Lectures on Practical Astronomy and Astronomical Instruments (1879)
Challis, James Rev. · Deighton, Bell and Co. (Cambridge) · leaf 184
THE MURAL CIRCLE. 155 of the box @ of the micrometer, which is transverse to the axis of the microscope, may be understood by referring to Figure 4 in page 24, so far as relates to the movement of the micrometer- … wire by turning the micrometer-head; but in the present case, instead of a single transverse wire, the turn of the micrometer- head moves two wires crossing each other, so as to be suitable for bisecting a line graduation inthe manner shewn in Figure 30 (2). The graduated rim r is divided into 60…
Book · Astronomy
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