298 POPULAR LECTURES AND ADDRESSES. 



attached to the bottom of the compass bowl. 



The aluminium rim and thirty-two silk-thread 



- \ > .. 

 spokes from a circular platform which bears a 



light circle of paper constituting the compass card 

 proper. 



Habitually, however, the whole movable piece 

 which turns to the north, consisting of magnets, 

 supporting frame-work, jewelled cap, and, in the 

 ordinary compass, pasteboard or mica with paper 

 pasted on it, is called for brevity the "card," or 

 the "compass card." In the new compass the 

 outer edge of the paper circle is notched and 

 folded down along the outside of the aluminium 

 rim ; pasted to tissue paper, with which the 

 aluminium rim is firmly coated, so as to give a 

 perfectly secure attachment ; and bound all round 

 with narrow silk ribbon to prevent the paper 

 from cracking off in any climate. For the sake 

 of lightness a circle of 6 inches diameter is cut 

 away from the middle of the paper, leaving an 

 annular band, 2 inches broad, on which are 

 engraved the points of the compass and a circle 

 divided to degrees. 



