night with the other, &c. Lastly, as the globe stands, count down by the meridian the same degree of latitude south, and that will give the place of the antipodes of London, being diametrically under or opposite to it; and so having all its times, both hours and seasons opposite, being day with the one when night with the other, and summer with the one when winter with the other.

5. "To find the distance of two places on the globe." If the two places be either both on the equator, or both on the same meridian, the number of degrees in the distance between them, reduced into miles, at the rate of seventy English miles to the degree, (or more exact sixty-nine and one fifth), will give the distance nearly. But in any other situations of the two places, lay the quadrant of altitude over them, and the degrees counted upon it, from the one place to the other, and turned into miles as above, will give the distance in this case. 6. "To find the difference in the time of the day at any two given places, and thence the difference of longitude." Bring one of the places to the meridian, and set the hour index to twelve at noon; then turn the globe till the other place comes to the meridian, and the index will point out the difference of time; then by allow ing fifteen degrees to every hour, or one degree to four minutes of time, the difference of longitude will be known. Or the difference of longitude may be found without the time, thus:

First bring the one place to the meridian, and note the degree of longitude on the equator cut by it; then do the same by the other place; which gives the longitudes of the two places; then subtracting the one number of degrees from the other, gives the difference of longitude sought.

7. "The time being known at any given place, as suppose London, to find what hour it is in any other part of the world." Bring the given place, London, to the meridian, and set the index to the given hour; then turn the globe till the other place come to the meridian, and look at what hour the index points, which will be the time sought.

8. "To find the sun's place in the ecliptic, and also on the globe, at any given time." Look into the calendar on the wooden horizon for the month and day of the month proposed, and immediately opposite stands the sign and degree which the sun is in on that day. Then in the

ecliptic drawn upon the globe, look for the same sign and degree, and that will be the place of the sun required.

9. "To find at what place on the earth the sun is vertical, at a given moment of time at another place, as suppose London." Find the sun's place on the globe by the last problem, and turn the globe about till that place come to the meridian, and note the degree of the meridian just over it. Then turn the globe till the given place, London, come to the meridian, and set the index to the given moment of time. Lastly, turn the globe till the index points to twelve at noon; then the place of the earth, or globe, which stands under the before noted degree, has the sun at that moment in the zenith,

10. "To find how long the sun shines without setting, in any given place in the frigid zones." Subtract the degrees of latitude of the given place from ninety, which gives the complement of the latitude, and count the number of this complement upon the meridian from the equator towards the pole, marking that point of the meridian; then turn the globe round, and carefully observe what two degrees of the ecliptic pass exactly under the point marked on the meridian. Then look for the same degrees of the ecliptic on the wooden horizon, and just opposite to them stand the months and days of the months corresponding, and between which two days the sun never sets in that latitude.

If the beginning and end of the longest night be required, or the period of time in which the sun never rises at that place; count the same complement of latitude towards the south or farthest pole, and then the rest of the work will be the same in all respects as above.

Note, that this solution is independent of the horizontal refraction of the sun, which raises him rather more than half a degree higher, by that means making the day so much longer, and the night the shorter; therefore in this case, set the mark on the meridian half a degree higher up towards the north pole, than what the complement of latitude gives; then proceed with it as before, and the more 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

8. "To find the time when the sun rises or sets." Find the sun's place for the given day; bring it to the meridian, and set the hour-hand to XII; then turn the globe till the sun's place touches the east part of the horizon, the index will shew the hour of its rising, after that, turn the globe to the west part of the horizon, and the index will shew the time of its setting for the given day.

9. "To find the length of any given day or night." This is easily known by taking the number of hours between the rising and setting of the sun for the length of the day; and the residue, to twenty-four, for the length of the night.

10. "To find the hour of the day, having the sun's altitude given." Bring the sun's place to the meridian, and set the hour hand to XII; then turn the globe in such a manner, that the sun's place may move along by the quadrant of altitude (fixed in the zenith) till it touches the degree of the given altitude, where stop it, and the index will shew on the horary circle the hour required.

11. "To find the place of the moon, or any planet, for any given day." Take White's ephemeris, and against the given day of the month you will find the degree and minute of the sign which the moon or planet possesses at noon, under the title of geocentric motions. The degree thus found being marked in the ecliptic on the globe by a small mark, or otherwise, you may then proceed to find the declination, right ascension, latitude, longitude, altitude, azimuth, rising, southing, setting, &c. in the same manner as has been shewn for the sun. 12. "To explain the phenomena of the harvest-moon." In order to this we need only consider, that when the sun is in the beginning of Aries, the full moon on that day must be in the beginning of Libra; and since when the sun sets, or moon rises, on that day, those equinoctial points will be in the horizon, and the ecliptic will then be least of all inclined thereto, the part or arch which the moon describes in one day, viz. 13°, will take up about an hour and a quarter ascending above the horizon; and, therefore, so long will be the time after sun-set, the next night, before the moon will rise. But at the opposite time of the year, when the sun is in the autumnal, and the full moon in the vernal equinox, the ecliptic will, when the sun is setting, have the greatest inclination to the horizon; and therefore, 13° will in this case soon ascend, viz.

in about a quarter of an hour; and so long after sun-set will the moon rise the next day after the full: whence, at this time of the year, there is much more moon-light than in the spring; and hence this autumal full moon came to be called the harvestmoon, the hunter's or shepherd's moon: all which may be clearly shewn on the globe.

