as a Vehicle for transporting Heat. 329 



To prevent the loss of heat arising from the cooling 

 of the different tubes through which the steam must 

 pass in coming from the boiler, all those tubes should 

 be well defended from the cold air of the atmosphere, 

 by means of warm covering ; but this may easily be 

 done, and at a very trifling expense. The horizontal 

 conductors may be enclosed within square wooden tubes, 

 and surrounded on every side by charcoal dust, fine 

 sawdust, or even by wool ; and the steam-tubes, as 

 well as the reservoir of steam, may be surrounded, first 

 by three or four coatings of strong paper, firmly attached 

 to them by paste or glue, and covered with a coating 

 of varnish, and then by a covering of thick coarse 

 cloth. It will likewise be advisable to cover the hori- 

 zontal conductors with several coatings of paper ; for, if 

 the paper be put on to them while it is wet with the 

 paste or glue, and if care be taken to put it on in long 

 slips or bands, wound regularly round the tube in a 

 spiral line from one end of it to the other, this cover- 

 ing will be useful, not only by confining more effectually 

 the heat, but also by adding very much to the strength 

 of the tube, and rendering it unnecessary to employ 

 thick and strong sheets of metal in the construction 

 of it. 



However extraordinary and incredible it may appear, 

 I can assert it as a fact, which I have proved by repeated 

 experiments, that if a hollow tube, constructed of sheet 

 copper jV of an inch in thickness, be covered by a coat- 

 ing only twice as thick, or ^ of an inch in thickness, 

 formed of layers of strong paper, firmly attached to it 

 by good glue, the strength of the tube will be more than 

 doubled by this covering. 



I found by experiments, the most unexceptionable 



