April 30, 1908J 



NA TURE 



615 



at the rate of more than 37 knots. The speed guaranteed 

 by contract was 33 knots. The vessel is 270 feet long, 

 the propelling machinery being Parsons turbines and six 

 Thornycroft water-tube boilers. 



There has been much controversy in recent years on 

 the subject of that class of Palseolithic stone implements 

 which have been called eoliths. The question has now 

 been taken up in the .'\pril number of llan by Mr. 

 Worthington Smith, who deals specially with discoveries 

 in the North Herts and South Beds plateaux, and in par- 

 ticular with the contorted drift, which contains all the 

 varieties of worked stones which were lying on its surface 

 at the time of its deposition, including older and newer 

 pateoliths and their ever-accompanying eoliths. The last 

 class he thus attempts to define : — " At the present day all 

 kinds of oddities in flint are passed oft as ' eoliths ' ; one 

 author says the examples must be bulbless ; another 

 describes well-formed bulbs. One says the secondary 

 flaking is vertical ; another that it is lateral. Sometimes 

 a proof of authenticity is said to rest on the fact that the 

 stones in question present no flaking at all, only rubbing. 

 If museums are visited one sees ordinary palaeoliths 

 masquerading as ' eoliths,' and rubbing shoulders with 

 minor well-known Palaeolithic forms, iron-stained neoliths, 

 surface flints, and late Victorian oddities of all sorts." 

 In short, Mr. Smith concludes that there are no such things 

 as " eoliths " at all, nine out of ten of the thousands 

 sent to him for examination being only natural flint frag- 

 ments. " The tenth has been a minor and well-known 

 Palaeolithic form, or, it may be, a bulbed, 'iron-stained, 

 Victorian flake, knocked off by the hoof of a farm animal." 

 None of those he has examined he believes to be as old 

 as the Boulder Clay. 



In a recently issued pamphlet (" Plato or Protagoras? " 

 London : Simpkin, Marshall and Co., price is. net) Dr. 

 F. C. S. Schiller propounds a novel and interesting view 

 of the real significance of the speech attributed to Prota- 

 goras in Plato's dialogue, " Theaetetus. " According to 

 this view, the argument of the speech was not invented 

 by Plato, but represents an attempt on his part to state 

 fairly the actual case of an opponent whom he had not 

 completely understood, and who had at the time of the 

 composition of the dialogue passed beyond the reach 

 of interrogation. Dr. Schiller seeks to justify his inter- 

 pretation by maintaining that the criticisms which are 

 directed by " Socrates " against the Sophist's arguments 

 do not really refute them, and, in fact, prove merely 

 that Plato had formed a very imperfect conception 

 of their meaning and scope. Incidentally, Dr. Schiller 

 takes occasion to claim that Protagoras was in all essential 

 points an early exponent of his own doctrine of humanism, 

 and that Plato's failure to refute him was prophetic of 

 the superiority of the pragmatic philosophy over all forms 

 of " intellectualism." 



The American Journal of Science for April contains an 

 article by Mr. H. M. Dadourian, of Yale, on the con- 

 stituents of atmospheric radio-activity at New Haven. 

 Mr. Dadourian suspended a negatively charged wire for 

 three hours in a cavity in the ground, and another for 

 four days in the air about 7 metres above the ground. 

 On determining the rate of decay of the radio-activity of 

 each wire, he found that 5 per cent, of the initial radio- 

 activity of the first, and 20 per cent, to 30 per cent, of 

 that of the second, was due to thorium and its products, 

 the rest to radium and its products. From this he deduces 

 that the amount of radium emanation present in the air 

 of New Haven is about 40,000 times as great as the 

 amount of thorium emanation. 

 NO. 2009, VOL. 77] 



The Adamson lecture, founded in 1903 in memory of 

 the late Prof. Robert Adamson, of Manchester, was 

 delivered last term by Prof. J. J. Thomson, and has 

 recently been published by the Manchester University 

 Press. It deals with the relation between ether and 

 matter brought to light by recent electrical investigations. 

 Prof. Thomson points out that in electrical phenomena we 

 are brought into contact with cases of interaction between 

 bodies charged with electricity, in which the action of 

 the first on the second is not equal and opposite to the 

 reaction of the second on the first. In such cases we sup- 

 pose that both bodies are connected with the ether around 

 them, and that Newton's third law holds when we consider 

 the ether and the two bodies as constituting the system 

 under examination. From this point of view, the potential 

 energy of an electrical system may be regarded as due 

 to its connection with an invisible subsidiary system 

 possessing kinetic energy equal in amount to the potential 

 energy of the original system. This conception may be 

 further extended to non-electrified bodies, and the ether 

 thus comes to play an important part in ordinary 

 dynamics. 



Prof. .Andrew Gray delivered an oration on Lord 

 Kelvin at the University of Glasgow on Commemoration 

 Day, April 22. The address dealt largely with the early 

 work of the great master at Glasgow, when he was 

 making the electrodynamic and electromagnetic theories 

 more explicit, and testing them experimentally under con- 

 ditions the antithesis of those which exist in the well- 

 equipped laboratories of the present day. Prof. Gray 

 mentions two views held by Lord Kelvin to which we may 

 at the present time well devote special attention. He , 

 believed that the study of natural philosophy ought not 

 to be excluded from the arts curriculum, and he was 

 strongly opposed to the tendency which has been manifest- 

 ing itself to separate the experimental from the mathe- 

 matical side of physical work. With him the mathematical 

 symbol was merely the servant of the idea, and mathe- 

 matical methods had their place among the tools and 

 instruments of research. The printed copy of the oration 

 contains portraits of Lord Kelvin in 1846, 1868, and 1905 

 respectively, and a view of the outside of the natural 

 philosophy rooms of the old college buildings. 



Prof. P. Zeeman, in his second note on the magnetic 

 resolution of spectral lines and magnetic force (Konink. 

 Akad. Wetens. Amsterdam, December 24, 1907), gives 

 some striking measurements of asymmetric separation, with 

 excellent photographic reproductions illustrating the various 

 stages. By means of the method of the non-uniform 

 magnetic field, described in the first article in the above 

 Proceedings for April, 1907, he finds it possible to study 

 at a glance any series of phenomena dependent on the 

 field intensity for a series of different intensities. The 

 class of asymmetric separations herein considered has 

 been predicted from theory by Voigt, and has also been 

 considered by Lorentz. One of the most interesting cases 

 is the yellow mercury line at \ 5791, the structure of 

 which cannot be satisfactorily made out by the interfero- 

 meter. The first-order spectrum of a Rowland concave 

 grating of 6-5 metres radius, with 10,000 lines to the 

 inch, has been employed for the investigation. It is seen 

 that while the 5791 line is resolved asymmetrically, the 

 neighbouring line, 5770, is resolved into a perfectly 

 symmetrical triplet. Of this pair of lines a nine-fold 

 enlargement of the original negative is given, showing 

 most distinctly the above effect. The intensity of the 

 magnetic fields employed varied from 14,800 to 29,220 

 Gaussian units. There are several points requiring further 



