534 



NATURE 



[June 15, 191 1 



and this before any continental glaciers had actually been 

 studied. The recent explorations of Norwegian, German, 

 Swedish, and Danish explorers, but more than all of Feary 

 in Greenland, and of Scott, Nordenskiiild, von Drygalski 

 and others, but especially of Shackleton in Antarctica, 

 have at last aflorded us observations upon the exist- 

 ing continental glaciers. When these reports are carefully 

 studied and compared, it is found that, as regards their 

 form, their erosional processes, and especially their 

 nourishment and waste, continental glaciers are as different 

 as possible from those of the Alpine type. Instead of 

 being nourished by snow precipitated from surface air 

 currents, which are forced to rise, their snow supply is 

 lorived from the fine ice grains contained in high-level 

 irrus clouds which have been drawn down to the glacier 

 >urface, been melted, and there reprecipitated. This action 

 is the work of a refrigerating air engine, which is 

 developed directly by the snow-ice mass itself. 



Front range of the Rocky Mountains in Colorado, by 

 Prof. W. M. Davis, Harvard University. The front 

 range of the Rocky Mountains in Colorado, now easily 

 accessible by various railroad lines which enter and cross 

 it from Denver and Colorado Springs, is an unusually fine 

 example of a mountain highland, which in a former cycle 

 of erosion was reduced to moderate relief, and since 

 elevation to its present altitude has been submaturely dis- 

 sected by its streams. The highland is surmounted by 

 numerous hills and mountains of from 500 to 2500 feet 

 relief, which represent the unconsumed residuals of the 

 former cycle of erosion, and therefore presumably 

 consist of the most resistant rocks of the region. The 

 uplift of the mountain belt to its present altitude was not 

 perfectly uniform, but arched gently from the plains 

 westward ; thus the crest of the range seems to correspond 

 to the crest of the arched uplift. A notable feaure of the 

 higher valley heads, among the surmounting mountains 

 near the range crest, is the occurrence of numerous amphi- 

 theatres or cirques, and over-deepened valley troughs, the 

 work of glaciers which for a moderate time, as geological 

 time is reckoned, replaced the water streams in the highest 

 districts. The contrast between forms due to ordinary or 

 normal erosional processes and to glacial erosion is thus 

 displayed with unusua' clearness. 



Astronomy. 

 An important astrophysical paper was presented on the 

 -olar constants of radiation, by Mr. C. G. .■\bbot, director 

 of the Astrophysical Observatory, Smithsonian Institution, 

 Washington. If we had no eyes we should still know of 

 the sun by the feeling of warmth. The most exact 

 measurements of the intensity of the rays of the sun, 

 whether they be visible to the eye or affect the photo- 

 graphic plate or not, are made by an electrical thermo- 

 meter called the bolometer. This instrument is so 

 sensitive that a millionth part of a degree change of 

 temperature is recorded by it. For seven years the bolo- 

 meter has been used by the staff of the Astrophysical 

 Observatory of the Smithsonian Institution to measure the 

 solar constant of radiation. This constant represents the 

 number of degrees (centigrade) which i gram of water 

 would rise in temperature if all the solar radiation which 

 could pass through an opening i centimetre square out- 

 side the earth's atmosphere, but at the earth's mean 

 distance from the sun, could be used for one minute to 

 heat the water. As all life, and almost all forces on the 

 earth, depend on the supply of solar rays, the solar 

 constant of radiation is at least equal in importance to 

 the knowledge of the sun's distance. 



The value of the solar constant was unknown within 

 wide limits only five years ago. It is now believed to be 

 within I per cent, of 1.93 calories per square centimetre 

 per minute. Measurements made at Washington (sea- 

 If'vel), Mount Wilson (i mile elevation), and Mount 

 Whitney (nearly 3 miles elevation) agree in fixing this 

 conclusion. 



Nearly 500 determinations have been made. Thev 

 indicate that the value is not really a "constant," but 

 fluctuates about the mean just given within a range of 

 R per cent. This conclusion means that the sun is a 

 variable star. It is hoped soon to verify it completelv, 

 and it may prove for meteorolog\- hardly less important 



NO. 2X72, VOL. 86] 



than the det* of the mean value of the solar 



constant itsell. 



