On theprefent State of Aerojlation. 27 



face to the wind, being attached by a long rope to a boat, 

 would outftrip the qiiickeft veflel, and might alfo be made to 

 deviate from the courle of the wind ; as the water would form 

 aconnter-refilting medium, the want of which in air-balloons 

 occafions the difficulty of (leering them. A fail-balloon fimilar 

 to the above might alfo be advantageoufly attached to a land- 

 carriage ; namely, by increafing the capacity of the balloon lo 

 that its power of afcenfion being nearly equal to the weight of 

 the appended carriage, the latter would be drawn along by 

 the impulfion of the wind againil the balloon and fails, while 

 the fridion over the ground, by the fmall overplus weight, 

 may be reafonably expe6fed to afford a refiflance fufficient to 

 guide the machine, and allow of a deviation in the carriage of 

 at leaft eicht points from the courfe of the wind *, 



To whatever degree of perfedion aerial navigation may 

 attain, the limits to which a traveller might foar will for ever 

 be confined to but a fmall diftance, even fuppofing that man 

 could exift in any ftation of the aerial regions however ele- 

 vated. The denfity of the atmofphere decreafing in a geo- 

 metrical proportion, it will be found that, if a fphere of (hect 

 copper t, of half a pound to the fquare foot, were conftrufted 

 of equal diameter with our earth ( 7920 miles), and totally 

 exhaufted of its inclofed air, fuch a globe would attain its 

 equilibrium at 70-047346 miles diftance from the furface of 

 the earth; nor would "it attain a greater elevation, although 

 its power of afcenfion at the inftant of departure would be 

 equal to 2871691637967270771712 pounds. 



The application of aeroftatic machines to-the advancement 

 of our knowledge of the various phaenomena in meteorology, 

 flands prominent, as the, perhaps, only means of maturing 

 our acquaintance with caufes yet known only by their effefts. 

 Their ufe will alfo be indicated in many urgent cafes where 

 other means of conveyance might fall fliort. At the fame 

 time I conclude with remarking, that the hitherto unfuccefs- 



* A land carriage to be moved by the wind is not a new contrivance : 

 a machine of tliis kind, rigged in aJl refpefts like a (loop, ufed occafionally 

 to be experimented upon on Barham Downs, near Catittrbury : the car- 

 riage being of a light conllrudlion, and containing two peifons, was found 

 capable of running a mile in three minutes and a half, upon level ground 

 and with a fair wind. Whether it could furmount the occafional nregu- 

 larities of a conimoa road, or deviate in any mcafure from the wind, I do 

 not now rccoiieft. 



t If metallic aeroftats were ever to be connru£ted agreeably to the fcheme 

 of the jefuit Francis Lana, means might be found to cxhauft them : but 

 to prevent their being crufiied together by the preirure of the atir.ofphcrc 

 would be more difficult to acccmplifli! 



ful 



