306 FERGUSON'S LECTURES. 



LECT. pole above the north point of the horizon, as many de- 

 VII1.&IX. g rees (counted from the pole upon the brazen meridian) 

 as are equal to the latitude of the place. Jf the place be 

 in the southern hemisphere, raise the south pole above 

 the south point of the horizon, as many degrees as, are 

 equal to the latitude. Then, turn the globe till the 

 place comes under its latitude on the brazen meridian, 

 and fasten the quadrant of altitude so, that the chamfered 

 edge of its nut (which is even with the graduated edge) 

 may be joined to the zenith, or point of latitude. This 

 done, bring the sun's place in the ecliptic for the given 

 day, (found by Prob. X.) to the graduated side of the 

 brazen meridian, and set the hour-index to XII at noon, 

 which is the uppermost XII on the hour-circle ; and the 

 globe will be rectified. 



Remark. The latitude of any place is equal to the elevation of 

 the nearest pole of the heaven above the horizon of that 

 place ; and the poles of the heaven are directly over the 

 poles of the earth, each 90 degrees from the equinoctial 

 line. Let us be upon what place of the earth we will, 

 if the limits of our view be not intercepted by hills, we 

 shall see one half of the heaven, or 90 degrees every 

 way round, from that point which is over our heads. 

 Therefore, if we were upon the equator, the poles of the 

 heaven would lie in our horizon, or limit of our view 

 if we go from the equator, towards either pole of the 

 earth, we shall see the corresponding pole of the heaven 

 rising gradually above our horizon, just as many de- 

 grees as we have gone from the equator : and if we were 

 at either of the earth's poles, the corresponding pole of 

 the heaven would be directly over our head. Conse- 

 quently, the elevation or height of the pole in degrees 

 above the horizon, is equal to the number of degrees 

 that the place is from the equator. 



