■WTLLSON. — ALTITUDE OF AEROPLANE FLIGHTS. 



43 



of the vertical plane of the sextant which affected the two observations 

 alike. No other discrepancy approaching this in amount occurred in 

 in the whole course of the observations. 



Figure 7. Time-altitude curve: Brookins (Wright biplane), September S. 



It remains to make grateful acknowledgment of the skill of the 

 observers and of the interest of many others, without which this 

 work would have been impossible ; especially of the assistance of 

 Mr. William Hunt in the observations and reductions, and in drawing 

 the curves which illustrate this paper. 



Students' Astronomical Labor.\tory, 

 Harvard University. 



