July 8, 1922] 



NA TURE 



39 



The Oldest known Rocks of the Earth's Crust. 



May I welcome Prof. A. P. Coleman's letter on 

 " Geology and the Nebular Theory " in Nature for 

 June 17, p. 775 ? It must be admitted that the 

 achievement of A. C. Lawson at Rainy Lake in 1887, 

 the elucidation by Sederholm of the floor of Finland, 

 and the illuminating work of Canadian geologists, 

 including Coleman, Adams, and Barlow, on the 

 Grenville Series, have been slow in penetrating 

 academic circles in the British Isles. The doorways 

 were almost closed against them, and against the 

 views of French geologists also, by the dead-weight 

 of theories of dynamic metamorphism. Yet our 

 confidence in a fundamental " Lewisian " gneiss was 

 well shaken thirty years ago by Sir A. Geikie's 

 announcement tha,t this rock penetrated a sedi- 

 mentary series (see A. Geikie, " Text-book of Geology," 

 4th ed., vol. 2, p. 890) ; and a more detailed acquaint- 

 ance with the ground would have led the same 

 observer to withdraw his statement (ibid., p. 895) as 

 to a violent unconformability " between gneisses 

 and Dabradian sediments in north-west Ireland. 

 Some of us have lost no opportunity of comparing 

 the conditions in our homeland with those of broader 

 Archaean areas. But even in our narrow lands, as I 

 have ventured to urge from 1900 onwards, the teach- 

 ing of the rocks themselves is unmistakable. The 

 oldest known rocks are sediments, and the streaky 

 structure of our ancient gneisses again and again 

 records the stratification of ordinary sediments in- 

 vaded by a granite magma. 



I have recently put this view before those who 

 may not be geologists in a volume of " unconventional 

 essays," containing a chapter on " The search for the 

 foundation-stones," where Prof. Coleman will find 

 that his expositions have not been thrown away upon 

 those whom he has so kindly guided in the field. 



Grenville A. J. Cole. 



An Exception to the Principle of Selection 

 in Spectra. 



In a recent communication (Phil. Mag., April 1922) 

 Messrs. Foote, Mohler, and Meggers have described 

 the excitation of a certain type of combination 

 lines in a new form of discharge tube in which the 

 applied electrostatic field can exert no influence 

 upon the radiation. Thereby thev made it somewhat 

 doubtful whether these and other exceptions to the 

 principle of selection can be attributed to the incipient 

 Stark effect of the applied field, as suggested by 

 Sommerfeld and others. In reply to this, Prof. N. 

 Bohr has pointed out (Phil. Mag., June, 1922) that, 

 " owing to the screening from external forces, the 

 experimental arrangement described would be especi- 

 ally favourable for the accumulation of ions in the 

 region of the discharge tube," and that " the field 

 due to the neighbouring ions and free electrons, 

 to which the emitting atoms have been subject, 

 may be of the order of magnitude claimed by the 

 quantum theory for the appearance of the new lines." 

 Consequently Prof. Bohr thinks that the results of 

 Foote, Mohler, and Meggers do not furnish a sufficient 

 basis for the conclusion they have drawn. 



Recently, however, in the course of an investigation 

 on the absorption spectrum of potassium, the results 

 of which will be published shortly, the combination 

 lines is— 2d (A4642) and 15—30' (^3649) have been 

 obtained as absorption lines. The existence of free 

 electrons and the consequent electrostatic field of 

 atomic origin in the absorption tube is highly im- 

 probable. The present experiment therefore seems 



NO. 2749, VOL. I io] 



to support the conclusion drawn by Messrs. Foote, 

 Mohler, and Meggers. S. Datta. 



Spectroscopy Laboratory, 



Imperial College of Science and Technology, 

 South Kensington, S.W.7. 



The Melbourne University Bill. 



In the issue of Nature for March 16, which has 

 just reached Australia, there is a leading article on 

 the Melbourne University Bill. That Bill was 

 drafted more than eighteen months ago, and though 

 we have a Government in sympathy with the highest 

 ideals of our University, it is still a Bill and has 

 not yet become an Act of Parliament. In the article 

 in question reference is made to a statement drawn up 

 by the University Association of Teachers, in which 

 the council of the university is criticised for failure 

 adequately to protect the interests of the university 

 and its staff. 



It would be unseemly, and probably uninteresting 

 to a large section of your readers, to enter into the 

 merits of a " family quarrel " which is the result of 

 misunderstanding and is, we hope, of a temporary 

 character. A letter was sent by the council to the 

 Minister for Public Instruction immediately after 

 the council was informed that the statement to 

 which you refer had been forwarded to members of 

 the Cabinet by the University Association of Teachers. 

 Let me point out a fact of which you may not be 

 aware, namely, that while the association contains the 

 majority of the teaching staff it does not represent the 

 whole body of professors and lecturers. The state- 

 ment of the association is crude and contains serious 

 inaccuracies. I shall deal only with the two criticisms 

 of the council which you single out. 



(1) It " failed to protect the interests of the 

 university by not raising fees." That is not a mere 

 financial question — it involves a question of general 

 policy. In view of the fact that an important 

 section of our community believes that the university 

 should charge no fees (the University of Western 

 Australia is free), would it not be childish to raise 

 the fees before Parliament has settled what our 

 grant is to be, and till we know definitely whether 

 that grant will enable us to pay adequate salaries 

 without raising them ? 



(2) The council failed " by asking for an inadequate 

 increase of the State Grant." I wish we could have 

 an increase of the grant for the asking. I think the 

 attitude of the council is clearly indicated by an 

 extract from the letter to the Minister for Public 

 Instruction already referred to. You will there find 

 the following : 



" The council is placed in a false position by 

 being obliged to correct these statements, for it does 

 not wish it to be inferred that it thinks the proposed 

 increase of the University Grant sufficient for what 

 are now in 1921 its legitimate needs." 



The management of the university council may 

 not satisfy the impatience of some, but no one 

 interested in university education need fear that it 

 will fail for lack of whole-hearted zeal. 



J. H. MacFarland, 

 Chancellor. 



The University of Melbourne, May 5. 



[The two criticisms to which Sir J. H. MacFarland, 

 chancellor of the University of Melbourne, refers, 

 were made by the University Association of Teachers, 

 and we expressed no opinion upon them, but we re- 

 marked, "It is obvious that if a university staff is 

 thoroughlv discontented its efficiency is bound to 

 suffer." The suggestions made at the end of our 



