DIY History | Transcribe | Scholarship at Iowa | Theory of the astronomical transit instrument applied to the portable transit instrument Wuerdemann no.26: a compilation from various authorities, with original observations by Harry Edward Burton, 1903 | Theory of the astronomical transit instrument applied to the portable transit instrument Wuerdemann no. 26: a compilation from various authorities, with original observations by Harry Edward Burton, 1903, Page 16

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Theory of the astronomical transit instrument applied to the portable transit instrument Wuerdemann no.26: a compilation from various authorities, with original observations by Harry Edward Burton, 1903

Theory of the astronomical transit instrument applied to the portable transit instrument Wuerdemann no. 26: a compilation from various authorities, with original observations by Harry Edward Burton, 1903, Page 16

The instrument is reversed by lifting the telescope and axis up out of the supports and carefully replacing the axis in the reverse position. 

The stride level. 
In order to level the rotation axis properly the transit instrument is provided with a delicate stride level. It is a glass tube, apparently cylindrical; but in reality it has a curvature of very large radius, or is ground on the inside to a curve of large radius. It is nearly filled with alcohol or ether. It is supported by two legs the bottoms of which are v-shaped. The length is such that these v's rest on the pivots of the axis where the level is placed in position. The convex side of the level being placed upward, the bubble of air which is allowed to remain in the tube will always occupy the highest point, and if either end of the level be elevated, the bubble will move in that direction. Therefore, if a divided scale be attached to the level, the motion of the bubble will measure.

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The instrument is reversed by lifting the telescope and axis up out of the supports and carefully replacing the axis in the reverse position. The stride level. In order to level the rotation axis properly the transit instrument is provided with a delicate stride level. It is a glass tube, apparently cylindrical; but in reality it has a curvature of very large radius, or is ground on the inside to a curve of large radius. It is nearly filled with alcohol or ether. It is supported by two legs the bottoms of which are v-shaped. The length is such that these v's rest on the pivots of the axis where the level is placed in position. The convex side of the level being placed upward, the bubble of air which is allowed to remain in the tube will always occupy the highest point, and if either end of the level be elevated, the bubble will move in that direction. Therefore, if a divided scale be attached to the level, the motion of the bubble will measure.