58 



NATURE 



[November 17, 1904 



should work hand in hand to aid one another in the 

 supreme object of education. A beginning- in that 

 direction has been made in the United States and in 

 some towns in England, where the young are taught 

 in the lecture theatre and are then conducted by the 

 teacher to the section of the museum dealing with the 

 subject of the discourse. In this way the young are 

 familiarised with the objects and uses of museums, to 

 which they will surely more readily return in after life, 

 and in the development of which they will take a keener 

 interest than they do at present. ' R. F. S. 



DR. FRANK McCLEAN, F.R.S. 

 T N Dr. Frank McClean astronomy has not only lost 

 -•• one of her most devoted and painstaking fol- 

 lowers, but a generous benefactor that can ill be 

 spared, especially in this country. His death came as a 

 surprise to most of his friends, for, although it was 

 known that his increasing years were beginning to 

 tell on his general activity, it was thought that there 

 was still much work left in him. Unfortunately, 

 however, this was not to be, for, at the latter end of 

 his usual trip on the Continent, he was taken ill at 

 Brussels, and very shortly afterwards passed away on 

 November 8 at the age of sixty-seven, surrounded bv 

 members of his family. 



Dr. McClean was the son of the late distinguished 

 engineer, Mr. J. R. McClean, F.R.S. , and was born 

 in 1837. .After the completion of his education at 

 Westminster, the College, Glasgow, and Trinity 

 College, Cambridge, of which he was a scholar, 

 graduating in 1859 as a wrangler, he took up the 

 profession of his father, and became apprenticed in 

 the same year to Sir John Hawkshaw; three years 

 later he was taken into partnership in the firm of 

 Messrs. McClean and Stileman. 



Up to the year 1870 his energy was directed to 

 engineering matters, but retiring from his profession, 

 he devoted the remaining years of his life to spectro- 

 scopic researches in connection with the sun and stars. 

 The success which rewarded his endeavours is best 

 shown by the numerous important papers which he 

 communicated to the Royal Society and Royal 

 Astronomical Society, and by the fact that the council 

 of the latter society awarded him, in 1899, the gold 

 medal, their highest honour for astronomical research. 

 The crowning work, which he fortunately completed, 

 and with which his name will always be associated, 

 was the conception and carrying out of the great 

 spectroscopic survey of the brighter stars over the 

 whole celestial sphere. 



He commenced his spectroscopic work with several 

 important researches, all of which were carried out 

 with zeal, patience, and thoroughness; these were 

 naturally closely allied, in fact preliminary steps, to 

 the great work to which he later devoted his energies. 

 The first of these dealt with the photography of 

 metallic spectra by means of an induction spark, after 

 which he turned his attention to the nearest star, the 

 sun, and made an elaborate series of comparative 

 photographs of the spectra at high and low altitudes. 

 An account of this, accompanied by a beautiful atlas 

 of plates, was submitted in 1890 to the Royal .Astro- 

 nomical Society. The high sun spectrum was taken 

 as far as possible when the sun's altitude was more than 

 45°, and the low sun when it was under y^°, so that 

 the depth of 'atmosphere traversed was in the pro- 

 portion of one to five respectively. For securing these 

 photographs he employed a fixed heliostat to reflect 

 the solar light into a telescope fixed parallel to the 

 polar axis, in conjunction with a spectroscope in which 

 was used a large Rowland plane grating. 

 NO. 1829, VOL. 71] 



The investigation brought out in a striking manner 

 the different effects of atmospheric absorption in the 

 solar spectrum, and put one on a firmer footing as 

 regards the variations due to atmospheric influences. 



.After the publication of these results, McClean 

 turned his attention again to terrestrial spectra, and 

 made a minute study of the comparative photographic 

 spectra of the sun and metals. The first results were 

 connected with the spectra of the gold and iron groups 

 of metals. These spectra were collated by means 

 of their common air lines with the iron spectrum, 

 and so by means of the iron lines with the solar 

 spectrum. In the gold group he found many lines 

 due to these metals which up to that time had not been 

 observed, and he also remarked some curious coinci- 

 dences that existed between the air lines in the metallic 

 spectra and lines in the solar spectrum. That he had 

 in his mind the eventual spectroscopic study of the 

 heavenly bodies is shown even in his brief accounts 

 of these experiments, for in one case he writes, " the 

 spectra of the metals appear to me to be fairly within 

 the scope of astronomy, as our knowledge of them 

 forms the basis of any knowledge we possess of the 

 composition of the heavenly bodies." 



.\t the end of 189 1 he published another set of com- 

 parative spectra of the sun and metals. The two 

 series consisted of six sections, corresponding to six 

 sections of Angstrom's chart; they were as follows: — 



.Section i. contained the spectra of the sun, iron, 

 platinum, iridium, osmium, palladium, rhodium, 

 ruthenium, gold, and silver. The last eight con- 

 stitute the platinum group of metals. 



Section ii. contained the spectra of the sun, iron, 

 manganese, cobalt, nickel, chromium, aluminium, 

 and copper. These seven metals constitute the iron 

 copper group. 



Throughout McClean's scientific career his greatest 

 work was undoubtedly the spectroscopic survey of 

 every star brighter than 3^ magnitudes scattered 

 throughout the whole celestial sphere. 



Such a programme seemed large for one man to 

 tackle single-handed, but McClean was equal to the 

 occasion, and succeeded not only in accomplishing it, 

 but in discussing and publishing the results. 



For the northern stars tiie photographs were secured 

 at his home, Rusthall House, Tunbridge Wells. 

 The instrument employed was a photographic tele- 

 scope having an object glass of twelve inches diameter, 

 and carrying an objective prism of the same aperture, 

 with a refracting angle of 20°. 



To secure the southern stars McClean worked at the 

 Cape of Good Hope from May to November, 1897. 

 He took with him the prism he had already used for 

 the northern work, and fixed it in front of the object 

 glass of the well-known Cape astrographic instrument, 

 which had been placed at his disposal by Sir David 

 Gill. Both series of photographs were thus secured 

 with practically identical instruments, the advantage 

 of which it is difficult to overestimate. 



Space does not permit, nor is it here necessary, to 

 enumerate at any length the results of such a far- 

 reaching research, which were so ably discussed, and 

 received such high praise. Mention, however, may be 

 made of the originality he displayed in referring the 

 stars to galactic latitude and longitude, instead of em- 

 ploying the usual system of right ascension and de- 

 clination. The celestial sphere he divided into four 

 equal areas by drawing a circle at a radius of 60° 

 from each galactic pole. By means of a great circle 

 passing through the galactic poles, he cut the sphere 

 into two halves, so that each of the four areas was 

 again equally divided. This apparently simple por- 

 tioning of the heavens was amply rewarded. 



