POLE STEAM-ENGINE. 



extremely gratifying. The duty performed by the engine in 

 giving a velocity of 8 feet in a second, thirty-six different times in 

 a minute, to 24 tons of matter, by the consumption of 2 bushels 

 of coal in an <hour, is indeed very great, amounting to about 

 fifty-seven and three-quarter millions. 80 that when you obtain 

 a proper burden, and the extraordinary friction arising from the 

 too close fitting of the plunger-pole and case is reduced, there 

 seems to be no doubt of your engine performing wonders. 



" I am of opinion that the stronger steam is used, the more 

 advantageous it will be found. To what degree it should be 

 applied expansively must be determined by experience in 

 different cases. It will depend on the rate at which the engine 

 requires to be worked, and on the quantity of matter put into 

 motion, so that as large a portion as possible of the inertia 

 given in the beginning of the stroke may be taken out of it at 

 the end. 



" Some recent experiments made in France prove, as I am 

 told, for I have not seen them, that very little heat is consumed 

 in raising the temperature of steam. And if this is true, of 

 course there must be a great saving of fuel by using steam of 

 several atmospheres' strength, and working expansive through a 

 large portion of the cylinder, I have really been impatient 

 for a week past to receive some account of your machine, having 

 learned nothing about it, except from a paragraph dated Hayle 

 in the Truro paper of last Saturday week, and somehow or 

 other the next paper has not reached me. 



" I hope to be in London about Tuesday next, but at all 

 events direct to me there, as my letters are regularly forwarded. 



" Believe me, dear Sir, 



" Yours ever most fajthfully, 



GIDDY." 



[Rough draft,] 

 " MR. JOHN ADAMS, " BROMSGROVE, Wi March, 1810, 



"Sir, I received your favour of the 12th February, but 

 did not answer it in due course, because I was then erecting 

 an engine on the new plan, which is now at work, and performs 

 exceedingly well. It is equal in power to a 72-inch diameter 



