Green’s Dictionary of Slang

trick n.3

(US Und.) a watch.

[UK]J. Poulter Discoveries (1774) 43: Loag or Trick; a Watch.
[UK]Whole Art of Thieving [as cit. 1753].
[US] ‘A Pickpocket’s Song’ in Confessions of Thomas Mount 20: She does them of their tricks.
[US]H. Tufts Autobiog. (1930) 292: Trick signifies a watch.