William Barlow (1544 – 1625) had a successful career as an Anglican cleric. He was, so to speak, born into the church, his father, also William Barlow (c. 1498 – 1568), was Bishop of St Davids. He was the eldest of two sons and five daughters. He studied at Balliol College, Oxford, graduating BA in 1564. Around 1571 he took holy orders and in 1581 he was made prebendary of Winchester Cathedral. A prebendary is the recipient of a prebend, an endowment, a fixed and independent income. A prebendary is a canon and as such part of the administration of the cathedral. He was also made rector of Easton. In 1588 he was appointed a prebendary of Lichfield Cathedral whilst retaining his prebendary of Winchester. In 1589 he resigned to take on the prebend of Sawley which included the position of treasurer of Lichfield Cathedral. From 1605 he was appointed tutor and chaplain to Henry Frederick, Prince of Wales, eldest son of James I & VI, a position he lost when Henry died in 1612. He was appointed prebendary of Southwell in 1614 and of York in 1617. In 1615 he was appointed Archdeacon of Salisbury Cathedral. The archdeacon is the chief administrator of the diocese. Barlow’s preferments were almost certainly due to nepotism. His father was Bishop of St Davids, when he was born and went on to become Bishop Bath and Wells and finally Bishop of Chichester. His five sisters all married bishops. Elizabeth married William Day (1529–1596) the Bishop of Winchester, Margaret married William Overton (c. 1529–1609) the Bishop of Lichfield, and Frances, in a second marriage, married Tobias Matthew (1546–1628) Bishop of York.
For a man comfortable ensconced in the arms of the Anglican Church, William Barlow had a strange hobby, he was fascinated by magnets, magnetism and the magnetic compass and became on of the leading experts of the period on the compass. One might well assume that as the author of The Navigators Supply (1597), a volume on all aspect of navigation, that William was a keen mariner or even a navigator. Nothing could be further from the truth. As he wrote in the dedicatory epistle to the book:
Touching experience of these matters’–compasses, &c.–’of myself I have none. For by natural constitution of body, even when I was young and strongest, I altogether abhorred the sea. Howbeit, that antipathy of my body against so barbarous an element could never hinder the sympathy of my mind and hearty affection towards so worthy an art as navigation is: tied to that element, if you respect the outward toil of the hand; but clearly freed therefrom, if you regard the apprehension of the mind.’
He justified his passion for the art of navigation, and everything connected to it with his love of mathematics:
However, learning that navigation was grounded upon mathematics, little by little he perfected himself in these arts, conferring often ‘with some of the skillfulest Navigators of our land.’
The Navigators Supply (1597) which contained the sum of Barlow’s investigations into the art of navigation and the instruments that he designed to aid navigators was dedicated to Robert Devereux, the second Earl of Essex (1565–1601), who was an active mariner, a close friend of Edward Wright (1561–1615), a patron of John Davis (c. 1550–1605), and a highly influential courtier. The full title is:
THE NAVIGATORS SVPPLY: Conteining many things of principall importance belonging to Nauigation, with the description and vse of diuerse Instruments framed chiefly for that purpose: but serving for sundry other of Cosmography in generall: the particular Instruments are specified on the next page.
Below this title is a reproduction of the instrument called ‘the Travellers’ Jewel’, with the following sentence to the right:
If any man desire more ample instruction concerning the vse of these instruments, hee may repayre vunto Iohn Goodwin dwellinge in Bucklersburye teacher of the grownd of these artes. The instruments are made by Charles Whitwell, over agaynste Essex Howse, maker of all sortes of mathematical intruments, and the graver of these portraytures.
Under the reproduction appears a verse from the 107th Psalm:
‘They that goe down to the Sea in Ships, and emply their labour in the great waters, They see the Workes of the Lord, and his wonders in the depe. Psal. 107.
Imprinted in London by G. Bishop, R. Newbery, and R. Baker. 1597
Barlow’s principal interest was directed towards the mariner’s compass which he saw as in need of serious improvement, he refers to the errors that dayly are committed to the making and framing of it.’ Further, ‘Let no man mistake me; I speake not save onely of ordinarie Compasses (being the most that ever I saw) such as are in common use, and are sale-ware for Masters.’ However, ‘their staves and Sea Cardes are neate and fine and their Astrolabes tolerable.’
Barlow set about creating a better mariner’s compass. He improved the compass needle and the method of mounting it. He was the first to truly examine the difference between iron and steel compass needles and demonstrate that the steel needle was far superior. He determined the best method of magnetising the needle with a loadstone. He was also the first to describe the gimbal mounting so that the compass remains horizontal despite the pitching and yawing of the ship.
Apart from descriptions on the improvement of the basic mariner’s compass Barlow also lists and describes various instruments of his own devising, perhaps the most notable of which was his variation or azimuth compass, which was superior to those of Robert Norman and William Borough. Variation compasses of his design continued to be produced well into the nineteenth century.
Barlow was the first to advise enclosing the dip circle within a glazed frame.
Barlow’s new inventions were his ‘traveller’s jewel’, the pantometer, the hemisphere, and the traverse board. The ‘traveller’s jewel’, of which he seemed particularly proud was an equinoctial sundial that enabled the user to find the time at any latitude on the globe. Barlow’s pantometer was a surveying instrument that enabled the user to measure both horizontal and vertical angles of terrestrial or celestial instruments.
Barlow claimed that his pantometer was as efficient as the theodolite of Leonard Digges (c. 1515–c. 1559) as published in his A geometric practice named Pantometria (1571), although in that publication the theodolite only measures horizontal angles; his instrument for measuring horizontal and vertical angles was named the topographicall instrument.
Barlow’s hemisphere was a portable skeleton globe on whose circles and plates problems of time, altitude, declination, and latitude could be solved. This was very similar to the nautical hemisphere invented by the Flemish cosmographer Michiel Coignet (1549–1623) and originally published in his Onderwijsinghe op de principaelste Puncten der Zeevaert (New Instructions on the Principal Points of Navigation) (Antwerp,1580) and republished in French under the title, Instruction nouvelle des poincts plus excellents et nécessaires, touchant l’art de naviguer… nouvellement practiqué et composé en langue thioise, par Michiel Coignet,… Depuis reveu et augmenté par le mesme autheur… in 1581
Barlow’s traverse board is basically a navigational adaption of the surveyor’s plane table with paper clamped by a scaled frame with ruler and protractor, which enabled the navigator to plot the ship’s speed and headings to be plotted on the paper and its course subsequently transferred to the chart.
With this plotting board he was the first to describe for the navigator the instruments necessary to enable him to follow out John Davis’ advice on plotting.
After the description of his instruments, Barlow describes the three principal map and chart projections in use, plane chart, Mercator chart, and paradoxal charts. Of the latter he describes the stereographical polar projection, the orthographical polar projection, but not the zenithal equidistant projection, which was the one that in practice navigators used.
Barlow advised young mariners to study to study mathematics and was one of those arguing for public lectures on mathematics to be set up in London, an aspiration that was realised by the appointment of Thomas Hood (1556–1620) in 1588.
Barlow communicated with William Gilbert, who was still carrying out his research on magnetism, at the time that would eventually be recorded in his De Magnete. We will take a closer look at the relationship between these two pioneers of magnetic research in a later post.
The Renaissance Mathematicus 