2 THERMOMETER. 



a distance of from twenty to twenty-four inches from the panes. 

 At half this distance, ten or twelve inches from the panes, and 

 at the height of the eye of the observer, when in the chamber, 

 pass from one piece of board to the other two small wooden 

 transverse bars (c d, c' d'), each an inch broad, for the purpose 

 of supporting the instruments. Upon the outer edge of the 

 boards fasten, in the usual way (H H), the latticed blinds which 

 were removed from the jambs, or two others provided for the 

 purpose. That blind behind which the instruments are to be 

 placed, is to serve as a screen, and must be fastened, almost en- 

 tirely closed, so as to make a little more opening ; the other will 

 remain entirely open, to allow a free access of air and light, and 

 is not to be closed except in great storms. The whole must be 

 covered with a small inclined roof of boards (B E), placed at 

 least fifteen or twenty inches above the instrument. The lower 

 part (J J), or the basis, may remain open. 



Fig. 1. 



View from the outside. 



[The foregoing is a convenient arrangement by which the ob- 

 servations can be taken without exposing the observer to the 



