C. GENERAL PHYSICS. 189 



entrance to the harbor. The pilot could give no information 

 about the compass, except that it was found on board the 

 wreck. It is of a circular form, measuring 13.5 inches across, 

 is cast in bronze, and weighs twenty-one pounds. It lias a 

 thick rim, in which two ordinary compasses are set, one on 

 each side. The centre of this remarkable plate-like looking 

 object is considerably raised from the surface, and is covered 

 with a number of raised spots or stars of various sizes, each 

 more or less connected by lines with its neighbors. The 

 shapes of these star-like objects are remarkable ; in the cen- 

 tre there are five which are larger than the rest. Then there 

 is another group very like a net ; another group represents 

 almost a complete circle of these stars ; another represents 

 a Y, with the arms closed together ; another a Y with the 

 arms extended. Altogether there are no less than two or 

 three hundred of these elevated spots of different sizes. 

 Runnino; throusjhout the whole series are several lines radi- 

 ating from a circle drawn around the centre. The brass rim 

 on which the compasses are set is divided into 360 degrees, 

 the same as in an English compass. At every thirty degrees 

 there is a Japanese character. Neither Captain Murray nor 

 any one to whom he has shown this curiosity at home or 

 abroad has any idea whatever of the meaning of the star-like 

 bodies in the centre, or for what purpose the Japanese used 

 them ; but it is quite certain that they must have been of 

 some use to them. It is most interesting that these rude 

 characters should be united in the same instrument with the 

 360 deG:rees of modern civilization. The castins; of the in- 

 strument is marvelous. 2 A, ISIQ. 



clamond's ^hermo-electkic battery. 



The latest form of the Clamond battery consists of an al- 

 loy of two parts of antimony and one of zinc as the negative 

 metal, and ordinary tinned sheet-iron as the positive element, 

 the current at the heated junction flowing from the iron to 

 the alloy. This alloy is cast in the form of a flat bar, broad- 

 er in the middle than at the ends, and measuring from two 

 inches to two and three-quarter inches in length, by three 

 eighths to one inch in thickness. The sheet-iron, properly 

 stamped out, is placed in a mould into Avhich the melted al- 

 loy is poured ; before the alloy has cooled the mould is open- 



