MECHANICAL AND TJSEFDL ARTS. 61 



REMARKABLE TROPERTT OF IRON. 



In 1S56, says a contemporary, Mr. Marsh, an able chemist con- 

 nected with the Royal Arsenal, discovered that it was an invariable 

 rule with Iron which has remained a considerable time under water, 

 when reduced to small grains or an impalpable powder, to become 

 red-hot. This he found by scraping from a gun some corroded 

 metal, which ignited the paper containing it, and burnt a hole in 

 his pocket. The knowledge of this fact may account for some spon- 

 taneous fires and explosions. The tendency of moistened particles 

 of iron to ignite was discovered by the French chemist, Lemery, as 

 far back as 1670. 



nasmyth's steam-hammer. 



We find in the Engineer the following deserved tribute to the 

 genius of the inventor of the Steam-hammer, a stupendous specimen 

 of which has been manufactured to be employed in forging Armstrong 

 guns, at Woolwich Arsenal. 



Without detracting in the smallest degree from the merit of any 

 engineers who have modified or improved this invention from time 

 to time (says the Engineer), we should like to see due prominence and 

 just praise given to Mr. Nasmyth, who first introduced the Steam- 

 hammer in a practically efficient form. The invention of this potent 

 and yet pliant tool is one of those affairs which seem exceedingly 

 simple in themselves, after they are accomplished, but which, never- 

 theless, are of incalculable value to mankind. It is not too much 

 to say that, but for Nasmyth's Steam-hammer, we must have 

 stopped short of many of those gigantic engineering works which, 

 but for the decay of all wonder in us, would be the perpetual wonder 

 of this age, and which have enabled our modern engineers to take 

 rank above the gods of all mythologies. 



Writing as we are for the perusal of engineers, we need not 

 dwell upon this subject. But there is one use to which the steam- 

 hammer is now becoming extensively applied by some of our manu- 

 facturers, that deserves especial mention, rather for the prospect 

 which it opens to us than for what has already been actually accom- 

 plished. We allude to the manufacture of large articles in dies. At 

 one manufactory in the country, railway wheels, for example, are 

 being manufactured with enormous economy by this means. The 

 various parts of the wheels are produced in quantity either by rolling 

 or by dies under the hammer'; these parts are then brought together 

 in their relative position in a mould, heated to a welding heat, and 

 then by a blow of the steam hammer, furnished with dies, are stamped 

 into a complete and all but finished wheel. It is evident that where- 

 ever wrought iron articles of a manageable size have to be produced 

 in considerable quantities, the same process may be adopted, and the 

 saving effected by the substitution of this for the ordinary forging 

 process will doubtless ere long prove incalculable. 



For this, as for the many other advantageous uses of the steam- 

 hammer, we are primarily and mainly indebted to Mr. Nasmyth. It 

 is but right, therefore, that we should keep his name in honour. In 



