Q. David Bowers
Into the Mint
Leaving our hotel we walk up Chestnut Street, and between Thirteenth and Fourteenth streets come to a fine, substantial, two-story marble building, entirely fireproof, and enclosing within its quadrangular walls a spacious courtyard.
Ascending the massive marble steps, we enter an airy hall, freshened by a gentle breeze which sweeps through into the courtyard beyond. Between the hours of nine and twelve visitors are admitted, who are escorted about the building by gentlemanly conductors, of whom there are seven. Passing through the hall, on one side are the Weigh-Rooms for bullion and the office of the Chief Clerk of the Treasurer, and on the other the offices of the Cashier and Treasurer. Glance into the latter, to see Mr. James H. Walton, Treasurer, as he is deep in the mysteries of columns of figures so long and broad that Jessie observes, "One must be a great adder (A punning reference to a large snake, an adder.) to run up those columns."
We cross the paved courtyard, spacious and orderly, with boxes piled neatly around, and stacks of copper and nickel ingots ready for rolling. The well-proportioned chimney, 130 feet high-somewhat bullet-marked by pistol practice of the night watchmen-towers above the surrounding roofs, which look low by contrast.
Ingots and Strips
Thus we are conducted into the melting, refining, and assaying rooms; but having witnessed these processes in the New York Assay Office, we will linger for a moment only to see the melter run the gold and silver, now reduced to standard quality, into ingots. The standard of nine-tenths fine gold is now adopted by all the principal nations of the world, except England and Russia.
These ingots are bars sharpened at one end like a chisel blade, and are about a foot long, three-fourths to two and half inches broad, and half an inch thick, according to the coin to be cut from them. Continuing our walk through a short entry, we come to the Rolling Room.
Be careful of your dress, Jessie: that light silk had better been left at home, for this is a greasy place; and dirty grease has a magnetic attraction for finery.
Those massive machines are the rolling mills-four of them in a row, with their black heavy stanchions and polished steel rollers. The old man who runs this mill has been in the Mint nearly 40 years, and young girls who came to work are now grandmothers, perhaps, with the tally of their good works marked on their foreheads, a virtue in every wrinkle; and he has gone on rolling out the ingots year after year, handling more gold in a year than you or I shall see in our lives. He has not tired of showing his machine to visitors, and caresses the surly old iron with a motherly pride and affection.
He measures two ingots, and shows us they are of the same length; puts one of them between the rolls, just above the clock-dial, chisel end first, and it is drawn slowly through. He measures it with the other ingot, and we see it has grown about an inch longer and correspondingly thinner. This is the "breaking down," but it is not yet thin enough; it must be rolled ten times if gold, or eight if silver, to reduce it sufficiently, occasionally annealing it to prevent its breaking. No wonder the rollers look bright, they breakfast on silver and dine on gold.
That dial is not exactly a clock, though it looks like one. Do you see We little crank handle on it, above the hands? That is to regulate the space between the rollers. By turning it the distance is increased or reduced, and the hands of the dial are moved by the same means, to show the interval between them. For instance, when the hands indicate 12 o'clock the rollers are as far apart as they can be. By turning the crank until the hands are at, say, half past one o'clock, the distance is reduced about the 16th of an inch. It has been ascertained that when the hands point to, for instance, half past six, the rollers will be at the right distance from each other for rolling the strips thin enough for half eagles. So instead of saying, "Roll that strip the eighth of an inch thick," it is "Roll it to half past six." The rollers can be brought very close together. Give him that visiting card in your hand-there, it is pressed so hard that its texture is destroyed, and it crumbles like crisp pie crust.
This dial arrangement, and some other improvements in the mill, are due to Mr. Franklin Peale, former chief coiner of the Mint, who devised it for the purpose of securing greater accuracy in measuring the distance between the rollers.
The pressure applied is so intense that half a day's rolling heats not only the strips and rollers, but even the huge iron stanchions, weighing several tons, so hot that you can hardly hold your hand on them. Every mill can be altered to roll to any degree of thinness, but usually the ingot passes through several mills, each reducing it slightly. This was quicker than altering the gauge so frequently. When the rolling is completed the strip is about six feet long, or six times as long as the ingot.
It is impossible to roll perfectly true. Now and then there will be a lump of hard gold, which will not be quite so much compressed as the rest. If the coin were cut from this place, it would be heavier and more valuable than one cut from a thinner portion of the strip. It is, therefore, necessary to "draw" the strips, they first being softened by annealing.
Just turn to your right and see those long round copper boxes, into which that clever, plump-looking man is putting the gold strips. He'll tell us all about it.
"Yes, mum; ye see we have to anneal this here gold, to make it soft so we can draw it. So we puts it in these boxes, and puts in the cover and seals it up airtight with clay. It don't do to anneal gold in the open fire like as we can silver; for if we only get a hole in the box no larger than the head of a pin, it will let in the air and tum the color of the whole gold. They call it oxydizing. In that furnace we anneal the silver, but we don't put silver into boxes, 'cause we can heat that in the open fire without its turning. We puts these boxes into this furnace-you can look in at the door while I lift it up. Those in there are red-hot, and we keep 'em in about an hour, mum, till all the gold gets red-hot too. It would twist about like a snake if we took out a strip while it was so hot. When it is well het we take the boxes out with the tongs, and put' em into that tank of water to cool 'em, mum. There's from a thousand to 12 hundred dollars in every one of those strips, mum."
It's too hot to stay here long, so pick your way carefully among these boxes of gold, silver and copper strips, and ingots, to the other end of the room. Be careful of that stand; it is terribly dirty. It is where they are greasing the silver strips and waxing the gold, to enable them to pass through the drawing bench easier. Wax is a better lubricator than grease for gold.
That long table, with the odd-looking, endless chain, running from right to left, making a deafening noise, is the drawing bench. In fact, there are two benches, one on each side of the table. At the right end you see an iron box secured to the table. In this are fastened two perpendicular steel cylinders, firmly supported in a bed, to prevent their bending or turning around, and presenting but a small portion of their circumference to the strip. These are exactly at the same distance apart that the thickness of the strip must be. One end of the strip is pinched somewhat thinner than the rest, to allow it to slip easily between the cylinders.
When through, this end is put between the jaws of a powerful pair of tongs, or pincers, fastened to a little carriage running on the table. One carriage you see has a flag fastened to it, and has drawn a strip nearly through. The carriage to the further bench is up close to the cylinders, ready to receive a strip, which is inserted edgewise. When the end is between the pincers, the operator touches a foot pedal which closes the pincers firmly on the strip, and pressing another pedal, forces down a strong hook at the left end of the carriage, which catches in a link of the moving chain. This draws the carriage away from the cylinders, and the strip being connected with it has to follow. It is drawn through the cylinders, which, operating on the thick part of the strip with greater power than upon the thin, reduces the whole to an equal thickness.
When the whole is through, the strain on the tongs instantly ceases, which allows a spring to open them and drop the strip. At the same time another spring raises the hook and disengages the carriage from the chain. A cord fastened to the carriage runs back over the wheel near the head of the table, and then up to a couple of combination weights on the wall beyond, which draw the carriage back to the starting place, ready for another strip.
The original machine was invented by Mr. Barton, controller of the British Mint; but this table has been so far improved by Mr. Peale as to be almost his own creation. Barton's table required two men to operate it, while Peale's requires only one. The arrangement of the combination weights to draw back the carriage, fast at first and slower as it reaches the starting point; the application of the pedals to close the tongs and attach the carriage to the chain, are Mr. Peale's invention. His machine is arranged to run with much less noise than Barton's, and has other minor improvements.