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 brick, and, besides, filled with refractory bricks piled up as shown in the figure. The partitions, C and C', are likewise of refractory brick, and are rendered as air-proof as possible. Apertures, D and D', are formed alternately at the base of one partition and the top of the adjacent one, in order to oblige the gases that traverse the series of chambers to descend in one of them and to rise in the following, whatever be the number of chambers in use. The two flues, E and E', lead from the bottom of the two nearest regenerator on each side to the bottom of the generator A, and serve to bring the current of air or steam into contact with the fuel. Valves, F and F', placed in these flues, permit of regulating the current in the two directions. Pipes, M and M', provided with valves, G and G', put the upper part of the generator in communication with the contiguous chambers, T and T'. Other pipes, N and N', with valves, H and H', permit of the introduction of a current of air from the outside into the chambers, T and T'. The pipes, O and O', and the valves, I and I', connected with a blower, serve for the same purpose. The pipes, P and P', and their valves, J and J', lead a current of steam. The conduits, Q and Q', and their valves, K and K', direct the gases toward the purifiers and the gasometer. Finally, the pipes, R and R', provided with valves, L and L', are connected with a chimney. The generator, A, is provided at its upper part with a feed hopper. The doors, S and S', of the ash box close the apertures through which the ashes are removed. When it is desired to use the apparatus, the pipes, P, Q, and R, are closed by means of their valves, J, K, and L, and the valve, I, of the pipe, O, is opened. The pipes, M and N, are likewise closed, while the flue, E, is opened. On the other side of the generator the reverse order is followed, that is to say, the flue, E', is closed, the pipes, M' and N', are opened, the pipes, O', P', and Q', are closed, and R' is opened.