TRANSACTIONS OF SECTION G. 81 b 



on any apparatus which floated in, and with, one medium. Yet it is thisvery 

 principle which I wish to advocate, and to state broadly a method by which I 

 believe we might sail through the air, which depends upon threewell-established 

 facts. First, a Inte retained by a string will ascend when a wind is pressmg on its 

 under surface, and will raise a considerable weight. Secondly, in the absence of 

 wind, the same eiiect may be produced by drawing along the kite through still 

 air. I have myself been lifted by a large kite under such circumstances. Thirdly, 

 by balloon ascents, observations on clouds, mountain records, and especially obser- 

 vations on high places as the Eiftel Tower, it has been found that the wind almost 

 invariably increases in velocity the higher we get, so that the currents of air 1,000 

 feet up move about three times as fast as those below. It follows from these prin- 

 ciples, that if two kites connected by a long string, so arranged that one floats in a 

 current of air blowing at a diflereut rate (or different direction) from that in which 

 the other floats, there will be a reciprocal action, the kite in the lower medium 

 being supported by being drawn along by the kite in the higher stratum, which in 

 its turn is kept aloft by being retarded by the other. 



A kite of 1,000 square feet area is capable of supporting a man in a breeze of 10 

 miles an hour, or when being towed at that rate through calm air. If the wind 

 near the surface of the earth be blowing at this rate (rather below the average), it 

 will usually be travelling at 30 miles per hour at an elevation of 1,000 feet. 



With two such kites connected together by a long rope, with a car attached to 

 the rope near the lower kite, if the lower one be drawn along 10 miles an hour 

 faster than the wind, it will support a man, and travel at a rate of 20 miles an 

 hour. But if the upper kite travel at this rate it will be retarded to an extent of 

 10 miles an hour, and hence the whole apparatus will float along with the wind. 

 In this way we might make a light apparatus for navigating the air. The extent 

 to which it might be steered out of the wind's course, practice alone can determine, 

 but even if this be not much, we still should have an air-ship possessing very many 

 advantages over a balloon, and to which propelling agents could be much more 

 easily applied. 



9. Receiver and Condenser Drop, By Professor A. E. Elliott. 



