A rare WW2 portable aneroid altimeter calibration pressure chamber by R. W. Munro limited, for use by the UK Air Ministry, circa 1940. The cylindrical brass vessel has a screw-clamp end cover which secures by turning a large four-spoke wheel sealing the chamber with a rubber gasket, Three raised circular glazed viewing apertures flanking internal lamp connection terminals to front and hand pressure pump beneath pipe work and valve taps to right hand side. The main body is mounted on a cast cradle supports fixed onto a rectangular mahogany base which also bears a brass trade plate engraved REF. 6C/63, PORTABLE CALIBRATOR MK 1, FOR ALTIMETER, R. W. MUNRO LTD, SERIAL No. 295/40. It has its original conforming box cover applied with repeat brass trade plate and is secured via knurled brass screw receptors in the base.
The firm R.W. Munro Limited was founded 1783 when James Munro was apprenticed to a mathematical instrument maker in Wapping. His son, also called James, carried on with the business, as did two of the younger James’ sons. The partnership between the brothers was amicably dissolved in 1864 when Robert W. Munro set up on his own account as an instrument manufacturer, and thereby founded the present company. The firm quickly gained a considerable reputation in the fields of mathematical, optical, meteorological and banking equipment, fields in which it is still prominent. Munro provided instruments for the Scott and Shackleton Antarctic expeditions and, in the 20th century supplied components for the construction of H.P. Babbage’s ‘Mill’, a connection which was renewed in 1956 when the company was commissioned by I.B.M. to construct a copy of the original. R.W. Munro and Co. is perhaps however best known for the development of the Dines anemometer (a design which has remained basically unchanged to the present day) – the demand for which came about in response to the Tay Bridge Disaster in 1879. The company was also involved at an early stage in the production of hydrological and experimental tank equipment, and was a pioneer in the field of aeronautical instruments.
This rare piece of specialist equipment would have almost certainly been supplied to the Air Ministry to facilitate the calibration of aircraft altimeters during WWII.
Condition: The original colour of this would have been black but it has worn through use and has a very original appearance which adds significant character to it. The pipework to the side looks incomplete and lacks a pressure gauge which would connect between the pump and chamber. The base has chips (see images) and has had a repair to one end, the top cover apears to be in good order. Internally the rubber seal still looks to be in good shape and seals when tightened and there is a wooden inner support, presumable to hold the altimeters when they are being tested.
We sell collectable and old usable tools that are lightly cleaned before being offered for sale. Used tools are not perfect and may have minor flaws due to wear and tear. Any major defects will be pointed out in the description. All items are sold in an “as is”condition and have not been tested; some reconditioning may be required according to buyer’s standards which can vary wildly. Whilst best reasonable efforts are made to ensure usable items are brought to a good standard, those expecting perfection from a used tools should consider buying new. Items described as ‘Antique’ or ‘Collectable’ are not sold for the purpose of use, if the buyer uses them we regard the item as sold or intends to use them it is their responsibility for additional costs to upgrade. If in doubt please ask as we are more than happy to help.
Prior to selling online we used the web as a buyers for quite some time and although there was a hiccup or two by other sellers we found them all to be helpful when they were made aware, I aim to be the same. Whilst I would like to think i’m perfect my wife would always say I had perfect intentions and was honest enough to hold my hands up when i get it wrong. So if on the rare occasion I do get it wrong it’s not intentional and i will do my utmost to put it right for you.
Postage: As you can appreciate there is a lot of work needed to bring these tools back to life as a result I do get quite dirty when working in the workshop. I do have to allocate a whole day to postage as a different operation because of this so I pack all orders every Monday and order the collection from Hermes which generally takes 1-2 days to collect. So depending on what day you order it will vary the delivery time. please allow 5 – 10 days for delivery for the UK.