452 



NATURE 



[March 7, 190T 



OUR ASTRONOMICAL COLUMN. 

 Variability of Eros.— In the Astronomische Nachrichten. 

 (Bd. 154, No. 3688), Dr. E. von Oppolzer describes his obser- 

 vation of the planet Eros, which led to his announcement of 

 its variations in brightness. The measures were made with the 

 Zollner photometer on a Grubb refractor of 8^, inches aperture 

 at Potsdam. 



In the same journal there are further confirmatory reports 

 from the observatories of Konigsberg and Heidelberg, 



New Type of Shortened Telescope.— In the Astro- 

 nomische Nachrichten (Bd. 154, No. 3691), M. E. Schaer 

 describes some experiments he has made at the observatoryi^of 

 Geneva with the object of facilitating the use of long focus 

 objectives. The light from the object glass is reflected back- 

 ward and forward from two silvered plane mirrors, so that 

 the distance between eyepiece and objective is only about 

 one-third the focal length. Good photographs of the sun's sur- 

 face were obtained by using unsilvered glass mirrors and giving 

 an exposure of about one-fiftieth of a second. 



Catalogue of New Variable Stars.— Harvard College 

 Observatory Circular, No. 54, contains a catalogue of sixty-four 

 new variable stars discovered by the observers at that institution. 

 The majority of these have been detected on examination of the 

 Draper Memorial spectra, by reason of the presence of bright 

 lines of hydrogen in the peculiar cases. For the purposes of 

 this catalogue the variables have been divided into two main 

 classes (i) those having a large range of variation, (2) those in 

 which the extent of variability is small — from half a magnitude 

 to a magnitude. The variables examined are then classified 

 under these headings, 39 of long, and 25 of short period. 



New Component of the Polar Motion. — In the Astro- 

 nomical Journal (vol. xxi. No. 490), Prof. S. C. Chandler 

 makes a preliminary announcement of the detection of a new 

 component relating to the motion of the terrestrial pole. In 

 addition to the already known 428-day and annual terms, he 

 now finds a variation having a period of 436 days and a radius 

 of o"'09 — considerably smaller, therefore, than the others. In 

 the absence of more minute data, the orbit is assumed circular, 

 and the author proceeds to investigate the nature of the variation 

 produced as the resultant of the old 428-day and the new 436- 

 day motions. 



The combined motion is found to be subject to a period vary- 

 ing from 431*4 and 415*0 days, the mean length being 428*5 

 days. The fluctuations are embraced in a cycle of about 57 

 periods, or 67 years.. With respect to the whole cycle, however, 

 the changes of period a;e of a remarkable character. During 

 five-sixths of the cycle the period remains between its mean value 

 and the upper limit, ?.£. between 428*5 days and 431*4 days; 

 then it suddenly shortens to minimum, 415 days, and imme- 

 diately rapidly lengthens again. In addition to this the variations 

 of the radius of motion are also singularly asymmetrical. It is 

 at present about o"*07 and approaching its minimum value of 

 o"*o5 ; there was a decrease from o"*i 7 too"*ii between 1890 

 and 1897. It will be interesting to note whether the predicted 

 variation of the period actually takes place. Between 1850 

 and 1890 it persisted at the value 430 days, is now about 428 

 days, and should continue to shorten to the minimum value of 

 415 days within the next few years ; but of course no sharply- 

 defined numerical limit can be stated on account of the fact that 

 the length of the harmonic cycle, which depends on the dif- 

 ference of the two component periods, is imperfectly determined 

 by existing observations. 



INAUGURATION OF A BIRMINGHAM 

 SECTION OF THE INSTITUTION OF 

 ELECTRICAL ENGINEERS. 



DUklNG the last few years, the Institution of Electrical 

 Engineers has actively encouraged the formation of local 

 sections, each having headquarters in some industrial centre. 



These; local sections are iree to manage their own affairs, but 

 the parent Institution arranges that important papers read at any 

 of the local centres are incorporated in their journal, as also are 

 local contributions to the discussion of papers read originally in 

 i,ondon. Of the five branches now existing, the most recently 

 formed is that in Birmingham. 



The Birmingham local section of the Institution of Electpcal 



Engineers has been fortunate in its first chairman. Dr. OJiver 

 Lodge, principal of the new University, who delivered an address 

 from -the chair on Wednesday evening, February 27, at the. 

