This obverse is similar to the one used on 1838 eagles but facing the other way. This particular design using the regular 'Small Letters' reverse die of 1839 is the only original produced from this obverse die. All other 1839 patterns are restrikes.
It is attributed to Gobrecht in the original editions of Judd but a July 12, 1843 letter from W.E. Dubois to Matthew Stickney in the Peabody Essex Museum attributes this design to Kneass as noted below.
"One half dollar of 1839, of a die which you never saw before, nor did I, until today. This die was made by Mr. Kneass, the late engraver, since deceased. A very few pieces were struck; I don't think I could get another, except for the Cabinet, where there is none as yet".
This reverse die, also used on regular 1839 no drapery proofs shows an extended die crack through the bottom of the letters in "Half Dol" and the top of "MERICA". This reverse develops a die crack or other damage in the lower right quadrant of the shield possibly due to die clash, as shown in the second image below, which tells us that the pattern was struck between the 1839 regular proofs and thus confirms that these are in fact 1839 products as the Bass coin does not show the crack whereas at least 2 examples, Dr Judd's and Stickney's show the crack. Eventually, this reverse cracks in half when used later on business strikes.
For an example of a regular issue proof in the later die state see lot 3167 in Heritage 2010 ANA sale ex Boyd, Kaufman which has an additional bisecting reverse die break from 3:30 to 7:30 through the eagle. According to Stewart Witham, these were struck with a collar having 148 reeds.
The Adams & Woodin book states that seven are known, a comment which was copied by Judd and others. At least that many are confirmed as follows:
2) Byron Reed, Durham Museum - ICG64
3) Gable (S.H. Chapman 5/1914) ?, Brand ?, Judd, Kosoff 2/70, B. Johnson-Hughes 1/79, Fred-B/M 11/95, Heritage 7/03 - PCGS64 - illustrated above. I cannot confirm an example of this design in the Brand journals.
4) Stickney-H.Chapman 6/1907 (from W.E. Dubois per July 12, 1843 letter noted above), J.S. Jenks (H. Chapman 12/21), P.C. Clark (Bolender 11/32), Col Green, Lohr, Cox-Stacks 4/62, 66 ANA, Witham-Auction 81, Superior 10/89, Superior 5/04 as NGC64, Simpson collection - PCGS65
5) Woodin, Newcomer, Col Green, J.M. Wade, 71 ANA, Harry W. Bass Jr. Research Foundation
6) H.P. Smith (H & S.H. Chapman 1906), Clapp, Eliasberg-B/M 5/96, Heritage 8/99 ANA - PCGS64
7) Miller, Brock, University of Pennsylvania, NN 41st 9/53
8) Heritage 1/15 FUN - PCGS66, same as #7 above?, illustrated below.
Farouk's is either #3, #4 or #5. Col Green owned 2 according to Eric Newman's ledgers of the Col Green patterns purchased by he and B.G. Johnson and are noted above. One of these is ex Haines (1/1863), Lilliendahl (12/1863), Seavey (1873), Parmelee (6/1890) and another is ex Mickley (1867), Hodge.
The unique? copper example J94/P106 is important as it is one of the first copper die trials of a pattern design. It first appeared in the 1864 McCoy sale as lot 1859, later to the Woodin, Newcomer, Farouk and Cox collections. A possible second piece is ex P.C. Clark (Bolender 11/32 lot 692).
Photos courtesy of Heritage.