The solar transit This account of the solar compass, and the meridian attachment for transit instruments was written for Young & sons . ne of collimation will describethe celestial equator AEO W, Fig. 1. In like manner, by set-ting off on the declination arc any given declination north orsouth, as A C B or A C E, the image of any celestial objecttraversing the circles B D or E T, Fig. 2, may be kept in thecenter of the field of view from rising to setting, by simplyrevolving the Telescope. The hour arc is attached to the Tele-scope at //, revolving at right angles with the polar axis, and,henc
The solar transit This account of the solar compass, and the meridian attachment for transit instruments was written for Young & sons . ne of collimation will describethe celestial equator AEO W, Fig. 1. In like manner, by set-ting off on the declination arc any given declination north orsouth, as A C B or A C E, the image of any celestial objecttraversing the circles B D or E T, Fig. 2, may be kept in thecenter of the field of view from rising to setting, by simplyrevolving the Telescope. The hour arc is attached to the Tele-scope at //, revolving at right angles with the polar axis, and,hence, in the plane of the equator. The appearance of the sun in the fieldof view is represented in Fig. 6. Thethree equatorial wires a b correspondwith the line of the celestial equator andcircles parallel therewith, while the hourwire c d corresponds with the hour circleor meridian towards which it may bedirected, The meridian is found in precisely as with the Ring Dial and Burt Solar set off the latitude and declination, and the hour circleto the approximate time, the sun can generally be brought into. 12 the field of view by simply revolving the Transit on its verticalaxis. The Transit then being clamped, the sun may be broughtaccurately between the equatorial wires with the tangent screws,at which time the Solar Telescope and also the Transit Tele-scope parallel to it, will be in the plane of the meridian. The same letters and lines have been used in the foregoingfigures for purposes of comparison, and to show the reader howthe three instruments described are based upon the same prin=ciples. Latitude. It will be readily understood from the above explanations,that the Meridian Attachment in common with all forms of solardevices for determining the meridian, depends for accuracy ofresults upon the indispensable condition that the polar axis ofthe instrument must coincide with the line P P7, Fig. 2, at sometime during a revolution of the Transit on i
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Keywords: ., bookcentury1800, bookdecade1880, bookidsolartransit, bookyear1887
