340 



MINT 



passed twice, and are then submitted to another pinch without altering the scale at 

 all ; so that what is called a spring-pinch is given, with the intention of effecting 

 the reduction of the fillet to one uniform thickness, for the breaking down and sub- 

 sequent rolling cause the fillets to become much thicker in their middle than at 

 their sides. The widening of the fillet is very trifling ; but width may be gained to 

 any desired extent at the will of the workman if the bars be submitted to a heavy 

 pinch instead of a scries of light ones. The fillet having been submitted to the fourth 

 spring-pinch, is gauged on its side by a steel instrument, of which Jiff. .1526 is a repre- 

 sentation. It is a hollow wedge, which is graduated to the thousandth of an inch. 



152G 



Supposing that the opening from A to B were extended until it were one inch wide at 

 A, the space would be divided between it and B into 1.000 parts, and then every fillet 

 passed into this opening would stop at a given point, say for instance, at 140; such 

 being the case, every part of the same fillet should be arrested precisely at the same 

 point. The fillets are reduced till they measure- 117 on this gauge, and are conse- 

 quently O'llT inch thick. They are then passed to the next mill, and then to a 

 third mill, where they receive very light pinches. They then pass to another mill, 

 still finer than any of the preceding, and here are submitted to very light pinches, by 

 which they are reduced to 0'058 inch, and are finally finished at the sixth or gauging 

 mill, where they receive three pinches, and are then 0'053 inch thick. 



The gauging mill is of different construction from the other mills, as may be seen by 

 reference tofff. 1527, where the rollers, a, b, are seen in the act of reducing a fillet. 

 The upper roller is fixed in brasses loosely clamped together ; the upper brass, u, being 

 firmly bolted to the main frame of the mill by screws, while the lower one, which 

 carries the weight of the roller when it is running empty, is supported by spiral springs 

 not shown. The lower roller works on a brass, which rests on a wedge shown at e ; the 

 brass being cut to fit the wedge, so that it may become similar to a solid mass, irre- 

 spective of any motion given to the wedge. By this mode of adjusting, a difference of 



1527 



the 0-001 of an inch may bo made with ease between the distance of the rollers, and 

 consequently in the thickness of fillets which may pass between them. The wedge ( 

 is moved forward and backward by the screw/, which itself has motion from tlu- pear 

 work, ff. Directly a fillet is passed between the rollers, the topmost one is forcei. 

 against its upper brasses, and further up\v;ird motion becomes impossible. As tho 

 g.iuger of fillets requires other tests besides that of tho thickness of the edge of tho 

 fillet, he punches out a blank from an occasional fillet by a hand-press ; the blank 

 falling through the bolster of the cutter is caught, and is then weighed in tho hand 

 scales against a standard weight, from which it must not vary more than 0'50 grain. 

 He has, in addition to the gauge represented by fig. 1526, one of great accuracy, by 



