The Kneass draped Liberty design here combined with a flying eagle reverse. It is believed to have been executed by Christian Gobrecht as Kneass was incapacitated by a stroke a few years prior.
These supposedly exist as both originals and restrikes.
True originals should weigh 206 grains and should only have die cracks through "F Dollar * America" as seen on the Liberty seated patterns of this year J79/P89 and J79A/P86. To date, none have been seen in this die state showing that these were produced later. The fact that the Mint collection does not contain an example may also be significant as this pattern would have been produced at the initial formation of the collection and likely would have been included if it was actually struck in 1838. The earliest state seen is shown below courtesy of PCGS.
It has a die break from AM in America to the eagle, a second from AR in Dollar to the eagle and a partial from the eagle heading toward the A in Half.
Restrikes exist with additional reverse die cracks, rust and obverse wear and are believed to have been made from the late 1840s continuing throughout the 1860s and 1870s. W.E. Dubois may have sold one to Matthew Stickney as noted in a letter dated July 12, 1843 in the Peabody Essex Museum which specifically mentions the restriking of 2 flying eagle half dollar patterns, which are believed to be this and a J79A/P86 as both were in the 1907 sale of his collection although both could have been J79A/P86.
Dubois paid an extra $3 to have them struck. If one of the pieces was a J73, it is unidentified today but a J79A/P86 in Stickney's collection when it sold in 1907 was purchased by Virgil Brand (journal #38995) and is identified by Kosoff as the Dr. Judd coin. The original Judd plate coin of this pattern does not have any central die cracks. If not, then these may have started being struck in early 1849 where George Eckfeldt's journal notes the following:
"The flying eagle for half dollars cracked and good for nothing."
In spite of this fact, the die was used anyhow on May 12, 1852 to strike additional pieces as shown below.
It is unclear if the number struck was 15, 25 or 45.
Restrikes made after 1853 should weigh 192 grains and may have various edge reed counts. According to a listing of reed counts by years supplied by Bill Bugert of the Liberty Seated Collectors Club, those struck with 143-145 reeds were likely struck in the 1840s or early 1850s; those struck with 146 reeds were likely struck in the mid-to-late 1850s while those struck with 152 reeds were likely made in the 1860s. Many pieces exist with weights between the 206 and 192 grain standards. These pieces need to be examined on a coin by coin basis and the reeds counted to possibly determine when they were struck.
Overall there are probably 50-60 known. All appear to have been struck in medal alignment.
There is also one example known in copper J74/P78. This coin, weighing 178.6 grains, is believed to be restrike from the 1870s with at least 5 die cracks running from the edge through the eagle and scattered rust and it is ex Woodside 4/1892 lot 21, Elder's 22nd 12/16/08 lot 954, Norweb, New Netherlands 41st 9/53, Macy's 6/54, Heritage 2008 ANA, Simpson collection - NGC66BN and is illustrated below.
Coin images courtesy of PCGS & Heritage.
Images of Eckfeldt journal courtesy of Alan Meghrig. Image of the Stickney letter courtesy of David Stone.