In 1862 W. V. Adams invented an adjustable handcuff. Prior to this date all handcuffs were a one size fits all item. Adams invented a ratchet mechanism allowing them to be adjustable. He received his patent on June 14, 1862.
Here is the report of the file patent:
No. 1,650.—George W. Reeo, assignor to W. V. Adams, New York, N. Y.—Handcuff.— Patent dated June 14, 1862; reissued April 5, 1864.
Claim.—First, a handcuff or shackle composed of the two sections A and B hinged together and constructed substantially as described, and provided with the lock C, or its equivalent
Second, in combination with the shackle as above described the clevis, or staple, substantially as set forth.
No. 35,576.—W. V. Adams, of New York, N. Y.—Improvement in Shackles or Handcuffs.— Pateut dated Juno 17, 186'i.—This device consists of two curved sections pivoted together at their upper ends and provided with a locking apparatus, so arranged as to render the shackle adjustable in size. Upon the pivot that secures the two sections together is a hasp, through the eye of which passes the link of tho connecting chain.
Claim.—The combination of the hasp E with the sections A and B, for the purpose of allowing to each one of a pair of shackles a motion independent of tho other when in use, as described.
Here's a picture of a pair of Adams Handcuffs that went on sale on the internet a while back.