36 AERIAL NAVIGATION. 
Prof. W. LeConte Stevens, of Brooklyn, N. Y., gave 
an address—illustrated with lantern projections—enti- 
tled ‘‘ Aerial Navigation,” of which the following isan 
abstract : 
The power to rise above the ground was, among the 
ancients, regarded as exclusively a divine prerogative. 
This idea is illustrated in several mythical stories, such 
as that of Icarus and Daldalus, and the Persian legend 
of Kai Kaoos, in which disaster is shown to have fol- 
lowed every human attempt to exercise superhuman 
power. 
Friar Bacon (1200-1300 A. D.) claimed the invention 
of a device for rising into the air, consisting of a thin 
globe of copper, ‘‘ to be filied with ethereal air, or liquid 
fire,’ and then launched forth from some elevated point 
into the atmosphere. He shared in the popular idea 
that the atmospheric ocean covering the earth had a well- 
defined boundary like the aqueous ocean, and claimed 
to believe that his copper globe would float on the upper 
surface of the air as aship floats on water. No account 
has been transmitted of any actual experiments by him 
on this subject, in the preparation of either liquid fire or 
a globe of suitable dimensions. 
A Jesuit priest, Father Lana, about 1670, evolved in- 
dependently Bacon’s idea of using a copper globe, 
which he rightly supposed capable of being pushed up 
by the buoyant force of the surrounding atmosphere, if 
it could be made sufficiently thin and perfectly ex- 
hausted. He seems to have been aware of the previous 
experiments of Torricelli and Pascal, and proposed to 
exhaust his globe by filling it first with water, lifting it 
toa height exceeding thirty-four feet, attaching a con- 
trollable tube dipping into water below, and thus pro- 
ducing a Torricellian vacuum. He calculated the neces- 
sary diameter of his globe to be about twenty-five feet, 
and its thickness 34, incli; but he had ‘little conception 
