182 



NA TURE 



\June 22, 1882 



elementary at solar temperatures. It will be seen that the 

 issue raised then could not be complained of as lacking 

 crispness and definiteness. What then are the facts ? 

 The facts have been exactly as they were predicted on the 

 rival hypothesis — the hypothesis, namely,that the elements 

 are not elementary ; and in future we are not likely to 

 hear much more of the "reversing layer." The solar 

 spectrum, indeed, appears now to be the result of the 

 absorptive work of an innumerable number of strata one 

 over the other, from top to bottom of the solar atmosphere. 

 If we could see the work of any one of these layers by 

 itself, it would be impossible for us, with our mere terres- 

 trial laboratory experience, to recognise it, whereas we do 

 recognise the sum total, because we get, and can only get 

 as a rule, a sum total in our laboratory experiments. 

 Should this result be generally accepted as one of the 

 results of this year's work a great step will have been 

 gained. Whether accepted or not, it is quite clear that 

 such observations as those to which attention has been 

 directed will demand much attention when next the sun 

 is eclipsed. Nor is this all. It is not too much to hope 

 now that M. Thollon has so admirably succeeded in 

 furnishing astronomers with a spectroscope which com- 

 bines the maximum of dispersion and light thatobservations 

 suggested by the new view may be made on theuneclipsed 

 sun and bring their tribute of precious facts every day the 

 sun shines. Such work, indeed, was actually started at 

 Sohag, and the test then afforded gave out no uncertain 

 sound ; but on this point it is not necessary to enlarge 

 upon the present occasion, as both MM. Thollon and 

 Trdpied are pledged to utilise the beautiful climates of 

 Nice and Algiers in carrying on this new survey at the 

 earliest possible moment, and the world of science will 

 doubtless soon hear something of the result of this new 

 attack. 



There is little doubt that on the occasion of future 

 eclipses attention will be much more concentrated on the 

 spectrum of the corona, and more specially-constructed 

 instruments will be brought to bear on it than has been 

 the case hitherto. We may already take for granted that 

 the blue lines photographically recorded (in addition to H 

 and K in the violet,) will have their position determined 

 with the greatest accuracy, and their coincidence or not 

 with marked Fraunhofer lines will have an important 

 bearing upon the questions to which attention has been 

 directed in the present letter. The work, too, has shown 

 that the new plates are so sensitive that it will be quite 

 easy at the next eclipse by means of a circular rotating 

 plate, or some such contrivance, to record all the spectro- 

 scopic phenomena, however evanescent they may be, 

 visible at the moment of disappearance or reappearance 

 of the sun. Such a method will not only give us a com- 

 plete history of what goes on, but will furnish us with a 

 scale of exact reference. So science advances. Each 

 effort, and especially the one most wisely planned, instead 

 of exhausting the supply of new phenomena brings still 

 newer efforts and richer harvests in its train. 



I have been very unfaithful to the task imposed upon me 

 if I have not convinced your readers that the expeditions 

 whose work it was my duty to chronicle have been richly 

 rewarded for their long preparations and tedious journey- 

 ings. They will all leave Egypt with the liveliest sense 

 of gratitude for the manner in which all their efforts for 

 the advancement of knowledge among men have been 

 seconded by the Khedive and the Egyptian Government. 



PROF. W. B. ROGERS 

 'THE death is announced of Prof. William Barton 

 -*- Rogers, whose name is so well known in connection 

 with the Massachusetts Institute of Technology at Boston, 

 U.S. Prof. Rogers died suddenly] of apoplexy, while 

 giving an address, on May 30 last, in connection with 

 the Annual Graduating Exercises of the Institute. From 



the Boston Daily Advertiser we obtain some facts con- 

 cerning Prof. Rogers' life and work : — 



William Barton Rogers, the second son of four in a 

 family noted for its scientific acquirements, was born in 

 Philadelphia, in December, 1805. His father, Patrick 

 Kerr Rogers, was a learned and enthusiastic lover of 

 natural science, and is credited with being among the 

 first in the United States to establish systematic courses 

 of instruction in chemistry and experimental physics for 

 the general public. Young Rogers was educated at 

 William and Mary College, in which institution his father 

 had been appointed Professor of Natural Philosophy and 

 Chemistry. At the age of twenty-one he delivered, at 

 the Maryland Institute, Baltimore, his first lectures on 

 science, and one year later he succeeded to his father's 

 position as professor at William and Mary College. In 

 1835 he accepted the appointment to the chair of natural 

 philosophy in the University of Virginia, and there began 

 instructing in mineralogy and geology. He remained 

 there until 1835, and was next appointed to the chair of 

 natural philosophy in the University of Virginia. There 

 he added the subjects of mineralogy and geology to his 

 course of instruction, and organised the geological survey 

 of the State. He remained at the head of the Geological 

 Survey until its discontinuance in 1842, and published 

 annual reports, together with much valuable material 

 which had been carefully collected. While at the Uni- 

 versity he published, for the use of the students, a short 

 treatise on " The Strength of Materials," and a volume 

 on "The Elements of Mechanical Philosophy." This 

 period of his life was a very busy and attractive one, 

 much of his time being given to original work in geo- 

 logy, and largely also in chemistry and physics. In the 

 Association of American Geologists and Naturalists, 

 organised in 1840, Prof. Rogers took a leading part. He 

 contributed to its volume of Transactions many valuable 

 memoirs, among them observations on the subterranean 

 temperature in the coal mines of Eastern Virginia. In 

 the exploration of the physical structure of the Appala- 

 chian chain, which formed the subject of one of the 

 memoirs above alluded to, Prof. W. B. and H. D. Rogers 

 were associated. Their generalisations were so novel 

 and important in the estimation of European, as well as 

 American geologists, as to give " the Gebriider Rogers " 

 a prominent place among their number. While a member 

 of the Asso:iation of American Geologists he was elected 

 several times its chairman. He presided at the meeting 

 which expanded this last-mentioned Society into the 

 American Association for the Advancement of Science, 

 in 1847, and presided over the latter association at its 

 meeting in Buffalo in 1876. 



In 1853 Prof. Rogers removed to Boston, and at once 

 identified himself with prominent educational interests 

 here. With a committee of gentlemen no less interested 

 than himself in the establishment in Boston of a school 

 which should place the teachings of science upon a more 

 practical plane than had hitherto been attempted, he 

 drew up a scheme entitled " Object and Plan of an Insti- 

 tute of Technology," and embraced therein also a school 

 of industrial science, a museum of arts, and a society of 

 arts. To the accomplishment of this purpose he bent 

 every energy, and at length a charter from the State was 

 granted, providing the land upon whieh the institute 

 buildings now stand. Subsequently the plans prepared 

 by Prof. Rogers were almost completely carried out ; and 

 he, more perhaps than any oftier one man, brought about 

 that admirable system of teaching which so characterises 

 the institute, and which finds its place in the laboratories. 

 His connection with the institute has been a most 

 prominent one. He occupied the chair as president for 

 many years, and at the start was at the head of the 

 department of physics and geology. Since his removal 

 to Boston, as well as before, Prof. Rogers has contri- 

 buted largely to scientific journals in the United States and 



