182 



THE INTELLECTUAL RISE IN ELECTRICITY. 



where you are, and by means of the compass as he de- 

 scribes it you have simply to follow the course you have 

 plotted. There would not be any difficulty in steering a 

 modern ocean steamer by means of Peregrinus's compass, 

 and in exactly the same way. 



After the time of Peregrinus, as we shall see, the com- 

 pass card was invented, and all of the thirty-two points 

 of the compass (beginning with north, and thence pass- 



PEREGRINUS' COMPASS. 



ing in order to north by east, north northeast, northeast 

 by north, northeast, northeast by east, and so on) were 

 named. 



The presence of the little needle of copper or silver 

 which Peregrinus thrusts through the pivot at right 

 angles to the iron needle is a matter of curious interest. 

 Peregrinus does not say why he uses it, nor what purpose 

 he expected it to serve. Probably it was intended merely 

 to indicate the east and west points and made of non-mag- 



1 From the Vatican Codex of Peregrinus' Letter. This is apparently 

 intended as a plain view of the floating compass. 



