. The railroad and engineering journal . se of engine and tender is47 ft. 6i in. The weight of the engine in working order is 106,000lbs., of which lbs. are carried on the driving-wheels,and 31,545 lbs. on the truck, SUNDIALS FOR LOW LATITUDES. By George L. Cumine, The design of a dial for any given latitude must be basedon a knowledge of the relative positions of the sun and theearth throughout the year ; that knowledge possessed, de-signing a dial is a process of simple projection, like thepreparation of an ordinary working drawing in elevationand plan ; and the accuracy of the m
. The railroad and engineering journal . se of engine and tender is47 ft. 6i in. The weight of the engine in working order is 106,000lbs., of which lbs. are carried on the driving-wheels,and 31,545 lbs. on the truck, SUNDIALS FOR LOW LATITUDES. By George L. Cumine, The design of a dial for any given latitude must be basedon a knowledge of the relative positions of the sun and theearth throughout the year ; that knowledge possessed, de-signing a dial is a process of simple projection, like thepreparation of an ordinary working drawing in elevationand plan ; and the accuracy of the more important dimen-sions can be checked by means of equally simple processesin plane trigonometry. Figs. I and 2 are respectively an elevation and plan ofthe plane in which the earth makes its annual circuit (inthe figures properlloH is necessarily disregarded) ; 5 rep-resents the sun ; in fig. 1 the earth appears at midwinterand midsummer, when the axis P P—about which itmakes its daily revolution—lies in a plane bisecting the sun. and perpendicular to the plane of annual circuit ; at theseperiods the angle E O T = 23° 27—approximately—andis at its maximum ; obviously at all other times it is less,and in the two other positions shown, in fig. 2 it becomeszero, the equatorial plane E E coinciding with the lineSO. The two circles T, T, each in latitude 23° 27, limit thetropics within which all parts of the earths surface are inturn subjected to vertical rays from the sun ; thus in fig. ithe suns rays strike vertically on one limit of the tropicsin the left-hand view of earth, and on the other limit inthe right-hand view. An ordinary sundial consists of a triangular plate—called the style or gnomon—set in a vertical plane,with its upper edge parallel to the earths axis, and a planeface, to which the style is rigidly attached, so graduatedthat the shadows successively cast by the upper edge ofthe style on the graduations indicate solar time. The cor-rections by whic
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectrailroa, bookyear1887
