MECHANICS AND USEFUL ARTS. 87 



heads to be produced, and is there passed to and fro between the rollers 

 across the breadth of the bar, thus receiving a pressure only at the 

 enlarged part of the rollers, which gives the necessary increase of 

 breadth at the heads. It is then taken to plain finishing-rollers, and 

 drawn out longitudinally in the usual manner, until it attains the 

 proper length and thickness. After this the heads are trimmed to the 

 exact dimensions by machinery, and the holes are drilled for the pins. 

 The chains of the bridge over the Danube at Pesth, which has so 



^j ' 



satisfactorily withstood the heavy strain brought upon it by a retreat- 

 ing army, were constructed on this plan, as have been the chains of 

 several other suspension-bridges. 



INVENTION FOR THE MANUFACTURE OF STEEL. 



THE Practical Mechanic's Journal furnishes a description of an in- 

 vention relating to the process of refining metal, and forcing currents 

 of atmospheric and gaseous air during the process, so as to convert it 

 into steel ; and also to prepare the metal previous to submitting it to 

 the process of conversion into steel. The apparatus consists of the 

 converting-furnace, to the tuyire of which a blast-pipe is attached 

 formed into three passages, provided with valves for regulating the 

 air-currents. Two of the passages communicate with two iron recep- 

 tacles in front of the converting-furnace, the centre passage passing 

 between them and to the front of the receptacles, which latter are pro- 

 vided with gratings, and ash-pits beneath, and with covers for closing 

 them. The process of converting the metal into steel by this appara- 

 tus consists in allowing the air to pass into the- two passages of the 

 blast-pipe communicating with the receptacles, which are filled witli 

 charcoal. The charcoal is then ignited and the receptacles closed by 

 means of the covers; the air thus passed through the receptacles is 

 formed into carbonic oxide and enters the tuyere of the converting- 

 furnace, where it is mixed with such a quantity of atmospheric air 

 from the centre passage as may be judged desirable ; though the pat- 

 entee states that a large quantity should generally be avoided. By 

 means of the valves, the quantity of gaseous or atmospheric air can be 

 regulated by the operator. To prepare the metal for the process of 

 conversion, if it be pig-iron, it is to be smelted sufficiently in a cupola- 

 furnace, to which the apparatus described is applied : but if it be 

 wrought-iron, a plumbago crucible is used, in which the metal is to be 

 placed, being properly stratified with charcoal or carbonaceous ma- 

 terial. 



/ IMPROVEMENTS IN THE MANUFACTURE OF METALLIC COMPOUNDS. 



WE find in Messrs. Barlow and Payne's Patent Journal an account 

 of a patent recently taken out in England for some new metallic com- 

 pounds. 1. The inventor produces a metal equal to refined iron by 

 taking one twentieth of scrap malleable iron and placing it in the hol- 

 lows of the pig-metal beds in the smelting, in which case the pig metal 

 envelops the wrought iron, which loses its tenacity, and becomes 



