The invention of the gasoline, or the Internal Combustion Engine as it is called, was the first great advance. The weight of the fuel was so small, compared with the power produced, that it revolutionized the art. And now began that series of developments which embraced every part of the vehicle from the wheels to the top. At first the improvements were slowly effected, and many of them were most unsatisfactory. FLASH BOILER SYSTEM.--The flash system of using water in boilers, invented by Serpollet in France, for a long time kept even pace with gasoline cars, in economy, and in ease of management; but now that system has been entirely driven out, and gasoline taken its place. This, in time, must make way for a still cheaper fuel, and one more easily handled, either through the crude oil itself, or from some cheap derivative of it; or, possibly, a spirit distillation, in the form of alcohol, which will take the place of the high-priced article now so universally used. The natural consequence of improvements has been to bring forth a multiplicity of devices, particularly in the direction of more readily assimulating and using the hydro-carbon fuels. The efforts of inventors will now be in the direction of eliminating many of them. THE CARBURETER.--Heretofore the carbureter has been regarded as an essential element in every system. What a world, or, rather, worlds of troubles, hung about the carbureter. It was, and is, delicate, susceptible of the most minute adjustment, and in times past, before it had reached the present perfected form, was the bane of every motorist. A fuel, ignitable at a very low temperature, or capable of ready volatilization, has been considered absolutely necessary to successful operation. Such is not the case now. IMPROVED STRUCTURE.--The delicate parts of the operative mechanism are being replaced by strong, non-breakable forms, all of which tend to make a more perfect machine, and this, in turn, insures a greater demand for vehicles. THE ORDER OF DEVELOPMENT.--In undertaking any work requiring mechanical skill, and in which the action of coöperative elements is necessary, the uses must be considered. In a vehicle, the first element is the weight to be carried; then the strength of the frame and wheels necessary to maintain the load. Next should follow, in order, the power needed, and this entails a consideration of the speed element. These features are comparatively simple with a motorcycle; but they are more complex with the automobile type, particularly as to the structure of the frame and the gearing and wheels which are to be operated by the motor. SPEED VS. POWER.--Thus, a motor exerting twenty horse power may run the vehicle at a maximum of twenty miles an hour, and carry a load of fifteen hundred pounds; or it may have a maximum speed of eight miles an hour, and carry three thousand pounds with equal safety. It will thus be seen that speed is just as important as power, in considering utility.