208 



NATURE 



[June 30, 1892 



he soon thought fit to leave this profession, and being 

 well equipped with the necessary private resources, he 

 commenced in the year 1848 to erect an observatory in 

 the city of New York at his own residence. On its com- 

 pletion, it was furnished with an I i^-inch refractor, which 

 he had made under his own personal direction by Fitz, 

 and a transit instrument. 



The first work he set himself to do related to the spectra 

 of the stars. As soon as Kirchhoff's discovery was an- 

 nounced, Donati, at Florence, in i860, made the first 

 efforts in this direction ; this was followed by other ob- 

 servers, among whom was Rutherfurd. In 1863 he pub- 

 lished his first paper on the spectra of the celestial bodies, 

 and indicated that the various stellar spectra which he 

 had then observed were susceptible of being arranged 

 in different groups. His paper, which was published in 

 Silliman's Journal, vol. xxxv. p. 71, contained the fol- 

 lowing extract with reference to this classification : — 

 " The star spectra present such varieties that it is difficult 

 to point out any mode of classification. For the present, 

 I divide them into three groups : First, those having 

 many lines and bands, and mostly resembling the 

 sun, viz. Capella, ^ Geminorum, a Orionis, &c. These 

 are all reddish or golden stars. The second group, of 

 which Sirius is the type, presents spectra wholly unlike 

 that of the sun, and are white stars. The third group, 

 comprising a Virginis, Rigel, &c., are also white stars, but 

 show no lines ; perhaps they contain no mineral sub- 

 stance, or are incandescent without flame." 



Turning his attention to object-glasses for visual and 

 photographic purposes, he described in 1865 a new form 

 which he had specially designed for the latter. This, 

 needless to say, brought about a great revolution in the 

 processes employed. The history of his early attempts 

 to produce photographically corrected object-glasses, and 

 the wonderfully sharp and beautiful photographs of the 

 moon which he finally obtained, will always be marked as 

 an important era in the application of the camera to the 

 equatorial telescope. The photographs taken at the pre- 

 sent day, even although they are produced with larger 

 lenses and with a more perfect knowledge of photographic 

 processes, and with the advantages afforded by dry plates, 

 excel only in a trifling degree those taken with the small 

 Rutherfurd equatorial. 



Another important piece of work, which occupied him 

 some considerable time, was the mapping, by means of 

 the photographic process, of star clusters and star groups. 

 His ingenuity in devising and constructing accurate 

 micrometers for measuring the impressions of the star 

 clusters opened out a new method by which the proper 

 motion of the stars could be photographically determined, 

 and even their parallaxes, eUminating entirely the errors 

 of observers. 



It was absolutely essential, as he knew, in order 

 to obtain a perfect method of measurement of the 

 photographs, to attain the utmost perfection in the 

 cutting of the threads of the micrometer screw, and 

 some idea of the care which he bestowed on them may be 

 gathered from the fact that he took three years to make a 

 single screw. In order to test its quality, it struck him 

 that it would be a happy thought to see if it would enable 

 him to rule a grating. He accordingly set the apparatus 

 up in his bedroom, and by means of an automatic Arrange- 

 ment kept it going all night, as at that time the local 

 vibrations were fewest. The result was that he was able 

 to make the most perfect gratings known, which are 

 only now surpassed by those of Rowland, who followed 

 in his wake. 



The photographic corrector, which consisted of an 

 additional lens to be applied to visual object-glasses, to 

 render them fit for photographic use, was also due to his 

 exceptional mechanical ability, and was brought out in 

 the year 1868. 



Owing to failing health he was at last obliged to give 

 NO. 11 83, VOL. 46] 



up all idea of making observations, so he resigned him- 

 self to a thorough supervision of the great number of 

 measurements of the photographs of the star clusters that 

 by this time had very considerably accumulated. 



In the year 1884, Columbia College, New York, was 

 the recipient of all his astronomical instruments,, 

 apparatus, and completed measures. It is only a fort- 

 night ago when a notice of the measures of the Pleiades,^ 

 which were prosecuted by Mr. jacoby, under the direction 

 of Prof. Rees, was made in these columns, and it will not 

 be long before several other clusters will be pubhshed. 



In this brief notice we have only referred to some of 

 the more salient points with which he enriched the 

 domain of astronomical science j and his was no mean 

 spirit striving to confine to his own use the various 

 methods of work and improvements he introduced : he 

 scattered his gratings with a lavish hand among all who 

 were likely to make any use of them, and his greatest 

 delight was to help others occupied in researches kindred 

 to his own. 



NOTES. 



Sir Archibald Geikie has been appointed by the Council 

 of the Royal Society to be one of the Governors of Harrow 

 School. 



It was with deep regret that we saw the announcement in 

 Monday's Times of the death of Admiral Mouchez, the Director 

 of the Paris Observatory. In him France has lost one of her 

 most active men of science, whose place it will be no easy task 

 to fill. 



At St. John's College, Cambridge, on July 9, at 2.30 p.m., 

 there will be held a meeting of the General Committee that was 

 formed lor placing a suitable memorial of the late Prof. Adams 

 in Westminster Abbey. This meeting is specially called to 

 consider a modification in the form of the memorial. The 

 resolution, as passed in February, was to the effect that the 

 memorial should " consist of a bust with tablet and inscription,'* 

 but as the Dean has been unable to sanction any site in that part 

 of the Abbey in which it was first proposed to be placed, 

 but has offered an excellent position lor a medallion, near the 

 monument of Newton and the grave of Sir John Herschel, and 

 close to the memorials of Darwin and Joule, the Executive Com- 

 mittee recommeud that this olier be accepted, and that the terms 

 of the former resolution be altered to "That the memorial consist 

 of a medallion and inscription." 



The Botanischt Zeitung publishes a programme of the 

 International Botanical Congress to be held in Genoa. On 

 Sunday evening, September 4, there will be a reception of the 

 foreign botanists present. On Tuesday the Botanical Institute 

 and Garden, presented to the Municipality of Genoa by Mr. 

 Thos, Hanbury, will be formally opened. On Saturday, Sep- 

 tember 10, the Acclimatisation Garden of Mr, Hanbury at 

 Mortola will be visited. The rest of the week will be occupied by 

 scientific sittings, receptions, and excursions. 



Dr, Benecke, the Director of the Experimental Station at 

 Klaten, Java, has offered a prize of 1000 marks for the best 

 essay, founded on original observations and experiments ia 

 cultivation, on the causes of the red colour in the fibrovascular 

 bundles of Sorglnun, which accompanies the disease known as 

 "sereh." A very similar disease has recently become very 

 destructive to the sugar-cane crop in Java, 



In our account last week of the Ladies' Conversazione of the 

 Royal Society we stated that the Telephone Company's installa- 

 tion was the means by which the music Irom the Paris opera, 

 was rendered audible. This, as we have reason now to know, 

 was incorrect. The Post Office undertook the whole affair, no- 

 company having anything at all to do with it. 



