Author Archives: ebruton

About ebruton

Historian of science. Cyclist. Vegetarian. Lover of the Great Outdoors. Drinker of Tea.

Hidden Histories: An ordinary capacitor?

The collection of historical scientific instruments held by the Physics Department at the University of Leeds is eclectic and diverse, ranging from instruments used by William and Lawrence Bragg to a wonderful collection of mechanical calculators and almost everything in between. One of the more obscure objects in the collection is a Siemens Brothers (London) Condenser No. 2 Mark II, now commonly referred to as a capacitor. There is a wide selection of capacitors squirrelled away in the Physics collection and this one would not stand out amongst them but for further information on its provenance.

A large paper label upon the side of this object states this capacitor was tested against standard instruments by the Wireless Testing Department at HMS Vernon, this being somewhat surprisingly not a vessel but a torpedo training school based in Portsmouth. The label is signed and dated although this is very hard to read – the year may be 1905 or 1908 with the latter being more probable. HMS Vernon was also the site of the initial wireless tests done with Marconi wireless apparatus by the Royal Navy in 1899 and hence would play a role in the world’s first commercial wireless contract, between the Marconi Company and the Admiralty.

This surprisingly ordinary object can be used to spin many a tale, of the early development of wireless in Britain or of shared apparatus between cable and wireless telegraphy. But the story I wish to tell with this object is less readily answered – how did this object come to be in the Physics Department at Leeds University? To be sure, condensers were commonly used in Physics teaching and research in the early twentieth century and indeed the Physics Department holds many a condenser. But what I want to talk about when I talk about this object is the transmission of knowledge between the spheres of physics, technology, and commerce. Condensers were an outcome of physical experiments and, through telegraphy and other practical electrical systems, came to be used in a diverse range of technological systems including commercial wireless. And then for some reason, possibly obsolescence, this piece of apparatus is no longer needed and ends up in the Leeds University Physics Department where it is used to teach and possibly form the basic of further experiments used to develop more technologies. And so the cycle of experimentation, innovation, and knowledge transmissions continues.

UPDATED: You can view my short video about the condenser on YouTube here.

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