58 ANXUAL OF SCIENTIFIC DISCOVERY. 



between the pipes. The air in the pipes is warmed ; this creates a draft, 

 and new air from the outside is drawn in to be poured into the rooms. The 

 boiler is connected with a small reservoir, in which is a float acting on a 



* O 



lock, making it self-feeding. Each hexagonal pipe is intersected by thin 

 plates of iron, which absorb the radiating heat emitted from each side of 

 the pipe, and from which it is taken by the air. It is alleged by the paten- 

 tee that these thin plates increase the heating power in an almost incredible 

 proportion. Thus he found that the longitudinal partitions being in the 

 pipes the air came out at 125 degrees, and with the strong draft, the parti- 

 tion being withdrawn, the draft was reduced and the temperature was only 

 ninety-five degrees. Another good effect results from inclining the boiler 

 in the brick work, so that the flames have a slightly downward motion ; it 

 is believed that this position facilitates the current of water constantly at 

 work inside, to bring the coldest water against the bottom, when that which 

 has just been heated rises, by reason of its diminished specific gravity. 



ON THE FEACTURE OF IRON. 



At a recent meeting of the Society of Civil Engineers, London, it was 

 stated, that a large anchor, which had been in store for more than a century 

 at Woolwich Dock, and was supposed to be made of extremely good iron, 

 had been recently tested as an experiment, and had broken instantly with a 

 comparatively small strain, the fracture presenting large crystals. In this 

 case, the effect was believed to be produced by magnetic influences depend- 

 ent on the length of time the iron had been in the same position. 



On the Change of Position among the Particles of Solid Metals, induced by the 

 Action of Gentle but Continued Percussion of the Masses they form. 



The following paper by Dr. A. A. Hayes, on the above subject, has been 

 recently presented to the American Academy. 



The change by which malleable iron becomes converted into a highly 

 crystalline metal, when subjected to pressure attended by a tremulous mo- 

 tion, as in the case of railway bars, has been often observed, and the at- 

 tendant circumstances noted. My attention has been called to many cases, 

 in which the same effects have followed a gentle percussive action on a 

 part of a bar, the metal becoming changed at one point only, and hence 

 by chemical dissection the bar being laid open the fibrous metal could 

 be seen united to that changed portion, which had become highly crystalline 

 and generally brittle. 



" It is well known that the crystalline condition, assumed after the iron 

 has been laminated to the extent of rendering it uniformly fibrous, is due 

 to motion and change of place between the molecules of the iron, without 

 the condition of softening or fluidity. The extreme cases often present us 

 with a polarized condition, in which the crystallized iron is as perfect indeed 

 as would have resulted from cooling a fluid mass in a state of repose. 



" Malleable iron in its fibrous arrangement may be assumed as exhibit- 

 ing its particles of broken-down crystals in a state of tension, in which cer- 

 tain physical conditions, such as specific gravity and resistance to strain, 



