202 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



don must be fastened a cross-piece, by means of which the 

 whole may be kept always vertical. A steel magnet is pro- 

 vided with a square slit, such that it can be placed any 

 where and in any position upon the parallelopipedon. Ac- 

 cording, then, as certain co-efficients in the expression for the 

 magnetic disturbance are larger or smaller, the magnet is to 

 be placed either parallel or transverse to the parallelopipe- 

 don, and is to be moved up or down until the needle points 

 accurately north and south, when the magnet is to be fastened 

 in that position. The ship is then to be swung, and a third 

 magnet is also to be fastened to the same parallelopipedon 

 in a certain manner described by Garbich, until when the ship 

 heads east and west the needle still points correctly north 

 and south, when this third magnet is to be fastened in its 

 place. With this adjustment the correction of the compass 

 is finished, except in so far as there may still remain a slight 

 error, due to the want of symmetry in the apparatus, and 

 which may be corrected by swinging the ship to the west as 

 well as to the east. In order to compensate for the remain- 

 ing rolling or heeling deviation, a cylindrical steel magnet, 

 about seven inches long and two thirds of an inch thick, is 

 appropriate, which is to be placed before the needle and in- 

 clined to the vertical, at an angle whose tangent is a well- 

 known co-efficient. This compensation becomes of great im- 

 portance in high latitudes. In passing into magnetic south- 

 ern latitudes, the vertical compensating magnet must be re- 

 versed end for end. The easiest method of directing the 

 ship toward any given point of the horizon will be attained 

 by the use of a compass described by Garbich, combining in 

 itself both magnetic and azimuthal compass, having three 

 concentric azimuthal circles, and which is to be used in con- 

 nection with the azimuthal tables computed by Labrosse, 

 which give, for every latitude of the ship and every position 

 of the sun, and for every hour of the day between sunrise 

 and sunset, the angle between the meridian and the sun's 

 vertical. " Mittkeilungen" Austr. ILjdrog. Office, 1874, 167, 

 257,426. 



ANCIENT MUSICAL INSTRUMENT IN CHINA. 



Among the ancient musical instruments of the Chinese is 

 the pien king, which is an assortment of sixteen stones ar- 



