The above diagram represents the Ground Plan of a Primary School-house in Central District of Norwich, erected after plans by E. BURDICK, Architect, at an expense of $3,000. The main building is 50 feet by 25 feet, with two wings, each 25 feet by 11 feet, and one story high. It is built of wood and finished throughout in the most workmanlike manner, with a spacious play-ground, well graded and enclosed. Both rooms are furnished with Ross's furniture,—the Alphabet, or Oral school with chairs, and the Primary department with a desk and chair for each pupil.

THE GYROSCOPE, WITH EXPLANATIONS AND EXPERIMENTS.

BY E. S. SNELL,

Professor of Natural Philosophy in Amherst College, Mass.

[The substance of the following article was delivered as a lecture before the Smithsonian Institution on Planetary Disturbances, in 1855, and published in the Report of the Regents for 1856. We are indebted to Prof. Henry, Superintendent of the Institution, for the use of the cuts with which it is illustrated.]

The Gyroscope, in the form here represented, (Fig. 1.) is essentially the same, on a smaller scale, as the Rotascope of Professor W. R. Johnson, a description of which was given in Silliman's Journal, Jan. 1832. And the Rotascope was an improvement on Bohnenberger's instrument for illustrating the Precession of the Equinoxes.* The experiments of the gyroscope are not new, nor inexpli

Fig. 2.

* Fig. 2, represents the rotascope recently constructed for the Smithsonian Institution, being somewhat more simple than that described by Professor Johnson. The disk, in the form of a very oblate spheroid, is about ten inches in diameter, made of box. wood, with a brass band in the equator, and a steel axis. This is suspended in two strong brass rings, the inner revolving on a horizontal axis, the outer on a vertical one, the pivots for the lat ter being at the top and bottom of a rectangular frame of mahog any, supported by a heavy base of the same material. The whole instrument weighs thirty or forty pounds. The disk is accurately centered in the inner ring, so as to rest in any position; and all the parts revolve on polished pivots, with the least possible friction. At the bottom of the frame lies a forked piece of wood, which works on a tight hinge, and can be turned upward so as to embrace and hold fast either the outer ring alone, or both the rings. By this means, the experimenter can have the use of both hands to give a swift rotation to the spheroid. This is best done as follows: