542 ANNUAL EECORD OF SCIENCE AND INDUSTRY. 



wrought iron, that the extension and compression were very 

 nearly equal to each other, and that the modulus of elastic- 

 ity of steel may be taken at 30,000,000, and, practically, equal 

 to that of wrought iron. 



The fourth series of experiments was made on riveted steel, 

 and it was shown that the same rules which apply to the 

 riveting of iron apply equally to steel. 12 A, 1873, 426. 



defty's puddling fuenace. 



In this newly devised arrangement, the fire-place is similar 

 to that of a common puddling furnace, and furnished with 

 blast and steam supply-pipes, as well as a pipe for carrying 

 off the gas and heat in making repairs. The air is admitted 

 through tubular grate bars, extending over the whole ash- 

 pit, whereby the air is heated, the efiiciency of the fuel thus 

 increased, and the bars at the same time kept cool ; the ash- 

 pit being closed with tightly fitting doors. The molten iron 

 is regularly admitted from a cupola to a peculiarly construct- 

 ed movable chamber, beyond the fire-bridge, and subjected 

 in regular order to the necessary decarbureting, desulphu- 

 rizing, and dephosphorizing processes. The lining of the 

 chamber is of a peculiar composition, and is continually re- 

 newed by the admission of the same material, as a powder, 

 into the arch through a small funnel. The flame passes 

 from this chamber through the blast-pipe, with the blast, into 

 the cupola, which is charged at the top through self-regulat- 

 ing doors, and which, by means of a tube above it, furnishes 

 steam for the whole establishment. All heat is thus utilized, 

 while the puddling process is continuous, and the iron ex- 

 posed to the action of the flame, as well as to the lining of 

 the furnace, as long as may be necessary. 18 C^ June 11, 

 1873,376. 



PNEUMATIC TUBES. 



It has been proposed to improve upon the pneumatic tele- 

 graph system, by substituting in the tube through which the 

 packages are conveyed by this system of conveyance aramo- 

 niacal gas instead of compressed or rarefied air. This gas is 

 disengaged by a slight heat from its solution in water, and, 

 on the other hand, when it is desired to absorb the gas filling 

 the tube in front of the packet, it is again taken up by the 



