WILLSON. — ALTITUDE OF AEROPLANE FLIGHTS. 



27 



tee room at the grandstand by a telephone line devoted to this use 

 alone. A chart, shown about one eighth size (Figure 1), was at hand 

 from which the height corresponding to simultaneous observations of 

 the altitude at either end of the base could be read off. 



The abscissas and ordinates represent the angles iVand /S' respec- 

 tively, and the curves give the values of ^ for each 100 feet, computed 

 from the above formula. The scale was one quarter of an inch for 

 each degree of X° or *S'°, and on this scale it was not difficult to read 

 with an error of less than ten feet up to altitudes of 15,000 feet. 



00 

 80 



70 



GO 

 50 

 40 

 30 

 20 

 10 







10 



•20 



30 40 



50 



GO 



70 80 00 100 110 120 



Figure 1. Chart for determining approximate altitude from sextant obser- 

 vations. 



This chart was not used, as was expected, to give out the altitude a 

 few seconds after each crossing, since the committee deemed it wiser 

 not to make any announcements of altitudes till the end of the day. 



The Distant B.\se. 



As a check on the observation at the field, and in order to give data- 

 for a closer investigation of all the circumstances of the flight, a second 

 base was occupied lying nearly east and west, about two and a half 

 miles south of the aviation field. Satisfactory stations were found, one 



