32 ANNUAL OF SCIENTIFIC DISCOVERY. 



truck. Another incidental and considerable advantage is, that with a single 

 shaft the bearing of the engine is thrown further forward, and the weight 

 necessary to adhesion is thrown further back upon the driving-wheels. 



IMPROVED LOCOMOTIVES. 



The introduction of cheap steel, and the gradually spreading fact that 

 combined strength and lightness at any reasonable cost will pay at once and 

 handsomely as features of locomotive machinery, are leading to a signal 

 improvement in the locomotive engine. At the Albany Iron Works, semi- 

 steel is being largely introduced for all parts of boilers, allowing twenty-five 

 per cent, increase of strength with the same weight, or twenty-five per cent, 

 decrease of weight with the same strength. It is probable that a higher 

 pressure will be employed, since it is economical in itself, and that boilers 

 will be somewhat lightened. Steel tires of the same make are now under- 

 going a so far promising trial. They will greatly add to the durability of 

 engines, and decrease weight where lightness is most needed in the parts 

 unrelieved by springs, which act as a forge-hammer directly on the rail. 

 The above features cost no more in semi-steel than in iron, and therefore 

 should come into much more rapid use. Krupp's Prussian steel axles the 

 best in the world arc finding favor at double the cost of iron. We do not 

 hear that they ever wear out or break. They have not been in use long 

 enough to show old age yet, though some have run in this country over a 

 dozen years. Another decided improvement in locomotives is in the propor- 

 tions of the boiler and the steam-generating apparatus. Smaller grates, 

 larger combustion room, a very much larger water-circulating space, allow- 

 ing less nominal and more real heating surface, and the modern appa- 

 ratus in the smoke-box for facilitating draft, have considerably decreased 

 the consumption of fuel and the wear of boiler in the production of a given 

 power. 



THE MANUFACTURE AND DEFECTS OF CAST-IRON CAR- WHEELS 



AN IMPROVED WHEEL. 



The supply of car-wheels to railway equipment has become a distinct and 

 extensive branch of the foundry business. Several very large establish- 

 ments, and many smaller ones, are constantly employed in this single manu- 

 facture. Wrought-iron wheels, such as are almost exclusively used in Eu- 

 rope, are too expensive, according to our railway policy a reduction in first 

 cost is the leading considci'ation ; while the flanges of wrought wheels rapidly 

 cut out on our most crooked roads, rendering a harder material desirable. 

 Steel tires, which are, scientifically considered, the best known for durability 

 and shape, roundness, are very much more expensive; and our roads 

 have not yet found it expedient to introduce them. The improvement we 

 shall describe will furnish many of their advantages at a very cheap rate. 



The service of car- wheels, especially on our rough roads, is very severe; 

 great strength to resist side and other strains, and the incessant hammering 

 of our jointless rails, and extreme hardness of the tread or rolling surface to 

 prevent rapid wear, together with the greatest possible lightness, are essen- 

 tial. To embody these conditions in a single casting is more difficult than 

 the uninitiated would imagine; the nature of the metal itself is in most re- 

 spects adverse to such a result, though in one respect it is extremely favor- 



