AN INSTRUMENT FOR SOLVING SPHERICAL TRIANGLES

CASELLA & CO, CIRCA 1886

细节

AN INSTRUMENT FOR SOLVING SPHERICAL TRIANGLES
CASELLA & CO, CIRCA 1886
the lacquered brass instrument with four scales and verniers, signed on the machine-tooled plane CASELLA & Co LONDON. S.W., ALTITUDE divided 0-80, the central rotating arc 0-80, the left hand plane with sextant-like lattice 40-0-40, the bottom plane with similar lattice scale 5-90 marked HOUR CIRCLE, housed in mahogany case.
9½in. (24cm.) high in box

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Accompanying this intriguing instrument is an acceptance of provisional specification from the patent office dated 2 Feb 1886 for No. 622 14 Jan'y 1886: "An improved instrument for constructing or solving spherical triangles; and particularly for determining the hour-angle in ascertaining longitiude".