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Pneumatic Tubes
The pneumatic tube was introduced into department stores in the 1880 by John Wanamaker, the Philadelphia retail magnate (Golden book of the Wanamaker stores, 1911). He had previously installed such a system in the US Post Office while he was postmaster general. The Manufacturer and Builder (Jan. 1881) states that there were two tubes to each counter - one for each direction. Each carrier was of the exact diameter of a silver dollar and could hold 30 such coins (so the tubes must have been quite narrow compared with later systems). "By means of steam engine and exhaust pump in the cellar, with proper attachments leading therefrom, the air is being constantly exhausted at the cashier's end of the tube and the counter end of the tube of each pair." The system ws also claimed to improve the ventilation of the building.
Pneumatic tubes had already been used for other purposes for many years. John Griffiths credits the invention of pneumatic message systems to William Murdoch, 1754-1839.
The vacuum plant usually consisted of a large fan, driven by an electric motor or other power unit. The fan took the form of a large disc with a number of vanes radiating from its centre. This was enclosed in a casing with an inlet pipe at the centre and an outlet pipe on the circumference. When the rotor was revovled the air was flung outwards by centrifugal force into the exhaust pipe. Air was drawn in to replace it, so causing a vacuum in the inlet pipe, which was used to draw the carriers through the transmission tubes. Small systems might be powered by a set of bellows in a cabinet, operated by a foot pedal.
As with wire systems, Lamsons dominated the market and took over many of their competitors.
The standard tubes in shops are 2 1/4 inches in diameter. (This is the same diameter as used by the Electric Telegraph Company for their second tube in London in 1858. By 1870, 3 inch tubes were the norm for telegraph companies.) Bends can be as small as 12 inches radius, but such tight curves cause a drag on the system and special inspection covers should be fitted. Radii of 2 - 3 feet are generally desirable if the system is to be efficient and cheap. (Westwood and Westwood).
The "independent system" employed two tubes to serve each station. This allowed sending and receiving at the same time, giving a faster service. Carriers could be sent at intervals of a few seconds and several could be in transit simultaneously. (Memo from Lamson Engineering, 17 March 1953)
Companies
Lamsons Dart Cash Sturtevants British Cash and Parcel Conveyors Modern systems
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Two pneumatic tube stations in the drapery department of a store. Taken from "Modern draper" (London: Caxton, 1924) |