Perreauxs patent pump valves in the International Exhibition, 1862. This method of constructing pump-valves is extremely ingenious, simple, and efficient; it is copied from the valves contained in the human heart. Perreaux valves are made of vulcanised indiarubber...[and] are of the form of a tube flattened at one extremity...The thickness of the sides of the upper part diminishes gradually to the top, where the two sides meet and form two lips, which when the valve is in a state of rest are in close contact, and prevent the downward passage of the fluid...owing to the...the elasticity of the material, they close perfectly and instantaneously the moment the pressure from below ceases...these valves...are extensively used in soap and alkali factories, and by paper-makers, tanners, bleachers, and dyers, in pumping paper-stuff, chemicals, tan-liquor, &c. Fig. 1 represents the section through the pump-barrel; fig. 2 the section of an ordinary bucket; and figs. 3 and 4 are sections of foot-valves. The pumps have glass cylinders or barrels, so that the action of the valves may be seen. It is found advantageous to use glass barrels, as they are free from corrosion and lubricate themselves with the material which is pumped through them. From "Illustrated London News", 1862.