What is this unit of measurement from 1728?

[bristolloggerheads]

lbs is the only suggestion which seems to fit both shoes and worsted stuff (worsted yarn was measured by weight and not length). They are definately not check marks - note the "C" for hundredweight above the bottom line.

[1pds]

Are you sure it's a measurement, and not a check-mark?

E.G. somebody's initials, after checking the quantities?

I think KGarard's suggestion is good.  If you take a pen and paper and write it out in your own hand, it's hard to make lbs or lds...

[KGarrad]

The loop seems to be horizontal, rather than the vertical loop of an "l"?

I just can't see "lbs" in that at all?

[1pds]

Nor me... 

[bristolloggerheads]

The 1675 Act of Tonnage and Poundage states that old shoes are to be counted in hundred dozen pairs and new shoes in pounds weight.

Worsted however is by the piece although all types of yarn are by the pound.