On the evening of April 21 Prof. Arrhenius, of Stock- 

 holm, gave an illustrated lecture on the physical con- 

 ditions of the planet Mars. He directed attention to ' 

 many similarities between Mars and the earth which '; 

 caused some to think that Mars is inhabited, but gave .i 

 as his opinion that later investigations are not favour- 

 able to this view. 



.'\t the executive session on Saturday, April 22, the 

 following new members were elected : — Residents of the 

 United States : Dr. G. A. Barton, Bryn Mawr, Pa. ; Dr. 

 B. B. Boltwood, New Haven, Conn. ; Dr. Lewis Boss, 

 Albany, N.Y. ; Dr. J. M. Clarke, Albany, N.Y. ; Dr. 

 W. M. Late Coplin, Philadelphia; Dr. J. Dewev, New 

 York City ; Dr. L. O. Howard, Washington, D.C. ; Dr. 

 J. P. Iddings, Chicago; Mr. Alba B. Johnson, Rosemont, 

 Pa. ; Dr. A. A. Noyes, Boston ; Dr. G. H. Parker. 

 Cambridge, Mass. ; Mr. A. Lawrence Rotch, Boston ; 

 Dr. L. S. Rowe, Philadelphia; Dr. William T. 

 Sedgwick, Brookline, Mass. ; and Dr. A. TrowbrMc 

 Princeton, N.J. Foreign residents: Prof. Svante .\ii;; 

 Arrhenius, Stockholm; Prof. J. B. E. Bornet, Paris; ..;.J 

 Sir John Murray, K.C.B., F.R.S., Edinburgh. 



As has been customary, the meetings ended with a 

 banquet at the Bellevue, Stratford, on Saturday evening, 

 at which the following toasts were responded to: — "The 

 Memory of Franklin," by President Schurman. of Cornell; 

 " Our Universities," by Count von BernstorfT and Presi- 

 dent Hadley, of Yale; "Our Sister Societies," by Sir 

 John Murray £nd Prof. W. M. Davis, of Harvard; and 

 " The .American Philosophical Society," by Prof. E. C. 

 Pickering, of Harvard. Thus ended one of the most 

 successful meetings in the history of the society. 



Arthur W. Goodspef- 



PHOTOGRAPHY AN AID TO ASTRONOMY.' 



T N my address last year I endeavoured to put before 

 ■*• you some of the problems which confronted th>^ 

 astronomer, and to illustrate the reasons why the most 

 refined methods of physical measurement available were 

 necessary in order to secure data for the solution of such 

 problems. To-day I propose to deal rather with the 

 methods in use, and the progress which has been, and 

 is being, made in securing the necessary data for dis- 

 cussion, and in particular to sketch to you the advances 

 which have been rendered possible through the introduc- 

 tion of photography as an aid. In these days, when port- 

 able hand cameras are accessible to everyone, when photo- 

 graphs can be taken by the mere expedient of pressing a 

 button, leaving the manufacturers who supply the material 

 to " do all the rest " at a trifling cost, or when even the 

 processes of development can be performed by an in- 

 experienced operator without the aid of any more elaborate 

 equipment than a supply of fresh water, one is apt to 

 forget how recent is the development of photography, not 

 merely as a science or art in itself, but still more as a 

 useful adjunct to almost every other branch of scientific^ 

 investigation. 



To appreciate the use of photography, try to imagine, 5fl 

 you can, a state of existence deprived of the sense off 

 sight, not only in the individual, but throughout the humans 

 race. The phenomenon of light could doubtless still exist, 

 and even be capable of exerting certain physiological 

 action, but this phenomenon is one with which we are| 

 primarily cognisant through the direct physiological action} 

 on the optical nerves, and without which the intercourse! 

 of the individual with the external world is, perhaps,"! 

 limited by the further senses of "sound," "touch." 

 " smell," and " taste." All these senses, even including 

 the first, are brought into operation only by closely 

 adjacent surroundings, whereas the additional sense of 

 sight, apart from its use as a means of communication 

 between individuals, is the sole remaining sense by which 

 we can obtain information regarding unexplored and other- 

 wise inaccessible regions. I venture to doubt whether, 

 under such conditions, the human intellect would have 



1 Presidential address delivered Kefore the Royal Societv of South .■\''rica 

 on April 19, by Mr. S. S. Hough, F.R.S. 



