Terrestrial and Celestial Globes Volume 2 / Their History and Construction Including a Consideration of their Value as Aids in the Study of Geography and Astronomy

by Edward Luther Stevenson

Attention has been called to certain suggested changes in the names of constellations as given by the ancients, as for example those suggested by the Venerable Bede, by Johannes Bayer, by Julius Schiller proposing that biblical or Christian names should be substituted for pagan names, and for these changes there was of course suggested an appropriate change in the figures for the several constellations. The proposal of Erhard Weigel has likewise been noted urging a substitution of the several coats of arms or heraldic devices of the European dynasties for the figures which had been so long and so generally accepted. There seems scarcely to be the need of stating that the names and figures of the ancients remain.[205]

A comparison of the work of the several artists who have set their hand to the draughting of figures for the numerous constellations is not without interest. Attention may here be directed in passing to the decidedly oriental cast of these figures as they appear on Arabic globes.[206]

It is to be regretted that in the present very practical or scientific day the star map, wanting the figures of the constellations or giving them in but the faintest outline, has come to supplant the artistic and not unscientific creations of earlier years.

The earliest references we have to globes, that is, to solid balls or spheres, make mention of their mountings, that is, to their encasing circles and their bases. The simplest mounting consisted of but a meridian and a horizon circle with probably a simple supporting base. The earliest spheres were doubtless made to revolve just as the globes of today, around their polar axes which turn within sockets firmly attached to the meridian circle. This meridian circle of brass or wood was usually graduated from one to ninety degrees, that is, from the equator to the poles, and being adjustable relative to the horizon circle, a globe could be set with a polar elevation for any desired latitude. Those who have had occasion to refer to the construction and the uses of the globe more or less in detail, make mention of what they call its threefold position. In the first of these positions either pole may be at the vertical point, the equator and the horizon being parallel or coinciding. This they termed a parallel sphere. In the second position the equator and the horizon circle are set at right angles. This they called a right sphere. In the third position, which was called an oblique sphere, the pole could be set at any elevation from zero to ninety degrees, counting from the horizon circle. In illustration of this third position it may be said that for the latitude of New York City, the north pole More conspicuous by reason of its width and importance in the mounting of the globe than the meridian is the horizon circle. It is through notches in this circle at the north and south points that the meridian circle passes, the notches also serving as gauges to keep the meridian from inclining more to the one side of the horizon circle than to the other. On the upper surface of this circle there were usually represented several concentric circles, the same being either engraved thereon, if it were of metal, and printed or pasted thereon if of wood, just as the globe map proper which covered the surface of the sphere. The number of concentric circles, and the information carried in each, varied, nor was the order of the circles invariably the same. Those globes giving fullest information exhibit ten or more of these circles. That one which was innermost and next to the body of the globe was divided into twelve parts, each part carrying the name of one of the signs of the zodiac with its character, and each divided into thirty equal parts or degrees, these being numbered by tens, as 0, 10, 20, 30. Next to the circle of signs, always remembering that the order might vary, was that containing the calendar including the names of the months, as January, February, March, etc., the days of the week being either distinguished by numbers or names. The old calendar was likewise usually given and so represented as to show the beginning of each month ten days earlier than in the new calendar. Here also were given the names of the church festival days. In the next circle were the names of the winds or directions, and first the Greek, Latin or Italian names of the eight, twelve or sixteen winds, as Greco, Libeccio, Ponente, Maestro, and next the names or initials of the thirty-two compass directions, the same generally in English or Dutch abbreviations. It may further be noted that a compass was often fixed in the horizon circle’s upper face. of the globe should be elevated 40 degrees 48 minutes above this circle.

A complete globe was further furnished with a quadrant of altitude, ninety degrees in length, this being attached at one end to the meridian circle, yet movable to any degree of the meridian, though commonly set at the zenith. This quadrant served for measuring altitudes or for finding amplitudes or azimuths.

The small hour circle,[207] fitted to the meridian, its center being the pole and for us the north, was marked with the twenty-four hours of the day, each hour being again divided into halves and quarters. An index attached to the axis of the globe pointed out successively the hours as the globe was revolved. The use of this hour circle was to indicate the time of the successive mutations, including the rising and the setting of the celestial bodies and the time of their passing successively the meridians.

As a compass was often set into the horizon circle so also we frequently find a large or small compass set into that plate which in certain globes was employed as a support, tying together, as it were, the lower extremities of the base columns.[208]

It will have been noted that the globes referred to in the preceding pages varied greatly as to size, from the small ball representing the earth, and but a few centimeters in diameter, to be found in the center of those armillary spheres representing the Ptolemaic geocentric system, to the great globe of Coronelli fifteen feet in diameter constructed for Louis XIV of France. With rare exceptions metal globes were made small in size. Those globe balls or spheres, in the construction of which a mould was employed, usually had a diameter under 50 cm., although we find some of them twice this size. Such spheres had the advantage of lightness though often were frail in structure and liable to lose their perfect sphericity.