The Cincinnati Tool Co. started in 1877. In 1924 they changed the name of the company to the Hargrave Tool Co., until they became part of the Warren Tool Corp. in 1962. Regardless of who owned Cincinnati, it seems that these clamps were marked Cincinnati, not Hargrave, or Warren.
Cincinnati handscrew clamps are high on my list of favorites. Some people really like the all-wood ones because of the “stickiness” of the wood threads, but I like these better, they’re stronger. I got a new 12″ handscrew clamp from Rockler, some time ago. Frigging handle split. Seek out some old Cincinnati ones instead.