This Method may possibly prove more effectual than the Umbrella-Wheels, on an horizontal Axis, of Mons. Carra;[108] as the Umbrella-Pendulum is easily unrigged, removed, and brought into the Car, in Case of a Whirlwind; by Means of a circular Rope fastened to the Axis or Bolt, one End being in the Car, and the other put throu’ the Aperture at the Bottom, and brought up from the Outside again into the Car.
The Umbrella-Pendulum may be made to turn round horizontally on the Bolt; the Ends of the Bolt being fastened under a circular hinged Socket, or Groove, of Iron.
CHAPTER LXII.
DEFECTS, IN THE COMPOSITION FOR BALLOONS, REMEDIED.
ALSO ON THE COCHUC-VARNISH.
Section 320. BALLOONS are defective in the Composition for the Varnish; which, till lately, was incapable of rendering the Balloon completely and durably Air-tight.
321. It was sometime ago reported at Paris, that Mr. Dutourny de Villiere had undertaken to construct a Balloon so truly impèrmeable, that he woud warrant the Duration of it, for several Weeks in the Air.
And it is since known that this Desideratum of the Art has been effected, in the Composition for the celebrated Balloon of Messrs. Auban and Vallet, first made subject to Direction.
322. Mr. Berniard, a French Chymist, has made curious tho’ unsuccessful Experiments, in order to melt the cochuc or elastic Bottle; as may be seen in the 17th Volume of the “Journal de Physique.”
Mr. Faujas and others made similar Trials.