Of the many advantages claimed for steel chains, it may be prominently noted that a very important saving of weight is effected on account of their possessing such a high breaking strain, compared with the ordinary welded iron chains.  To illustrate this, it may be stated that a given length of the weldless steel chain is 35 to 40 per cent. less in weight than an equivalent length of iron chain, will stand the same breaking strain as the latter, and indeed, where steel of special quality is used in making the weldless chains, this difference can be increased as much as 70 to 80 per cent.  Whereas superior iron chains break at a strain at 17 tons per square inch, these weldless steel chains will stand a strain of 28 to 30 tons, with 20 to 26 per cent. elongation.

[Illustration:  Figures 1.  Through 9., 1_a_, 1_b_ and 3_a_
               MANUFACTURE OF WELDLESS CHAINS.]

Again, there is greater security in their use from the fact that there are no welds, and they give warning of the limit of strain to which they can bear being approached, by elongation, which can be carried to a considerable extent before the chain breaks.  Moreover, over, in chains made by this process, the links are all exactly alike.  Though the life of a weldless steel chain is said to be twice that of an ordinary one, the price per length is little more than that of best iron chains.

They are made in lengths of from 40 to 50 feet, being compressed from a solid rolled steel bar, the section of which is shaped like a four-pointed star.  In the first place holes are pierced at intervals down the length of the bar, thus determining the length of the several links.  Then the bar is notched between the holes so as to give the external form of the links.  The next step is “flattening out,” which presses the links into shape on their inner side, but leaves the openings still closed by a plate of metal.  They are then stamped out so as to round them up, and the metal inside them is punched out, and the edges “cleaned,” or trimmed off.  The links are now parted from one another and stamped again, to insure equal thickness in all parts of the chain.  The only processes now to be gone through are dressing and finishing.  According to the die used, the shape of the links can be varied to suit any required pattern.  The lengths of chain thus made are joined by spiral rings made of soft steel, the convolutions being afterward hammered together till they become solid.  A ring of this description, 3/4 inch diameter, underwent a strain of 46,200 lb., that is, 23 tons to the square inch, its elongation being 21 per cent.

These chains have passed satisfactorily the tests of the Bureau Veritas, and both that association and Lloyd’s have accepted their use on the same conditions and under the same tests as ordinary chains.

So much for the general idea of punching steel chains.  We will now describe a recent invention by which superior steel chains are produced, the author of which is Mr. Hippolyte Rongier, of Birmingham, Eng.  He says: