MECHANICS AND USEFUL ARTS. 85 



platform, as first proposed, Mr. Stephenson determined, on mature 

 reflection, to take upon himself the responsibility of reporting to the 

 directors of the Chester and Holyhead Railway' that this extra cate- 

 nary support which would have cost the company 150,000, was whol- 

 ly unnecessary. Indeed, such was the superabundance of power at his 

 command, that, without adding 1 to the weight of the rectangular gal- 

 leries, he could materially have strengthened them by using at their 

 top and bottom circular flues instead of square ones, which, merely 

 for the sake of cleaning, &c., were adopted, although the former were 

 found on experiment to bear about 18 tons to the square inch before 

 they became crushed, whereas the latter could only support from 12 to 

 14 tons. 



"But the security which Mr. Stephenson deemed it necessary to 

 insure for the public may further be illustrated by the following very 

 extraordinary fact. It has been mathematically demonstrated, as 

 well as practically proved by Mr. Fairbairn, that the strain which 

 would be inflicted on the iron-work of the longest of Mr. Stephen- 

 son's aerial galleries, by a monster train sufficient to cover it from end 

 to end, would amount to six tons per square inch, which is exactly 

 equal to the constant stress upon the chains of Telford's magnificent 

 suspension Menai Bridge when it has nothing to support but its own 

 apparently slender weight." 



NEW METHOD OF SMELTING IRON. 



MR. M. SMITH SALTER, of Newark, N. J., has obtained a patent 

 for a new method of making iron direct from the ore, with anthracite 

 or bituminous coal, by a single process. By means of this remarkable 

 invention, Mr. S. proposes to make wrought-iron at a cost of $25 to 

 $30 per ton, at least half the usual cost. His furnace has three com- 

 bined chambers, one above the other, and all actuated by the same fire. 

 The upper chamber is used for deoxidizing the ore, impurities, such 

 as sulphur, &c., being carried off at a low temperature, the middle 

 chamber for fluxing and working, and the lower chamber for reducing 

 and finishing. The metal is taken from the last named to the hammer 

 or squeezers. The whole time occupied in this process, from the time 

 the ore is put into the furnace until finished by the hammer, is only 

 two hours. One, of his furnaces is now in operation at Boonton, in 

 Morris County, N. J. Perhaps a more important invention if fuller 

 experiments should verify present anticipations has not been intro- 

 duced in many years. 



IMPROVEMENTS IN PUDDLING IRON. 



IN the ^usual mode of puddling iron, the furnace is prepared by the 

 introduction of roughly pulverized iron ore, or scoria, which is accu- 

 mulated against the sides; this defends the plates, bridges, and bot- 

 tom from the action of the melted iron ; but a portion of it will collect 

 in the interstices between the particles of scoria, from which it cannot 

 be separated, and a loss of iron is the result. An improved method of 



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