Thank you very much, George. Thanks to you, I now have the 1927 edition of the Admiralty Handbook (archive.org has it, as well as volume 1 of the 1938 edition).

And thanks to this thread, I have learned that the jar, as a unit of capacitance, is 10/9 nF. Apparently, it was mainly used by the Royal Navy. I wonder what the prototype jar was (Leyden? Marmite?)

--Cheers,
Tom

-- 
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070

On 9/2/2022 05:20, Labguy wrote:

I happen to have a 1931 copy of The Admiralty Handbook of Wireless Telegraphy, a great tome for its day. It speaks of capacitance in jars.

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I also have a 1927 copy of "Les Ondes Electriques Courtes" (Short Electric Waves). I picked this up at a university book fair for $0.50 some years ago. Makes for great reading to see how things were done in those days.

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I had a look to see if it contained anything about units for capacitance. It shows circuits for transmitters, but all have the transmit signal that is used to drive output triodes derived from mechanical generators. The output stage shows a capacitor in the tank circuit, but unfortunately no units.

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Cheers,

George

VK2KGG

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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Tom Lee
Sent: Thursday, 1 September 2022 7:16 PM
To: [email protected]
Subject: Re: [Test Equipment Design & Construction] Cal Lab Magazine - International Journal of Metrology

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I just took a look at a few hobbyist magazines and some product

schematics from several different decades, and your speculation looks

pretty solid. Based on that random, statistically insignifcant sample,

the UK has been quite consistent over time and across publications aimed

at quite different readers. The US, not so much, even within a single

company. The earliest schematic for HP's first product, the 200A,

surprised me with its use of the mu symbol. A schematic for the same

product, but of later manufacture, uses "m" for micro. a seemingly

backwards step. Textbooks and refereed journals paid the extra ha'penny

for a mu, but hobby magazines were a different story.

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I did not check any German or French pubs to see what conventions were

followed there.

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-- Cheers,

Tom

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