A narrative of the two aerial voyages of Doctor Jeffries with Mons. Blanchard; with meteorological observations and remarks [electronic resource] : The first voyage, on the thirtieth of November, 1784, from London into Kent: the second, on the seventh of January, 1785, from England into France. By Doctor Jeffries. Presented to the Royal Society, April 14, 1785; and read before them, January, 1786