John Birmingham

“ To every person interested in lunar topography it is certainly indispensable; and the observer who sees something in the Moon not shown by Lohrmann, or Beer and Mädler, may be saved from imagining a new discovery by finding that the object is represented by Schmidt. This may be easily understood when it is known that the number of craters shown by Lohrmann is 7177, and by Mädler 7735, while in Schmidt’s map they reach the extraordinary amount of 32,856. ”

“ Schmidt. The differences are startling; and as examples may be given the mountain Huyghens, where one measure gives double the height of another, and Curtius (of which Dr. Schmidt took no less than 80 measures) , where the height by one measure over another is more than quadrupled. In cases of such extreme differences, a mean can scarcely be much relied on. Mountains, when precisely on the limb, can be measured by their addition to the angular diameter of the moon at the time of observation. Whatever this diameter is calculated to be, the measure will give the height of the mountain above it. ”

“ In a work of such magnitude as his it would be manifestly senseless to imagine that even sufficiently obvious objects might not, in some instances, have escaped him. With a telescope not superior to the Athenian refractor I have observed a few things not indicated by him,—such as a second large crater in Gruithuisen’s Schröter, a dilapidated diaphragm dividing Endymion into two, &c.; I should, however, be far from concluding on that negative evidence that they were not old formations. I believe the instances of Schmidt’s oversights of rather obvious objects to be wonderfully rare ”

“ Many remarkable forms observed by Schmidt are not found in Mädler, who, on the other hand, has noticed some not seen by the former. With high powers a vast number of minute light-spots may be found, and in many of them, as in Linné, are little craters. It may be conjectured that here are the most recent of lunar formations, and that changes on the surface are by no means to be classed among the most infrequent phenomena. ”

“ The correct representation of the several forms of lunar mountains belongs to a higher department of art, and can have been hitherto but in a few instances attained. With all his industry Lohrmann failed in this design, while he made the ridges too broad, and almost entirely misrepresented the character of the crater walls. Mädler was more fortunate, and his chart contains remarkable illustrations of individual forms. In Schmidt’s chart the shadings present a general uniformity, and the desire to show characteristic differences was sacrificed on account of other considerations. ”

“ Schmidt’s great task. It is, in all truth, a performance highly creditable to the age in which we live, and to Teutonic intellect and perseverance. It is a splendid example of great results from small beginnings. We have, first, the astronomer, as a youth of 14, viewing the Moon with a little telescope steadied by a lamp-post, and probably the laughing-stock of many a passer by ”

“ Even recollecting the far inferior gravitating power at the Moon’s surface, and admitting a much greater eruptive force, still much would remain unaccounted for, especially, among other matters, the excentric direction of many of the rays, which, traced backwards, run past on one side of the place from which they must have issued. ”

“ In even a cursory examination of Schmidt’s map its completion by a single observer must seem almost incomprehensible to a man of ordinary powers; but it requires protracted study to well realize the extent of the work. Any person who tries with the aid of a 6-feet telescope to give a closely detailed delineation of even a small area of the Moon, will soon conclude that a period of thirty-three years was comparatively a very short one for the accomplishment of Dr. ”

“ The rills number in Lohrmann 77, in Mädler 71, and in Schmidt 348. As regards other objects, such as hills, ridges, banks, crater-terraces, &c., Schmidt’s map easily surpasses the others in comprehensiveness. Still, of course, the survey cannot be considered exhaustive even within the range of a 6-feet telescope; and although, by referring to Schmidt’s map, an observer may find an object which otherwise, by its absence in other maps, he might be led to suppose was new, it would be plainly wrong to infer that a formation must necessarily be recent because it is not noticed even by Schmidt. ”

“ Only one of them might be compared in form to Chimboraço, while it was far from exhibiting the steepness of Cotopaxi and other volcanoes of the earth. There are no striking elevations on the N.E. or S.W. limbs. On the N.W. there are some visible at times of favourable libration. ”