314 FERGUSON'S LECTURES. 



whereby lt exeedeth twelve, double that number, 

 the sum will answer to the climate in which the 

 place is. 



PROBLEM XXIX. 



The latitude, and the day of the month, being given ; to 

 find the hour of the day when the sun shines. 



Set the wooden horizon truly level, and the brazen 

 meridian due north and south by a mariner's compass : 

 then, having rectified the globe, stick a small sewing- 

 needle into the sun's place in the ecliptic, perpendicular 

 to that part of the surface of the globe : this done, turn 

 the globe on its axis, until the needle comes to the 

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

 then, turn the globe on its axis, until the needle points 

 exactly towards the sun (which it will do when it casts 

 no shadow on the globe) and the index will shew the 

 hour of the day. 



PROBLEM XXX. 



A pleasant way of shewing all those places oj the earth 

 which are enlightened by the sun, and a/so the time of 

 the day when the sun shines. 



Take the terrestrial ball out of the wooden horizon, 

 and also out of the brazen meridian ; then set it upon a 

 pedestal in sun-shine, in such a manner, that its north 

 pole may point directly towards the north pole of the 

 heaven, and the meridian of the place where you are, 

 be directly towards the south. Then, the sun will shine 

 upon all the like places of the globe, that he does on the 



of latitude, that the length of the longest day in the one exceeds that 

 in the other by half an hour ; bat from the polar circles to the poles, 

 where the sun keepa long above the horizon withont setting, each 

 climate differs a whole month from the one next to it. There are 

 twenty-four climates between the equator and each of the polar cir- 

 cles ; [and six from each polar circle to its respective pole. Note by 

 the Author. 