 Inaugural , Meeting of the section, before a large gathering of 

 engineers. The president of jthe Institution, Prof. John Perry, 

 was present to support the local movement. 



In the course of some opening remarks. Dr. Lodge congratu- 

 lated the parent Institution on its wisdom and enterprise in 

 forming local branches. Multiplicity of publishing centres was 

 bad for science ; but the lack of stimulus to local exertion was 

 had top. By the present action of the Institution both evils 

 were avoided. 



The original Society of Telegraph Engineers dealt chiefly with 

 cable enterprise. Then it took over successively the telephone, 

 electric lighting, transmission of power, and tramcars ; and now 

 it seemed about to take over underground traffic, and, in some 

 countries, the railways themselves. Again, a warship was full 

 of electrical contrivances, and the Institution sent a corps of 

 experts to add to the land forces in South Africa. 



With regard to the engineer's education, the chairman pointed 

 out that it must be truly scientific. Some said that a general 

 education and mathematics were unpractical and useless encum- 

 brances. What they really meant was that if a youth had these . 

 and nothing else he was useless, and that he would be more 

 useful if he failed to possess these, but did possess many other 

 powers and aptitudes. This was true ; but the two were not 

 mutually incompatible. ' 



Mathematics, for example, was often so taught that by the 

 time a man had acquired a great deal of it he was somewhat 

 unfitted for anything else. A common-sense mathematical 

 training was an essential for an engineer or for a physicist. 

 Euclid himself was splendid. So was his book for its day and 

 generation, and its purpose as a system of geometrical philosophy 

 admirable ; but it had had its day, and for elementary and popular 

 purposes should now cease to be. We were too busy ; there 

 was too much to learn nowadays to have time to cross every 

 river by ascending to its source and walking down the other side. 

 Professional guides along the . old river path still attempted to 

 hide the bridges, because if they were too easilyseen their occu- 

 pation would begone; but the bridges were there, and sooner 

 or later even schoolboys would be permitted to make use of them 

 and enjoy the country on the other side, without spending all 

 their days in a toilsome and deterrent mode of getting there 

 over a route approved by the ancients. 



The pursuit of pure science for its own sake was a good and 

 wholesome formula up to a certain point, because the tendency 

 of unregenerate man had always been opposed to it. The use- 

 fulness of scientific application needed no preaching,^ but, 

 strangely enough, there was a great tendency to forget or fgnore 

 the scientific foundation on which they rested. And the human 

 mind was so constituted that, as a rule, the necessary powers and 

 aptitudes for the two things did not go together. The man who 

 co'ild pursue pure science did so best, as a rule, when he was not 

 distracted by considerations of utility ; the applier of science, 

 on the other hand, soon got so immersed in practical details 

 and pecuniary considerations which were clearly vital that he 

 had neither leisure nor inclination, nor always the right kirld of 

 ability, for advancing the pure science itself. 



Pure science must always advance into territory which ap- 

 peared for the moment rather useless and barren and aloof from 

 hum?inity ; it must be so, since it was new ground never open 

 to humanity before. Consequently there was a weird unearthli- 

 ness about it which to people engaged in the turmoil of business 

 might be cold and repellent, it ever they allowed themselves 

 to be assisted to breathe its atmosphere for a moment. The 

 strange, new, unknown, bracing air had a fierce fascination of 

 its own, akin to that of the lone ice-packs of the Arctic seas to 

 the healthy and intrepid explorer, or as the mountain tops were 

 to the members of the Alpine Club. So enticing did the at- 

 mosphere of pure science become to those who frequently 

 breathed it that to them sometimes it seemed the only air worth 

 breathing, and the everyday atmosphere of humanity was close 

 and stifling in comparison. Let such men of genius alone ; 

 encourage them in their quest ; they were not too numerous, 

 and whither they showed the way others hereafter would 

 follow. Moreover, the region which they entered was 110 

 limited Arctic circle in reality ; it was, as it were, the Arctic 

 entrance to another world, whence, if they penetrated further in 

 pursuit of the pioneers, they would ultimately reach the tem- 

 perate zones of work and livelihood and applied science ; nor 



NO. 1636, VOL. 63] 



