Its only interest is that the method of mounting employed is a small scale model of that of the great telescope in the S.-E. dome. In the German or Fraunhofer form of mounting for an equatorial there is but a single pillar, which carries a comparatively short polar axis. At the upper end of the polar axis we find the declination axis, and at one end of the declination axis is the telescope, whilst at the other end is a heavy weight to counterpoise it. The German mounting has the advantage that the telescope can easily point to the pole of the heavens; its drawbacks are that, except in certain special forms, the telescope cannot travel very far when it is on the same side of the meridian as the star to which it is pointed, the end of the telescope coming into contact under such circumstances with the central pier, whilst the introduction of mere deadweight as the necessary counterpoise, is not economical. It has been already pointed out that the present Astronomer Royal has not only considerably modified the German mounting in the great collection of telescopes in the Thompson dome, but has used a powerful reflector as a counterpoise to the sheaf of refractors at the other end of the declination axis. The English equatorial requires two piers. Between these two piers is a long polar axis. Both in the little Shuckburgh and in the great 28-inch equatorial the frame of the polar axis consists of six parallel rods disposed in two equilateral triangles, with their bases parallel to each other, the telescope swinging in the space between the two bases. The construction of this form of equatorial, therefore, is expensive, as it requires two piers. It takes much more room than the German form, and the telescope cannot be directed precisely to the pole. But the instrument is symmetrical, there is no deadweight, and the telescope can follow a star from rising to setting without having to be reversed on crossing the meridian. The great stability of the English form of mounting, therefore, commended it very highly to Airy, and he designed the great Northumberland equatorial of the Cambridge Observatory on that plan, as well as one for the Liverpool Observatory at Bidston, and in 1858 the S.-E. equatorial at Greenwich. The telescope at first mounted upon it had an object-glass of 12-3/4 inches' aperture, and 18 feet focal length. That was dismounted in 1891, and is now used as the guiding telescope of the Thompson 26-inch photographic refractor. Its place was taken by an immensely heavier instrument, the present refractor of 28 inches' aperture, and 28 feet focal length; and that this change was effected safely was an eloquent testimony to the solidity of the original mounting.