310 FERGUSON'S LECTURES. 



LECT. horizon, and then, the elevation of the pole will be equal 

 Vlll.&lX. to the latitude requ i re( j. 



PROBLEM XXII. 



The latitude of a place, not exceeding 663 degrees, and the 

 day of the month being given ; to fold the sun's ampli- 

 tude, or point of the compass on which he rises or sets. 



Rectify the globe, and bring the sun's place to the 

 eastern side of the horizon ; then observe what point of 

 the compass on the horizon stands right against the 

 sun's place, for that is his amplitude at rising. This 

 done, turn the globe westward, until the sun's place 

 comes to the western side of the horizon, and it will cut 

 the point of his amplitude at setting. Or, you may 

 count the rising amplitude in degrees, from the east 

 point of the horizon, to that point where the sun's place 

 cuts it ; and the setting amplitude, from the west point 

 of the horizon, to the sun's place at setting. 



PROBLEM XXIII. 



The latitude, the sun's place, and his altitude," being given ; 

 to Jind the hour of the day, and the sun's aximuth, or 

 number of degrees that he is distant from the meridian. 



Rectify the globe, and bring the sun's place to the 

 given height upon the quadrant of altitude ; on the east- 

 ern side of the horizon, if the time be in the forenoon ; 

 or the western side, if it be in the afternoon : then, the 

 index will shew the hour ; and the number of degrees in 

 the horizon intercepted between the quadrant of altitude 

 and the south point, will be the sun's true azimuth at 

 that time. 



N. B. Always when the quadrant of altitude is men- 



Nole 87. The sun's altitude, at any time, is his height in degrees above 

 the horizon at that time. Note by the Author. 



