FIG. 4.—WINDMILL ACTUATING THE BELLOWS OF AN ORGAN.
CHAPTER III.
THE ORIGIN OF THE STEAM ENGINE.
All works that treat of the history of the steam engine speak of the eolipile of Heron as the most ancient manifestation known of that power which to-day fills the world. But very few persons know that we also find in the “Pneumatics” of the Greek engineer the germs of the tubular boiler and of the Papin cock which has been replaced in modern engines by the long D-valve. Here, in the first place, is a literal translation of the two passages that have reference to the apparatus, so often cited, of Heron:
“Balls may be held in the air by the following method:
“Fire is lighted under a boiler that contains water and is closed at its upper part. From the cover starts a tube which rises vertically, and at the extremity of which a hollow hemisphere is in communication with it. On placing a light ball in this hemisphere it will happen that the steam, on rising through the tube, will raise the ball in such a way that it will remain suspended.[9]
[9] [Fig. 1] is borrowed from a MS. of the “Pneumatics” dating back to the Renaissance. The boiler should have been represented over a fireplace.