The solar transit This account of the solar compass, and the meridian attachment for transit instruments was written for Young & sons . ojected on a line engraved on the inner edgeof the equatorial circle. The block d could be set to any re-quired declination A C B, by means of graduations along theopening in which it moved. The meridian circle was utilizedas a latitude arc. The dial was suspended from a ring attachedto the vernier / which was set to the latitude of the place, A Z 8 fc r0); JhC ?iS °f thC instrument ^en corresponded withthe hne Z N and was revolved slowly thereon, until the su
The solar transit This account of the solar compass, and the meridian attachment for transit instruments was written for Young & sons . ojected on a line engraved on the inner edgeof the equatorial circle. The block d could be set to any re-quired declination A C B, by means of graduations along theopening in which it moved. The meridian circle was utilizedas a latitude arc. The dial was suspended from a ring attachedto the vernier / which was set to the latitude of the place, A Z 8 fc r0); JhC ?iS °f thC instrument ^en corresponded withthe hne Z N and was revolved slowly thereon, until the crossed the equatorial line, the hour being ind cated bvgraduates uoon the lower half of the equatorial cirde With the instrument firmly fixed in this position the would follow the equatorial line, and, hence its axis ofmottort would correspond with^, which wouId J£j™°fwuh^the polar axis PP, and, hence, with the of the The Ring Dial, if pr0perly mounted, would thereforeanswer all the purposes of a Solar Compass in dete min nf as well as the time of day. ermining the Burts Solar *-Ws Sol„Compa„ H O Hortzon; P P, Polar Axis; A Q, C Z _ P C O, ; C A , _ A C E, South Declination. The first practical application of these principles to the artof surveying, was made by William A. Burt, of Michigan, inhis invention of the Solar Compass, the prominent features ofwhich are represented in Fig. 4. The bar f revolves in theplane of the equator A O about the polar axis jZ^, carrying thedeclination arc^ and bar de. The suns image is brought to afocus at the intersection of lines engraved on a silver plate at eby means of a lens in the opposite end of the bar. To find themeridian, the latitude P C O is set off on the latitude arc /, andthe declination A C E on the declination arc^. The Compassis then revolved about its vertical axis Z N, and the Solar ap-paratus about its polar axis until the image of the sun is b
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Keywords: ., bookcentury1800, bookdecade1880, bookidsolartransit, bookyear1887
