Strange Cancel(?) On US #65

I found this marking, which I hesitate to call a cancellation, on this stamp in a fairly recent collection I am going through. It is ink and is very, very precise. It looks, from the edges of the line, to have been applied by pen rather than stamp but that is just a supposition on my part, and there is no bleed through of ink to the back. The spacing of the lines, if that is significant, is about 3.5 mm apart on the vertical and about 4.5 mm apart on the horizontal.

The time taken to apply these precise lines if they are done with a pen would seem to preclude use as postage or as a revenue but I am at a loss as to their origin and purpose.

Can anyone shed any light on this?

Pen cancels were quite common on early U.S. issues. The lines on your example are very straight and parallel and may have been a "silent precancel". Most silent precancels of his time period were simply a horizontal line(s).

Russ - thanks for the suggestion of a silent precancel. I know that pen cancels were common, as they were in Canada. It was just that they were usually quick and simple - a scrawled line, an initial, a scribble ... and this is so very precise. I suppose though if someone were precancelling an entire sheet? But drawing ruled lines through every stamp 4 times would take forever!

Time was not so precious back then.

still could do a great cross section study of Washington bust. (just can't think of a good reason why)