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ssss1In “Newtonian” telescopes the image formed by the large speculum is obliquely reflected from a small plane mirror to the side of the tube, where it is viewed with an ordinary eye-piece. With a “Gregorian,” the observer looks straight forward, the image being thrown back by a little concave mirror through a central perforation in the speculum where the eye-piece is fitted.

These absorbing occupations were interrupted by the unwelcome news that Dietrich, the youngest of the Herschel family, had decamped from Hanover “with a young idler” like himself. William instantly started for Holland, where the fugitive was supposed to be about to take ship for India, but missed his track; and, after having extended his journey to Hanover to comfort his anxious mother—his father had died in 1767—returned sadly to Bath. There, to his immense surprise, he found the scapegrace in strict charge of his sister, “who kept him to a diet of roasted apples and barley-water.” His ineffectual escapade had terminated with an attack of illness at Wapping, whither Alexander Herschel, on learning how matters stood, had posted off to take him in charge and watch his recovery. Musical occupation was easily procured for him at Bath, since he was an accomplished violinist—had, indeed, started on his unprosperous career in the guise of an infant prodigy; but he threw it up in 1779 and drifted back to Hanover, married a Miss Reif, and settled down to live out a fairly long term of shiftless, albeit harmless, existence.