AERONAUTICS. 55 



"AERONAUTICS.' 

 By L. Hargrave. 



[Bead before the Royal Society of N. S. Wales, June 1, 1898.'] 



Since the paper on the possibility of soaring in horizontal wind 

 was read, no efforts have been spared to determine the essential 

 features of curved surfaces that are of any practical utility to 

 aeronautics, and the models shown in Figs. 1 and 2, embody what 

 is known to date. The poles and horizontal cord have been found 

 a most useful method of experimenting; indeed it may safely be 

 said that without them the trifling amount of available wind 

 would have been quite inadequate to find out anything new. As 

 suggestions to those who wish to advance this matter rapidly, it 

 may be stated that the wind near the ground is comparable to the 

 surf on the sea shore, which all will admit is not suitable for 

 testing the sailing capacity of yachts or boats. To utilize wind 

 from all directions, a platform of wire netting should be placed 

 in a situation like the top of the shearlegs on Garden Island. 

 The top of a building, cliff or rugged mountain would be unsuitable, 

 as walls and vertical surfaces merely create the aerial breakers 

 which it is the wish of the experimenter to avoid. 



It is well at this point to have a distinct understanding that 

 soaring is quite different from kite-flying and gliding. In gliding 

 as practiced by Lilienthal and others, a free apparatus descends 

 from an eminence and its fall is more or less retarded by the air 

 on which it slides. In kite-flying, a weight attached to the earth 

 is raised and supported by the wind sliding under it. In soaring, 

 the mechanism is unattached to the earth, and maintains its 

 elevation by using as a motor the vortex that its peculiar shape 

 generates. Most people would at once say the last statement 

 involves perpetual motion, and therefore is not worth considering; 

 a few will see that a ball retaining its position in front of a nozzle 

 against gravity and the downward thrust of a high-pressure jet 



