42 PROCEEDINGS OF THE AMERICAN ACADEMY, 



Figure 4, plotted from Table III, represents the highest flight of the 

 meet, that of Brookins on September 10, at an average rate of about 

 100 feet per minute. From 5'* 43™ to 5" 57™ the transits were tempora- 

 rily assigned to Grahame-White in a Farman biplane, who was far off 

 the course to the southeast and could not be frequently observed by 

 the sextants, while the latter instruments were sufficient for the obser- 

 vations of Brookins, who was describing large but regular circles above 

 the field. At 5^* 52™ Grahame-White was cut off" from view at Milton 

 by a large tree which lay farther off" the course than it was supposed 

 that any aviator would go in an altitude attempt, and the transits 

 were turned back upon Brookins. 



The single sextant observation of Grahame- White's descent, however, 

 combined with the fact that his usual rate on the beginning of the 

 downward spiral was at least 800 feet per minute, enables us to fill out 

 the dotted part of the curve, and conclude that he reached a height of 

 approximately 2200 feet. A comparison of all the curves shows that 

 if the highest point of the ascent is not actually observed by the tran- 

 sits, it may always be closely fixed by the intersection of the upper 

 portions of the curves of ascent and descent. 



The spiral of Brookins in this flight is shown in Figure 5. In the 

 long interval between points 5 and 6, when the transits were turned 

 upon Grahame-White, the general curve of the spiral, however, is 

 plainly shown by the sextant observations, although the aviator 

 changed the direction in which he was circling the course, apparently 

 in order to make his crossings against the wind. 



Figure 7 shows the time-altitude curve of Brookins on September 8, 

 when he was lost to sight in a light cloud for five minutes at an alti- 

 tude of 1500 feet, climbed another 500 feet and disappeared a second 

 time, when he stopped his engine, descending to the 1 500 foot level 

 again out of the cloud, and then taking a somewhat diff"erent line of 

 flight, ascended without further difficulties to a height of nearly 4000 

 feet. The conditions were such that the early part of the spiral was 

 not well determined, and it does not seem worth while to reproduce it 

 here. The main features are shown on the ground plan which is shown 

 on the map of Plate 1. The very discordant sextant observations at 

 5^ 19™ and 5^ 22™, shown in Figure 7, are unexplained. The former 

 was made with the machine about 1000 feet south of the southern 

 station, nearly overhead, and moving in a course nearly parallel to 

 the line, so that the vertical angle was changing very rapidly, and the 

 observation difllicult. 



No such cause can be assigned for the second error, and it is perhaps 

 more probable that both were caused by some accidental disturbance 



