CHRISTEN S HYPSOMETER. 



23 



the triangles with the sides 11 II D and /• // d ; that is to say, 

 the followino; equation holds good : — 



and 



d:h=D:H 



Fig. 16. — Christen's Hypsometer. 



If, therefore, the units of the scales, which give h and d, are 

 of the same size, and d is so fixed that its units are the same 

 number as the units of the measured distance D, it follows, 

 that the above formula gives the height. 



Christen's Instrument. — It consists of a piece of metal (see 

 Fig. 16) with protruding upper and lower edges (see a and 1)) 



