Conservation of Biram Anemometer by 'John Davis'
(National Coal Mining Museum For England)
Biram type anemometers were mechanical instruments used to determine the volume of air entering or exiting mine workings. This type of anemometer was invented by Benjamin Biram, house steward to the Earl Fitzwilliam, owner of numerous collieries in South Yorkshire, England, in 1844. These instruments gave a measurement of airflow in square feet of air per minute. Anemometers, as used in mines, were produced in two styles, the Biram style which have the the dials and vanes on the same plane and the offset style which has the dials perpendicular to the vanes. Most have 8 vanes but can range from just 4 up to 12 vanes, and normally have 1 to 6 dials on the face.
John Davis & Son (Derby) Ltd. was a manufacturer of scientific instruments between 1820 - 1927. Their manufacturing was based on the expansion of railways and mining in the 1840s. Davis continued to build many mining related items, such as anemometers, mining lamps and even coal cutters.This is a very early example of one of their Biram type instruments and features waxed parchment vanes, hand stitched in place. Later examples would feature copper alloy vanes.
The original parchment section were in poor condition - being torn and missing completely in some areas.
It was decided to carry out sympathetic conservation of these areas. After liaising with curators at the museum it was decided to replace the missing areas with a new material to show the original form of the vanes. This way, the original sections could still be seen and there would be a distinct visible difference between old and new.
Minimal intervention methods would be used to stabilise other areas of the object where necessary.
The object was photographed and written notes taken to record the objects original construction and condition.
Metal parts of the object were de-greased with appropriate solvents to remove dust and dirt.
A thin layer of conservation wax was then applied to protect these metals further.
All torn sections of each vane were joined on the rear of the anemometer using strips of conservation tissue. Two types of adhesive were used a water based one was used first, but due to the difficulty of this adhering to the waxed surface of the original parchment, a solvent based one was used where necessary.
Sections of a heavy gauge conservation grade mulberry paper were cut to shape, slightly larger than required, where the original vane sections were missing. This was then adhered in place using adhesives as above.