C08

HISTORY OF ENGINEERING.

Book I.

LI LI III 111

i ; :l

Fig. 671

ELEVATION OP PART OP CORRIDOR.

The prisoners can communicate at any time with the officers of the prison by means ofa large bell or gong in the centre of each line of cells. A handle attached to a label and

Fig. 572.

LABEL IN THE CORRIDOR WHEN SHUT AND OPEN.