GLOBE. 



exact time and length of the longest day 

 and night will be found. 



11. * A place being given in the torrid 

 zone, to find on what two days of the year 

 the sun is vertical at that place." Turn 

 the globe about till the given place come 

 to the meridian, and note the degree of 

 the meridian it comes under. Next turn 

 the globe round again, and note the two 

 points of the ecliptic passing vinder that 

 degree of the meridian. Lastly, by the 

 wooden horizon, find on what days the 

 sun is in those two points of the ecliptic ; 

 and on these days he will be vertical to 

 the given place. 



12. " To find those places in the torrid 

 zone to which the sun is vertical on a giv- 

 en day." Having found the sun's place in 

 the ecliptic, as in the eighth problem, 

 turn the globe to bring the same point of 

 the ecliptic on the globe to the meridian; 

 then again turn the globe round, and note 

 all the places which pass under that point 

 of the meridian ; which will be the places 

 sought. 



After the same manner may be found 

 what people are ascii for any given day. 

 And also to what place of the earth, the 

 moon, or any other planet, is vertical on 

 a given day ; finding the place of the pla- 

 net on the globe by means of its right 

 ascension and declination, like finding a 

 place from its longitude and latitude giv- 

 en. 



13. " To rectify the globe for the lati- 

 tude of any place." By sliding the brass 

 meridian in its groove, elevate the pole as 

 far above the horizon as is equal to the la- 

 titude of the place ; so for London, raise 

 the north pole fifty-one and a half degrees 

 above the wooden horizon : then turn the 

 globe on its axis till the place, as London, 

 come to the meridian, and there set the 

 index to twelve at noon. Then is the 

 place exactly on the vertez, or top point 

 of the globe, at ninety degrees every way 

 round from the wooden horizon, which 

 represents the horizon of the place. And 

 if the frame of the globe be turned about 

 till the compass needle point to twenty, 

 two and a half degrees, or two points west 

 of the north point (because the variation 

 of the magnetic needle is nearly twenty- 

 two and a half degrees west), so shall the 

 globe then stand in the exact position of 

 the earth, with its axis pointing to the 

 north pole. 



14. " To find the length of the day or 

 night, or the sun's rising or setting, in any 

 latitude ; having the day ot the month 

 given." Rectify the globe for the lati- 

 tude of the place ; then bring the sun's 

 place on the globe to the meridian, and set 



the index to twelve at noon, or the upper 

 twelve, and then the globe is in the pro- 

 per position for noon-day. Next turn the 

 globe about towards the east till the sun's 

 place come just to the wooden horizon, 

 and the index will then point to the hour 

 of sun-rise ; also turn the globe as far to 

 the west side, or till the sun's place come 

 just to the horizon on the west side, and 

 then the index will point to the hour of 

 sun-set. These being now known, dou- 

 ble the hour of setting will be the length 

 of the day, and double the rising will be 

 the length of the -night. And thus also 

 may the length of the longest day, or the 

 shortest day, be found for any latitude. 



15. " To find the beginning and end of 

 twilight on any day of the year, for any 

 latitude." It is twilight all the time from 

 sun-set till the sun is eighteen degrees 

 below the horizon, and the same in the 

 morning from the time the sun is eighteen 

 degrees below the horizon till the moment 

 of his rise. Therefore, rectify the globe 

 for the latitude of the place, and for noon, 

 by setting the index to twelve, and screw 

 on the quadrant of altitude. Yhen take 

 the point of the ecliptic opposite the sun's 

 place, and turn the globe on its axis west- 

 ward, as also the quadrant of altitude, till 

 that point cut this quadrant in the eigh- 

 teenth degree below the horizon ; then 

 the index will shew the time of dawning 

 in the morning ; next turn the globe and 

 quadrant of altitude towards the east, till 

 the said point opposite the sun's place 

 meet this quadrant in the same eighteenth 

 degree, and then the index will shew the 

 time when twilight ends in the evening. 



16. " At any given day, and hour of the 

 day, to find all those places on the globe 

 where the sun then rises, or sets, as also 

 where it is noon-day, where it is day-light, 

 and where it is in darkness." Find what 

 place the sun is vertical to, at that time ; 

 and elevate the globe according to the 

 latitude of that place, and bringthe place 

 also to the meridian ; in which state it 

 will also be in the zenith of the globe. 

 Then is all the upper hemisphere, above 

 the wooden horizon, enlightened, or in 

 day light ; while all the lower one, below 

 the horizon, is in darkness, or night : 

 those places by the edge of the meridian, 

 in the upper hemisphere, have noon-day, 

 or twelve o'clock ; and those by the me- 

 ridian below, have it midnight: lastly, all 

 those places by the eastern side of the ho- 

 rizon have the sun just setting, and those 

 by the western horizon have him just ris- 

 ing. 



Hence, as in the middle of a lunar 

 eclipse, the moon is in that degree of the 



