[5] The Strength of the Rope, or Cable, if its Length does not exceed 10 or 12 Yards, ought to be such as to support a weight, greater than the Weight of the Balloon and it’s Appendages, for the Resistance made by the Grapple against the Balloon acted on by the Wind is immediate: The Rope ought therefore to be made of Indian-Gut, as most elastic, or Silk, as lightest. But if the Rope be half a Mile, or a Mile long; the Resistance is gradual: the Balloon descending for some Minutes; and having an open Space to move in through the Air: the Rope or Cable acting as a Radius, and the Levity of the Balloon and Opposition of the circumambient Air preventing it from falling with any Violence. The shorter Cable may be used at the Height of 10 Yards; in aid of the longer, to prevent it from rising; or to moor it, by winding the Reel, and hauling down the Balloon close to the Ground. [6] The Resistance being as the Square of the Velocity; therefore if the Velocity be increased 3 Times, the Resistance will be as 3×3=9, i.e. will be increased 9 Times. [7] Pounds Averdupois. Weight of the Aironaut 160 Provisions and Articles calculated at 20 Sand-Ballast prepared in Bags 44 Levity for Ascent 10 ——— _Sum total_, 234 [8] Ancient Warriors among the Arabs, Spaniards, Romans, Gauls, and Germans, being frequently obliged to pass deep Rivers, never undertook a Campaign without them. For the above Anecdote, and many curious Experiments on Air, see Sam. Reyheri, _Dissertatio de Aëre_, tertium edita. Kiliæ. 1673. [9] Equal Time with a Regulator corrected by an Observation. [10] Being a Dial-Compass, the Dipping of the Needle was frequently checked by the Glass at the Top. A Mariner’s Compass is the best. [11] [Sidenote: The Defect of the Reel remedied] The Loop shoud have been furnished with a +Swivel+: or the Lath or Reel shoud have been a Kind of Pulley, a Foot in Diameter, and two Inches wide. The Hook of which having also a Swivel might have been held in the Hand: and thus the Twine woud have run off in a short Time with the greatest Readiness; the Swivel conforming to the circular Motion of the Balloon. [12] +Slate+ (according to Cronstedt) is the +Whetstone+ _of fine Particles_, composed of Glimmer, Quartz; and, in some Species, of a martial argillaceous Earth, See “Essay on Mineralogy” by Mendes Da Costa, Sect. 264. [13] [Sidenote: Method of discovering Haze round the Sun, in bright Weather.] _To know whether the Air is hazy, tho’ the Sun continues shining._