46 ANNUAL OF SCIENTIFIC DISCOVERY. 



inside of which a cone of wood of the same shape is fitted, enveloped in a pad- 

 ding of hemp. An oil vessel keeps the hemp continually lubricated, and the 

 wooden cone is so contrived as to press steadily against the inside of the cop- 

 per, and to rotate rapidly by means of a crank turned by hand or horse-power. 

 The whole of the boiler outside of the copper cone is filled with water. 

 Thus constructed, the machine, with 400 revolutions a minute, makes 400 

 litres* of water boil in about three hours by the mere effect of the friction of 

 the oiled tow against the copper. When once the boiling point is reached, it 

 may be maintained for any length of tune, or as long as the movement is con- 

 tinued. It is quite easy to keep the steam in the boiler at a pressure of two 

 atmospheres. 



SIEMENS' REGENEBATIVE ENGINE. 



The following is a description of Siemens' Eegenerative Engine, as given by 

 the inventor at a late meeting of the Royal Institution, London. The engine 

 described was the result of experiments instituted to endeavor to produce 

 an engine as far as possible a practical application of the dynamic theory of 

 heat. After giving a sketch of the gradual improvements in the application of 

 steam as a source of power from the time of Hero to Watt, and allud- 

 ing to the researches of Joule, Thomson, and others on heat, he proceeded to 

 consider the identity of heat and mechanical force, to which end their researches 

 lead. He supposed a hammer suspended in vacua, without any friction on its 

 bearings, to fall on a perfectly elastic anvil, and which would rise to precisely 

 the point from which it started. If a piece of copper were placed on the 

 anvil, the hammer would cease to rebound, the copper becoming the recipient 

 of its force. Let now a machine be applied to raise the hammer to its first 

 position ; let it strike the copper any number of times ; and let the copper be 

 turned on the anvil, and made to assume the same shape at the end of the 

 operation as it had at the beginning. In this case the sole expression of the force 

 which has been used to lift the hammer will be found in the heat which has 

 been conferred upon the copper by the repeated blows. If it were possible to 

 use the Tieat thus produced as the motive power of the machine which lifts the 

 hammer, a perfect dynamic engine would be obtained, and such an engine 

 would consume only one-fourteenth part of the fuel required by a perfect Boul- 

 ton & Watt's condensing engine. Mr. Siemens then explained in detail the 

 engine of which he was the inventor. The principal parts are the following, 

 viz. 1. A cylinder termed the Regenerator, having a piston moving in it. This 

 cylinder, into which the steam from the boiler is first admitted, is connected at 

 the top with 2. A cylinder of cast iron, of peculiar form (the end of which is 

 exposed to the direct action of the fire, but the temperature of which is mode- 

 rated by the proximity of the boiler), inclosing another open cylinder, which 

 also contains a piston. The regenerator is connected at the bottom with an- 

 other cylinder, exactly similar to the preceding. These two are the Working 

 Cylinders. 3. An apparatus termed a Respirator, disposed around each work- 

 ing cylinder, being the communication between the cylinders and the regene- 



* A litre is about a quart. 



