ngth is the arc-light, which is too
strong for ordinary negatives to be enlarged not more than fourfold on
ordinary bromide paper. Used with any of the slower papers it will be
found very serviceable and satisfactory. Next comes the lime-light, which
has pretty much the same advantages and disadvantages. After these come
acetylene, a gas giving an intense light of high actinic power. This is
within the reach of nearly all, as a first-class generator costs only
about twelve dollars, and the uses of the gas are manifold. The same
generators and burners can be used with a projecting lantern and will be
found far more satisfactory than oil. Acetylene burners can be had in
various sizes, ranging in power from thirty to several hundred
candle-power. The carbide from which the gas is generated is not expensive
and costs only a few cents each time the machine is loaded. By an
adjustment attached to the generator the gas is kept at a constant
pressure, and hence the light is unusually steady. All in all this light
has many advantages. After it in strength comes the Welsbach burner,
suitable for those having gas in the house. After this comes the ordinary
gas-burner, and then oil. The reader, knowing now what will be required of
his light, can take his choice.

Perhaps the simplest form of light-box is where the light is placed in one
room and the enlarging done in an adjoining one, the light being admitted
through a suitable opening. This prevents the possibility of stray light
reaching the paper and is productive of no additional heat in a room
presumably already hot enough.

If this is not feasible a light-box must be constructed. As these vary so
much in material and design, and must be altered with different forms of
light in use, I will merely state the requirements. First of these is that
it must be light-tight, and second, that it must have adequate ventilation
and be fire-proof. Following these in importance, there should be a simple
arrangement for looking at the light from time to time to see that it is
burning properly and some means for readily attending to it if it is not.

Having the light-box, the burners must be placed in it properly. Here the
shortest way out of the difficulty is to go to an expert. If electricity
is used go to an electrical supply house; if gas, go to a gas-fitter. As
will be seen later the flame itself must be placed in a certain relation
to other portions of the apparatus, and provision must