MINT 



349 



To the lower part of the cup is fastened 4, which carries the upper die. So that, just 

 at the moment that the levers G have permitted the collar to enclose the blank, the 

 upper die reaches the full force of its blow, and comes upon the blank. The force of 

 the blow, by converting the blank into a coin, causes an instantaneous recoil of the 

 screw D, which is assisted in its rise by a kind of balance just equal to its weight. 

 The nature of this arrangement will be better understood by reference to fig. 1538, 

 where the funnel-shaped tube A is seen to be traversed by a rod A', which terminates 

 in the head of the screw D; the opening in the funnel being for the convenience of 

 fixing this rod to D. At the top is a swivel, where the twisting motion is lost. It is 

 connected at its upper end with a balanced beam, the other end of which is in com- 

 munication with a partially -exhausted chamber: an arrangement which, while it 

 becomes a counterpoise to the weight of the press, is used as a regulator of the blow 

 to be given, so that it is quite possible to coin blanks of differing denominations by 

 the agency of this chamber without altering the vacuum in the large vessel ; for it 

 must be explained that the motive power of the press, that which brings down the 

 die with force, is gained by the pressure of the atmosphere. 



As the coined money issues from the press it is collected in trays and examined ; 

 all imperfect coins, curiously termed ' brockages,' are picked out ; and the good coins 

 weighed into drafts of 701 sovereigns, equal in weight to about 180 ounces ; these are 

 at present sent to the weighing-room, where they are examined for imperfect coins, by 

 passing over a kind of blanket, so arranged on a series of rollers that each coin lying 

 on its surface can be seen as the blanket revolves. 



Fig. 1539 gives a view of the milled collar A. B being a representation of the lower 

 die, with its long neck which fits nicely into the milled collar A. c, the upper die, 

 also passes to a small distance into the collar, so that at the moment of the blow the 

 blank is absolutely enclosed. The blow, which is estimated at 40 tons, forces the metal 

 into every engraved part of the collar and dies. The press, which has been described 

 with as few technical terms as possible, coins from 60 to 80 blanks per minute, finish- 

 ing by one blow the obverse and reverse impressions, and adding the milled edge. 

 (For the manufacture of dies, see DIES.) 



The coins when struck are collected at frequent intervals and carefully overlooked 

 to find any which may be defective, for with all the beauty of the mechanism of the 

 press, accidents cannot be avoided, and it is found that about one coin in 200 is im- 

 perfect in its finish whatever its size or value. The imperfect coins are returned, with 

 the ends cut from the bars, the scissel, and the imperfect and out-of-remedy blanks, 

 to the melting-house every morning. The coins are weighed into bags, each containing 

 701 sovereigns, and at intervals, depending on the requirements of the Bank, sent to 

 the weighing-room, where each coin is weighed separately in Mr. Cotton's balance. 



Mr. Cotton's weighing-machines form perhaps the most elegant and clever invention 

 of modern times. They effect the process of weighing far more accurately than man 

 can hope to do; and with extraordinary accuracy determine the weight of about 23 



