-air" kiln.

Most furniture factories have considerable bent stock which must of
necessity be thoroughly steamed before bending. By steaming, the
initial process of the Moist-air kiln has been consummated. Hence, the
Blower kiln is better adapted to the drying of such stock than the
Moist-air kiln would be, as the stock has been thoroughly soaked by
the preliminary steaming, and all that is required is sufficient heat
to volatilize the moisture, and a strong circulation of air to remove
it as it comes to the surface.

The Moist-air kiln is better adapted to the drying of tight cooperage
stock, while the Blower kiln is almost universally used throughout the
slack cooperage industry for the drying of its products.

For the drying of heavy timbers, planks, blocks, carriage stock, etc.,
and for all species of hardwood thicker than one inch, the Moist-air
kiln is undoubtedly the best.

Both types of kilns are equally well adapted to the drying of 1-inch
green Norway and white pine, elm, hemlock, and such woods as are used
in the manufacture of flooring, ceiling, siding, shingles, hoops, tub
and pail stock, etc.

The selection of one or the other for such work is largely matter of
personal opinion.

Kilns of Different Types

All dry kilns as in use to-day are divided as to method of drying into
two classes:

The "Pipe" or "Moist-air" kiln;
The "Blower" or "Hot Blast" kiln;

both of which have been fully explained in a previous article.

The above two classes are again subdivided into five different types
of dry kilns as follows:

The "Progressive" kiln;
The "Apartment" kiln;
The "Pocket" kiln;
The "Tower" kiln;
The "Box" kiln.

The "Progressive" Dry Kiln

Dry kilns constructed so that the material goes in at one end and is
taken out at the opposite end are called Progressive dry kilns, from
the fact that the material gradually progresses through the kiln from
one stage to another while drying (see Fig. 31).

In the operation of the Progressive kiln, the material is first
subjected to a sweating or steaming process at the receiving or
loading end of the kiln with a low temperature and a relative high
humidity. It then gradually progresses through the kiln into higher
temperatures and lower humidities, as well as changes of air
circulation, until it reaches the final stage at the discharge end of
the kiln.

Progressive kilns, in