Perkins'' Steam Engine. 51 



Second, by the increased friction occasioned by the great 

 pressure on the valves. Third, the carbonization of the lu- 

 bricating material, whether tallow, oil, or other fat, which 

 was used for the piston and valves. Fourth, the diffi- 

 culty of preventing the steam from becoming surcharged 

 with caloric, which at times, would be at such an excess, 

 as to melt the joint packings, and heat the steam pipe red 

 hot. 



The first mentioned difficulty is removed by a very novel 

 method, by which the eduction pipe and valve are dispen- 

 sed with. At the end of the stroke, the metallic piston en- 

 ters an enlargement at that part of the cylinder, and passes 

 three-quarters of an inch below it, leaving sufficient space 

 for the steam to flash out at the dead point, into a tube lead- 

 ing to the chimney, at which instant the vacuum valve [?] 

 closes, and shuts off seven-eighths of the steam, which es- 

 capes up the chimney, and the other eighth, under the pis? 

 ton, is easily condensed by a spray of water, which is after- 

 ward used for generating steam. At the next puff, the con- 

 densed steam, water, and air, are thrown out, and the hea- 

 ted water runs into the cistern of the pump, from whence it is 

 forced into the generator, dispensing with the complicated 

 and expensive air pump, as well as with condensing water. 



The second difficulty is removed by rendering the employ- 

 ment of an eduction valve unnecessary ; for the induction 

 valve requires to be only one thousandth part of the area of 

 the cylinder ; the power required therefore to lift it, (even if 

 the valve was not so constructed as to neutralize the pres- 

 sure,) would be very little. 



The third difficulty, which was a very serious one, when 

 the temperature of the steam employed was five hundred 

 pounds upon the inch, is removed by using a metallic piston, 

 made of a peculiar alloy, requiring no lubrication whatever, 

 since it glazes by its working. And as for valves, there is 

 only one little, simple, lifting induction valve, and that, be- 

 ing destitute of friction, requires, of course no oil. 



Fourth, preventing the steam from becoming surcharged 

 with caloric. This important part of Mr. P's. invention, we, 

 for certain reasons, are restrained from explaining at pres- 

 ent ; it is however, accomplished, and will be made known 

 when the specification of the last patent is enrolled. 



We understand that Mr. P. has taken some orders for his 

 high pressure, safety engines, and guarantees the saving of 



