On the prefent State of Airoftation. a^ 



I {hould propofe the parachute to be conftrufted of var- 

 niftied cambric miiflin (or light linen), covered externally 

 with a netting, the meOies of which Ihould converge fmaller 

 as ihev approach the central portion of the machine ; obferv- 

 ing alfo to fix the netting on the farface by fewing it down 

 up'on various parts of the fame. The diameter of the para- 

 chute (forming only a fmall fegment of a fphere), when ex- 

 tended, not to exceed twenty^feet. The central aperture of 

 the umbrella (to allow the efcape of the air through, as the 

 machine defcends), not lefs than three feet in diameter, and 

 provided with a (liutter moving upon a hinge and opening 

 inwards * ; furnilbed alfo with a cord Aiding over a fingle 

 pulley to fiiut the aperture, and a fecond cord to open the 

 fame (each cord reaching to the car), thus fubjeaing the 

 fhulter to the will of the aeronaut. By this mechamfm the 

 ftupefying vibrations of the car may be moderated, if not 

 wholly prevented, by drawing down the Ihutter fo as to fully 

 expofe tlie aperture,'' whereby the refiftance of the parachute 

 to the atmofphere being kflcned by all this diminution of its 

 oppofing furface, the gravitating power of the appended weight 

 (tending to draw the body of the machine continually in the 

 perpendicular) will have 'proportionally a greater efteft: the 

 dcfcent in the inlerim will be aUb relatively more rapid j but 

 this mav be checked in a moment by clofing the orifice, efpe- 

 ciallv when near the furface of the earth f. 



A ftrong cord iliould proceed perpendicularly from the 

 centre of the car to a point formed by the convergence of a 

 number of cords proceeding from the fecond ring of wicker- 

 work, the effed of which would be an immediate extenfion 

 of the parachute to its full diameter at the inttant of defcent, 

 as before adverted to. Alfo, and laltly, a third hoopof 

 wicker-work, of fu or eight feet diameter, fixed in the in- 

 ternal concave of the umbrella, to fecure againft any acci- 

 dental collapfe of the fides before the machine has become 



ili;ite!y reftored the machine to it" perpendicular fituation, but for \yhich 

 lic'could not accounr. An attempt to obviate thefe inconveniences is the 

 ob'f(f> of the valve of the parachute r.K-ntioned hereafter. 



• This aperture, or, more properly, valve, of the parachute, may be 

 conftru6ted either of clofi; wicker-wuik, or varnifhed linen ftrengthened 

 by 3 pi- ce <.f netting externally, and tixed to a ring of wicker-v/ork adapted 

 to cloCe the diameter of the fecond ring of wicker-work, to which are fixed 

 the pieces of varr.i.'hcd linen compofins; the concave iimbreila. This latter 

 circle is ind.pfndci.t of the third hoop" of wicker-work of fix or eight feet 

 diameter, afterwards mciitioncJ, whofc ufe is to prevent a collapfe ot the 

 fides of the m.ichinc, . . - 



i Hv an enlargement of the diameter of the valve, this diminution of 

 futf.ccmij:;iit be carried to fuch extent as to infurc i fafc defcent by the 

 i.ar,ichutc even in the moil teiiiptlluooj weather. 



dittended 



