Revolving 'Storm door structure'.

Image courtesy of  FreeDigitalPhotos.net

How many of you wonder, as you complete your half-circle journey when using one, who invented the revolving door.

Well, the answer is a Swiss-American gentleman called Theophilus Van Kannel – Born 1841, Died 24 December 1919 – is considered as the inventor of the style of revolving door as we know it today. It was on this date one hundred and twenty-five years ago (7th August 1888) that he obtained the United States patent number 387571 for his invention of a 'Storm door structure'.

However, the first world patent was in fact granted, six-and-one-half years before that to Theophilus, to H Bockhacker, from Berlin, who obtained a German patent on the 22^nd December 1881 for his 'Tür ohne Luftzug' (Door without draft of air). It was Van Kannel's design that became the commercial success.

The door was not invented, as some people believed at that time, to stop horses entering into buildings.

It was devised as a means; to prevent wind, dust, snow, rain and other weather elements from entering the internal space when it is used to access a building; to allow persons to pass both in and out at the same moment in time without colliding into each other; the exclusion of street noise intruding into the building; and to reduce the adverse effect of the difference in air pressure inside and outside of a property has on opening conventional hinged-doors in the entrances of a multi-storey edifices. The original design and specification was for a three partition door system. To enable long objects through the revolving door a partition included a hinge facility to allow it to be folded back.

In more recent times additional benefits have materialized from the system. In the control of air-conditioned environments; being an aid to energy efficiency; by keeping warm air in, and cold air out, of a building. In security control the system can be used to manage the flow and speed of persons entering or leaving an area. Within the partitioned sections a scanner can be installed to unobtrusively examine people and their possessions.

Which way do revolving doors circulate? The answer is – in countries which drive on the right-hand side of the road the rotation is normally counter-clockwise whereas in those countries (Australia and New Zealand for example) that drive on the left it is clockwise. It means one travels round with the door the same direction as round a roundabout when in a vehicle. However, to add to the confusion, in the United Kingdom it can be either way. In the City Hall in London they seemed not to be able to decide which is best so installed a duo-counter-rotating revolving door.

For the 'Usefulness of his invention' Van Kannel was awarded the John Scott Medal by the Franklin Institute in 1889. The 'Storm door structure' wasn't his only invention. He went on to develop the 'Cherry Stoner', a 'changeable fulcrum door check', an aid to help close hinged doors automatically, and a fair ground ride called 'Witching Waves' – this was a predecessor of the dodgem type rides – which was installed on Coney Island, New York, in 1907.

I wonder if you will think about Theophilus Van Kannel next time you use a revolving door at the supermarket, department store, office building, or airport.