The solar transit This account of the solar compass, and the meridian attachment for transit instruments was written for Young & sons . ngs the credit due to skillful workmanship and good judg-ment in the arrangement of the details of construction. Aftersix years trial in the field, it is found that the following advan-tages over the old form have been secured : (a) Compactness of form, especially adapting it for attach-ment to the Engineers Transit. The instrument being com-plete in itself, the Transit Telescope and vertical arc are not io required to do double duty. The view of the needle bo
The solar transit This account of the solar compass, and the meridian attachment for transit instruments was written for Young & sons . ngs the credit due to skillful workmanship and good judg-ment in the arrangement of the details of construction. Aftersix years trial in the field, it is found that the following advan-tages over the old form have been secured : (a) Compactness of form, especially adapting it for attach-ment to the Engineers Transit. The instrument being com-plete in itself, the Transit Telescope and vertical arc are not io required to do double duty. The view of the needle box andverniers is unobstructed. (b) The sun being observed through a telescope, its imagecan be brought sharp and clear between the equatorial wireswith greater exactness than can be attained by the old plan offocussing upon a silver plate ; and, hence, the meridional resultis more accurate. (c) The polar axis, which from the preceding remarks willbe recognized as the vital part of a Solar Attachment, is longerthan in any other form. (d) The suns image can be clearly defined in hazy weatherwhen the old forms cannot be used at Fig. 5. —Smiths Meridian Attachment. H O, Horizon; P P, Polar Axis: A Q,Equator ? ACZ = PCO, Latitude ; ac i> ^ A C B, North Declination 11 The Meridian Attachment is represented in Fig. 5 , C is theSolar Telescope revolving in collars r and rt whose line ofcollimation and axis of revolution coincide with the polar axisP P/. The declination arc d is fixed to the side of the Tele-scope, the vernier being attached to the arm e which turns on-its axis a reflector at c in front of the object-glass of the Tele-scope. The collars in which the Telescope revolves are firmlyattached to the latitude arc /, having a horizontal axis, the wholebeing mounted on the frameyy7 which is attached to the stan-dards of the Transit. Tangent screws / and tf give slow mo-tions to the declination arm and latitude arc. The arm e is so adjusted that the declination vernier
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Keywords: ., bookcentury1800, bookdecade1880, bookidsolartransit, bookyear1887
