Biot's important monograph on mirages and horizontal refraction

BIOT, Jean-Baptiste.

Recherches sur les réfractions extraordinaires qui ont lieu près de l'horizon.

Paris: Garnery, 1810.

1st Edition. Soft cover. Very Good. Item #003265

4to (272 x 218 mm). [4], 268 pp., including half-title, woodcut vignette on title, 9 engraved folding plates at end. Original sprinkled paper-wrappers, printed paper-label to spine (paper-label and spine ends partially chipped, upper wrapper partially split towards foot, wrappers slightly creased and corners dog-eared). All pages uncut and unpressed. Light age-toning of text and plates, occasional spotting, foxing and marginal dust-soiling, fraying of edges in places. All in all a very good, unsophisticated copy. ---- EXCEPTIONALLY RARE FIRST EDITION of one of the fundamental analytical studies on atmospheric refraction near the horizon by Jean Baptiste Biot. Biot's calculations provide an explanation for the observed flattening of the setting sun and why refraction behaves differently near the horizon than it does over most of the sky. A theorem about the magnification at the horizon is named after Biot. "Heinrich Wilhelm Brandes (1807) published a monograph on mirages and refraction in which he tabulated thousands of observations of terrestrial refraction, together with temperature differences measured at different heights up to 16-1/2 feet (5 m) above the ground. In a summary paper, Brandes (1810) stated as his first result that ''if one frequently observes the apparent height of individual objects above the Earth, and simultaneously investigates the heat of the air each time at different heights, one finds quite generally that the apparent height of each object is the greater, the warmer the higher layers of the air are in comparison with the lower ones.' In the same year, J.-B. Biot (1810) published his own monograph on horizontal refraction and mirages, in which the theory was worked out in detail and extensive quantitative comparisons between measured altitudes and temperature gradients were used to confirm it. Biot's monograph is exceedingly thorough; it encompasses refraction, dip of the horizon, superior as well as inferior mirages, looming, etc. So the importance of temperature gradients in the very lowest part of the atmosphere was already well established early in the 19th century." (Andrew T. Young, Sunset Science. IV. Low-altitude refraction. In: The Astronomical Journal, vol. 127, 2004, p.3624). Biot's work is quite rare in the trade with no copy traced at auction in the past 20+ years. - Visit our website to see more images!

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