Whitworth "wheat sheaves" Mark.

[Dean Romig]

I copied and enlarged the picture of the stamps on both barrels and they are done with two seperate dies.

[Austin W Hogan]

Some(?) Whitworth barrels were numbered and shipped with certificates. The Czar gun is a good example. There may be pictures of this in the Julia catalog; I'll check my disc.
Parker probably turned or filed some Whitworth barrels to achieve weight or balance specified by the customer. This might remove Whitworth's marks.

Best, Austin

[Bill Murphy]

Possibly all or most Whitworth tubes were shipped with certificates. However, the assumption would be that gunmakers thought them worthless and discarded them.

[Austin W Hogan]

I could not find a picture of the Whitworth Trade mark in my Czar gun file. The Whitworth registry numbers are stamped on the barrel flats.

Best, Austin

[Bill Murphy]

By Parker Brothers, apparently.