Theory of Circulation by Respiration

Suppose the heart divided into right and left hearts by dissection at the septum: the circulatory system might then be represented by an endless tube. Let such an one, nine or ten feet in length, and of one inch bore (to be filled with water) be placed upon a horizontal table. Let an enlargement of the tube be made by a tin vessel to represent the lungs, which shall contain about one-fifth part of the water. Let the tube connected with the right side of the vessel have, at a little distance from the vessel, a smaller enlargement, composed of india-rubber, which can be grasped by the hand, to represent the heart’s right ventricle, with a valve on each side opening towards the tin vessel, the two to represent the tricuspid and semi-lunar valves. Let the whole be made nearly full of water; then, under the tin vessel (representing the lungs), let a fire be made. As the water heats, it will expand; and as the valve closes to the right, it will go off to the left side of the vessel. But, as no water will come in from the right, on account of the valves, there will be no current.