Dating Historical Scientific Equipment
Catalogues of scientific equipment have been available in Great Britain since at least 1843, from specialised dealers. Since these catalogues have diagrams or photographs of the equipment, it can be compared visually. So these catalogues are a reference for dating.
Equipment offered from dealers by means of catalogues always carries the name of the maker or dealer. These makers have an established date and when mergers have occured the dates of these mergers are recorded on the catalogues themselves together with the changed names of the new firms. The following table traces the origins of important British firms since 1843 (source: Griffin & George catalogue of 1961; a short history).
1843 R. & J. Beck Ltd. (optical instruments only)
1848 John Joseph Griffin & Co.
1872 F. E. Becker & Co.
1881 Baird & Tatlock
pre 1897 W. & J. George Ltd.
1897 George & Becker Ltd.
1906 Standly Belcher & Mason Ltd.
1909 Gallenkamp & Co catalogue at Sir Temi Zammit Laboratory, Castellania
1928 Griffin & Tatlock
1944 (October) W. & J. George & Becker Ltd.
1954 Griffin & George Ltd.
1960 R. & J. Beck equipment offered through Griffin
So, reference to the manufacturer can give the date of manufacture of equipment within 15 years on average. If catalogues are available the equipment can usually be traced to within 4 years of its manufacture. Equipment without the name of the manufacturer could be one-off pieces and if not recent can be valuable pre-1843.
Examination of the items themselves will yield accurate estimates of the date of manufacture. The constructional materials of the bulk of the item and special materials used can give good indications.
Solid brass on instrument bodies indicates pre 1900. Brass sheet on instruments can indicate 1900-1950. Of course, brass can be used as a traditional constructional material in later special equipment such as barometers and other meteorological instruments.
The insulators used in electrical equipment can give an indication of the date of manufacture as in the following table:
pre-1900 wood as insulator in low voltage equipment
from 1930 paraffin wax to insulate windings; also glass for high insulation in this period
about 1900 ebonite
1920 bakelite (phenol formaldehyde)
1940 polyethylene and other thermoplastics
1960 newer thermosetting resins
pre-1900 glass domes
post-1900 glass fronts (glass sheet set in grooves to the present days)
plating on brass from 1950; chrome and nickel.
wood on older equipment was mahogany, other woods later
Insulation on wires silk pre-1930
Other insulators mica 1930
moulded ceramic 1950 to 1970
Raymond Libreri 31 January 1900