Fig. 1 is a modification of the German principle, and it should be a sufficient recommendation to remark that it is the principle used by a maker of such experience as Mr. John Browning, and is, without doubt, the very best style of mounting for a fixed equatorial, especially when clockwork is employed, because clock power is applied to the polar axis itself direct from the driving worm.

The driving part, viz., the worm and wheel, which is out of the observer’s way (being between the standards), is not liable to meet with accident, and the driving wheel being near the lower end of the axis, is at the most rigid part, viz., the foundation of the instrument. As it has a long and very firm polar axis, and is connected with the foundation plate, it secures the utmost steadiness and freedom from strain.

[Pg 12] An equatorial mounting, with two long and stiff shafts for the axes, has always the advantage of firmness; the h. . . Read More