426 Machinery at the Exhibition. 



of constructive science, we must not pass over unnoticed those 

 proofs, afforded by the present Exhibition, that for some the 

 teachings of experience are of little avail, and that time, in- 

 genuity, and money are often wasted on contrivances which 

 have been sufficiently tried before and found wanting. The 

 principle of expansion is now universally received as of un- 

 questionable utility, but the way in which it is carried out 

 is not always in accordance with the progress which has been 

 made : and hence we find engines exhibited, in which it is 

 applied by the methods of" Hornblower and Woolff, that have 

 been long since exploded. It has been clearly established that 

 no practical advantage is gained by expanding the steam in a 

 separate cylinder. A heavy flywheel is almost always found to 

 produce sufficient uniformity of action, but if the variation of 

 power consequent on carrying the expansions to great lengths 

 is found inconvenient in particular cases, it is a more advan- 

 tageous and almost as simple a mode of remedying the incon- 

 venience to use the two cylinders in the form of a double 

 engine, whose piston rods, as in the case of marine engines and 

 locomotives, act on the crank axle at right angles to each other. 



The caloric engine also is exhibited, although many experi- 

 ments have shown that it is surrounded with difficulties, which 

 in practice cannot be overcome. This would have been an 

 excellent opportunity for repeating the experiments which have 

 been recently made at Paris, and, as it has been triumphantly 

 asserted, with so much reason for hope. 



We find electro-magnetic engines also. In 1851 numbers 

 of these were exhibited ; and the jury, as they inform us, enter- 

 tained very sanguine expectations of their ultimate success. 

 Time, however, has shown these expectations to have been 

 without foundation, and they are now indulged in by very few. 

 The electro-magnetic engine, as we have shown, page 22 (I am 

 referring to the first number of the Intellectual Observer), 

 cannot possibly compete with the steam-engine in economy, 

 were there no other obstacle to its adoption. Electro-magne- 

 tism has been recently apphed to a purpose the success of 

 which is far more probable — the production of artificial fight. 

 The principle on which this is sought to be effected is illus- 

 trated, at the Exhibition, by two machines of considerable 

 power ; the one English, with commutators, the other French, 

 without them. It is certainly capable of emitting a very intense 

 fight : and, after the machine is constructed, at the cost of little 

 more than a small amount of steam power ; nevertheless, though 

 its advocates are very confident of success, there does not seem 

 at present much probability of its general application as an illu- 

 minating agent, even in lighthouses, for which it is supposed 

 to be specially adapted. 



