I proceed to describe the disposition of the tubes, and the apparatus destined to put the water in motion.
The two tubes, placed side by side, were closed at each extremity by a single glass plate, fixed with gum-lac in a position exactly perpendicular to their common direction. Near each extremity was a branch tube, forming a rounded elbow, which established a communication with a broader tube reaching to the bottom of a flask; there were thus four flasks communicating with the four extremities of the tubes.
Into one flask, which we will suppose to be full of water, compressed air, borrowed from a reservoir furnished with an air-pump, was introduced through a communicating tube. Under the influence of this pressure the water rose from the flask into the tube, which it then traversed in order to enter the flask at the opposite end. The latter could also receive compressed air, and then the liquid returned into the first flask after traversing the tube in an opposite direction. In this manner a current of water was obtained whose velocity exceeded
. A similar current, but in an opposite direction, was produced at the same time in the other tube.
Within the observer's reach were two cocks fixed to the reservoir of air; on opening either, currents, opposite in direction, were established in both tubes; on opening the other cock the currents in each tube were simultaneously reversed.
The capacity of the reservoir, containing air at a pressure of about two atmospheres, amounted to
(half a cubic foot), that of each flask to about
