equals 

 one-tenth of an inch of rain. Designed by G. V. Jagga, Rao of Vizagapatain, 

 and introduced to the Society by Sir Walter Elliot, Member of Council, and 

 described in the Society's Report, quarter ending June 1861, p. 9. 



2850. Marine Bain Gauge. 



Scottish Meteorological Society. 



This instrument is composed of a cylinder poised on an upright pivot 

 projecting from the bottom of a square box, enclosing the whole, having the 

 top open to the atmosphere. The cylinder is divided into two parts, an upper 

 one having a diaphragm to collect the rain, and the lower, the receiver for the 

 same having a conical floor inside in which works the pivot below. The 

 horizontal bearing of the gauge is thus maintained in all cases of the rolling 

 and pitching of the vessel by the motion on the pivot. 



2851. Bonalds' Bain and Vapour Gauge, erected at the 

 Kew Observatory in 1843. 



Kew Committee of the Royal Society. 



An instrument constructed at the Kew Observatory in 1843, by Mr. Francis 

 Ronalds, for indicating a mean result from the quantity of water which may 

 have fallen between any two given periods, minus the quantity of vapour 

 A?hich has evaporated in the same time, on and from a circular plane of one 

 foot diameter. It is described in the British Association Report for 1844. 



It consists of two cylindrical vessels, connected by a tube, the one being 

 one foot in diameter, and open at the top, whilst the other is 3 inches, and 

 (with the exception of a small hole) entirely closed by a cover, which car- 

 ries a frame, holding a circular divided arc, with an index moving over it. 

 The index is attached to a small pulley, over which a cord passes, having 

 its end fixed to the float in the cylinder. This, rising and falling with 

 the changes of water level, indicates the amount of rain or evaporation on the 

 metal scale. 



