The Collaborative International Dictionary of English v.0.48:

Tales \Ta"les\ (t[=a]"l[=e]z), n. [L., pl. of talis such
   (persons).] (Law)
   (a) pl. Persons added to a jury, commonly from those in or
       about the courthouse, to make up any deficiency in the
       number of jurors regularly summoned, being like, or such
       as, the latter. --Blount. --Blackstone.
   (b) syntactically sing. The writ by which such persons are
       summoned.
       [1913 Webster]

   Tales book, a book containing the names of such as are
      admitted of the tales. --Blount. --Craig.

   Tales de circumstantibus [L.], such, or the like, from
      those standing about.
      [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

TALES DE CIRCUMSTANTIBUS, practice. Such persons as are standing round. When
ever the panel of the jury is exhausted the court order that the jurors
wanted shall be selected from among the bystanders which order bears the
name of tales d circumstantibus. Bac. Ab. Juries, C.
     2. The judiciary act of Sept. 24, 1789, 1 Story, L. U. S. 64, provides,
Sec. 29, that When from challenges, or otherwise, there shall not be a jury
to determine any civil or criminal cause, the marshal or his deputy shall,
by order of the court where such defect of jurors shall happen, return
jurymen de talibus circumstantibus sufficient to complete the panel; and
when the marshal or his deputy are disqualified as aforesaid, jurors may be
returned by such disinterested persons as the court shall appoint. See 2
Hill, So. Car. R. 381; 2 Penna. R. 412; 4 Yeates, 236; Coxe, 283; 1 Blackf.
63; 2 Harr. & J. 426; 1 Pick. 43, n.