But efficient as the "horsed" engine is, it has its limitations. Animal strength and endurance are not an indefinite quantity; while the fireman grudges even the few short moments which are occupied by the inspanning of the team. In many towns, therefore, we find the mechanically propelled fire engine coming into favour. The power for working the pumps is now given a second duty of turning the driving-wheels. A parallel can be found in the steam-engine used for threshing-machines, which once had to be towed by horses, but now travels of itself, dragging machine and other vehicles behind it.
The earlier types of automobile fire engines used the boiler's steam to move them over the road. Liverpool, a very enterprising city as regards the extinction of fire, has for some time past owned a powerful steamer, which can be turned out within a minute of the call, can travel at any speed up to thirty miles an hour, and can pump 500 gallons per minute continuously. Its success has led to the purchase of other motor engines, some fitted with a chemical apparatus, which, by the action of acid on a solution of soda in closed cylinders, is enabled to fling water impregnated with carbonic acid gas on to the fire the moment it arrives within working distance of the conflagration, and gives very valuable "first aid" while the pumping apparatus is being got into order.
[Illustration: Two Motor Fire-engines built by Messrs. Merryweather, London. That on the left is driven by petrol, and in addition to pumping-gear carries a wheeled fire-escape. That on the right is driven by steam. Both types are much faster than horses, being able to travel at a rate of over 20 miles an hour.]
As might reasonably be expected, the petrol motor has found a fine field for its energies in connection with fire extinction. Since it occupies comparatively little space, more accommodation can be allowed for the firemen and gear. Furthermore, a petrol engine can be started in a few seconds by a turn of a handle, whereas a steamer is delayed until steam has been generated. Messrs. Merryweather have built a four-cylindered, 30 h.p. petrol fire engine capable of a speed of forty miles an hour. It has two systems of ignition--the magneto (or small dynamo) and the ordinary accumulator and coil--so that electrical breakdowns are not likely to occur. A fast motor of this kind, with a pumping capacity of 300 gallons per minute, is peculiarly suited for large country estates, where it can be made to perform household or farm duties when not required for its primary purpose. Considering the great number of country mansions, historically interesting, and full of artistic treasures, which England boasts, it is a matter for regret that such an engine is not always included among the appliances with which every such property is furnished. How often we read "Old mansion totally destroyed by fire," which usually means that in a few short hours priceless pictures, furniture, and other objects of art have been destroyed, because help, when it did come, arrived too late. Owners are, however, more keenly alive to their responsibilities now than formerly. The small hand-worked engine, or the hydrant of moderate pressure, is not considered a sufficient guard for the house and its contents. In many establishments the electric lighting engines are designed to work either the dynamo or a set of pumps as occasion may demand; or the motor is mounted on wheels so that it may be easily dragged by hand to any desired spot.