The expediency of using such opportunities was obvious; and it has accordingly been determined to erect a good equatorial in this tempting situation, elevated 9,375 feet above the troubles of the nether air. The expense incurred will be trifling; no special staff will be needed; the post will simply constitute a dependency of the Paris establishment, where astronomers thrown out of work by the malice of the elements may find a refuge from enforced idleness, as well as, possibly, unlooked-for openings to distinction. We must now ask our readers to accompany us in one more brief flight across the Atlantic. After a successful observation of the late transit of Venus at Jamaica, Dr. Copeland, the chief astronomer of Lord Crawford’s observatory at Dun Echt, took advantage of the railway which now crosses the Western Andes at an elevation of 14,666 feet, to make a high-level tour of exploration in the interests of science. Some of the results communicated by him to the British Association at Southport last year, and published, with more detail, in the astronomical journal “Copernicus,” are extremely suggestive. At La Paz, in Bolivia, 12,050 feet above the sea, a naked-eye sketch of the immemorially familiar star-groups in Taurus, _made in full moonlight_, showed seventeen Hyades (two more than are given in Argelander’s “Uranometria Nova”) and ten Pleiades. Now ordinary eyes under ordinary circumstances see six, or at most seven, stars in the latter cluster. Hipparchus censured Aratus—who took his facts on trust from Eudoxus—for stating the lesser number, on the ground that, in serene weather, and in the absence of the moon, a seventh was discernible.[26] On the other hand, several of the ancients reckoned nine Pleiades, and we are assured that Moestlin, the worthy preceptor of Kepler, was able to detect, under the little propitious skies of Wurtemberg, no less than fourteen.[27] An instance of keensightedness but slightly inferior is afforded by a contemporary American observer: Mr. Henry Carvil Lewis, of Germantown, Pennsylvania, frequently perceives twelve of this interesting sidereal community.[28] The number of Pleiades counted is, then, without some acquaintance with the observer’s ordinary range of sight, a quite indeterminate criterion of atmospheric clearness; although we readily admit that Dr. Copeland’s detection of ten in the very front of a full moon gives an exalted idea of visual possibilities at La Paz.