PEREGRINUS' COMPASS. l8l 



the first time, produces the pivoted compass. The floating 

 bowl and the large vessel of water are abolished, and in 

 place of them there is the ordinary circular compass-box 

 of to-day. Its edges are marked as those of the bowl were 

 with the degrees of the circle. It is covered with a 

 plate of glass. In the centre of the instrument, and 

 stepped in the glass cover and in the bottom of the box, is 

 a pivot, through which passes the compass needle, now no 

 longer an ovoid lodestone, but a true needle of steel or iron. 

 Then, at right angles to this needle is another needle, 

 which, curiously enough, he says is to be made of silver or 

 copper. Pivoted above the glass cover is an azimuth bar, 

 as before, with sight pins at the ends. Now, he says, 

 you are to magnetize the needle by means of the lodestone 



PEREGRINUS' PIVOTED COMPASS. 



in the usual way, so that it will point north and south ; 

 and then the azimuth bar is to be turned on its centre so 

 as to be directed toward the sun or heavenly bodies, and in 

 this way, of course, the azimuth is easily measured. In 

 fact, the device is the azimuth compass of the present 

 time. "By means of this instrument, " says Peregrinus, 

 "you may direct your course towards cities and islands 

 and all other parts of the world, either on land or at sea, 

 provided you are acquainted with the longitudes and lati- 

 tudes of those places." Or, in other words, find the posi- 

 tion in latitude and longitude of the place whither you 

 wish to proceed, which is obviously the first thing neces- 

 sary ; note the direction of that place from the place 



1 From Bertelli, cit. sup. 



