348 History of Mechanical Inventions and 



third inch piston diameter, and six and a half feet stroke, lifted a co- 

 lumn of water forty inches diameter, and forty feet high, making fourteen 

 six and a half feet strokes per minute, consuming not more than 120 pounds 

 of coals per hour. But as the engine never worked more than two hours 

 at any one time, it is impossible to say what the actual saving of the fuel 

 would be. After the engine is completed, and worked day after day with- 

 out interruption, then the economy in the fuel will be clearly ascertained. 

 The area of the pump being twenty times larger than the area of the 

 steam-engine cylinder, and the water being lifted forty feet high, it ba- 

 lanced the weight or power of twenty-five atmospheres ; but as the friction, 

 &c. must be added to the power required to lift the water, it was found ne- 

 cessary to raise the steam to about thirty- two atmospheres to give a lively 

 stroke to the pump. 



The safety of this engine has been proved by the frequent openings or 

 fractures which have taken place (without injuring any one) in the expe- 

 riments made in generating high steam. The maximum of high steam 

 has not yet been ascertained, but, undoubtedly, the higher it can practi- 

 cably be used, the greater is the economy. The greater portion of the 

 gain in high steam appears to be owing to its expansive property. The 

 higher the steam is raised the sooner the stroke can be cut off; of course 

 more is gained by expansion. The highest Mr Perkins has ever used his 

 steam for his steam-engines, is 800 pounds to the inch, or about fifty-se- 

 ven atmospheres. That the gain goes on in a geometrical ratio, his expe- 

 riments on the steam-gun have fully demonstrated. In some of these ex- 

 periments, a pressure of 1600 pounds to the square inch has been used 

 with perfect safety, and was found to project musket balls of the same 

 weight and distance one quarter farther into the target than the strongest 

 gunpowder. Mr Perkins has made another very curious discovery in ex- 

 perimenting on high steam, namely, that temperature does not always 

 show the true power of the steam, although the steam is in contact with 

 the water from which it is generated ; hut we cannot be so particular on 

 this point as we could wish, on account of Mr Perkins not having complet- 

 ed his patent for the remedy. 



We feel great pleasure in adding to the above, the testimonials of two 

 gentlemen, Messrs Hornblowers, whose names are well known in con- 

 nection with steam engines. 



" We, the subscribers, have, for some time past, been employed as prac- 

 tical engineers at Perkins and Company's steam-engine manufactory, in 

 applying Mr Perkins's system of generating high steam, to the Cornish 

 single-stroke pumping engine, of which we have had nearly twenty years' 

 practice. From what we have witnessed, we are perfectly satisfied that no 

 danger can be apprehended from explosions. Its great power is established 

 by the fact ofiis having lifted a column of water 40 feet high, and 40 inches 

 diameter, with a 9 h inch piston. As to the economy of fuel, which is evi- 

 dently great, we cannot exactly say, owing to some parts of the engine 

 being incomplete, especially the injection pump. The longest the engine 

 has worked at any one time was two hours : at that time it was inak- 



