86 CONSTRUCTION OF BA LI.OON S. 



Daniel (Philosophical Magazine, vol. iv.) also ot Martin, and the 

 proposal* for performing the same bv menu's of eagles trained for 

 the purpose ; or by a reversed paradise In retard the direct pro- 

 gress of tlie balloon, whereby less |>o\\er will he necessary to impel 

 it in a lateral direction ; all these plans remain obsolete and tinprac. 

 tNed from the lime of their suggestion. \Vilh respect to the pro. 

 Lability of directing aerostatic machines, we iua\ inter it to be 

 possible, although the methods hereto tried have been inadequate; 

 perhaps because they were not sufficiently powerful ; as, to expect 

 to make so large a body as a balloon to vary from the wind by the 

 impul>ioii of an oar of six or eight feet in length aud one or two in 

 breadth (and that by only endeavouring to draw the car out of ihe 

 perpendicular) is to expect, by means of a boat's oar, to impel a ship 

 of burthen. Oars are doubtless the most likely means to effect this 

 purpose, if they were of dimensions proportionate to the fleets they 

 are \islied to produce. The addition of sails, were any variation 

 from the wind is desired, will prove injurious till we have attained a 

 method (perhaps only to be accomplished by oars) of keeping the 

 aame point of the balloon continually in a given direction. Yet we 

 doubt not but these also might prove of great service in quick dis- 

 patches, by water j as, for instance, where it is required to pass a 

 fortress or flirt for the succour of a besieged town, or convey dis. 

 patents thereto : a small balloon, of ten or twelve feet diameter, 

 pioMilin \\itli sails to expose a large surface to the wind, being at- 

 tached by a lung rope to- a boat, would outstrip the quickest vessel, 

 and might also b- made to deviate from the course of the wind ; as 

 tlie water would form a counter-resisting medium, the want of which 

 in air balloons occasions the <;imcully in steering them. A sail bal- 

 loon similar to Ihe above might also be advai>tiig>u-l\ attached to 

 aland carriage; namely, by increasing the capacity of tlie balloon, 

 so that i.s | oer of ascension being nearly equal to the weight of 

 the appended carriage, the latter would be drawn along ly the im- 

 pulsion of the wind against the balloon and sails, while the friction 

 over tlie "round, by the small overplus weight, may be reasonably 

 expected to aflord u resistance sutiicirnt to guide the machine, and 

 allow <.f a (U-viat ion in the carriage ot at least eight points from the 

 course of the wind. Indeed Ihe uses of the art of aerostation, even 

 in is pre>ent incomplete state, may be very considerable. Air 

 balloons may sene the purpose of escaping from ships that cannot 

 safely land, from besieged places, and from other circumstances of 



