ss B design. The wheels are made with mild steel spokes,
which are secured by metal straps in the recesses cut in the annular
flanges on the boss, and by a taper bolt or rivet through the tire and
rim. These spokes can be easily taken out and renewed when necessary by
any unskilled person in a few minutes. The spokes being twisted midway
of their length give greater strength to the wheel and power to resist
side strains in pulling out of deep ruts or holes, without increasing
the weight. The bosses and straps are made of malleable iron, in which
the metal bushes are secured by means of a key with a washer screwed up
on the front end. They are also fitted with steel oil caps to the end of
the bushes, which are provided with a small set screw, so that the cap
need not be taken off when it is necessary to lubricate the wheel, as by
simply taking out the set screw oil may be poured through the hole into
the cap. The set screw also forms a fulcrum for a key, so that the cap
can be taken off or put on when required, as well as a means of
preventing the cap being lost by shaking loose on rough roads. In all
hot and dry climates, the continued shrinking of wood wheels and
loosening of the tires is a constant source of expense and
inconvenience. This wheel having a tire and rim entirely of metal does
away with the difficulty, as the expansion and contraction are equal,
consequently the tires need only be removed when worn out, and others
can be supplied, drilled complete, ready for putting on, which can be
done by any unskilled person. The wheels of class B design are the same
in principle of construction as those of class A, but they have cast
metal bosses or naves, without loose bushes, and are suitable for
general work and ordinary roads where the strains are not so severe. The
bosses or naves are readily removed in case of breakage, and they can be
fitted with steel oil caps for lubricating.--_Iron_.

* * * * *

APPARATUS FOR THE PRODUCTION OF WATER GAS.

The apparatus shown in the accompanying engraving is designed for the
manufacture of water gas for heating purposes, and is described in a
communication, by Mr. W.A. Goodyear, to the American Institute of Mining
Engineers.

The generator, A, is lined with refractory bricks and is filled with
fuel, which may be coal, coke, or any suitable carbonaceous material. B
and B' are two series of regenerating chambers lined with refractory
b