Bairnson's Ex-Meridian Tables, Being the Shortest Method Yet Offered to the Public

Not dated but circa 1880. 126pp. Red cloth-covered boards with blind rules and decoration, gilt lettering (cloth worn and little soiled, rubbed on edges and corners, rounded corners, backstrip missing). Pencil notes and calculations, in a contemporary-looking hand, on front and rear endpapers, else internally neat, clean, bright and tight barring perhaps a hint of toning. Slightly shaken. It could be argued that the ex-meridian method of calculating latitude at sea should have become obsolete with the development of the chronometer, but in practice seamen continues to use this method at least until the mid-20th century. Several tables of calculations were produced to assist sailors in making the calculation, perhaps the most famous being J T Towson of great circle sailing fame. Bairnson's tables were designed specifically for Sun observations. Later versions tended to include star-sights as well. As a result, such Sun-specific tables are now hard to find.