I got a bunch of old tools from my late grandfather, who was a machinist and worked on tanks in the Army for a while. Among them, some of the noteable ones include two miniature Disston D-8's, a Snap-On Midget M-70L, and some calipers. While there is a little bit of information on the other two, I've found nothing on these calipers. They are pretty well tarnished, and I sprayed them with penetrating oil just to get them to move. The only marking on them seems to be Thewlis & Co, Warrington. Anyone know anything about these? 
