BALL-MAKING.

About eighteen years ago Col. Pope said to the writer, referring to the first [Columbia], then in market and the first American product, that it would cost $25 to put ball bearings on the back wheel (or possibly it was on both wheels). The usual extra on English makes at that time for balls to back-wheel was one pound sterling; the first ball pedals were also expensive, but for some years past any bearing without balls, even on the lowest-priced wheels, would have been rejected by every buyer. The difference has come largely by cheapened processes of ball-making, and, as in other things, reduction in cost and betterment in quality have come together. There are several ways of producing balls. According to one of the best, the Simonds Rolling Machine Co. of Fitchburg use forging machines, which are substantially two uprights, a half-die on each upright, and work automatically. Heated rods of tool steel are inserted in this machine, which forges a ball rough and at the same moment bites off the bit from the rod with the die. Next follow grinding and polishing automatically between horizontal disks about three feet in diameter in conjunction with emery wheels; finally come tempering, the last polishing and gauging automatically. Ordinarily a maximum variation of ¹⁄₁₀₀₀ of an inch has been considered close enough, but this Company are able to guarantee a variation not over ⁴⁄_10,000, the highest accuracy and uniformity being naturally considered somewhat in the price. The machines used are patented, and this bare outline is all we are permitted to publish.

There remains to be considered the four-point bearing, and no better example of this can be given than in the cut of one as used on the used on the “[E. & D].” as made by the Canadian Typograph Company of Windsor, Ontario. It is proper to say here that only minor details on this are patentable, for the principle is old and was in the old Bown Eolus bearing as long ago as 1877. Reference to the cut shows clearly that the ball rests on two points on cone and cup each, that its diameters are equal at these places of contact, and (most important of all) that the direction of pressure on the ball is at right angles to the axle, and hence that the ball will roll on an axis parallel to the axle; therefore there can be no sliding or skewing.

The contact surfaces are a right angle V in section, or can be made by cutting open a square diagonally. At the last show in New York, as a test, ten single wheels of this make were suspended in pyramidal form, and these were all run, day after day, by a single length of No. 100 sewing silk. A wheel was also shown with the balls removed from one bearing and tightly screwed in the other. This wheel was then whirled, being supported by one end of the axle on the finger, gyroscope fashion, to show the extraordinary absence of friction.