GLOBE. 



matter applied: thus they continue alternately to apply the 

 compolitioii, and dry it, till fuch time as the bali every- 

 where accuratL-ly touches the fcmi-circle ; in wliich ilatc it is 

 perfeftly fmooth, regular, firm, Sec. 



Tlie ball thus finifhed, it remains to pafte the map or de- 

 fcription thereon : in order to this, the map is projected in 

 feveral gores or gufTets, all wliich join accurately on the 

 fpherical furface, and together cover the whole ball. To 

 dirett the application of thefe gores, lines arc drawn by a 

 femi-circle on tlie furface of the ball, dividing it into a num- 

 ber of equal parts correfponding to thofe of the gores, and 

 fubdividing thofe again anfwerably to the Unes and divillons 

 of the gores. 



The papers thus pafted on, there remains nothing but to 

 colour and illuminate the globe, and to varnilh it, the bet- 

 ter to refill dull, moiilure, &c. 



The globe ,itfe!f thus finiflied, they hang it in a brafs 

 meridian, with an hour circle and quadrant of altitude, and 

 thus fit it into a wooden horizon. 



Globes, Defcript'wn of the. The things common to both 

 globes are cither delineated on the furface, or added at. ap- 

 pendages without it. 



Without the furface are, i. The two poles whereon the 

 globe is turned, reprefenting thofe of the world. (See 

 Pole.) 2. The brazen meridian, which is divided into de- 

 grees, and pafFes through the poles. 3. The wooden hori- 

 zon, whofe upper fide reprefents the horizon, and is divided 

 into feveral circles ; the innermoft whereof contains the 

 twelve figns of the zodiac, fiibdivided into their degrees ; 

 the next the Julian ; and the third the Gregorian calendar ; 

 without fide of all thefe, are drawn the points of the winds. 

 4. A brafs "quadrant of altitude, divided into 90 degrees, to 

 be fattened on the meridian at the diilance of 90 degrees from 

 the horizon. 5. The hour-circles, divided into twice twelve 

 hours, and fitted on the meridian, round the poles, which 

 carry an index pointing to the hour. A mariner's compafs 

 is fometimes added on the bottom of the frame, and fome- 

 times a femi-circle of pofition. 



On the furface are delineated, i. The cquinoftial line, 

 divided into 360 degrees, commencing from the vernal in- 

 terfeClions. 2. The echptic, divided into twelve figns, and 

 thefe fubdivided into degrees. 3. The zodiac. 4. The 

 two tropics. And, 5. The polar circles. All which fee 

 under their proper articles. 



What elfe belongs to globes, cither as to conftruclion or 

 defcription, is different as the globe is either celejlial or ter- 

 reftr'ujl- 



Our common globes, though inftruftive inflruments for 

 explaining the firft rudiments of geography and the fpherical 

 doctrine of aftrononiy, yet labour under feveral defects ; as 

 they do not ihcw how the phenomena, illuftrated by tliem, 

 arife f»om the motion of the earth, which is the principal 

 thing beginners efpecially fnould have in view, and as they 

 are only formed for the prefent age, and do not ferve the 

 purpofes of chronology and liillory, which they might be 

 made to do, if the poles, whereon they turn, were contrived 

 to move in a circle round thofe of the ecliptic, according to 

 its prefent obliquity. 



Mr. John Senex, F.R.S. invented a contrivance for reme- 

 dying thefe defefts, by fixing the poles of the diurnal motion 

 to two ihoulders or arm.s of brafs, at the diilance of 33°;: 

