How Thick Was a Trade Dollar?

By Roger W. Burdette, special to CoinWeek …..
Today, the thickness of a coin is seldom a topic of discussion among coin collectors. It mostly comes up when someone finds a coin that seems too thin or too thick, and this leads to discussion about thin planchets cut from the end of a coinage strip or possibly something made on a planchet intended for a different denomination or even another country. Other than us collectors, the only ones who care are vending machines and coin counting machines.

But back when Trade dollars were real money, coin thickness really mattered.

Almost everyone handling money – bankers, payroll clerks, store owners, commuter rail and trolley companies – counted coins by hand or with little counting boards. This involved counting a fixed amount into a small stack, or pile, them making more stacks of the same height without counting the coins. If there were 10 silver dollars in a stack, then all other silver dollars the same height should also contain 10 dollars.

Maintaining coins at a uniform thickness was critical to accurate counting, but it wasn’t an easy thing to do when there were four or five mints churning out the same denominations every month. Complaints about uneven “piling” were common among letters to United States Mint directors.

Here’s an example from late 1877:

Having occasion this morning to count some Trade dollars, we found that upon placing a pile of twenty-five of those stamped with an “S” alongside of a pile of the same number without a mark, the latter was the tallest [sic] by almost the thickness of one of the coins.

As people expect to find equal piles of the same denomination of silver coins to contain the same number, it occurs to us that the matter may be worthy of attention.

We would add that there is a difference of 1 grain in weight between the individual coins above mentioned.

We send by bearer a pile of each for your inspection.

This situation, if confirmed, would require anyone handling Trade dollars made by more than one mint to count each pile, or risk a costly over/under count.

Philadelphia Mint Superintendent James Pollock asked the Coiner, Oliver Bosbyshell, for an explanation, and received the following letter February 7, 1878:

In reference to so much of the Director’s letter to you of the 6th inst., as relates to the piling of Trade Dollars, I have the honor to say, that I am unaware of any standard height of a pile of twenty (20) pieces of Trade Dollars; at least the law does not fix either the diameter or thickness of our coin.

Custom has fixed a standard, and we gauge our coins accordingly. The thickness of a Trade Dollar according to custom is 82/1000ths of an inch; a pile of twenty (20) then should be 1-640/1000ths of an inch high.

However, our coins cannot be put to so severe a test as this, as circumstances over which we have no control, cause the thickness to vary. The blow given each piece we know is the same; the diameter must be the same, as the steel collar holds the metal rigidly; but the character of the metal struck is not always the same. If we could secure a uniform character of metal, so that the resistance [to striking] would always be exactly the same, then being able to regulate the power of the blow, and of determining the diameter, we might hope to have a positively uniform thickness.

A deviation from the customary thickness (82/1000ths) of a Trade Dollar of 4/1000ths of an inch (say a hair’s thickness), would for a pile of twenty make almost the difference of one piece.

Sometime since Messrs. Powers & Wightman, of this city, sent to the Mint two packages of Trade Dollars – 25 struck on this Mint and 25 struck in the Mint at San Francisco – with an inquiry as to why, when the two piles were placed side by side, there was room on the pile of San Francisco dollars to put an additional piece. By placing them together I found this correct; 25 Philadelphia Trade Dollars were as high as a pile of 26 San Francisco dollars. An examination of the several coins showed that the reeding on the edges of the Philadelphia pieces came up square from edge to edge, whilst that on the San Francisco pieces was only on the center of the edge, leaving rounded spaces between where it left off, and the border of the pieces.

We felt satisfied that this was caused by these pieces having ben struck in a looser collar than those made in Philadelphia, and this made them a shade thinner, which difference widened to an additional piece in a pile of twenty-four.

An examination of the collar sent from the San Fran cisco Mint, suggests other reasons for a difference in the heights of piles of twenty.

Applying our Standard Gauge to this collar, we find it to be correct from bottom of reeding. It shows, however, that the pieces were struck at the top of the collar. The collars are made with a slight slope from the top to the bottom so that the diameter of the top is a trifle larger than the diameter of the bottom. This is done in order to allow the struck piece to be easily shoved up out of the collar by the lower die [He means the collar was slightly wider at top than at bottom. –RWB]. Our pieces are struck in the center of the collar; hence, a very trifle less in diameter than pieces struck in the collar sent from San Francisco. This would make a difference in the height, quite perceptible in piles of twenty.

To prevent mistakes, coins should not be piled higher than tens. The pieces from Powers & Wightman were subjected to this test, and no perceptible difference in the height of such piles was noticeable.

Very respectfully, Your obedient servant

O. C. Bosbyshell, Coiner

The final determination was that the piling discrepancy was correct, and the cause was that San Francisco positioned the collar so that coins were struck near the slightly wider top, rather in the center as intended. The solution was not to correct the minting error, but to tell the customer to pile coins in stacks of 10, not 20 or 25 pieces.