THE SMITHSONIAN INSTITUTION. 



229 



Fig. 10. 



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quantity of the rain fallen, together with the time it has lasted, is to he 

 noted separately in the column of remarks. 



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 have been made at the Smithsonian Insti- 

 tution with rain-gages of, different sizes and different forms, the 

 result of which, as far the observations have been carried, is to induce 

 a preference for the smallest gages. The one which was first dis- 

 tributed by the Institution and the Patent Office to the observers, is 

 represented in Fig. 10. It consists of the funnel a, terminated 



above by a cylindrical brass 

 ring, bevelled into a sharp edge 

 at the top, turned perfectly 

 round in a lathe, and of pre- 

 cisely five inches diameter. The 

 rain which falls within this 

 ring is conducted into a twQ- 

 quart bottle, h, placed below to 

 receive it. To prevent any water 

 which may run down on the 

 outside of the funnel from en- 

 tering the bottle, a short tube 

 is soldered on the lower part of 

 the former and encloses the neck 

 of the latter. The funnel and bottle are placed in a box or small 

 cask e, e, sunk to the level of the ground, which is covered with a board 

 d, d, 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, c, c, may be tacked upon it. 



The object of placing the receiving ring so near the surface of the 

 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 contents measured in the graduated tube/, and the quantity 

 in inches and parts recorded in the register. The gage, or tube, 

 which was first provided for this purpose, will contain, when full, 

 only one-tenth of an inch of rain, the divisions indicating hundredths 

 and thousandths of an inch. As this, however, is found to be too 

 small for coijvenience, another gage, which will contain an inch of 

 rain, and indicating tenths and hundredths, will be sent to observers. 

 Another and simpler form of the gage has since been adopted 

 by the Institution and the Patent Office, to send by mail to distant ob- 

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

 Institution, and is a modification of a gage which we received from 

 Scotland, and which has been recommended by Mr. Pvobert Eussell. 



