312 PETITION TO PAHLIAMENT. 



prospect is great, beyond anything I ever knew offered on 

 such easy terms. Waiting your reply, 

 " I remain, Sir, 



" Your very humble servant, 



" RICHARD TREVITHICK." 



" DEAR TREVITHICK, " EASTBOURNE, December 2Qth, 1831. 



" I am sorry to find that you have not any prospect of 

 assistance from Government. I have not any copy or memo- 

 randum of my letter to Mr. Spring Rice ; but it was to the 

 effect of first bearing testimony to the large share that you 

 have had in almost all the improvements on Mr. Watt's engine, 

 which have altogether about trebled its power ; to your having 

 made a travelling engine twenty-eight years ago ; of your having 

 invented the iron-tanks for carrying water on board ships, &c. 



" I then went on to state that the great defect in all steam- 

 engines seemed to be the loss, by condensation, of all the heat 

 rendered latent in the conversion of water into steam ; that 

 high-pressure engines owed their advantages mainly to a reduc- 

 tion of the relative temperatures of this latent heat ; that I had 

 long wished to see the plan of a differential engine tried, in 

 which the temperatures and consequently elasticities of the fluid 

 might be varied on the opposite sides of the piston, without 

 condensation ; that the engine you have now constructed pro- 

 mised to effect that object ; and that, in the event of its 

 succeeding at all, although it might not be applicable to the 

 drawing water out of mines, yet that for steam-vessels and 

 for steam-carriages its obvious advantages would be of the 

 greatest importance; and I ended by saying that although it 

 was clearly impossible for me to ensure the success of any plan 

 till it had been actually proved by experiment, yet judging 

 theoretically, and also from the imperfect trial exhibited on 

 the Thames, 1 thought it well worthy of being pursued. Your 

 plan unquestionably must be to associate some one with you 

 (as Mr. Watt did Mr. Boulton), and I certainly think it a 

 very fair speculation for any such person as Mr. Boulton to 

 undertake. 



" It is impossible for me to point out any individual, as never 



