326 FERGUSON'S LECTURES. 



PROBLEM IV. 



The latitude of the place, and day of the month, being 

 given; tojindthe time when any known star will rise, 

 or be on the meridian, or set. 



Having rectified the globe, turn it about until the 

 given star conies to the eastern side of the horizon, and 

 the index will shew tlie time of the star's rising ; then 

 turn the globe westward, and when the star comes to the 

 brazen meridian, the index will shew the time of the 

 star's coming to the meridian of your place ; lastly, turn 

 on, until the star comes to the western side of the 

 horizon, and the index will shew the time of the star's 

 setting. 



N. B. In northern latitudes, those stars which are 

 less distant from the north pole, than the quantity of its 

 elevation above the north point of the horizon, never 

 set ; and those which are less distant from the south 

 pole, than the number of degrees by which it is de- 

 pressed below the horizon, never rise ; and vice versa in 

 southern latitudes. 



PROBLEM V. 



To Jind at what time of the year a given star will be upon 

 the meridian, at a given hour of the night* 



Bring the given star to the upper semicircle of i\\e 

 brass meridian, and set the index to the given hour ; 

 then turn the globe, until the index points to XII at 

 noon, and the upper semicircle of the meridian will then 

 cut the sun's place, answering to the day of the year 

 sought ; whicli day may be easily found against the like 

 place of the sun among the signs on the wooden 

 horizon. 



