upon poles. A stove of some kind should be placed in the corner of each
building, but it must be entirely covered in with woodwork, and as small a
length of steam pipes should be within the building as possible.

In the case of a factory where nitro-glycerine and dynamite are
manufactured, it is necessary that the work-people should wear different
clothes upon the danger area than usual, as they are apt to become
impregnated with nitro-glycerine, and thus not very desirable or safe to
wear outside the works. It is also necessary that these clothes should not
contain any pockets, as this lessens the chance of matches or steel
implements being taken upon the danger area. Changing houses, one for the
men, and another for the girls, should also be provided. The tools used
upon the danger area should, whenever the building is in use, or contains
explosives, be made of phosphor bronze or brass, and brass nails or wooden
pegs should be used in the construction of all the buildings.

[Illustration: FIG. 2.--MELSENS SYSTEM OF LIGHTNING CONDUCTORS.]

~Lightning Conductors.~--The Explosive Substances Act, 38 Vict. ch. 17,
clause 10, says, "Every factory magazine and expense magazine in a
factory, and every danger building in a magazine, shall have attached
thereto a sufficient lightning conductor, unless by reason of the
construction by excavation or the position of such magazine or building,
or otherwise, the Secretary of State considers a conductor unnecessary,
and every danger building in a factory shall, if so required by the
Secretary of State, have attached thereto a sufficient lightning
conductor."

The exact form of lightning conductor most suitable for explosive works
and buildings has not yet been definitely settled. Lightning-rod engineers