1911 Encyclopædia Britannica/Vacuum-cleaner
VACUUM-CLEANER, an appliance for removing dust from carpets, curtains, &c., by suction, and consisting essentially of some form of air-pump drawing air through a nozzle which is passed over the material that has to be cleaned. The dust is carried away with the air-stream and is separated by filtration through screens of muslin or other suitable fabric, sometimes with the aid of a series of baffle-plates which cause the heavier particles to fall to the bottom of the collecting receptacle by gravity. In the last decade of the 19th century compressed air came into use for the purpose of removing dust from railway carriages, but it was found difficult to arrange for the collection of the dust that was blown out by the jets of air, and in consequence recourse was had to working by suction. From this beginning several types of vacuum cleaner have developed.
In the first instance the plants were portable, consisting of a pump driven by a petrol engine or electric motor, and were periodically taken round to houses, offices &c., when cleaning was required. The second stage was represented by the permanent installation of central plants in large buildings, with a system of pipes running to all floors, like gas or water pipes, and provided at convenient points with valves to which could be attached flexible hose terminating in the actual cleaning tools. The vacuum thus rendered available is in some cases utilized for washing the floors in combination with another system of piping connected to a tank containing soap and water, which having been sprayed over the floor by compressed air is removed with the dirt it contains and discharged into the sowers; or in a simpler arrangement the soap and water is contained in a portable tank from which it is distributed, tobesucked up by means of the vacuum as before. In their third stage vacuum cleaners have become ordinary household implements, in substitution for, or in addition to the broom and duster, and small machines are now made in a variety of forms, driven by hand, by foot, or by an electric motor attached to the lighting circuit. In addition to their domestic uses, other applications have been found for them, as for instance in removing dust from printers' type-cases.