566 



NA TURE 



[Oct. 14, 1880 



was. The work was the revelation of the man. He felt 

 precisely where lay the difficulties and wants which met 

 him in his work, because he was sensitive and sympa- 

 thetic, lie could deal successfully with these difficulties, 

 and supply these wants, often in a masterly and original 

 way, because he could think for himself cautiously and 

 yet boldly. He could work out his conceptions in new 

 and difficult directions to a successful issue, because the 

 constancy of his character showed itself here in concen- 

 tration of thought and perseverance of action. These 

 qualilies, sensitive sympathy, wise prudence, constancy, 

 were those which pre-eminently characterised him as a 

 man and a friend. 



In the history of science Mr. Lassell's name must rank 

 with those of Herschel and the late Lord Rosse in con- 

 nection with that essentially lirilish instrument, tlic 

 reflecting telescope, whether wc consider the genius and 

 perseverance displayed in the construction of these in- 

 struments, or the important discoveries which have 

 resulted from their use. About 1820 Mr. Lassell, then 

 in his twenty-first year, began to construct reflecting 

 telescopes for himself. It is perhaps to circumstances 

 which Mr. Lassell at the time considered most unfavour- 

 able that science is indebted for much that Mr. Lassell 

 has accomplished. At that time he did not possess 

 sufficient means to enable him to purchase expensive 

 instruments, and besides " his business avocations were 

 such as most men consider of an engrossing nature." 

 The value to him in his subsequent work of the energy 

 and power of resource which were in this way so strongly 

 dcvelojjed in his character at an early age it is difficult to 

 appraise. His success with the two first instruments 

 which he attempted simultaneously, a Newtonian of 

 7-inch diameter and a Gregorian of the same size, 

 encouraged him to make a Newtonian of 9-inches 

 .iperturc. The several mirrors made for this instrument 

 were of great e.xccllence. The observatory note-books 

 of the late Mr. Dav.'es, which are in the writer's pos- 

 session, bear record to the delicate tests for figure 

 to which these mirrors were put on the occasions of 

 the visits of Mr. Dawes to the observatory of his friend 

 at Starficld, near Liverpool, where the instrument was 

 erected. 



The instrument may be said to form an epoch in the 

 history of the reflecting telescope, in consequence of the 

 successful way in which Mr. Lassell, on a plan of his own, 

 secured to it the inestimable advantage of tlic equatorial 

 movement. 



About 1844 Mr. Lassell conceived the bold idea of 

 constructing a reflector of 2 feet aperture and 20 feet focal 

 length, to be mounted cquatorially on the same principle. 

 Mr. Lassell spared neither pains nor cost to make this 

 instrument as perfect as possible, both optically and for 

 tlie mechanical side. As a preliminary step he visited 

 the late l^arl of Rosse at 15irr Castle, and commenced 

 the specula for this instrument with a machine similar in 

 construction to that employed by that nobleman. After 

 some months work he was not satisfied with this appa- 

 ratus, and was led, in consequence, to contrive a machine 

 for imitating as closely as possible those motions of the 

 hand by which he had been accustomed to produce 

 perfect surfaces on smaller specula. " The essential 

 difl^erence of these constructions," to use the words of Sir 

 George Airy, "as regards the movements of the grinder is 

 this : that in Lord Rosso' s apparatus every stroke is very 

 nearly straight, while in Mr. Lassell's apparatus there is 

 no resenibl.ince to a straight movement at any part of the 

 stroke." This is not the place to describe the many new- 

 contrivances in the mode of support of the mirror, in the 

 equatorial mounting, and in the polishing machine, which 

 enabled Mr. Lassell to bring this instrument to a high 

 degree of perfection. I must not omit to notice, to 

 use Sir John Herschel's words, "that in Mr. Nasmyth he 

 .vas fortunate to find a mechanist capable of executing in 



the highest perfection all his conceptions, and prepared 

 by his own love of astronomy and practical acquaintance 

 with astronomical observation, and with the construction 

 of specula, to give them their full effect." Mr. Lassell 

 was very successful in the great brilliancy and per- 

 manency of polish of his metal. Within the last few 

 years the writer has been shown specula by Mr. Lassell 

 which had not been polished for more than twenty years, 

 and which appeared as bright as if but just removed from 

 the polishing machine. 



With this fine instrument he discovered the satellite of 

 Neptune. This minute body was first seen on October 

 10, 184C, but it was not until the next year that it could 

 be satisfactorily followed and its existence fully con- 

 firmed. 



The superiority of the telescope and the vigilance and 

 skill of the observer were further shown by the discovery 

 in 1848, simultaneously with Prof Bond in America, of an 

 eighth satellite of Saturn, of extreme minuteness, which 

 was named Hyperion. 



In 1851, after long and careful search, he discovered 

 two additional satellites of the planet Uranus (Umbriel 

 and Ariel), anterior to the two discovered by Sir W. 

 Herschel in 1787. In the autumn of 1852 he took his 

 20-foot telescope to Malta, and observed through the 

 winter of that year. 



A most careful drawing of the nebula of Orion and 

 dr^iwings of several planetary nebula will be found in 

 vol. xxiii. of the Memoirs of the Royal Astronomical 

 Society. With respect to the planets, to use his own 

 words, "his discoveries were rather negative than other- 

 wise," for he was satisfied that without great increase of 

 optical power no other satellite of Neptune could be de- 

 lected. With regard to L'ranus he says, " I am fully per- 

 suaded that either he has no other satellites than the four, 

 or if he has they remain yet to be discovered." 



I\Ir. Lassell's energy and zeal in the cause of science 

 did not permit him to remain content with this magnifi- 

 cent instrument. His last work was a much larger tele- 

 scope, four feet in aperture and thirty-seven feet focus, 

 mounted cquatorially. This grand instrument was erected 

 at Malta in 1861, and the work done with it, with Mr. 

 Marsh's assistance during the next four years, is fully 

 described in vol. xxxvi. of the Memoirs. This work 

 consists of numerous observations of nebulx and 

 planets and a catalogue of the places of 600 new nebulas 

 discovered at Malta. It is not possible to suppress a 

 feeling of regret that this magnificent instrument no 

 longer exists. 



After his retarn from Malta Mr. Lassell purchased an 

 estate near Maidenhead, and erected in an observatory 

 his equatorial telescope of 2-feet aperture. Mr. Lassell's 

 experience in repolishing his 4-feet mirrors suggested 

 to him some alterations in his polishing machine. After 

 his return he was able to carry out these experiments in a 

 workshop erected at Maidenhead, and succeeded in con- 

 structing an improved form of polishing machine, which 

 is described in the Transactions of the Royal Society for 

 1874. In 1839 Mr. Lassell was elected a Fellow of the 

 Royal Astronomical Society, received its gold medal in 

 1849, and in 1870 was elected its president, which office 

 he held for two years. He became a Fellow of the Royal 

 Society in 1849, and received one of its gold medals in 

 1858. Among other honours conferred upon him may be 

 mentioned an honorary degree from the University of 

 Cambridge, and the honorary Fellowships of the Royal 

 Societies of Edinburgh and Upsala. 



The numerous papers by Mr. Lassell to be found in the 

 Monthly Notices and the Memoirs of the Royal Astro- 

 nomical Society bear abundant record to his industry 

 and skill, and make us feci that in Mr. Lassell's death we 

 have to deplore the loss of one who contributed largely to 

 the advancement of the science of his age. 



William Huggins 



