EARLY USE OF STEAM. 869 
enters the gun barrel, and issues by the lateral horizontal ° 
opening. Except as to intensity, this steam in escaping 
will act like the gases disengaged from the powder in the 
barrel of the gun when closed at the end, and pierced 
laterally ; only, we should not have but a mere shock 
as occurred in the instance of the sudden and harsh 
explosion from the gun; on the contrary, the rotatory 
motion will be uniform and continuous, like the cause 
which engenders it. 
Instead of only one gun, or rather instead of merely 
one horizontal tube, let several be adapted to the ver- 
tical rotatory tube, and we shall have, with the exception 
of some slight differences, the ingenious apparatus of 
Hero of Alexandria. 
Here we should, doubtless, have a machine in which 
the steam of water creates motion, and may produce 
mechanical effects of some importance; it would be 
truly a steam-engine. But let us hasten to add that it 
would have no real point of contact, either in its shape, 
or the moving power’s mode of action, with the machines 
of that kind now in use. If ever the reaction of a cur- 
rent of steam becomes practically useful, we must, with- 
out hesitation, refer the idea back to Hero; though at 
present the rotatory eolipyle can only be quoted here as 
carving on wood is cited in the history of printing.* 
* These reflections are applicable also to the project that Branca, 
an Italian architect, published at Rome, in 1629, in a work entitled 
Le Machine, and which consisted in generating a rotatory movement 
by directing the steam issuing out of an eolipyle as breathings, or in 
a current, or on the pallets of a wheel. If, contrary to all probability, 
steam is some day usefully employed in the simple form of blowing, 
Branca, or the author, now unknown, from whom he may have bor- 
rowed the idea, will take the first rank in the history of this new 
species of machines. Relative to the machines of the present day, the 
claims of Branca would be quite null. 
16 * 