 from the poles of the ecliptic. Thefe (lunilders are ftrongly 

 faltened at the other end to an iron axis, which pa,Tes through 

 tlie poles uf tlie ecliptic, and is made to move round with a 

 very lliff motion ; fu tiiat when it is adjutted to any point of 

 jhe ecliptic, which the equ.:tor is made to interftd, the 

 diurnal motpo of Uie globe on its axis will not be able to 



difturb it. When it is to be adjufted for any time, paft or 

 future, one of the brazen fiionlders is brought under the me- 

 ridian, and held fall to it with one hand, whilft the globe is 

 turned about with the other, fo that the point of the echp- 

 tic, which the equator is to interfeft, may pafs under o de- 

 gree of the brazen meridian : then holding a pencil to that 

 point, and turning the globe about, it will defcribe the equa- 

 tor according to itspolition at the time required ; and tranf- 

 ferring the pencil to 23 ', and 66 \ on tlie brazen meiihan, 

 the tropics and polar circles will be fo defcribed for the fame 

 time. By this contrivance, the ccleftial globe may be fo 

 adjuflcd, as to exhibit not only the rifings and fettingsof the 

 ftars, in all ages and in all latitudes, but llkevvife the other 

 phenomena thai depend upon the motion of the diurnal axis 

 round the annual axis. Senex's celellial globes, efpecially 

 the two greatell, of feventeen and twenty-eight inches in 

 diameter, have been conftrudled on this principle : fo that by 

 means of a nnt and fcrcw, the pole of the equator is made 

 to revolve about the pole of the ecliptic. Phil. Tranf. N° 

 447, p. 201. 203. or Marty n's Abr. vol. viii. p. 217. and N'^ 

 493, art. 18 in Phil. Tranf. vol. xlvi. p. 290. 



Mr. Jofeph Harris, late affay-maller of the mint, contrived 

 to remedy the former of the defects above-mentioned, by 

 placing two horary circles under the meridian, one at each 

 pole ; thefe circles are fixed tight between tv>'o brafs collars 

 placed about the axis, fo that when the globe is turned, 

 they are carried round with it, the meridian Icrving as an 

 index to cut the liorary divifions. The globe, in this ilatc, 

 ferves readily for folving problems in north and fouth lati- 

 tudes, and alfo in places near the equator ; whereas, in tlie 

 common conftruttion, the axis and horary circle prevent the 

 brafs meridian from being moveable quite roiuid in the hori- 

 zon. This globe is alfo adapted for (hev.ing liow the vicifTi- 

 tudes of day and night, and the alteration of their lengths, 

 are really oecafiuned by the motion of the earth ; for this 

 purpofe, he divides the brafs meridian, atone of the poles, 

 into moiiths and days, according to the fun's declination, 

 reckoning from the pole. Therefore, by bringing the day 

 of the month to the horizon, and rectifying the globe accord- 

 ing to the time of the day, the horizon will reprefent the 

 circle feparating light and darknefs, and the upper half of the 

 globe the illuminated hemifphere, the fun being in the ze- 

 nith. 



Mr. Harris alfo gives an account of a cheap machine for 

 (hewing how the annual motion of the earth in its orbit caufes 

 the change of the fun's declination, without the great ex- 

 pence of an orrery. Phil. Trani N 456, p. 321, &c. or 

 Martyn's Abr. vol. viii. p. 352. 



The late Mr. George Adams, mathematical inftrumcnt 

 maker to his majefty, has made iome ufeful improvements 

 in the conftruction of the globes. His globes, like others, 

 are fufpended at their poles in a ftrong brafs circle, and turn 

 therein upon two iron pins, .whicli are the axis. They have 

 befides a thin brafs femi-circle, moveable about ttie 

 poles, with a fmall, thin, Aiding circle upon it. On 

 the terrellrial globe, the thin brafs ferai-circle is a move- 

 able meridian, and its fmall fiiding circle the viuble horizon 

 of any particular place to which it is fet. On the cehilial 

 globe, the femi-circle is a moveable circle of declination, and 

 its fmal! annexed circle an artificial fun or ph.aet. Each 

 globe hath a brafs wire circle, placed at the limits of tlie twi- 

 light, which, together v;ith the globe, is fet in a wooden 

 frame, fupported by a neat pillar and claw, with a mag- 

 netic needle at its bafe. On the terreilrial globe the diviiion 

 of the earth into land and water is laid down from the lateft 

 difcovcries ; there are ,.!lo many additional circler., as well as 

 the rhumb-lines, for folving all the neceflary geographical anti 



nautical 



