Accident at the Gymnasium.

A serious and probably fatal accident occurred yesterday afternoon at the Gymnasium.

The new engines which have been put in there necessitated a change in the draft of the flues. The old ventilating pipes were being taken out and larger ones inserted. Thomas O'Brien, a laborer, was at work in the bottom of the shaft when a large section of the pipe broke loose and fell directly upon his head, injuring him seriously. He was taken at once to the Cambridge Hospital, but the chances for his recovery are exceedingly slight.