a6 On the pre/ent Siafe of Aerojlathn. 



dtftended by its preflure on the cylinder of air immediately 

 beneath it. 



With refpeft to the probabilitv of direfting aeroflatic ma- 

 chines *, we may infer it to be polfible, although the methods 

 hitherto tried have been inadequate; perhaps becaufe they 

 were not fufficiently powerful ; as, to expetl to make fo large 

 a body as a balloon to vary from the wind bv the impulfion 

 of an oar of fix or eight feet in length and one or two in 

 breadth (and t,hat by only endeavouring to draw the car out 

 of the perpendicular), is to expert, by means of a boat's oar, 

 to impel a fliip of burthen. Oars are doubtlefs the nioft likely 

 means to effe£t this purpofe, if they were of dimenfions pro- 

 portionate to the effefts they are wifhcd to produce f. The 

 addition of fails, where any variation from the wind is de- 

 iired, will prove injurious till we have attained a method 

 (perhaps only to be accomplifhed by oars) of keeping the 

 fiime point of the balloon continually in a given direction. 

 Yet I doubt not but thefe alfo might prove of great fervice in 

 quick difpatches by water; as, for inRance, where it is re- 

 quired to pafs a fortrefs or fleet for the fuccour of a befieged 

 town, or convey difpatches thereto : a fmall balloon, of ten or 

 twelve feet diameter, provided with fails to expofe a large fur- 



* 'Tis a matter of furprife, that the various hints for diiefting balloons 

 appear to lie dormant with their projeiftors, who feem indiCpofed to make 

 a:iy attempts to carry their plans into execution : thus the inventions of 

 piofcffor Danzel (Philofophical Magazine, vol. iv.), alfo of Martin, and 

 the proppfais for performing the fame by means of eagles trained for the 

 purpofe; or by a reverfed parachute to retard the dircft progrefs of the 

 balloon, whereby Icfs powtr will be neceffary to impel it in a lateral di- 

 reftion ; all thefe planh remain obfolete and unpradVifed from the tinne of 

 their fuggcftion. 



f According to the prefent mode of rowing balloons from the car, 

 whatever deviation is made may be compared to the lee- way of a fhip at 

 fea ; the power being applied fo as merely to pievent at a certain inftant 

 the car from following the balloon, which will therefore be impelled, 

 during tiiit ihort interval, in a barely diagonal direflion amounting per-» 

 liaps, in the end of the voyage, to fcarcely half a point from the wind. 

 For oars to ptoducc their full effcft they fliould be not lefs than twenty 

 feet long, and three in width at their extremities ; while the roweis fhould 

 bt; fcatcd one on each hde of the machine in appropriate cars attached to the 

 body of the balloon, and nearly on a line with its equator.: this might eafily 

 be pra6tifcd with a balloon capable of carrying four pcrfons and ballaft ; 

 the greater weight in the car below the machine, containing two tiavelhrs 

 with ballaft, being fiifFicicnt to keep the whole apparatus in a fttatly pofi- 

 tion, and tliat more elpecially if the fame be fulpeiukd at a confiderable 

 diftance beneath tlie b^'loon. The oars recommended (being made of only 

 varnifhed linen ftretched over netting fixed to arms of pliable wood) might 

 be cafily worked, if a projefting ftaff of wood were attached to each lateral 

 oar, fo as to form at its extremity a fulcrum whcfeon torcll the oar at eight 

 <-'t tea feet diftance from the lovvcr. 



6 face 



