1851 Great Exhibition: Official Catalogue: Class X.: J. Nasmyth
688. NASMYTH, J., Manchester.
Map of the moon: exhibiting the relative positions and character of the most striking features of its surface, as they appear when seen under the most favourable circumstances in respect to light and shade, with drawings from nature of certain portions of the lunar surface, as seen by the aid of a very powerful telescope.
[The number and magnitude of crater-formed mountains with which every portion of the moon's surface appears to be covered, seems to lead to the conclusion that these are really the craters of extinct lunar volcanoes., the frequent occurrence of the central cone being considered as the result of the last eruptive efforts of an expiring volcano, a feature of volcanic craters on the earth's surface. This central cone has been shown to exist in the majority of the lunar craters; and the conclusion consequently appears probable that they are the result of the same kind of action which has produced them on the volcanos of the earth.
The cause of the vast numbers of such volcanic mountains with which the lunar surface is covered, has been assigned by some to the rapid consolidation and contraction of the crust of the moon; whose mass or bulk being only 1-64th of that of the earth, while its surface is the 1-16th, has, in consequence of these proportions, a radiating or heat-dispensing surface four times greater than that of the earth in relation to its bulk. From this consideration, it has been suggested by the exhibitor, that by the rapid cooling and collapse of the crust of the moon on its molten interior, the fluid matter under the solid crust has been by this action forced to find an escape through the superincumbent solid crust, and come forth in those vast volcanic actions which in some remote period of time have covered its surface with the myriads of craters and volcanic features that give to its surface its remarkable character.
The vast magnitude of the lunar craters, it has also been suggested, are due to this rapid collapse of the moon's crust on its molten interior, — the action as regards the wide dispersion of the ejected matter being enhanced by the lightness of the erupted matter, seeing that the force of gravity which gives the quality of weight to matter on the moon, as on the earth, is less on the surface of the moon than on the earth,— so that the collapse action had to operate on a very light material. The causes of those vast ranges of mountains seen on the moon's surface has been suggested to be produced by the continued progress of the collapse action of the solid crust of the moon crushing down or following the contracting molten interior, which, by the gradual dispersion of its heat, would retreat from contact with the interior of the solid crust, and permit the crust to crush down and so force a portion of the original surface out of the way, and in consequence of this action, cause such to assume the form and arrangement of mountain ranges. In illustration of this important action, the familiar case of the wrinkling of the surface of an apple, by reason of the contraction of the interior and the inability of the surface to accommodate itself to the change otherwise, has been adduced.
The origin or cause of those bright lines which radiate from certain volcanic centres on the moon's surface (Tycho, for instance) has been illustrated by the experiment of causing the surface of a globe of glass filled with water to collapse on the fluid interior, by rapidly contracting the surface while the water had no means of escape. The result was the splitting or cracking up of the surface of the globe in a multitude of radiating cracks, which bear the most remarkable similarity to those on the moon. This subject is also illustrated by reference to the manner in which the surface of a frozen pond may be made to crack by pressure from underneath—so yielding radiating cracks from the centre of divergence where the chief discharge of water will take place, while simultaneously all along the lines of radiating cracks the water will make its appearance:—thus explaining how it is that the molten material, which had in like manner been under the surface of the moon during that period of its history, appears to have come forth simultaneously through the cracks, and appeared on the surface as basaltic or igneous overflow, irrespective of surface inequalities.]