order to overcome the blowholes produced by the air and gases entrained into or generated in the casting, and to minimize the detrimental effect of these blowholes, I do not intend to dispute the efficiency of this process for obtaining the results aimed at. The experience of many years, however, and of numerous investigations with ingots of the largest size, entitles Krupp to the assertion that he employs a most excellent process of his own for producing solid castings, and results of comparative experiments have pronounced in favor of the Krupp method as being much more efficient than the fluid compressing process.

In regard to the question as to which material is the best and most reliable for shafts, it should not be omitted to point out the many advantages which distinguish Krupp's crucible steel from any other kind of steel produced by any other process, for crucible steel has just those qualities which make ingots proper for such forgings as shafts. The superiority of this material is founded upon the arrangements designed especially for this purpose, and furthermore upon the practice of many years which guarantees the complete control of the process, and especially the ability of charging thousands of crucibles uniformly, filling them exclusively with puddled iron and steel, manufactured especially for this purpose, by being repeatedly refined and freed from cinder by welding, hammering and rolling and by picking out by experienced workmen. Krupp is further enabled by means of the iron mines and blast furnaces which he owns to always obtain the best raw material, and to charge every crucible exactly the same, so that at the very outset a determined hardness and quality can be expected with confidence.

The melting furnaces have been improved to such a high degree that the greatest precision in the attainment of the required heat in all the furnaces, and in all crucibles necessary for one ingot is guaranteed.

A further advantage of the crucible process is the complete absence of the detrimental effect of the furnace gases, cinder, oxygen, and other gases in the molten steel, an indispensable condition for the production of solid ingots, and a condition that requires no fluid compressing to doctor up. The existing arrangements permit the casting of ingots of crucible steel up to 85 tons, which maximum has hitherto been more than sufficient for the largest shafts likely to be ordered.

Regarding the process of forging hollow upon a mandrel it may here again be pointed out that the selection of a much larger ingot at Krupp's Works, which allows a forging down of the crosssection of the ingot from 9 to 1, surpasses completely the advantages, if there be any, of hollow forging, especially so if the forgings are bored out after having been forged under the presses than if, as is done at some works, the ingots are only drawn out from 4 to I.

Never having seen the report of a test piece taken from the in

side wall of a shaft that has been forged hollow on a mandrel, I cannot say that it is not as dense as the inside wall of a shaft that has been cast solid, forged and then bored. But theoretically I cannot see why it should be, as the mandrel does not act as an anvil or die, since the shaft being forged, is not suspended upon the mandrel, but rests upon the press die, from which point the resistance is offered to the forging pressure applied.

If the metal in the centre of a solid ingot is not compressed by hydraulic forging, the mandrel in a hollow ingot would be only a useless substitute for the core removed. If the centre or core of a solid ingot is compressed by the forging press, it is decidedly a better method to forge to the centre the greater volume of impurities and afterward remove them by boring, as per the Krupp method, than to remove only a portion of them and forge the rest into the shaft, as must be the case if the mandrel is at all effective.

The origin of the hollow shaft is supposed to have been at the Krupp Works and no other maker has made as many nor any that have given greater universal satisfaction, but he does not deviate from the principle of casting solid, then forging and next boring.

Furthermore, the oil tempering and annealing to which, of course, at Krupp's Works nearly every shaft as well as nearly every forging is subjected after having been bored out, outweighs and even surpasses to a much higher degree the advantages claimed of greater density and finer grain from forging hollow, and the arrangements for oil tempering and annealing forgings of the largest dimensions can be considered as a standard, and the practice in the treatment of the different qualities is assisted very efficiently by the most improved apparatus for measuring the temperatures

The certainty in the control of the crucible process guarantees the production of a material of higher tensile strength, without diminishing the ductility and toughness. There have been supplied for use in the United States a great number of shafts of the largest dimensions, the elastic limit of which was specified to be 45,000 lbs. per square inch, with an elongation of 18 per cent in 10 inches, and in all cases these minimums required for elasticity and elongation were considerably exceeded.

It may be here mentioned that at Krupp's Works nickel steel is used on a large scale for the production of shafts for steamers, also for axles and crank axles for locomotives, etc. A short time ago the Krupp's Works turned out some nickel steel shafts for the large, fast steamers, which have been built for the North German Lloyd line. The ingots, from which these shafts were forged, had a diameter of 72" and weighed 60 tons each, the diameter of the crank shaft is 24" and the weight of a single crank bored and finished complete (three cranks to each engine), is 14 tons, while in the forged state the weight was 28 tons, or twice the weight of the finished shaft.

The following are the results of the physical tests of the above material made by experts of the company:

"Several extremely large hollow bored, oil tempered, crucible steel shafts have been furnished by the Krupp Works for service in the United States from which test bars 2" in diameter, 48" long, tested at the Watertown Arsenal by the United States Government inspectors showed an ultimate tensile strength of 97.780 lbs., and an elastic limit of 64,000 lbs. per sq. inch, and a reduction of area at point of fracture of 51% and elongation in 48 inches of 6.67 inches."

The usual quality of open hearth and crucible steel furnished.