Mr. Chanute has taken the greatest step yet made towards overcoming the difficulty of responding to changes in the velocity of the fickle air, but whether or not it will be possible to construct apparatus that will not only adjust itself to changes in the force of the wind, but to eddies and changes in direction as well, remains to be seen, the more that it must act not on planes six feet in length, but on surfaces infinitely larger. The proper method of constructing the wings of an aeroplane so as to insure stability and utilize the power of the wind to the best advantage, and some hints as to balancing and steering are the main assistance that we seem likely to gain from a study of the structure and flight of birds. ELECTRIC AUTOMOBILES. BY WM. BAXTER, JR. As electricity has been so successful in the street railway, where it has superseded all other forms of motive power, it might naturally be supposed that it would do equally well in the automobile; but when the difference in the conditions is taken into consideration it will be found that such a conclusion is not justified. In the street railway systems the cars run continuously over the same route, and on that account the electric current required to operate the motors can be conveyed to them from a central power station by means of wires. With the automobile the case is very different; the vehicle has no fixed course, but is required to go everywhere, and the current must be supplied from a source carried by it. If primary batteries could be made so as to furnish electric currents at a low cost, then the electric carriage would be in the same position as those operated by steam or gasoline, and it could go wherever the proper chemicals to renew the battery could be obtained. But as there are no such primary batteries, the only way in which the current can be supplied is by the use of storage batteries, and these cannot give out any more energy than is put into them, and in practice cannot give quite as much. Thus if the capacity of the battery is sufficient to run the vehicle forty miles when this distance has been traversed the propelling power will be exhausted, and the batteries will have to be recharged before the carriage can go any further. If the recharging could be done in a few minutes, the storage battery would be as good as a primary battery that would generate electricity economically; but as it requires three or more hours, the electrical vehicle cannot be used for long runs, unless the user is willing to make long stops each time the battery has to be recharged. Even then an electric vehicle could not go everywhere, for it would be compelled to follow routes along which facilities for recharging the batteries could be found. From this fact it can be seen that the electric automobile carriage cannot cover the same field as the steam or the gasoline (in the present state of electrical development). Within the limits to which it is applicable, however, it