. Edinburgh New Philosophical Journal . and the centre of the attached semicircle, whose radius is equal to the semiparameter. The use of such a lamp in a steam-vessel, is to shew an object a-head of tiie vessel, and to assist them in navigating narrow channels or rivers at night. The canal-boats go now with these lamps, in a dark night, at the rate of ten miles an hour, as safely as in the day. The same principle is applicable to a pier-light, or a direct- ing light, wliich extends throiigh a part only of the horizon, so as to render lenses inapplicable. This arrangement is shewn in the follo
. Edinburgh New Philosophical Journal . and the centre of the attached semicircle, whose radius is equal to the semiparameter. The use of such a lamp in a steam-vessel, is to shew an object a-head of tiie vessel, and to assist them in navigating narrow channels or rivers at night. The canal-boats go now with these lamps, in a dark night, at the rate of ten miles an hour, as safely as in the day. The same principle is applicable to a pier-light, or a direct- ing light, wliich extends throiigh a part only of the horizon, so as to render lenses inapplicable. This arrangement is shewn in the following drawing :— 'N^- -a.—
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Keywords: ., 1840, bookcentury1800, bookcollectio, bookdecade1830, bookyear1839
