MECHANICS AND USEFUL ARTS. 27 



cepted, arid, indeed, are considered by some high authorities as based 

 on faulty and incorrect experimentation. 



SUPERHEATED STEAM. 



Much has been written within the last few years relative to the 

 above topic, and there can be no doubt that, if superheated steam is 

 properly used, a saving of fuel may be effected. Many of the state- 

 ments published, however, have made the success too great.^ Some 

 time since the English Pacific mail steamers had their engines ar- 

 ranged to use highly superheated steam (450 to 500 degrees), and for 

 a while the change was regarded as beneficial. It is now, however, 

 found that this high heat is very destructive to the engines, injuring 

 the cylinders, pistons, valve faces, and valves ; and so great has the 

 injury been, that they have commenced to take out and much re- 

 duce the number of superheating tubes. 



COAL AND WOOD-BURNING LOCOMOTIVES. 



By a late report of John O. Sterns, Esq., superintendent of the 

 New Jersey Central Railroad, we learn that very fair tests have 

 been made with wood and coal-burning engines on that road, all of 

 which have terminated favorably for coal, as it regards economy. 

 There are thirty-eight locomotives, six of which have been altered 

 from wood to bituminous coal-burners ; twenty-four burn wood, and 

 eight anthracite coal. 



During the last two years and nine months, the wood-burning en- 

 gines have run 1,353,909 miles, the anthracite coal engines 165,585, 

 and the bituminous engines 112,757 miles. Regarding the perform- 

 ance of these three classes of engines, Mr. Sterns says: "The 

 three comparatively perfect anthracite engines make a saving in fuel 

 of seven cents per mile over three equally good wood engines, and 

 the difference in cost for repairs cannot exceed three cents per mile, 

 leaving a net saving of four cents per mile run by substituting an- 

 thracite coal for wood. . . . From our past experience, I am 

 satisfied there is a saving by using bituminous coal instead of wood, 

 of about three cents per mile, and that it is expedient to alter sev- 

 eral of our wood-burning freight engines to burn bituminous coal, 

 especially as the change is easily and cheaply made." 



The wood used by this company is oak, rated at five dollars per 

 cord ; the bituminous coal is the same cost per ton, while the anthra- 

 cite is set down at three dollars per ton. The wood-burning engines 

 run at the rate of 28.3 miles per cord; three good anthracite coal 

 engines average 31 miles to a ton of coal. Mr. Sterns states that if 

 all the freight trains on the New Jersey Central Railroad had been 

 drawn by good anthracite coal engines, twenty thousand dollars 

 would have been saved to the company last year alone. Where 

 wood is very cheap, as in Canada and on some of the Southern rail- 

 roads, of course it is preferable to use it ; but wherever it can be 

 shown that coal is cheaper than wood on any railroad, those who 

 have the management of affairs are culpable if they run wood-burn- 

 ing engines. Scientific American. 



