WILLSON. — ALTITUDE OF AEROPLANE FUGHTS. 



29 



given point or line. If thus restricted, the Bldriot monoplane espe- 

 cially is at a disadvantage, as its construction renders it extremely 

 dilHcult for the operator to see the ground at points anywhere near 

 directly beneath him. The discussion of his ascending spiral, checked 

 by observations of his descent, fixes his highest point c^uite accurately 

 without placing any burden upon the aviator himself. (In reference 

 to this point, see the flight of Grahame- White discussed on p. 42.) 



The character of the results obtained may best be shown by the 

 records of some of the flights and the methods of discussing them 

 which follow. 



To illustrate the whole process, we may take the observations of tho 

 flight of Brookins, September 12, the last day when any considerable 

 flight was made, and at a time when the observers had had several 

 days of practice. No great altitude was reached, but the flight was in 

 many respects typical, and exemplifies some of the advantages of the 

 two methods used, as controlling and checking each other. 



TABLE I. 



Flight of Brookins, Sept. 12, 1910, as Measured by Sextants. Base 

 Line, Distance between Stations, 5000 feet. Sextants 9 feet above 

 Course. 



If the angular altitudes at the two stations are X° and .S"" res])ec- 

 tively, and the length of the field base r>()<K) feet, the altitude in feet, 

 fi, given in column 7, is computed by the expression 



