On Aerial Navigation. 129 



though a matter of the greatest difficulty, is by no meatis im- 

 possible. The principles are well worthy the attention of the 

 scientific mechanist, who would be most usefully employed in 

 clearing the way, by removing false principles. If he cannot 

 attain complete success, let him at least contribute any useful 

 hints, let him feel superior to the ignorant ridicule thrown 

 upon the subject, since no man of science ever touched a 

 question, and left it as he found it. 



The balloon, by being carried with the same velocity as the 

 current of air, wants what sailors call " head-way," or "steer- 

 age-way." Its indifference of position cannot be modified by 

 keel, rudder, or sail, unless it acquire a relative velocity with 

 regard to the current, unless it moves slower or faster than 

 the air in which it floats. If your readers have read of, or 

 thought of, any means of producing such an effect, even re- 

 motely plausible, except the following, it would be desirable 

 that they should appear in your Journal. 



1. It has been suggested, that by ascending and descending 

 while a plane attached to the balloon maintains given angles 

 to the current, the resolution of forces will enable us to make 

 some progress. The best method of bringing into action this, 

 and indeed all other principles for the guidance of these ma- 

 chines, will be to unite a larger and a smaller balloon by 

 means of a platform. This platfoi-m may be lowered or raised 

 at any angle, by sliding a weight towards that balloon which 

 we may wish to depress. That the principle of angular mo- 

 tion will be occasionally used, especially in calm weather, is 

 highly probable, whatever other means shall succeed ; but 

 that this alone will be effectual, can scarcely be expected. 



2. It has been proposed to connect the balloon with a lower 

 stratum of the air, of greater density and less velocity, so as 

 to retard the motion of the machine. This would allow us to 

 employ a keel, rudder, and sails ; and though we could not 

 proceed against the current, it would enable us to deviate a 

 few degrees to the right or left of the general direction. 



3. It has been proposed to act on the air, as the tail of a 

 fish acts on water, or as a single oar behind acts in the mo- 

 tion of a boat. The principle is not generally understood. 

 By resolution of forces it will appear, that when the animal 

 bends its tail, the tendency is to draw it back-ward. It is im- 

 pelled forward by rapidly jerking the tail to its first natural 

 position. The tail is bent sloxvli/, and unbent quicklt/; and 

 since the resistance varies nearly as the square of the velo- 

 city, the force forward is nmch greater than the force b.'ick- 

 ward. This shows how very nuiterial in the (juestion it is 



Vr)l. on. No. 5122. Feh. 1 825. R that 



