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“Clusters and beds of worlds, and bee-like swarms

Of suns and starry streams,”

previously unseen, and even unsuspected, might, by the strong focussing of their feebly-surviving rays, be brought to human cognisance. The contemplated “reviews” would then be complete just in proportion to the grasp of the instrument used in making them.

The first was scarcely more than a reconnaissance. It was made in 1775, with a small reflector of the Newtonian make.ssss1 Its upshot was to impress him with the utter disproportion between his daring plans and the means as yet at his disposal. Speculum-casting accordingly recommenced with fresh vigour. Seven- and ten-foot mirrors were succeeded by others of twelve, and even of twenty feet focal length. The finishing of them was very laborious. It was at that time a manual process, during the course of which the hands could not be removed from the metal without injury to its figure. One stretch of such work lasted sixteen hours, Miss Herschel meantime, “by way of keeping him alive,” putting occasional morsels of food into the diligent polisher’s mouth. His mode of procedure was to cast and finish many mirrors of each sort; then to select the best by trial, and repolish the remainder. In this manner he made, before 1781, “not less than 200 seven-foot, 150 ten-foot, and about 80 twenty-foot mirrors, not to mention those of the Gregorian form.” Repolishing operations were, moreover, accompanied by constant improvements, so that each successive speculum tended to surpass its predecessors.