Monday 25 October 2021

Henry Briggs, Halifax and Logarithms


Think of maths lessons at school think of Logarithms then think of Henry Briggs 1561-1631, if you didn’t like log tables he would be the man to blame and he was a Yorkshire man. Although he didn’t invent the logarithm he made them more useable in the scientific community. He was also a damn good astronomer!

Born at Warleywood near Halifax, he would become a mathematical astronomer; Briggs went to a local grammar school before going on to St John’s College Cambridge in 1577. During the 1590s he was working closely with the mathematician and map maker Edward Wright who in the 1580s had been ordered by Elizabeth I to go with an expedition to attack the Portuguese Azores to carry out navigational studies, he also helped Emery Molyneux to produce the first celestial globes in England in 1593. Briggs and Wright who came from Norfolk collaborated with their astronomical studies; we know their observations included those of the Sun and his was very interested in the study of eclipses which took up much of his time. He was also a great believer in the idea of Copernicus that the Sun was at the centre of the solar system and not the Earth.

Briggs was also fortunate enough to obtain a copy in English of one of the most important books in the history of astronomy shortly after it was published. Don’t forget most books at this time will be written in Latin. Astronomia Nova or New Astronomy was written by Johann Kepler who for ten years had observed the path of Mars around the sky and his observations confirmed that the path of Mars across the sky only worked if the Sun was at the centre.

Astronomers use globes and maps with their studies today, but the first person from Yorkshire to have one was Henry Briggs in the early 1590s!

And it is amazing to think that it was with his work with Wright that Briggs met the astronomer Thomas Harriot who is now credited as the first astronomer to draw an astronomical object after viewing it through a telescope: he drew a map of the Moon on 26 July 1609, this was several months before Galileo.

In an age where astrology was an important topic for most men of learning, Briggs strongly opposed it however that did not stop him working with astrologers for example when in 1603 there was a conjunction of the planets Saturn and Jupiter. A conjunction of planets occurs when two or more planets appear to be very close to each other in the sky. This is of course just a line of sight effect because the planets are all many millions of miles apart from each other. They tried to put an astrological interpretation but had observed the event so the astronomical observations they made were very useful.

An event then occurred for which Briggs is probably better known. In 1616 he visited John Napier at Edinburgh who had invented the Logarithm in order to discuss some changes he wanted to make; he proposed that the original logarithms that Napier had introduced should be changed into common (base 10) logarithms, which are sometimes known as Briggsian logarithms in his honour.

The common logarithms were more useful and a great aid to Briggs when he published his works on navigation, astronomy, and mathematics. In fact it was Briggs who was the man most responsible for scientists' acceptance of logarithms.

In 1596, he became first professor of Geometry in the recently founded Gresham College, London; where he taught geometry, astronomy and navigation. He would lecture there for nearly 23 years, in 1619 he was appointed Savilian professor of geometry at Oxford.

There is even a little bit of Yorkshire on the Moon! Henry Briggs has a crater on the Moon named after him; Briggs is located in the western part of the Oceanus Procellarum or Ocean of Storms. He died on January 26th 1631 is in the top 25 astronomy podcasts on the web

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