Notes from the Collection: A Chart of the Banks of Newfoundland

A Chart of the Banks of Newfoundland, Drawn from a Great Number of Hydrographical Surveys, Chiefly from those of Chabert, Cook and Fleurieu, Corrected and Ascertained by Astronomical Observations, Robert Sayer and John Bennett, London, 1775

This chart was acquired by the Museum last year.  A new acquisition is always welcome, but what’s in a chart?  Beyond the extraordinarily detailed mapping of the rich cod fishing Grand Banks off Newfoundland, why should we examine it further?  And why is Cook paired here with two Frenchmen - Chabert and Fleurieu?

Cook’s work in Newfoundland was immediately recognised as the authoritative charting of the island.  While Cook had been diverted in 1768 to more distant voyages, the work was completed by Michael Lane, and a complete chart of Newfoundland published by the respected map publisher, Thomas Jefferys in 1770.  This chart, which used Cook and Lane’s work, fomed part of The American Atlas, 1775, issued by the successors to Thomas Jefferys’ business, Robert Sayer and John Bennett.  It was a prestigious volume, bringing together the latest surveys of a teritory about which little was known in definitive cartographic terms.

Two questions immediately arise.  Who were the two French cartographers named on the chart and why was there such an emphasis on ‘Astronomical Observations’? 

The names of the Marquis de Chabert-Cogolin and the Comte du Fleurieu, to give them their titles, may not be familiar to British readers, but were important figures in French efforts to solve the problem of calculating longitude at sea. From the early 18th century, French astronomers and mathematicians had been just as preoccupied as the British with the longitude problem. Both nations realised that the ability to calculate longitude reliably was key to achieving maritime dominance.

Chabert (1724-1805) was trained in astronomy and mathematics, and sent to Louisbourg, the French fortress in Nova Scotia, in 1750-51 (before the British captured the fortress in 1758), in order to rectify existing charts by checking its position with astronomical observations. He rose steadily in the French Navy, becoming Director of the Dépôt des Cartes in 1776, just after this chart was published.

Fleurieu (1738-1810) was a little younger than Chabert and engaged under the direction of Ferdinand Berthoud (1727-1807) to test the latter’s marine clock on a voyage to the Caribbean in 1768-69. Earlier French work on the longitude problem had tended to focus on astronomical methods, but when news of Harrison’s marine timekeepers filtered across the Channel in the 1760s, Berthoud, who was a skilful clockmaker, became extremely interested. Berthoud made two visits to Britain and met with Harrison at his workshop in London to view Harrison’s models. Berthoud was even invited by the Board of Longitude to see Harrison give an explanation of his latest clock as an independent observer. Harrison however refused to show its workings, fearing that Berthoud would simply copy his method and that he might be deprived of the longitude rewards. Industrial espionage was far from uncommon in the 18th century! In the end the principal working of Harrison latest watch (the H4) was revealed to Berthoud by another London clockmaker, though Berthoud’s own designs in the end owed little to Harrison. Berthoud’s watch was tested on Fleurieu’s voyage in 1768-69, and apparently performed well.

It is fascinating to note that Berthoud and Chabert were both elected Fellows of the Royal Society in London in 1764, a year after their compatriot, the astronomer Jérôme Lalande, and only a year after the end of the Seven Years War. At one level there was much mutual discussion and exchange of knowledge on intellectual and scientific subjects, so characteristic of European Enlightenment culture, with little attention paid to what might be thought of as matters of national interest and security.

Turning to the second question, why was there such an emphasis on correction by ‘Astronomical Observations’ as seen in the 1775 chart?

In part because the reliability, let alone availability, of marine timekeepers at sea was still in a very early phase. Astronomy was considered, particularly in France, as the ‘queen of the sciences’, a science for the learned elite, and the best and still most dependable method of verifying calculations of position. Emphasizing this, the chart has a small table in the bottom righthand corner showing precisely who made which observations and when, in other words, the people upon whom the mapmakers relied.

Chabert features in seven out of the eleven entries, Fleurieu in two with Berthoud’s marine clocks mentioned, Cook in one, and one states that ‘the Latitude calculated by Cassini; the Longitude by Borda and Pingré from their Observations made with the Marine Clocks’. Giovanni Cassini (1625-1712) was an Italian-born French mathematician and astronomer in the service of Louis XIV. His work on using the satellites of Jupiter to calculate longitude on land influenced astronomers at the time but was regarded as impractical for use at sea. French astronomers tended in any case to have a low opinion of the ability of seafaring men to undertake complex mathematical calculations. Alexandre Guy Pingré (1711-1796) and Jean-Charles de Borda (1733-1799), mentioned in the same section as Cassini, were two more important French mathematicians involved in scientific voyages and testing marine clocks.

So the chart relies heavily on French work as well as that by Cook. It encapsulates a moment in the history of navigation where two different methods – astronomical observation and mathematical calculation versus reliance on the accurate timekeeping of a marine clock – were both called upon to testify to the accuracy of a chart. It hints too at a history of rival research on the subject, not only between nations, but in France between different astronomers and mathematicians, and between different institutions, the Académie des Sciences in Paris and the Académie de la Marine in Brest. At the same time, there was much openness and exchange of information in characteristic Enlightenment fashion. The chart presents a nice juxtaposition in the pairing of Yorkshire-born James Cook with two elite Continental savants. In this sphere at least, Cook’s achievement was already assured, ahead of more general recognition and acclaim – in any case for most of 1775 he was still on his second voyage, returning only in July.

Mapmakers of course copied and used every possible source in their efforts to produce the most up-to-date maps. Equally, as Olaf Janzen, historian of Newfoundland, says, ‘‘While the surveys compiled an enormous amount of information about economic potential and included detailed sailing directions, they were first and foremost exercises in sovereignty”. Cartography went hand in hand with the growth of empire. The American Atlas, independently published, could of course be purchased by anyone with the means to do so. A year later the American War of Independence began. This chart was no doubt very useful to the American privateers who sought to disrupt the Newfoundland fisheries – but that is another story!

Note: for those interested in longitude, Richard Dunn & Rebekah Higgitt, Finding Longitude, Royal Museums Greenwich, 2014, provides an excellent text.

SF May 2024