Kent Scientists

Leonard Digges  (c1515-c1559) 

Lived at Barham

He put mathematics to practical use and invented the theodolite.

In Tudor England, Leonard Digges, from a distinguished family in East Kent, led the way in turning mathematics from a dry academic discipline into something with real practical uses.

In several respects he was the first of a new breed of mathematician. Unlike his predecessors he did not just study the subject; rather he wanted to make practical use of it, for example in surveying or in ballistics – predicting how projectiles will travel. Another innovation was that he wrote his books in English rather than Latin, and made them accessible for ordinary readers, not just scholars. As a result his books went through many editions and were widely read.  

Digges Tectonicon

An  illustration from Digges’ book 'Tectonicon', an instruction manual for masons, carpenters and ‘landmeaters’ (measurers of land), in which he shows how to measure land, timber, stone, and other commodities. The diagram shows how to measure the height of a tower from a distance.

When he died, Leonard Digges left behind an unfinished manuscript on practical mathematics called Pantometria. This was eventually completed and published by his son Thomas. It includes a tantalising mention of Leonard having used lenses and curved mirrors to make something called a ‘perspective glass’, by which distant objects could be seen more clearly. Could it be that Leonard Digges invented the reflecting telescope a century before Isaac Newton did so? Some have claimed so, but the evidence is inconclusive and there is no consensus. More certain is that Leonard Digges described an angle-measuring instrument which he called Theodelitus, known today as a theodolite.  

A page from Digges' 1555 book 'Prognostication' with instructions for predicting the weather.

Another of his books, 'Prognostication' was a diverse compendium of practical information, mainly meteorological, astronomical and astrological. It includes rules to judge ‘alteration of weather’, ‘natural causes’ of phenomena such as the rainbow, eclipses, rain, dew, hail, lightning, comets ‘and other horrible fiery sights’. Calendar tables cover sunrise and sunset, the phases of the moon, the rise and fall of the tides, the most auspicious days of the month for purging, bathing and letting blood, a table to find the movable feasts (Easter etc). Previous almanacs of this sort covered only a single year, but Digges’ was intended to last 'for ever'.

Digges Place sign

The present Digges Place in Out Eastern Lane, Barham, is a later building on the site of Leonard Digges' home.

Leonard Digges spent much of his life at Digges Place in Barham, between Canterbury and Dover.  He did not hold any public offices, but must have had a terrifying few months in 1554 when he unwisely became involved in the short-lived Wyatt rebellion against Queen Mary, in which a number of Kentish gentlemen were implicated. Digges had all his land and goods confiscated and was sentenced to death for high treason. Fortunately he was soon pardoned and allowed to remain, though subject to certain conditions, and at this point he moved a few miles up the valley to Wootton Court, a mansion which no longer survives.   His precise date of death and place of burial are unknown.