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LX. Experiments tending to prove the Pnssibilily of causing 

 Bnllooits to deviate cnnsidera/hj from the general Direction 

 of the Current of fVind iv/tick carries Ikem along in the At- 

 mosphere. By Mr. John Evans, Jun. 



To Mr. Tillach. 



Sir, — JL HE numerous metliods hitherto proposed for guiding 

 balloons h.'ive so totally failed, that philosophers of the present 

 day seem much inclined to regard the solution of the problem as 

 an impossibility. The writer of the present paper is fully aware 

 of this circumstance; and, in offering to your notice a plan which 

 he lias had the satisfaction to see attended with success, cannot 

 but express his wish that no position here advanced should be 

 received, unless it be evidently founded on the laws of mechanics, 

 or directly proved by experiment. 



The first object ought certainly to be the discovery of a 

 moving power sniiicientiv great to overcome the vast resistance 

 which a balloon experiences from the air. Indeed, the failure of 

 all the experiments winch have been m.ade with oars, is evidently 

 to be attributed to the very trifling size of the machinery and 

 the smailness of the force employed on it. In the present plan, 

 the ascending and descending forces, or in other words its levity 

 and gra'^ity, are alternately the moving powers. It is evident 

 that these forces are sulhciciitly powerful. It will, however pro- 

 bably be urged that tiie ascending and descending forces always 

 act perpendicularly, and hence cannot be of any service in the 

 present iixjuirv. That tliese forces always act perpendicularly 

 is readily granted, but it by no means follows that the motion 

 which they cause the balloon to assuuie sliould be in a perpen- 

 dicular direction. The direction of the motion is regulated by 

 another cause, viz. the form of the resisting surfiice ; and hence, 

 spherical l)alloons having their form perfectly unifoim on all 

 sides must necessarily ascend perpendicularly. Now the princi- 

 ple of the present invention consists in applying a resisting sur- 

 face in such a manner as to cause the ascending or descending 

 motion of the balloon to deviate by a considerable angle from 

 a perpendicular direction. This was attempted and accom- 

 plished by a method v.hich I now proceed to describe. 



A sip-iii-e plane ABCD (fig. 1, PI. VI.) is formed by extending 

 paper or linen on the cross constructed of the slight pieces of 

 wof)d AC and BD. This plane is attached to the balloon by 

 strings adjusted so that the diagonal BD shall constantly lie 

 parallel o the horizon, whilbt the other diagonal AC may be 

 placed at any angle whatever. A small triangular sail E is also 



Vol. 4(5. No. 211. Nov. 1815. X applied 



