
This is a Dec 18, 1857 usage of three plate 8 stamps.
The date is of particular interest, as 1857 usages of 1c #24's are not super common.
There were 3 Ty V (#24) plates active in the latter part of 1857: Plates 5,7 & 8.
The EDUs, respectively are -
Plate 5 - 12/2/57
Plate 7 - 12/31/57 (maybe 12/1/57 - never verified, also Neinken's 12/30 listing is wrong, its 12/31)
Plate 8 - 11/17/57
Based upon the above data, it appears that there were only about 6 weeks during 1857 when #24's were being used. The above cover is Ex-Chase, and he noted that, at the time, he had only seen two such covers used in 1857. There are more now, but they are still nice items to find.
I have not fully verified the platings yet, but they appear correct: 11R8, 41R8, 3R8.
41R8, the center stamp shows the curl over E in CENT plainly, although this image may not show it well. Its a nice variety.
The early intense blue printings from Plate 8 are always quite nice.
This cover also shows an inverted year date slug, along with a nice cameo advertising corner card.
All in all, a very cool cover with a lot of interesting aspects to it.