Accession Number: 1984.187.121885F
Title: FLYING CLIPPER, First mate and officer using sextants, 1948
Category: PHOTOGRAPHS - SOFT NEGATIVES
Overall Size: overall: 5 x 4 in.; 12.7 x 10.16 cm
Date Created: 1948-10-3
Photographer: Rosenfeld and Sons
Description: 4 x 5 Kodak safety negative taken by Rosenfeld and Sons on October 3, 1948. View of the first mate and another officer, seen aboard the Isbrandtsen Line steamer, FLYING CLIPPER. Both young men seen using sextants to "shoot" the sun. Both squint through the telescopic eyepiece at a small glass square attached to the forward leg of the sextant. The right half of the glass is mirrored; the left half is clear. The sextants have both sun and horizon shades to provide a clear view of the sun. With his left hand, each moves an index arm that is pivoted on top of the index arm, and as they adjust the angle of the arm they direct the reflection of the sun (or moon, or star) in that mirror down to the half-mirrored glass on the sextant frame. Using the fine adjustment screw on the index arm they align the base of the sun's reflections with the horizon line visible through the clear half of the glass to get an exact measure of the altitude of the sun (or moon, or star) above the horizon, which is indicated by the position of the index arm on the arc. The brass scale on the arc is calibrated in degrees and minutes, and a vernier on the bottom of the index arm indicates minutes and seconds of a degree. Star or moon sights at twilight, a local apparent non sun sight, and several morning and afternoon sun sights all produce angles of altitude above the horizon that, with reference to the ship's chronometer, tables in teh Nautical Almanac, and a process of mathematical calculation, would produce a sequence of lines of position along the ship's course on the chart. [Log of Mystic Seaport, Autumn 2003, Volume 50, No. 2, page 49]. Typed on original negative sleeve: "121885F 10.3-4/48 / Isbrandtsen S/S Co / S/S Flying Clipper story / 5029".
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