1855.] 



THE MINTS OF THE UNITED STATES. 



131 



and perfect efl&ciency, varying in rate according to the denom- 

 ination of the coin, between 200 and 800 pieces per minute, 

 and at the same time separating any pieces that are notably 

 imperfect. 



It must be understood that the operation here termed " mil- 

 ling," is merely for the purpose of thickening and preparing 

 the edge, so as to give a better and more protective border to 

 the coin, the ornament or reed, commonly known I believe in 

 this country as " milling," being given to the piece by the 

 reeded collar of the die in which the piece is struck. 



The coining presses, 10 in number, and milling machines 

 are worked by a high-pressure horizontal steam-engine, made 

 from the design and under the direction of the present chief 

 coiner, in the workshops of the establishment in 1838. 



The presses are three sizes, the largest applicable to the 

 striking of silver dollars and the double eagles : — the second 

 to pieces of medium value : — and the smallest to the dime, half 

 dime, and 3 cent, pieces. The first is usually run at the rate 

 of 80 per minute, the last at 104 per minute, — the average 

 rate of the whole is 82 per minute. This rate can be in- 

 creased if required. 



If all the presses were employed in coinage at the usual rate, 

 they would strike in one day (9 working hours) 439,560 

 pieces ; and if employed upon gold, silver, and copper, in the 

 usual manner, and on the usual denomination of coin, they 

 would amount in value to 8966,193. 



During the past year, on one occasion 8 of the presses were 

 run 22 out of 24 consecutive hours, and coined in that time 

 814,000 pieces of diflFerent denominations of coin. 



The presses have been made principally in the workshops of 

 the Mint. They possess in common with the presses of 

 Uhlhorn, in Germany, and Thouellier in Paris, the advantage 

 of " the progression lever," " le genou" or " toggle joint," a 

 mechauical power admirably adapted to this operation ; but in 

 almost every other particular they are original in arrangement, 

 being the result of experience, beginning as far back as 1836. 



In order to supply these presses various means have been de- 

 vised ; among them and not the least important, is the " shaking 

 box," in which advantage is taken of a disposition observable 

 in similar bodies, or bodies of similar form, to arrange them- 

 selves in similar positions. This is a box, whose bottom is 

 constructed with parallel grooves adapted to the size of the 

 blanks or planchets to be arranged. A quantity of them is 

 thrown indiscriminately into the box, w'hich is then quickly 

 shaken in the direction of the grooves, the pieces immediately 

 lay themselves side by side in parallel rows, from which they 

 can easily be lifted in rouleaux as required to be passed to the 

 feeding tubes of the mills or presses. 



It is very evident to all visiting the establi.ihmcnt that such 

 a largo number of pieces could not be coined and manipulated 

 by such a limited number of hands without the aid of some 

 labour fxcilitating arrangements, one of the most worthy 

 of remark of which is the method of counting the pieces coined 

 — if counting it can be called, for in principle it is a measuring 

 machine. The arrangement of this counting frame, or tray, 

 may be understood from the following sketch of its con- 

 struction. 



A board or tray of such dimensions as may be required, is 

 divided by a given number of parallel metallic plates dissected 

 into its plane and slightly elevated above it, the edges of 



which rise no higher than the thickness of the coin for which 

 it is intended. The board is of such a length as will admit 

 of a few more than the required number of pieces to be laid 

 longitudinally in the rows and is divided across and at right 

 angles with the rows, and hinged at a point opposite to a given 

 number. One of those employed by this department counted 

 1000 pieces, that is to say, it had 25 parallel grooves or rows 

 sufficiently long to receive 45 pieces. Now, having thrown 

 on this board a large excess of pieces, it is agitated by shaking 

 until all the groves are filled, and then inclined forwards until 

 all the surplus pieces have slid off, one layer only being re- 

 tained by the metallic ledge ; the hinged division is then 

 suffered to fall, which at once throws off all but the 45 pieces 

 in the length of each row. This operation, somewhat difficult 

 and tedious to describe, is performed in a few seconds, and re- 

 sults in retaining on the board 1000 pieces, each piece exposed 

 to inspection, and the whole accurately counted withouv tho 

 wearisome attention — so likely to result in error — required 

 under usual circumstances. 



The very large number of pieces coined during the last 

 year has been counted almost exclusively by two Icmalc 

 manipulators, assisted by a man who had the duty of weighing 

 them in addition as a testing check. The same amount ot 

 labour by ordinary means could not have been performed with 

 fewer than thirty or forty hands, to say nothing of inferior 

 accuracy. This machine was originally arranged and patented 

 by the late R. Dyler, coiner of the New Orleans Branch Mint, 

 but materially improved in its application and construction 

 by Mr. Franklin Peale. 



The balances of the Mint of the United States have received 

 the attention necessary to an instrument of such importance in 

 mint operations. They have been arranged and made gene- 

 rally in the workshops of the establishment, and operate 

 entirely to the satisfaction of the department. It is not 

 neces.sary to enter into details of their construction, as a full 

 and minute description is given in the Journal of the Frank- 

 lin Institute for July 1847. I, perhaps, ought to mention 

 that since that appeared, some slight improvements have been 

 made by inclosing all but the stirrups and pans in glass, by 

 these means excluding dust and protecting them from the in- 

 fluence of air currents. 



In concluding this brief sketch of the practical working of 

 the two most important departments of the United States 

 Mint, I cannot omit a reference to the very excellent remarks 

 of the chief coiner on the employment of females in some of 

 the operations in his department. This, he informed me, 

 had generally excited the surprise of, and been commented 

 upon, by foreigners, who had visited the Mint. His experi- 

 ence, however^had led him to believe, that in places of trust, 

 where no great physical exertion was called for, but where 

 accuracy and strict integrity were of first importance, the 

 moral perceptions of the female, generally stronger and of a 

 higher standard than in the man, would qualify her as his 

 substitute, and thus, while opening a new field of labour f jr 

 the occupation of females, would strengthen their claims to it 

 by the s\iperior accuracy aud economy of their work. 



On Marine Boilers. 



Bv J. A. RoEDLINfl, C.E., Xl.tCAR.i F.VLIS. 



The furnace of a boiler should be so constructed as to render 

 comtiustiun as perfect as possible, but it can do no nmre than 

 produce carbonic acid. If only one-half of the oxygen neccs- 



