TERRESTRIAL MAGNETISM, ETC. 279 



for use on land only in its gimballed bowl, here is 

 Gilbert's description of it, a literal translation of 

 the eighth chapter of his Fourth Book, entitled " On 

 the Composition of the Nautical Compass in 

 Ordinary Use, and on the Difference of Compasses 

 of Different Nations." 



" In a round wooden bowl closed above with 

 *' glass a pin fixed upright in the middle bears the 

 *' fly-card. The glass cover protects the interior 

 ' against wind or any impulse of air from without, 

 *' and at the same time allows the card and inner 

 u lid of the bowl i.o be distinctly seen. The fly is 

 '* circular and of light material, as cardboard. The 

 u magnetized needles are fixed to it below. Its 

 " upper side is divided into thirty-two spaces, com- 

 '* monly called points, corresponding to that 

 '' number of equal angular intervals of the horizon, 

 " or of the winds, which are distinguished by 

 " proper marks and a lily to mark the north point. 

 ' The bowl, \vith a lead weight attached to its 

 '' bottom, hangs balanced horizontally in a brass 

 %< ring, which, in a sufficiently complete compass, is. 

 il transversely pivoted on another ring, this last 



