. 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 follow
. 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.—. The lines/R, /R, &c., give the rays divergent in every direction horizontally, and only rendered parallel in the verti- cal planes, through eacli of the '//. The zone of light. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original
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Keywords: ., 1840, bookcentury1800, bookcollectio, bookdecade1830, bookyear1839