13. "To represent the face of the starry firmament for any given hour of the night." Rectify the globe, and turn it about, till the index points to the given hour; then will all the upper hemisphere of the globe represent the visible half of the heavens, and all the stars on the globe will be in such situations as exactly correspond to those in the heavens; which may therefore be easily found, as will be shewn in the sixteenth problem.

14. "To find the hour when any known star will rise, or come upon the meridian.” Rectify the globe, and set the index to XII; then turn the globe till the star comes to the horizon or meridian, and the index will shew the hour required.

15. "To find at what time of the year any given star will be on the meridian at XII at night." Bring the star to the meridian, and observe what degree of the ecliptic is on the north meridian under the hori zon; then find in the calendar on the horizon the day of the year against that degree, and it will be the day required.

16. "To find any particular star." First find its altitude in the heavens by a quadrant, and the point of the compass it bears on; then, the globe being rectified, and the index turned to the given hour, if the quadrant of altitude be fixed on the zenith, and laid towards the point of the compass on which the star was observed, the star required will be found at the same degree of altitude on the said quadrant, as it was by observation in the heavens.

The invention of globes is of great antiquity. Some allusions to the celestial globe may be found as early as Hipparchus's time, in the writings of Pliny and Ptolemy. Strabo makes mention of the terrestrial globe; and a contemporary of his, Propertius, refers directly to depicted worlds; and Claudius, who describes Archimedes' glass sphere, evinces great knowledge of the constructions of an orrery, spheres, &c. that then existed among mathematicians.

Among the improvers and makers of globes may be subsequently ranked the following, as chief: Tycho Brahe, Regiomon

tanus, Schonerus, Gemma Fricius, Gr. Mercator, J. Hondius, Johnsonius, Wm. Saunderson, Wm. Bleau, &c.; some of whom wrote learnedly on their uses: but, in this respect, the preference is certainly due to our countryman, Mr. Robert Hues, whose Latin treatise was afterwards published by Handinus, and then by Pontanus with figures and notes. This work was afterwards translated into English by J. Chilmead, in the year 1639.

No globes had any pretensions to acccuracy, taste, or elegance, till the time of Mr. John Senex, F. R.S.: who, about the year 1759, delineated and engraved sets of plates for globes of nine, twelve, seventeen, and twenty-eight inches in diameter, which he used with the globes then manufactured by himself, and making these instruments more accurate and useful than any former maker. The terms and names of places on the globes of seventeen and twenty-eight inches in diameter were in Latin.

About the year 1759, and just after the decease of Mr. Senex, Mr. Benjamin Martin, a learned optician, became possessed of Mr. Senex's plates, and continued for many years to manufacture the globes, but with additional skill, and with various improvements.

About the year 1765, the late Mr. George Adams caused new plates for eighteen and and twelve inches globes to be engraved. The terms and names of these, like the larger ones of Senex, were printed in Latin. In stead of horary circles fixed on the meridian, with moveable indices for computation of time, Mr. Adams contrived circular wires, to envelope the globe about the equinoctial circles, with sliding brass points; so that, as the globes were revolved on their axis, the time by these was pointed out on the graduations of the above great circle; which consequently gave a more extensive and conspicuous scale of time, than could be had by means of the smaller horary circles. He also applied to each globe a semicircular slip of brass, connected at the poles, having on the terrestrial a sliding compass, bearing circle; and on the celestial a small sliding sun. The brass slips were graduated each way from the equinoctial, so the positions for rhomb-lines, right ascensions, and declinations, could be better and more readily obtained.

The horary, or hour circle, of the globes being usually attached to the external edge of the meridians, prevented a free and uninterrupted motion of the meridians, with

their poles through the horizons of the globes, to admit of an universal position of the axis, with respect to the horizon, for all latitudes of places. Mr. James Harris, of the Mint, in the year 1740, contrived a method of fixing the brass horary circles at the poles, under the meridians; i. e. between the surface of the globes and interior edge of the meridian, and to be occasionally moveable, independent either of the globe or meridian. In this manner the globes were rendered completely useful for the solution of problems in all latitudes.

About the year 1785, Mr. G. Wright contrived a moveable index, applicable to the poles of a globe, to act in a similar manner to the circle of Mr. Harris, which pointed to a circle of hours engraved round the poles of each globe. This he considered a method of obviating the great friction, or adherence, that sometimes inconveniently takes place between the surfaces of the circle and globe.

From the lapse of years, the numerous astronomical and geographical discoveries, and the Latin terms adopted in the larger globes of Senex and Adams, these globes became inconvenient, embarrassing, and finally obsolete. A short time before, the year 1800, sets of new and accurately engraved plates were suggested, and considered as a desideratum in astronomy by the Astronomer Royal, Dr. Maskelyne, Sir Joseph Banks, Professor Vince and others; and conformably to this object, in the year 1800 were completed and produced a set of entirely new plates for globes of eighteen inches in diameter, and under the denomination of the "New British Globes." The graduations and lines are laid down in the most correct manner, and with much greater accuracy than in any former globe plates. The drawing from which the terrestrial is engraved, was an entirely new one, from the hands of Mr. Arrowsmith, an eminent geographer. The latitudes and longitudes of places are rectified from the latest and best authorities; and there are likewise inserted all the authentic discoveries to the present time. The celestial globe contains a description of a complete catalogue of stars, clust. ers, planetary, nebula, &c. to the amount of nearly 6,000, from the observations and communications of Dr. Maskelyne, Dr. Herschel, Rev. Mr. Wollaston, &c., and inserted from calculations made by Mr. W. Jones, op. tician of Holborn, in their exact positions, to the present period. To the principal stars are annexed Bayer's Greek letters of