220 



L. HARGRAVE. 



rotates slower, draws in less air past the guide and restores the 

 equilibrium. 



8. Some of the discharge from the race may pass into the dead 

 air to windward of the hook and so over the top of the soaring 

 curve, or if the dead air space is filled up solid with part of the 

 material of the soaring curve the whole discharge is carried under 

 the vortex and may or may not be drawn in again between the 

 vortex and the guide. The discharge cannot mingle with the 

 air of the vortex, as every circumferential particle of its air is held 

 at a fixed distance from the centre by the tenuity of the vacuum. 



9. The lower front quadrant does not add to the head resistance 

 as it is rotating to leeward nearly as fast as the relative wind. 



10. The after part of the soaring curve if it extends to leeward 

 of the divide acts as an aero-curve. 



On October 20, 1898, the wind was about seventeen miles per 

 hour, and it was found that Kite N could be loaded with lead to 

 a total weight of 3*6 lbs. on 1*69 square feet = 2-13 lbs. per square 

 foot, and that when so loaded it would rise at an angle of 70° or 

 80° to windward until it was fifteen feet from the sand, it then 

 got into wind of greater velocity and drifted to leeward. Here I 

 am confronted with a difficulty that at present is unsurmountable. 

 Either the soaring machine must be started from such a height 

 that the weight can be approximately adjusted to the existing 

 wind; or, the weight must automatically adjust the negative angle 

 of the propeller as the wind increases. 



Kites O (Figs. 11, 12), P (Fig. 13), Q (Fig. 14) have a different 

 system of adjustment and suspension of the weight. A piece of 

 •§" tube is secured rigidly to the propeller and nearly parallel to 

 its chord. The connection between the tube and propeller in O 

 and Q is a steel plate ^f" x iV' and long enough to keep the weight 

 at the required distance below the propeller. The weights are 

 lead cylinders J" diameter and about 1J" long. A sufficient 

 number are strung on a £" wire. The adjustment of the position 

 of the weight is effected by pushing the string of weights in or 



