Illustrious family came from a faulty line


Richard Lovell Edgeworth, whom we encountered yesterday devising a novel way to measure relative humidity, was singularly unlucky with his wives: he lost three in quick succession.

Edgeworth, you will recall, was the eccentric and scientifically inclined father of Maria Edgeworth, author of Castle Rackrent and other Irish novels. He lived from 1744 to 1817.

In the late 1790s Edgeworth presented to the Royal Irish Academy a paper entitled An Essay on the Art of Conveying Secret and Swift Intelligence. His idea was to build a line of telegraphic stations across the country along which visual signals could be passed, from one station to another, all the way from Galway to Dublin.

It was similar in concept to the means devised by Chappe in France a few years previously, which was immortalised by featuring in the Dumas novel, The Count of Monte Cristo.

Edgeworth argued that his device would allow news of any invasion to reach the capital quickly, on which grounds the authorities readily agreed to fund the scheme.

Edgeworth put a young friend of the family, Francis Beaufort, future admiral and deviser of the Beaufort Scale, in charge of implementing what he called his "tellograph".

Unfortunately, Edgeworth had neglected to take account of Irish weather, and seldom was visibility sufficiently good for transmission on every segment of the chain; rarely could a message be relayed right across the country. Edgeworth's tellograph never saw useful service and was soon abandoned.

But the venture had a happy outcome, resulting in the first in a series of marriages which united, right into the 20th century, a number of families with close meteorological connections.

In 1797 Edgeworth took unto himself his fourth wife; she was Fanny Beaufort, Francis Beaufort's sister. Then in 1838, to cement the bond between the two tribes, Beaufort, himself by now a widower, married Edgeworth's daughter, Honora, half-sister of the author Maria, and became thereby Edgeworth's posthumous son-in-law, as well as brother-in-law, which he had been already.

Some years later another of Edgeworth's children, Fanny Beaufort's daughter, Lucy Jane Edgeworth, married Thomas Romney Robinson, the director of Armagh Observatory, who designed the familiar rotating cup anemometer, the standard method of recording wind speed.

And finally, in the last quarter of the 19th century, Thomas Romney Robinson's daughter, Mary Susanna, married Sir George Gabriel Stokes.

Stokes, who died in 1905, is remembered by physicists for Stokes's Law, and by mathematicians for Stokes's Theorem. For meteorologists, however, he is the man who designed the instrument which uses a glass sphere for measuring the duration of bright sunshine, and which is still in daily use as the Campbell-Stokes sunshine recorder.