Fig. 140. Terrestrial Globe Gores by Johannes Oterschaden, ca. 1675.
In the matter of special ornamentation or decoration, to be observed in globe mountings, individual taste was given unlimited freedom to express itself, and in certain instances it will have been noted that these mountings were exceedingly elaborate.
Primarily we may say that globes were constructed for the useful purpose of promoting geographical and astronomical studies, generally recording the latest and best geographical or astronomical information and in form superior to that which could be set down on the plane map, but they also had a place of importance, secondary we may call it, on account of their decorative value. They came to be considered almost essential as adornments for the libraries of princes, of prosperous patricians, and of plodding students, and their mountings were often especially fashioned for the places they were to occupy. They seemed to lend an air of scholarly respectability; to suggest that their possessors wished to pay, certainly a modicum of homage to the sciences which globes were calculated to promote.
A brief concluding word may well be added touching those globes which may of course be classed as celestial, but which are known as moon globes and planetariums or orreries. There could be no practical value in an attempt to set forth a map of the surface of the stars, nor of the planets while our knowledge is so limited, although Schiaparelli has undertaken, with measurable success, to map the surface of Mars,[209] and it would be next in order to construct a Mars globe. Of the surface of our moon much is known and maps of it have been constructed, as indeed have been moon globes. We are informed that about the middle of the seventeenth century the Danish astronomer, Hevelius, who designed so successfully star maps, entertained the idea of constructing a moon globe,[210] but we do not know that he set his hand to the work. A century later it appears that the French astronomer La Hire actually completed a moon globe,[211] but it has been possible to obtain only the briefest reference to it.
Tobias Mayer of Nürnberg, a contemporary of La Hire, set himself to the draughting of gore maps[212] intended for use in the manufacture of moon globes. Mayer found employment in the Homann establishment of Nürnberg, being regarded as an exceedingly skilful draughtsman, able to sketch on his draughting sheet that which he saw through his telescope. His plan contemplated the making of twelve gores or segments, six for the northern half of the moon and six for the southern. His plan, of course, would enable him to represent but one side of the moon,—that turned toward the earth,—although it appeared that he contemplated the addition of two segments on which, in at least a fragmentary manner, he was to represent what we may call the border of the opposite side of the moon. Mayer seems not to have completed his work, since we find nowhere an example of his finished product.
It was not until near the close of the eighteenth that we again meet with an attempt to construct a moon globe and it seems that the task was accomplished by the Englishman, John Russel. It was in the year 1796 that he proposed to raise by subscription the necessary funds for making his undertaking a success. His globe has a diameter of 12 inches,[213] and was furnished with the necessary adjustable shield that the moon’s waxing and waning could be represented. That this moon globe was actually constructed, although no copy has been located, we are informed by Wolf. Such attempts as were made in the nineteenth century with a good measure of success do not here call for consideration.
It has been previously noted that the so-called globe of Archimedes may have been a sort of planetarium, and that during the middle ages such instruments were constructed and employed in astronomical instruction. None, however, have come down to us out of those early years. Astronomers of the seventeenth and eighteenth centuries, as we know, made frequent use of planetariums, such for example as were constructed by the Dutch astronomer, Christiaan Haygens (1629-1695) for the illustration of planetary motion according to the Copernican system. Each of the planets was represented in his machine by a small ball, attached to an arm, which could be made to move through an orbit around the sun. In the more complicated machines the several planetary moons, such as the moons of Jupiter, were represented and were made to perform their proper motions.