Today’s been wet.

Too wet for a walk or gardening, and of course a bike ride is out of the question for a day or two until a replacement tyre arrives in the mail.

So, I’ve been off down an internet rabbit hole.

At the moment my bedtime reading is ‘A Bitter Remedy’ by Alis Hawkins.

Set in late Victorian Oxford, it’s an absorbing mystery novel, and for me, all the better for involving nineteenth century patent medicines, not to mention a walk on part for Charles Dodgson, aka Lewis Carroll and a little bit of cryptography.

I admit I’m a sucker for well written mysteries, but this is a fascinating one.

And I learned something I did not know.

In the story there’s a throw away line that Charles Babbage had cracked the Russian codes during the Crimean war. Well, I had to check that out.

The story’s a little more complicated.

In 1845, Babbage realised that Vignère ciphers could be cracked mathematically, but did nothing with the idea until, in 1852, John Thwaites, a Bristol dentist, claimed to have produced a new secure cipher

Babbage cracked it and showed that it was really just a variation on the Vignère cipher.

However, credit for breaking the Vignère cipher is usually given to Friedrich Kasiski, an officer in the Prussian army, who published a method of cracking Vignère ciphers some twenty years later.

The reason why Babbage’s discovery was not publicised was that the Russians were using Vignère ciphers to encode diplomatic telegrams in the run up to the Crimean war. At the time all telegrams were sent over the public network by clerks in telegraph offices, who typed, and sometimes retyped the text along the way as a sort of human signal repeater, meaning that if a telegram was to be kept confidential it needed to be encoded prior to being sent.

Vignère ciphers were though to be uncrackable, or so the Russians thought. Babbage’s discovery meant that the British could, with some effort, and a lot of paper and pencil, read the Russian official telegrams. And of course, having cracked the Russian code, the British could crack any similar code.

Given the sensitivity of this information, Babbage’s role was downplayed and he never really received credit for his role in breaking the Russian codes until the 1980’s.

These codes had a surprising longevity, being in use as late as the Korean war.

Sir Francis Beaufort, the manager of the Royal Navy’s hydrographic service and the officer responsible for training Robert FitzRoy, later commander of the Beagle during Darwin’s voyage and the inventor of the Beaufort scale, was a friend of Babbage and developed his own variation on the Vignère cipher which was later used in the US Army Hagelin encoding machine, very broadly the US equivalent of the German Enigma machine.

Encoding machines were needed to encrypt messages as morse code radio transmission could of course be listen in to by anyone with a suitable radio receiver.

Beaufort would have understood the need for encrypting communications, as he had worked with his brother in law to install a semaphore telegraph in Ireland during the Napoleonic wars to warn of a repeat of the French invasion of the west of Ireland in 1798.

On a more human note, Beaufort also used a simpler code to encrypt some of his private papers, including his diaries. When his diaries were decoded they revealed that after the death of his first wife he had had an incestuous affair with his sister Harriet. Both were in their fifties at the time, and the affair continued until he later married Honora Edgeworth, his brother in law’s daughter, in 1838, which I suppose was one way of keeping it all in the family.

Harriet, sometimes known as Henrietta, is today principally remembered as botanist.