Weigh the whole Coil, or any Number of Yards, so as to obtain the whole Weight.
Mark the whole Length of the Cord, with different coloured Worsted, or otherways, at the Distance of every eight Yards: as a sounding Line.
Note the Marks in a Pocket-Book.
These Things being done; give the Balloon, by inflation, a Power of Levity at least equal to the known Weight of the Cord: which may be easily obtained by throwing into the Car, already ballasted and prepared, a Weight equal to the Aironaut, together with that of the Cord.
The Cord must also, previous to the Ascent, be rolled upon a Reel, (made fast in the Ground) whose Diameter shoud be two Feet: each Turn of the Wheel may be called two Yards.
A Barometer with an attached Thermometer fixed in the same Frame, also a second or detached Thermometer placed at the Distance of a Yard from the Frame, shoud remain upon the Ground during the Inflation.
The same Apparatus of Barometer with attached and detached Thermometer, shoud be suspended in the Car.
The Instant the Balloon ascends, an Observer below is to note in a Book the Point at which the Quicksilver stands in each of the three Tubes of the lower Apparatus, also the Time of Ascent: the Aironaut the same.
The Rope is, previous to the Ascent, to be tyed to a Center above the Car: and as soon as the Balloon has elevated the Car 100 Yards; the Observations, as before, are to be set down below, and by the Aironaut: and repeated at the Height of each 100 Yards: a Drum to beat; during the Time each Observation below is noting down; and the Balloon not suffered to rise, till the Drum has ceased. By such repeated Notice, and Silence; the Aironaut will know the exact Height, at which the Balloon is checked in its Elevation: and the exact Time during which its Elevation is impeded.
This Process is to continue, till the Rope is raised to its full Length.