414 



NAIL RE 



[March 2, 1905 



ments, was found to be practically independent of the 

 voltage between o and 8 volts. When once a magnetic field 

 had been applied, ol sufficient strength to stop all the slow- 

 moving electrons, a large increase in its value had no effect 

 on the magnitude of the positive charge. I think these ex- 

 periments undoubtedly show that the a particles do carry 

 a positive charge, and that the previous failures to detect 

 this charge were due to the niaslcing action of the large 

 number of slow-moving electrons emitted from the plates. 



Observations were made under different e.xperimental con- 

 ditions, and with very concordant results. In one set of 

 expeririients a weight of 0-19 mg. of radium bromide was 

 used, spread on a glass plate, which was covered with a 

 thin sheet of aluminium foil ; in the other 0.48 mg., spread 

 on an aluminium plate. The saturation current due to the 

 latter plate, measured between parallel plates 35 cm. apart 

 by means of a galvanometer, was found to be 78 X 10- 

 amperes. It is possible that the failure of Prof. Thomson 

 to detect the positive charge carried by the a rays from 

 radio-tellurium was due to the smallness of the elTect to be 

 measured ; for with the plate of radio-tellurium in my pos- 

 session, the current was only about 1/40 of the above value. 



Since the film of radium' bromide is so thin that all the 

 a particles escape from its surface, it is easy to deduce from 

 the observed charge from a known weight of radium the 

 total number of a particles expelled per second from one 

 gram of radium bromide. Taking into consideration that 

 half of the a particles were projected into the radium plate, 

 and assuming that the a particle carries the same charge 

 as a gaseousion, it was deduced that one gram of radium 

 bromtde emits 35 X 10" particles per second. Now the 

 activitv of radium bromide in radio-active equilibrium is 

 four times this minimum, and contains four products which 

 emit a particles at the same rate. It is thus probable that 

 one gram of radium bromide in radio-active equilibrium 

 emits 1-4X10" particles per second. I had previously de- 

 duced (/oc. fit.), from indirect data, the value about 

 r-ixio", so that the theoretical and experimental numbers 

 are in very good agreement. 



I have also made experiments, by a special method, to 

 determine the total number of S particles emitted from one 

 gram of radium bromide in radio-active equilibrium, and 

 iiave found a value about the same as the number of a. par- 

 ticles emitted at its minimum activity. It is thus seen that 

 four a particles are expelled from radium for each /3 par- 

 ticle. The number of /3 particles obtained by Wien was 

 much smaller than this, but, in his experiments, a large 

 proportion of the more slowly moving j3 particles was ab- 

 sorbed in the radium itself and in the envelope enclosing it. 



The number of o particles expelled per second from one 

 gram of radium is a most important constant, for on it 

 depends all calculations to determine the volume of the 

 emanation, and of helium, the heat emission of radium, and 

 also the probable life of radium and the other radio- 

 elements. E. Rutherford. 



McGill University, Montreal, February 10. 



Compulsory Greek at Cambridge. 



The conclusion to be drawn from Mr. Bateson's letter 

 seems to be that it is useless to compel candidates to get up 

 subjects for which they have no aptitude, or in which they 

 take no interest. The glories of " another world." whether 

 in science or art, are reserved for those that can see them, 

 and a bright boy, not to say a dull one, is unlikely to discover 

 the beauties of compulsory Greek, if he happens to have a 

 distaste for dead languages. But is it not rather a narrow 

 view which recognises only one new world and the entrance 

 to it through compulsory Greek? It is said of a great 

 creative mathematician that surveying his subject from a 

 high pinnacle of abstract thought, he exclaimed, " And we 

 too are poets"; but the most enthusiastic would scarcely 

 expect this feeling to be aroused by compulsory mathematics 

 in a dull boy ; it does not seem to have occurred even to an 

 ixceptionally bright one. 



Sullied, as Mr. Bateson seems to consider mathematics, by 

 ' Icgr.iding usefulness to " trade and professions," it nfver- 

 "••less remains of essential importance to nine-tenths of our 

 Stirntific work, and most of those of us who have but little 

 of it sigh that we have not more. Mr. Bateson himself has 

 NO. 184.4, ^OI- 71] 



not disdained its assistance in his work on breeding and 

 heredity. 



