NATURE 



453 



THURSDAY, MARCH 17, i88i 



SIR WILLIAM HERSCHEL 1 

 IT. 



HERSCHEL'S removal from Bath to Datchet appears 

 to have been brought about by the unvviUingness 

 he felt, at the time of his visit to London, to continue the 

 toils of teaching, which, with the tastes he had now 

 formed, his sister tells us, " appeared to him an intoler- 

 able waste of time," and he chose rather the alternative 

 of a salary of 200/. from the king. " Never bought 

 monarch honour so cheap ! " exclaimed his friend Sir 

 Thomas Watson, to whom alone the sum was mentioned, 

 all other inquirers being simply assured that "the king 

 had provided for him." From letters received by the 

 family at Bath during Herschel's stay in London, they 

 had been led to infer that the king would not suffer him 

 to return to his profession again. Herschel took part in 

 the musical service at St. Margaret's Chapel at Bath for 

 the last time on Whit-Sunday, 17S2, when the anthem for 

 the day was of his own composition. 



On August I he arrived at Datchet. " The new home 

 was a large neglected place, the house in a deplorably 

 ruinous condition, the garden and grounds overgrown 

 with weeds." But these circumstances had no effect 

 upon him : there was a laundry which would serve as a 

 library, and roomy stables which were just suitable for the 

 grinding of mirrors, and a grass-plot where " the small 

 twenty-foot" could be erected. Under such conditions 

 the end of the introductory epoch of his hfe, as Prof. 

 Holden expresses it, was reached : henceforth he lived in 

 his observatory, rarely leaving it, from his forty-fourth 

 year onwards, except for short periods to submit his 

 classic memoirs to the Royal Society, and even selecting 

 for such visits periods when moonlight interfered with the 

 work of the telescope. We are told that much of his time 

 was occupied, soon after he was settled at Datchet, in 

 going to the Queen's Lodge, to show objects through the 

 7-feet reflector to the king and Court, but " when the 

 days began to shorten, this was found impossible, for the 

 telescope was often (at no small expense and risk of 

 damage) obliged to be transported in the dark back to 

 Datchet, for the purpose of spending the rest of the night 

 with observations on double stars for a second catalogue." 



In his paper entitled " An Account of Three Volcanoes 

 in the Moon," communicated to the Royal Society in 

 17S7, Herschel refers to previous observations of a 

 similar kind, and Prof. Holden gives a translation of a 

 letter written by Baron de Zach, from London, to Bode, 

 the editor of the Bcrlinei- Jalirbiich, in which these 

 observations are mentioned. An occultation of a star at 

 the moon' s dark limb was to take place on the evening 

 of May 4, 1783, and was observed by Herschel and Dn 

 Lind, a physician in Windsor. Mrs. Lind also placed 

 herself at a telescope to watch the phenomenon. 

 " Scarcely had the star disappeared before Mrs. Lind 

 thought she saw it again, and exclaimed that the star 

 had gone in front of, and not behind, the moon. This 

 provoked a short astronomical lecture on the question, 

 but still she would not credit it, because she saw differ- 

 ently. Finally Herschel stepped to the telescope, and in 



' Continued from p. 431. 



Vol. XXIII. — No. 594 



fact he saw a bright point on the dark disk of the moon, 

 which he followed attentively. It gradually became 

 fainter, and finally vanished." . . . Zach professes to 

 report what actually fell from Herschel's lips : Mrs- 

 Lind' 5 observation might be supposed to refer to the 

 apparent projection of a star upon the moon's dark limb, 

 of which we have other instances, but that after an astro- 

 n0mic.1l lecture, however brief, Herschel should have 

 looked into the telescope and still found the same 

 bright point is hardly reconcilable with this explana- 

 tion : and further if there was no misapprehension of 

 Herschel's words on Zach's part, he seems to have 

 ascribed the appearance to a lunar volcano. 



In 17S3 Herschel maiTied a daughter of Mr. James 

 Baldwin, a merchant of the City of London, and the 

 widow of Mr. John Pitt : she was entirely interested in 

 his scientific pursuits, and brought him a considerable 

 jointure. Their only child was John Frederick William, 

 born March 7, 1792. 



Writing in 1783, Herschel says he had finished his 

 third review of the heavens, which was made with the 

 same instrument as the second, but with the power in- 

 creased from 227 to 460. It extended to all the stars of 

 Flamsteed's Catalogue, " together with every small star 

 about them to the amount of a great many thousands 

 of stars." He tells us of this third review, that he 

 had " many a night, in the course of eleven or twelve 

 hours of observation, carefully and singly examined not 

 less than 400 celestial objects, besides taking measures, 

 and sometimes viewing a particular star for half an hour 

 together." The summer months of 1783 were occupied 

 in energetic efforts to get the large 20-feet reflector ready 

 for observations during the ensuing winter, and with 

 success ; the sweeps for the fourth review of the heavens 

 were commenced before the end of the year. Caroline 

 Herschel relates that at the end of 1783 her search for 

 comets and nebulse was interrupted to write down her 

 brother's observations with the large 20-foot, and states 

 that in the early use of so cumbrous an instrument and 

 its appurtenances in the open air, she could give " a 

 pretty long list of accidents " which were near proving 

 fatal to her brother or to herself. 



In the long days of the ensuing summer months many 

 10- and 7-feet mirrors were finished. Prof. Holden 

 mentions that in 1785 the cost of a 7-feet telescope, six 

 and four tenths inches aperture, stand, eyepieces, &c., 

 complete, was 200 guineas, and a lo-feet was 600 

 guineas. A 20-feet telescope would cost from 2500 to 

 3000 guineas. Herschel made four lo-feet telescopes 

 for the king, one of which was delivered in July, 1786, 

 as a present fropi the king to the Observatory of Gottin- 

 gen. Later a 7-feet telescope complete was sold for 100 

 guineas. For a 10- and a 7-feet telescope the Prince of 

 Canino paid 2310/. 



Prof. Holden reproduces a letter addressed to Bode 

 about this time by De Magellan, which appeared in the 

 Jahrbuch for 1788, from which we make one or two 

 extracts. He writes : — " I spent the night of the 6th of 

 January at Herschel's at Datchet, near Windsor, and had 

 the good luck to hit on a fine evening. He had his 20-foot 

 Newtonian telescope in the open air and mounted in his 

 garden very simply and conveniently. It is moved by an 

 assistant who stands below it. ... In the room near it 



