DIKECTIONS 



FOB 



METEOROLOGICAL OBSERVATIONS, 



ADOPTED BY THE SMITHSONIAN INSTITUTION 



THE following directions were originally drawn up for the use 

 of the observers in correspondence with the Smithsonian Insti- 

 tution, by Professor GUYOT, of the College of New Jersey, 

 Princeton, and are now reprinted, with a series of additions, for 

 more general distribution. The additions are indicated by 

 brackets, [ ]. 



SECRETARY S. I, 



PLACING AND MANAGEMENT OF THE INSTRUMENTS. 

 THERMOMETER. 



Placing. Place the thermometer in the open air, and in an 

 open space, out of the vicinity of high buildings, or of any ob- 

 stacle that impedes the free circulation of the air. It should be 

 so situated as to face the north, to be always in the shade, and 

 be at least from nine to twelve inches from the walls of the build- 

 ing, and from every other neighboring object. The height from 

 the ground may be from ten to fifteen feet, and, as far as possible, 

 it should be the same at all the stations. The instrument should 

 be protected against its own radiation to the sky, and against 

 the light reflected by neighboring objects, such as buildings, the 

 ground itself, and sheltered from the rain, snow, and hail. The 

 following arrangement will fulfil these requirements (Fig. 1) : 



Select a window situated in the first story, fronting the north, 

 in a room not heated or inhabited ; remove the lattice blinds, if 

 there be any, and along the exterior jambs of the window place 

 oerpendicularly two pieces of board (a b a' b f ), projecting to 



1 



