THE occurrence of fires in metalliferous mines is fortunately very rare; but, as is well known, the experience of fire-fighting underground is a bitter one. In years past much money has been expended in fighting fires and sealing off affected areas, and, above all, lives have been lost which might have been saved had there been in existence an efficient apparatus by the use of which men could stay for periods in a poisonous atmosphere. Smoke jackets and helmets, which have been introduced of late years for working in irrespirable atmospheres, have gone far to remedy this deficiency, but great care must be exercised in the selection of an apparatus suitable to the conditions, for it must be remembered that even the best of them have grave faults, which have caused fatal accidents to the wearers even when expert in the use of their jackets. Thus, it will be admitted that the safety of any selected type will depend on - (1) The apparatus being in perfect order. (2) The wearer being thoroughly versed in the use and limitations of his jacket, and confident that he can do a certain maximum quantity of work in a certain time.