651,540. Demonstration models. ROUCKA, E. May 14, 1948, Neo. 13319. [Class 146 (ii)] Hydraulic apparatus for demonstrating how the heart and blood circulation of the human body functions, and the effect of various muscles, valves and other factors, comprises a pipe system, at least one pulsating pump, with variable delivery rate, adjustable mechanical devices which can influence the flow of liquid in the system, and a storage container arranged so that extra liquid can be withdrawn therefrom into the pipe system, or excess liquid can be discharged thereto from the pipe system. As shown, there are four pumps A, B, C, D representing the heart, and devices E, F, G, H representing the lungs, elasticity of the arteries, peripheral circulation of the blood, and blood collectors, respectively. A rubber tube 124 shows the pulse action, and a flow meter 73, 74 registers the rate of liquid flow. Pressure gauges are incorporated at various points in the system. The pump A comprises a container 1 having a flexible top 2 provided with a projection 2a adapted to be engaged by a pivoted lever 4. The lever 4 is actuated from a cam 9 on a shaft 119 which is driven from a motor through variable-speed gearing 120, 121, 122. The pump C is of the same construction, and the pumps B and D are similar to A and C except that crank discs replace the cams. Liquid from the pipe 88, which represents the veins, enters the pump A through a non-return valve 3, and is pumped past a flap valve 11 to pump B. It passes from pump B through a flap valve 23 to the device E which comprises a container 27 having a flexible loaded top 28 provided with a throttle valve 30 adapted to control the opening in outlet pipe 35. The liquid passes through pump C, through a flap valve 46, pump D, a flap valve 60, and into device F. The device F includes a container 65 with a flexible top 66 which is loaded by a lever 67, spring 68, and screw 69. The pivot 70 for the lever 67 can be displaced by a screw 71. The liquid passes through the flow-meter 73, and a valve 77, to the device G which comprises a container 79 having two flexible top covers 80, 81, the latter having a valve 82 controlling the outlet to the pipe 88. The covers 80, 81 are loaded by a lever 83 and weight 84. The lever 83 presses a movable roller 85 against a pivoted lever 86 attached to the cover 81. A branch pipe 123 leads to the devices J, K through pipes 116, 117. The device K consists of a container 100, and two flexible covers provided with valves 103, 104 throttling, respectively, a pipe 118 connecting the pipe 88, and the pipe 116. Each combined cover and valve is connected to a pivoted balancing lever 105 so that when one valve is closed, the other is open. Levers 107, 108, connected by a link 106 to the lever 105, and pivoting about displaceable rollers, are connected, respectively, by a rod 110 to a weighted pivoted lever 111 adapted to actuate a flexible cover 113 of a container in device J, and by a rod 114 to a pivoted weighted lever 115. A pipe 98 connects the device K to the device H which comprises a storage container 90 having flexible top and bottom covers 91, 92. A pivoted lever 93, connected to the top cover, is forked and suspended by springs 94, 95 to an adjustable rod 96. In use, the system is first filled with liquid, and the motor-driven shaft 119 adjusted to the desired pulses per minute. A lever and spring means 5, 6 can adjust the force of the lever 4 in pump A to imitate fatiguing of the heart muscles, the valve 11 is adjusted by levers 12, 13 to represent the " trienspidalis and stenosis, the lever 16 in pump B adjusted by means 19, 20, 21 to demonstrate changes in elasticity of the heart muscle &c, and the valve 23 adjusted by levers 24, 25 to imitate the " pulmonalis." The lung device E can, by means of lever 32 and spring 31, vary the flow of liquid therethrough and the pressure therein. The pump C is variable by spring and lever 40, 41, the valve 46 can be adjusted by levers 47, 48 to imitate the " mitralis," and the valve 60 controlled by levers 61, 62 to represent the valve of the aorta. In the device F the varying elasticity of the arteries is imitated by adjusting the roller 70 and tension of the spring 68. For demonstrating the peripheral circulation of the blood, the valve 77 and the valve 82 in device G, are adjusted. To imitate blood circulation of different intensities, liquid is transferred into the system from the storage device H by displacing rollers 109, 125 to tilt the lever 105 clockwise, or by adjusting the rod 96 downwardly ; a reverse proceedure expels liquid from the system into the device H. The variations in the arteriole pressure can be imitated in the device J by displacing the rollers 109, 125. Modifications of the apparatus may include parallel, instead of series, branches in the system, and pistons and cylinders or loaded rubber balloons, instead of containers with flexible covers.