TRANSACTIONS OF SECTION A. 535 



those whose horizon is limited to the Latin and Greek that they have learned — ^or 

 should I say limited by instead of to ? This recollection came back to me when 

 not long ago I was visiting one of the best organised and most skilfully conducted 

 works in the country — I mean Willans & Robinson — when I remembered that 

 another great manufactory, conducted on American lines, was near by, and when 

 across the road I saw the walls of one of our most famous English schools. I 

 pictured the old contrast : on the one hand the conviction impressed upon me when 

 a boy that there is something intellectually superior in the struggle with a paragraph 

 of Xenophon or a page of Homer, while manufacture is merely mechanical, 

 sordid and base, with what I believe to be the reality on the other. I wondered 

 in what spirit the erection of these works was viewed at the school and to what 

 extent the high intellectual attainment there so essential and so evident is properly 

 appreciated. 



Of the last of the three headings, Strenuousness, we have plenty, but at school 

 it is most apparent in cricket and football, and in after life in various expensive 

 ways of murdering defenceless animals. 



However, a change is already beginning to be felt. The public schools no 

 longer withhold the elements of chemistry and physics, and those who have 

 benefited, even in small degree, are taking responsible places vacated by those 

 who had no such opportunity. The numerous polytechnics are providing more 

 .serious instruction to thousands of our young men, and it may be hoped that in 

 time even' the official — I mean the mere official whose only conception of activity 

 is centred in obstructing progress and enlightenment — will have some appreciation 

 of things as well as of words. 



The following Papers were read : — 



1. On the Electro-ethereal Theory of the Telocity of Liyht in Gases 

 Liquids, and Solids. By Lord Kelvin, O.M., G.C.V.O.^ 



This communication is an advance proof of the last five pages of Lecture XX., 

 as written afresh for a long-promised volume of twenty lectures, given originally 

 in the Johns Hopkins University, of Baltimore, U.S.A., in October 1884, and now 

 nearly ready for publication by the Cambridge tJniversity Press. It is founded on 

 two recent contributions to ' electro-ethereal ' theory referred to as ' Appendix D ' 

 and ' Appendix A,' previously published in the ' Philosophical Magazine ' (1902, 

 1st half-year, and 1900, 2nd half-year), under the titles ' Aepinus Atomized,' and 

 * On the Motion produced in an Infinite Elastic Solid by the Motion through the 

 Space occupied by it of a Body acting on it only by Attraction or Repulsion.' 

 The long title of Appendix A contains virtually a complete statement of the 

 theory which constitutes its subject. 



2. Discussion en the Nature of the Emanations from Hadium. Opened 

 by Professor E. Rutherford. 



Contribution by Lord Kelvin, O.M,, G.C.V.O. 



Let us first consider the mere fact, now known as a result of observation and 

 experiment, that radium has been found to emit three types of rays : — 



a, Positively electrified, and largely stopped by solid, liquid, or gaseous screens. 



^, More penetrative than a, and negatively electrified. 



y, Electrically neutral, and much more penetrative than either a or /3; passing 

 with but little loss through a lead screen 1 centimetre thick, which is an almost 

 perfect screen against a and j3 rays. 



A simple prima facie view is to regard the ' y rays ' as merely vapour of radium. 

 ' Appeared in full in Phil. Mag. vol. ii. October 1902. 



