Herschel and his amazing apparatus having been selected by the Board of Longitude to observe the transit of Mercury, the Cape of Good Hope was chosen because, upon the former expedition to Peru, acting in conjunction with one to Lapland, which was sent out for the same purpose in the eighteenth century, it had been noticed that the attraction of the mountainous regions deflected the plumb-line of the large instruments seven or eight seconds from the perpendicular, and, consequently, greatly impaired the enterprise. At the Cape, on the contrary, there was a magnificent table-land of vast expanse, where this difficulty could not occur. Accordingly, on the 4th of September, 1834, with a design to become perfectly familiar with the working of his new gigantic apparatus, and with the Southern Constellations, before the period of his observations of Mercury, Sir John Herschel sailed from London, accompanied by Doctor Grant (the supposed informant,) Lieutenant Drummond, of the Royal Engineers, F. R. A. S., and a large party of the best English workmen. On their arrival at the Cape, the apparatus was conveyed, in four days time, to the great elevated plain, thirty-five miles to the N. E. of Cape Town, on trains drawn by two relief-teams of oxen, eighteen to a team, the ascent aided by gangs of Dutch boors. For the details of the huge fabric in which the lens and its reflectors were set up, I must refer the curious reader to the pamphlet itself—not that the presence of the “Dutch boors” alarms me at all, since we have plenty of boors at home, and one gets used to them in the course of time, but because the elaborate scientific description of
