NEPHOSCOPE (from Gk. vioAtc, nephos, cloud + CrK Sk 0 pC111 . to view). An instru ment used by meteorologists for observing the clouds, and especially for determining the amount and direction of the horizontal com ponent of the apparent motion of a cloud. The modern nephoseope is the development of an idea embodied by AnniA 1S46, in his so-called `reflecting anemometer.' and in its hest form it has a wide range of usefulness. The simplest form is merely a horizontal mirror, having a cir cular graduated edge. The observer brings one eye to such a position that the reflected image of the cloud is seen to pass from the centre of the mirror to the circumference, and he merely re cords the direetion in which the image appears to pass otT. The Marvin nephoscope. an instru ment of high precision. is used by the United States Weather 'Bureau observers, and has been exten sively employed in chitin] ohservations. A form of nephoseope for use on vessels at sea was de vised by Professor Finemann :Ind used by him about ISSR. About the same time Professor Abbe devised his marine nephoseope and a method of using it for determining absolute altitudes and movements of clouds at sea. It consists essen
tially of a light bronze circle fitting rather loosely on top of the ordinary ship's compass; it there fore replaces the nearly horizontal circle of the apparatus ordinarily used by the navigator to sight upon the sun When measuring azhnuths. 'Hie bronze circle is graduated, and at its zero point carries a hinge and an adjustable arm, ing at its end a knob which serves to define the line of sight. The eirele also carries a glass mirror from which the quicksilver backing has been removed, leaving a transparent circle. through which the graduation of the compass needle can be read. As this marine nephoscope enables one to locate a storm centre by the our Of the lower clouds better than can he done by the wind, and as it gives the direction of the pennant at masthead much more accurately than it can be observed by the eve, it is strongly recommended for use by navigators at sea. To ordinary meteorological observers it has the special advantage of being the only instru ment by means of whivb observers at sea can easily determine the absolute altitude and move of clouds.