Printed in U SA The World's First Sextants

The first navigation sextant in the world was made by the London instrument maker, John Bird, in the year 1757. It, and four others by him are known to have survived, four of the five in museums in the United States, England, & Holland, and one in the possession of the author. Bird also published two booklets for the Board of Longitude on his methods of making and dividing the scales of astronom-ical instruments which contain brief reference to his sextants. These, taken with contemporary commentaries on his work, and newly discovered early documents, form the complete record on this major development in the history of navigation. The author has examined four of the five sextants in detail and has obtained data on the fifth. This is a comprehensive report on the historical aspects, mechanical design, and scale division of these instruments, together with the first set of pho-tographs of all five ever published in one place