The most common object in the History of Science collection: thermionic valves

Published on: Author: Harriet Gaston Leave a comment

A staff post by Dr Nicky Reeves, Curator of Scientific and Medical History Collections at The Hunterian.

In terms of frequency or number of examples, thermionic valves are by far the most common type of object within The Hunterian’s History of Science collection. There are 147 thermionic valves listed in our catalogue, but we know that there are several hundred more which are currently uncatalogued.

These items are principally from the middle decades of the 20th century. Thermionic valves were ubiquitously used in pre-transistor radios and in other pieces of communications and calculating equipment and were thus a very common piece of electrical engineering equipment. Made of delicate glass and filaments, much like lightbulbs, they were inherently fragile and prone to break or explode. Their widespread utility and application coupled with their fragility meant that they were produced in enormous numbers.

The majority of the valves in The Hunterian’s collections were transferred to the museum in 1987 from what was then the University of Glasgow’s Department of Electronics and Electrical Engineering. The majority are brand-new, individually wrapped in paper and in cardboard boxes. There are many duplicate items. The boxes themselves are one of the most interesting aspects of the items, illustrating mid-20th century commercial design, typography and colour printing, and are often very stylish. Many of the major manufacturers are present in the collection, including General Electric, Ferranti, Osram and Mullard.

The manner in which these objects became part of The Hunterian’s collections is typical but telling. Almost certainly the Department of Electronics and Electrical Engineering were having a clear out of their store cupboards, and The Hunterian took possession of everything. Sometimes this method of acquisition can be unhelpful: if the museum ends up with more material than it can take care of, this is a problem, and often it would be preferable to only take a sample or a small set of representative items.

Museum staff have to think very carefully about space, and storage, and the relevance of any offered item to our long-term Collections Development plan. In this particular case the repetitious nature of the collection does, however, say something interesting and helpful historically: the sheer number of items in what was in effect the Department’s spare parts room tells an important story about the ubiquity of thermionic valve technology in 20th-century electrical engineering.

To discover more, you can search our collections online by entering “thermionic valve” in the search field.

Not many of the catalogue records contain photos, but a couple that do are, for instance, GLAHM:105755, a ‘Mazda’ valve made in the 1930s by British Thompson Houston Co Ltd, Enfield, England or GLAHM:105753, a valve also made in the 1930s, by the Mullard Radio Valve Co Ltd, London.

Here also you can see a selection of photos taken in 2016 of uncatalogued valves and boxes which give a hint as to the size of the collection and the nature of the valves and the boxes:

Several hundred unused, pristine and boxed mid-20th century thermionic valves, dating approximately from the late 1940s to the mid 1960s.

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