Going to jail on a Speculation.
--The Boston Traveller notices an incident which could hardly have occurred out of Yankee land.--One of the witnesses for the defence in a robbery case at Roxbury, declined obtaining bonds, although he could probably have done so, but allowed himself to be committed to jail. He will have to stay there three months, receiving $1 per day and his board.--He will have about $90 at the end of his term of imprisonment, double the sum which he would have been able to earn, above his board, as a common laborer.