432 



GLOBE. 



metrically opposite to each other. The equinoctial 

 jxiints are Aries and Libra, where the ecliptic cuts 

 the equinoctial. The point Aries is called the vernal 

 equinox, and the point Libra the autumnal e</i/i/io.r. 

 When the sun is in either of these points, the days and 

 nights on every part of the globe are equal to each 

 other. The solstitial points are Cancer, and Capricorn. 

 When the sun enters Cancer, it is the longest day to 

 all the inhabitants on the north side of the equator, 

 and the shortest day to those on the south side. 

 When the sun enters Capricorn, it is the shortest day 

 to those who live in north latitude, and the longest 

 day to those who live in south latitude. A hemi- 

 sphere is half the surface of the globe ; for every 

 great circle divides the globe into two hemispheres. 

 The horizon divides the upper from the lower hemi- 

 sphere in the heavens ; the equator separates the 

 northern from the southern on the earth ; and 

 the brass meridian, standing over any place on the ter- 

 restrial globe, divides the eastern from the western 

 hemisphere. The latitude of a place, on the terres- 

 trial globe, is its distance from the equator in degrees, 

 minutes, or geographical miles, &c., and is reckoned 

 on the brass meridian, from the equator towards the 

 north or south pole. (See Latitude.) The quadrant 

 of altitude is a thin piece of brass, divided upwards, 

 from to 90, downward, from to 18 ; when used 

 it is generally screwed to the brass meridian. The 

 upper divisions determine the distances of places on 

 the earth, the distances of the celestial bodies, their 

 latitudes, &c. ; and the lower divisions are applied 

 to finding the beginning, the end, and duration of 

 twilight. The longitude of a place, on the terrestrial 

 globe, is the distance of the meridian of that place 

 from the first meridian, reckoned in degrees and parts 

 of a degree, on the equator. Longitude is either 

 eastward or westward, according as a place is to the 

 east or west of the first meridian. No place can have 

 more than 180", or half the circumference of the 

 globe. (See Longitude.) Hour circles are the same 

 as meridians. They are drawn through every 15 of 

 the equator, each answering to an hour. The brass 

 meridian and these circles always correspond. (For 

 an account of climate, see Climate.) For an account 

 of the zones, see Zone.) The crepusculum, or 

 twilight, is tliat faint light which we perceive before 

 the sun rises and after he sets. It is produced by the 

 rays of light being refracted in their passage through 

 the earth's atmosphere, and reflected from the differ- 

 ent particles thereof. The twilight is supposed to 

 end in the evening, when the sun is 18 below the 

 horizon. The angle of position between two places 

 on the terrestial globe, is an angle at the zenith of 

 one of the places, formed by the meridian of that 

 place, and a vertical circle passing through the other 

 place measured on the horizon, from the elevated pole 

 towards the vertical circle. Rhumbs, are the divi- 

 sions of the horizon into thirty -two parts, called the 

 points of the compass. 



Problem 1. To find the latitude of any place. 

 Rule. Turn the globe till the place comes to the 

 graduated edge of the brazen meridian, and the de- 

 gree on the meridian with which the place corres- 

 ponds is the latitude north or south, as it may be 

 north or south of the equator. 



Problem 2, To find the longitude of any place. 

 Rule. Turn the globe till the place comes to the 

 brazen meridian, and the degree on the equator, in- 

 tersected by the brazen meridian, shows the longi- 

 tude. 



Problem 3. To find any place on the globe, having 

 the latitude and longitude of that place given. Rule. 

 Find the longitude of the given place on the equator, 

 bring it to that part of the brass meridian which is 

 numbered from the equator towards the poles ; and 



then, under the given latitude, on the brass meridian, 

 you will find the place required. 



Problem 4. To find t he difference of latitude of any 

 tin, places. Rule. If the places are in the same 

 hemisphere, bring each to the meridian,and subtract 

 the latitude of the one from that of the other; if in 

 different hemispheres, add the latitude of the one to 

 that of the other, and the sum will show the difference 

 of latitude. 



Problem 5. To find the difference of longitude 

 between any two places. Rule. Bring one of the 

 places to the brazen meridian ; mark its longitude ; 

 then bring the other place to the meridian, and the 

 number of degrees between its longitude and that of 

 the first mark is the difference of longitude. When 

 this sum exceeds 180, take it from 360 P , and the 

 remainder will be the difference of longitude. 



Problem 6. To find the distance between tii~o 

 places. Rule. When the distance is less than 90, 

 lay the quadrant of altitude over both the places, so 

 that the division marked O may be on one of the 

 places ; then the degree cut by the other place will 

 show the distance in degrees. Multiply these degrees 

 by 69^, and the product will be the distance in 

 English miles. The distance between two places, 

 with the angle of position, may be found, at the same 

 time in the following manner : Elevate the globe for 

 one of the places, bring it to the meridian, screw the 

 quadrant of altitude over it ; then move the quadrant 

 till it come over the other place, and observe what 

 degree of it this last place cuts. Subtract this 

 distance from 90, and the remainder will l;e the 

 distance in degrees. The quadrant of altitude, on 

 the horizon, will now show the angle of position. 

 When the distance is greater than 90, find the 

 antipodes of one of the places, and measure the 

 distance between this and the other place with the 

 quadrant of altitude. Subtract this distance from 

 180, and the remainder will be the whole distance 

 required, fallen the angle of position is required, 

 this case may be performed thus : 1 . Elevate the 

 globe for the antipodes of one of the places, and, 

 having fixed the quadrant over it, bring its edge over 

 the other place, and add the degree cut by it to 90 

 and the sum will be the distance required. 2. The 

 quadrant will show the position ; only, W. must be 

 read for E. ; E. for W. ; N. for S. ; and S. for N. 



Problem 1. The hour being given at any place, 

 to find what hour it is in any other part of the world. 

 Rule. Bring the place, at which the time is given, 

 to the meridian, set the index to the given hour, 

 then turn the globe till the other place comes to the 

 meridian, and the index will show the time required. 

 Obs. The earth turns round on its axis from the W. 

 towards the E., and causes a different part of its 

 surface to be successively presented to the sun. 

 When the meridian of any place is directly opposite 

 to the sun, it is then noon to all places on that meri- 

 dian. Meridians towards the E. come opposite to 

 the sun sooner than those towards the W. ; and hence 

 the people there have noon much sooner, and all the 

 other hours of the day will be proportionably advanced. 

 The earth takes twenty-four hours to turn on its axis, 

 and the rate at which it turns every hour may be 

 found, by dividing 360 by 24; the quotient, 15, 

 is the number of degrees the earth turns in an 

 hour. Hence it is that a place lying 15 to the 

 east of another, will have noon one hour sooner ; 

 if it is 30 or 45, it will have noon two or three 

 hours sooner than the other ; and so on, in the same 

 proportion, for all places farther removed. Places 

 that lie 15, 30 Q , or 45, to the W. of that place at 

 which it is noon, will have noon one, two, or three 

 hours later ; and so on, in the same proportion. 



Problem 8.. To adjust the globe for the latiiudv 



