266 M. Arago's Biographical Memoir of James Watt. 



remark the uncommon fertility of invention with which Watt 

 was endowed. " I have thought," observed Dr Darwin on 

 one occasion, " of a kind of double pen, a pen with two points, 

 by which one might write the same thing twice over at the 

 same time, and thus supply himself at once with the original 

 and with a copy." " I hope," replied Watt, almost imme- 

 diately, " to discover a better method for accomplishing the 

 same object. I will mature my ideas to night, and communi- 

 cate them to you to-morrow." The Copying Press was in- 

 vented the next day ; and even a small model was prepared, 

 ready to shew its powers. This most useful instrument, now 

 so generally adopted in all the offices and counting-rooms in 

 England, has recently received some slight modifications, of 

 which various artists have assumed the credit to themselves ; 

 but I can truly affirm, that the present form was described 

 and delineated as early as the year 1780, in the patent of our 

 associate. 



Heating by means of Steam was an invention three years 

 later in time, which Mr Watt introduced into his own dwelling 

 in 1783. We have no ^^^sh here to conceal, that this inge- 

 nious method was previously described by Colonel Cooke, in 

 the Philosophical Transactions for 1745 ;* but there it long 

 lay overlooked and neglected. Mr Watt, however, had the 

 sole merit of reviving it. He was the first to apply it ; and it 

 was his calculations upon the extent of surface necessary to be 

 heated in rooms and edifices of different sizes, which served at 

 the first as the basis of the plans of most English engineers. 



Had Watt, during his long career, done nothing more than 

 introduce the separate condenser, the working steam expan- 

 sively, and the jointed parallelogram, he would have occupied 

 one of the first places among the small number of individuals 



• By the work jf Mr Robert Stuart, I find that Sir Hugh Platte, pre- 

 vious to Colonel Cooke, had foreseen the possibility of applying steam to 

 the heating of apartments. In the Garden of Eden of this author, published 

 in the year 1C60, we find mention made of something of an analogous kind 

 for preserving plants during winter in greenhouses. Sir Hugh Platte pro- 

 posed to place covers of tin, or of some other metal, upon the vessels that 

 were used for cooking, and thus to connect pipes to openings in the covers 

 of these vessels, by which the heated vapour might be carried wherever it 

 was desired. 



