To give an adequate description of the vast mass of labour completed during the next four busy years of his life at Feldhausen would require the transcription of a considerable portion of the _Cape Observations_, a volume of unsurpassed interest and importance; although it might perhaps be equalled by a judicious selection from Sir William's "Memoirs," now scattered through some thirty volumes of the _Philosophical Transactions_. It was published, at the sole expense of the late duke of Northumberland, but not till 1847, nine years after the author's return to England, for the cogent reason, that as he said, "The whole of the observations, as well as the entire work of reducing, arranging and preparing them for the press, have been executed by myself." There are 164 pages of catalogues of southern nebulae and clusters of stars. There are then careful and elaborate drawings of the great nebula in Orion, and of the region surrounding the remarkable star in Argo. The labour and the thought bestowed upon some of these objects are almost incredible; several months were spent upon a minute spot in the heavens containing 1216 stars, but which an ordinary spangle, held at a distance of an arm's length, would eclipse. These catalogues and charts being completed, he proceeded to discuss their significance. He confirmed his father's hypothesis that these wonderful masses of glowing vapours are not irregularly scattered over the visible heavens, but are collected in a sort of canopy, whose vertex is at the pole of that vast stratum of stars in which our solar system finds itself buried, as Herschel supposed, at a depth not greater than that of the average distance from us of an eleventh magnitude star. Then follows his catalogue of the relative positions and magnitudes of the southern double stars, to one of which, [gamma] Virginis, he applied the beautiful method of orbital determination invented by himself, and he had the satisfaction of witnessing the fulfilment of his prediction that the components would, in the course of their revolution, appear to close up into a single star, inseparable by any telescopic power. In the next chapter he proceeded to describe his observations on the varying and relative brightness of the stars. It has been already detailed how his father began his scientific career by similar observations on stellar light-fluctuations, and how his remarks culminated years afterwards in the question whether the radiative changes of our sun, due to the presence or absence of sun-spots, affected our harvests and the price of corn. Sir John carried speculation still farther, pointing out that variations to the extent of half a magnitude in the sun's brightness would account for those strange alternations of semi-arctic and semi-tropical climates which geological researches show to have occurred in various regions of our globe.