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 27

Transcribe
Translate

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 27

not be injured.
If the bubble of the stride level is not in the center of the scale bring it there by means of the declination tangent screw, at the same time, using the alidade tangent screw to keep the alidade level bubble in the center of its scale. 
Turn the declination tangent screw forward so as to move both bubble toward the south ends of the scales. Read the position of the bubble of the stride level and then that of the alidade level bubble. Suppose the reading of the stride level is 10N and 19S, while that of the alidade level is 0N and 8.5S. Then the middle of the stride level bubble is 4.5S and that of the alidade level is 4.25S. The position of the middle of either bubble is the mean of the end readings, if we consider the readings opposite in sign, and is put in a column headed "Mean". Turn the declination tangent screw backward, thus sending each bubble toward the north end of its scale. Suppose that now the stride level reads 19N and 9S, while the alidade level reads 7N and 1.5S . Then the means are 5N for

Saving...

not be injured. If the bubble of the stride level is not in the center of the scale bring it there by means of the declination tangent screw, at the same time, using the alidade tangent screw to keep the alidade level bubble in the center of its scale. Turn the declination tangent screw forward so as to move both bubble toward the south ends of the scales. Read the position of the bubble of the stride level and then that of the alidade level bubble. Suppose the reading of the stride level is 10N and 19S, while that of the alidade level is 0N and 8.5S. Then the middle of the stride level bubble is 4.5S and that of the alidade level is 4.25S. The position of the middle of either bubble is the mean of the end readings, if we consider the readings opposite in sign, and is put in a column headed "Mean". Turn the declination tangent screw backward, thus sending each bubble toward the north end of its scale. Suppose that now the stride level reads 19N and 9S, while the alidade level reads 7N and 1.5S . Then the means are 5N for