Indian Peace Metal

Some of our readers may recall our Spring 2001 newsletter in which we told of our assignment to determine whether a cast-iron statue of Avalokitesvara was of ancient origin or merely a century-old souvenir. (Yes, indeed it was of ancient origin.) Well, recently we had a somewhat similar assignment, this time to check the authenticity of a silver Indian Peace Medal purportedly dating from Abraham Lincoln's administration.

So, what exactly is an Indian Peace Medal? Peace Medals started back in colonial times, when the British, Spanish, and French governments produced silver medals bearing the likeness of their respective monarchs. The medals were given to influential Native American chiefs and warriors as tokens of friendship and cooperation. After the United States achieved independence from England, George Washington's administration recognized the importance to the young nation's security of forming alliances with Native American tribes that it considered friendly. Consequently, the tradition of the Indian Peace Medals was continued, this time, of course, with the medals bearing the likeness of George Washington rather than King George.

The practice continued with subsequent administrations, all the way through the administration of President Benjamin Harrison, 1889-1893.

The original Indian Peace Medals of Abraham Lincoln's administration were struck in silver, in two sizes, a larger, 3-inch diameter medal and a smaller, 2 1/2-inch diameter medal.

Only 100 original silver medals were struck by the mint, but subsequently, during the next ten years or so, an additional four large medals and 12 small medals were struck in silver, and at about the same time, an additional 132 large medals were struck in copper. Given their rarity, and the ongoing popularity of Lincoln memorabilia, an original silver Lincoln Indian Peace Medal is very valuable in today's collector market.

No peace medals were issued during the administration of President William Henry Harrison, who died in office only a month after his inauguration in 1841--popular lore holds that his death was the result of pneumonia caught after delivering a nearly two-hour inaugural address outdoors during a snowstorm while wearing neither a hat nor coat. President Harrison holds the dual distinction of having delivered the longest inaugural address and having served the shortest tenure in office. Oh, and until Ronald Reagan was elected in 1980, he was also the oldest person elected president in the country's history, at 68 years of age.

Of course, here's where our story takes a turn toward the shady side of things. It turns out the US Mint has also produced, in modern time, thousands of bronze copies of the medals for collectors, using the original dies. So, if someone were to take one of these bronze copies—which, incidentally, are available for as little as $25—and plate it with silver, and then subject it to an appropriate "massaging" so as to make it resemble a well-worn original, it could be worth a great deal of money, provided the rospective buyer doesn't investigate it too thoroughly.

In this project, the medal in question had been purchased by a museum curator and had already undergone a preliminary visual examination by an expert, who suggested it might be authentic; however, he had recommended a more detailed examination be conducted, utilizing nondestructive elemental analysis, which is where we entered the picture. Our assignment was to examine the medal and determine if it was authentic. Oh, yes, and for what are probably obvious reasons, we weren't allowed to cut it up into pieces as we usually like to do for analysis.

Research indicated the original Lincoln silver Indian Peace Medals were likely of silver coinage composition in use at the time, namely, 90% silver and 10% copper. An elemental analysis in the scanning electron microscope with our x-ray spectrometer quickly revealed a disappointing result: no copper; the silver was simply that—silver, with no significant alloying elements. So right off the bat, things didn't look too promising for the owner. Then, after not being able to find any copper alloyed with the silver on the face of the medal, we visually noticed a copperish color in a more incriminating location, namely within the bore of a hole that the medal had to allow it to be mounted on a lanyard and worn about the neck. Obviously, the presence of copper within the bore of the hole suggested the medal was probably a copper alloy, with a silver plating on the outside to make it resemble the original silver Peace Medals

Lewis and Clark, on their 1804-1806 Corps of Discovery trip to the Pacific Northwest, brought along 32 Jefferson Indian Peace Medals (in three sizes), which they presented to Native American chiefs they encountered on their journey.

So, you ask, how does one accurately measure the specific gravity of an irregularly shaped object such as a medal? It's quite easy actually. You accurately weigh the medal in air, and you accurately weigh it in water. Subtracting the two numbers gives you the weight of the displaced water, from which you can calculate its volume - and hence, the volume of the medal - by simply knowing (i.e., looking up in a reference table) the density of water at the measurement temperature. From the volume and weight, you can easily determine the density, from which you can determine the specific gravity.

With our suspicions now thoroughly aroused, we proceeded to measure the specific gravity of the medal, which would allow us to tell whether it was just an alloy of mostly copper with a silver plating on the outside to fool the unwary, or whether it was really a silver-copper alloy throughout, as the owner hoped.

No luck for the owner—that test put another "nail in the coffin" -the specific gravity was almost exactly the same as the specific gravity of a 95% copper-5% zinc alloy commonly used for coinage and medals, far less than the specific gravity of a 90% silver-10% copper alloy.

As a final indication of the medal's lack of authenticity, we noted that while the medal itself appeared to be well-worn, the bore of the hole was not worn at all, showing it most likely didn't date from a century and a half ago. Because the current US Mint restrikes don't contain mounting holes, the absence of wear in this hole indicates that this was likely a restrike medal which someone had drilled, abraded, and silver plated in an attempt to duplicate an original. Interestingly, the hole itself was particularly ineptly done; it had been countersunk, probably in an attempt to make it look worn around the edges, but of course the countersinking machining marks were immediately apparent under the microscope, clearly showing that it wasn't wear at all; not only that, but the countersinking had gone too deep and machined off the top of the letter "E" in the word "PRESIDENT"—not exactly indicative of a high precision minting/machining operation!

All-in-all, it was a very interesting assignment, even if the results of our sleuthing were a disappointment to the owner. On the bright side though, the museum curator asked us to prepare a series of slides so she could present the information to other interested parties as a learning experience on a few of the methods that can be employed to authenticate (or, in this case, maybe we should say "disauthenticate") a historic item.

Sylvan Overpass Strain Gages

Those of you who regularly drive the Sunset Highway westbound out of downtown Portland have no doubt been following the progress of the Sylvan overpass/off-ramp project. (Unfortunately, you may have had more of an opportunity to ponder the project than you would like at times, such as when you've been stuck in bumper-to-bumper, stop-and-go traffic.) As part of the $80.6 million Camelot-to-Sylvan Interchange Project, Phase 2 passed a major milestone in August with the opening of the new eastbound off-ramp, which ties into the new overpass.

In late spring and early summer, we had an interesting strain gage assignment on the new overpass. The Oregon Department of Transportation (ODOT) designed the overpass knowing this was a long, wide span that was going to be subject to high use. We were asked to assist in verifying the design by installing electric resistance strain gages inside the steel beams of the overpass.

We worked with the ODOT design engineers to select locations to measure the strain on the beams. Strain gages were mounted in 80 test sites to measure axial and triaxial strains. The gages were mounted after the beams were lifted into position but before the concrete bridge deck was placed.

Using these "zero" readings as a starting point, we were able to measure the increase in stress within the beams when they were subjected to the additional loading imposed by the concrete bridge deck. Because the additional load of the concrete was accurately known, the ODOT engineers were able to verify their design assumptions by comparing the increase in actual stress with the predicted design values, thus verifying the bridge was responding to the loading as expected.

Later, we'll be taking additional measurements under dynamic loading conditions imposed by fully loaded trucks driven over the bridge. This behind-the-scenes effort helps insure the bridge will perform safely for many years, just as the designer engineers intended.

MEI-C People

Chris Gerdes, engineering technician, rejoined us in September, having been off at Basic Training and Advanced Individual Training since March with the Army National Guard. Welcome back, Chris!