OBSERVATIONS ON THE TERRESTRIAL GLOBE. 319 



horizon, as they are farther from, or nearer to, that LECT. 

 tropic which is all above the horizon : and when the sun ^r^-x 

 is not in either of the tropics, his diurnal course must 

 be in one or other of these circles. 



15. To all places in the northern hemisphere, from 

 the equator to the polar circle, the longest day and 

 shortest night is when the sun is in the" northern tropic ; 

 and the shortest day and longest night is when the sun 

 is in the southern tropic ; because no circle of the sun's 

 daily motion is so much above the horizon, and so little 

 below it, as the northern tropic ; and none so little above 

 it, and so much below it, as the southern. In the sou- 

 thern hemisphere, the contrary. 



16. In all places between the polar circles and poles, 

 the sun appears for some number of days (or rather 

 diurnal revolutions) without setting; and at the oppo- 

 site time of the year without rising ; because some part 

 of the ecliptic never sets in the former case, and as 

 much of the opposite part never rises in the latter. And 

 the nearer unto, or the more remote from the pole, these 

 places are, the longer or shorter is the sun's continuing 

 presence or absence. 



17. If a ship sets out from any port, and sails round 

 the earth eastward to the same port agaiu, let her take 

 what time she will to do it in, the people in that ship, 

 in reckoning their time, will gain one complete day at 

 their return, or count one day more than those who re- 

 side at the same port ; because, by going contrary to 

 the sun's diurnal motion, and being forwarder every 

 evening than they were in the morning, their horizon 

 will get so much the sooner above the setting sun, than 

 if they had kept for a whole day at any particular place. 

 And thus, by cutting off a part proportionable to their 

 own motion, from the length of every day, they will 

 gain a complete day of that sort at their return j without 

 gaining one moment of absolute time more than is 

 elapsed during their course, to the people at the port 



