IN RAIN AND SNOW, IN THE UNITED STATES. 7 



two or three feet square, on which the snow is received. The place selected for 

 this purpose must be one where the snow has not been heaped up or swept away 

 by the wind, and where it presents, as near as possible, the mean depth of the layer 

 that has fallen. In order to take only the snow which may fall in the interval 

 between two observations, the board should be swept after each measurement, and 

 the place designated by stakes. The collected snow must be melted by placing 

 the gauge, covered with a board to prevent evaporation, in a warm room, and the 

 quantity of water produced measured by pouring it into the glass cylinder. The 

 rain water and melted snow water must be separately entered in the journal. 

 During abundant rain-falls it is well to measure the water more than once a day, 

 or at least immediately after the rain, and the quantity of rain fallen, together 

 with the time it has lasted, is to be noted. When it freezes, it will be necessary 

 to protect the receiver by filling in the interior of the barrel with straw." 



"A series of observations has been made at the Smithsonian Institution with 

 rain-gauges of different sizes and different forms, the result of which, as far as the 

 observations have been carried, is to induce a preference for the smallest gauges. 

 The one which was first distributed by the Institution and the Patent Office to the 

 observers (represented on p. 229 of the Secretary's Report for 1855), consists of a 

 funnel terminated above by a cylindrical brass ring, bevelled into a sharp edge at 

 the top, turned perfectly round in a lathe, and of precisely five inches diameter. 

 The rain which falls within this ring is conducted into a two-quart bottle placed 

 below to receive it. To prevent any water which may run down on the outside of 

 the funnel from entering the bottle, a short tube is soldered on the lower part of 

 the former and incloses the neck of the latter. The funnel and bottle are placed 

 in a box or small cask, sunk to the level of the ground, which is covered with a 

 •board having a circular hole in its centre to receive and support the funnel. To 

 prevent the rain-drops which may fall on this board from spattering into the mouth 

 of the funnel, some pieces of old cloth or carpet may be tacked upon it." 



" The object of placing the receiving ring so near the surface of th° earth, is to 

 avoid eddies caused by the wind, which might disturb the uniformity of the fall of 

 rain." 



" In the morning, or after a shower of rain, the bottle is taken up, and its con- 

 tents measured in the graduated tube, and the quantity in inches and parts recorded 

 in the register. The gauge or tube which was first provided for this purpose will 

 contain when full only one-tenth of an inch of rain, the divisions indicating hun- 

 dredths and thousandths of an inch. As this, however, was found to be too small 

 for convenience, another gauge which contains an inch of rain, and indicating 

 tenths and hundredths, was sent to observers." 



Another and simpler form afterwards adopted by the Institution and Patent 

 Office is one of those which have been experimented on at the Institution. It is 

 a modification of a gauge which was received from Scotland, and which has been 

 recommended by Mr. Robert Russell. It consists (see figure on p. 230 of the 

 Secretary's Annual Report for 1855) of a large brass cylinder two inches in dia- 

 meter, to catch the rain ; a smaller brass cylinder for receiving the water and reduc- 

 ing the diameter of the column to allow of greater accuracy in measuring the height ; 