The point of previous letters is not that the writers had 

 no aptitude for Greek, but that they found it useless to 

 them in the studies to which they devoted their life. German 

 is indispensable ; soon we shall have to read Russian too, 

 and if a man is to keep abreast of his subject he must not 

 only read German, but read it with ease, so great is the 

 bulk of literature to be got through. Arbitrarily to compel 

 a boy to learn Greek, which, if he does not appreciate it, will 

 be perfectly useless to him, when he might be learning 

 German, which, whether he likes it or not, is indispensable 

 for the full pursuit of his scientific studies, seems to be one 

 of the cruellest conceivable tyrannies of pedantic folly. Could 

 there be greater intellectual waste, and could any means 

 be designed more likely to defeat the end for which it is 

 designed ? Compulsion and education are terms as opposed 

 philosophically as they are etymologically ; let the student 

 be encouraged to work at the subjects he has really at heart 

 and he will proceed from one success to another, and may 

 even find his training in natural science leading him to the 

 higher things in Greek literature. 



But since the most natural classification of candidates 

 would seem to be into those having a tendency to exact 

 thought — who will naturally gravitate towards mathematics, 

 and those with a love of art — who will naturally aspire to 

 literature, and those with a little of both — who will be given 

 over to natural science, why not allow a first class in anv 

 two of the three to count as a pass? such a measure would 

 prove a great relief both to congenital non-mathematicians 

 and non-linguists. 



Finally, why should a want of sympathy with Greek, the 

 noblest language of the noblest literature the world has 

 known, be imputed to those who think that it is too good a 

 thing to be wrested to injurious purposes? X. 



If Mr. Bateson's case is that of hundreds, I make bold to 

 say the case of the boy who wastes hundreds of hours on 

 Greek grammar is that of thousands. 



We do not want to abolish compulsory Greek because it 

 has no value in the market, but because, stopped where the 

 Ijoy who takes it no further than the Little-Go stops it, the 

 study of Greek has no value, ninety-nine times out of a 

 hundred, in the forming of an active, living intelligence. 



Mathematics may have contributed nothing to the forma- 

 tion of Mr. Bateson's mind ; it is not unlikely, though it is 

 deplorable. But if Mr. Bateson seriously thinks that 

 elementary mathematics contributes no more than elemen- 

 tary Greek to the sound training of an average mind, surely 

 he is curiously destitute in experience of the run of faculties 

 in a young human being. This explanation of Mr. 

 Bateson's astonishing argument suggests itself the more 

 readily, because his idea that Greek is one of the things that 

 put " one touch of art in the life of a dull boy, and open 

 his eyes to another world," appears absolutely grotesque. 



The narrow (and conspicuously unintelligent) utilitarian 

 idea of education represented by Mr. Bateson's " in- 

 telligent lady " must be fought with all our strength, but it 

 cannot be fought successfully with the rusty sword of Mr. 

 Bateson's reactionary classicism. That is a weapon which 

 will break in our hands and leave us defenceless to the 

 spoiler. A. G. Tanslev. 



New University Club, London, S.W., February 23. 



May I be permitted to suggest, with all deference, that 

 Mr. Bateson's statement that his knowledge of mathematics 

 is " nil " must be taken cum grano ! He is now, I believe, 

 largely engaged in the business of counting chickens before 

 thry are hatched. How could he do this without some 

 mathematics? As a matter of fact, the research in which 

 he is engaged involves mathematical conceptions of no mean 

 order, yet I presume he knows something about his subject. 



Mr. Bateson's letter might be a good argument in favour 

 of lowering the mathematical standard in the previous 

 examination. But, as he uses it, it is merely an unusually 

 frank example of the reasoning which is the real support 

 of compulsory Greek, viz., " When I was a little boy the 

 big boys bullied me ; now that I am a big boy myself I 

 mean to lake it out of the little ones ! " 



Edward T. Dixon. 



Racketts, Hylhe. Hants. February 24. 



