(2 syl.). Persons in the court from whom the sheriff or his clerk makes selections to supply the place of jurors who have been empanelled, but are not in attendance. It is the first word of the Latin sentence which provides for this contingency. (Tales de circumstantibus.)
“To serve for jurymen or tales.”
Butler: Hudibras, part iii. 8.
To pray a tales. To pray that the number of jurymen may be completed. It sometimes happens that jurymen are challenged, or that less than twelve are in the court. When this is the case the jury can request that their complement be made up from persons in the court. Those who supplement the jury are called talesmen, and their names are set down in a book called a talesbook.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894