Dave, I took a picture of the graduations on each side for you.
That one is kind of an oddball...16ths, 32nds, 64ths, and 100ths. Not sure offhand what type that translates to, as an example a 4R graduated rule (most common type, by far) is 8ths, 16ths, 32nds, and 64ths.
I was just curious what it had to see if I needed to bestow a "YOU ****" on you for the rule alone, lol. Starrett rules are pricy new, only one I've ever bought new was a rigid 12" that was a hair under $50 back in '06. However, I prefer rules that have decimal inches, easier for me to read and instantly know ballpark in thousandths, rather than converting fractions in my head, as decimal makes more sense to me (hybrid of metric and inch).
Yours only has one decimal scale, in 100ths...which can be a little busy trying to read, like 64ths, but with longer hash marks every tenth, still works okay.
The fact it is stamped L.S.S. Co. leads me to believe it is an older rule, a rough timeline is anything in a typewriter font is oldest, L.S.S. Co is slightly newer, THE L.S. STARRETT CO. ATHOL, MASS. USA newer still, and finally their modern offerings usually just say STARRETT TEMPERED, which I don't like as there is no USA, like how Snap-on aficionados don't like the ratchets that don't say USA.
I'll go ahead and give you a "YOU ****" anyway, I would have picked it up too. 18" is a handy size for a rule, sometimes you need more than 12" and 24" just too much.
One more question, kind of hard to tell in pics but do you think it has a satin chrome finish, or is it bare steel?