The indications are obtained by means of a delicately poised fan-wheel, the recordings being commenced by the long hand, which traverses the extreme outer circumference of the main dial for the passage of one hundred feet of air. The enumeration is continued up to ten million of feet (say 1894 miles) by a series of smaller dials as shown in the illustration. A Disconnecter projecting from the band of the instrument, opposite the fan-wheel, serves to throw the mechanism out of gear, and arrest its action when required. The instrument is packed, with the usual Universal jointed socket holder, in a neat deal box about four inches square. It comes complete with instructions, in its original box, together with a fitting for attaching to the base.Complete and all in very good original condition. Mechanical everything is working correctly and the dial registers as the fan-wheel rotates. This is a very delicate mechanical instrument and care should be taken to never touch the rotating fan blades. The item "Air Flow meter by Joseph Davis & Co, Fitzroy Works, London S. E" is in sale since Thursday, June 7, 2018. This item is in the category "Antiques\Science/Medicine\Scientific Instruments". The seller is "pacman25" and is located in Harwich. This item can be shipped to United Kingdom, Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Australia, United States, Canada, Brazil, Japan, New Zealand, China, Israel, Hong Kong, Norway, Indonesia, Malaysia, Mexico, Singapore, South Korea, Switzerland, Thailand, Chile.