﻿10G2 Intelligence and Miscellaneous Articles. 



Italy which he had personally visited, was so sound, so firmly based 

 •on experiment and research, and so entirely in accordance with 

 modern knowledge, that he must be considered the one great 

 geological predecessor of L} r elL 



Since publication of his discoveries was impossible, Leonardo 

 left a record of them in his paintings, as in the background of the 

 ' Monna Lisa,' the ' Madonna & St. Anne,' and in a less degree in 

 our own ' Madonna of the Rocks ' in the National Gallery. Here 

 we find pictures of the primeval world as he imagined it, when 

 seas and lakes ran up to the foot of the mountains, to be slowly 

 displaced and silted up by the detritus which the rain carried down 

 from the summits. From this reconstruction the pictures derive 

 that sense of action, apart from place or time, which has fascinated 

 generations who could not understand Leonardo's meaning as we 

 -can understand it now. 



XCIX. Intelligence and Miscellaneous Articles. 



THE BUCKLING OF DEEP BEAMS. 



To the Editors of the Philosophical Magazine. 



Gentlemen, — 



I wish to thank Professor Timoshenko for his letter in the May 

 number of the Philosophical Magazine, in which he gives 

 references to earlier work on the above subject. I had discovered 

 some time ago that other people had preceded me in this investi- 

 gation, but I had not taken the trouble to look up their papers 

 as my own were already published. Since reading Professor 

 Timoshenko's letter, I have, however, examined Mr. Michel l's 

 paper in the Philosophical Magazine for September 1899, and 

 was astonished to find how closely my own first paper (Phil. Mag., 

 'Oct. 1918) resembled his. We have solved the same problems in 

 much the same way, and agree perfectly except on one question, 

 the one numbered IV. in Michell's paper, and Case 5 in mine. 

 Here I venture to say that he is wrong, for his solution makes 

 the torque zero at the ends, which is obviously not true for the 

 actual problem. My second paper carries the subject a little 

 further, but, of course, it is the first step that counts, and 

 Professor Timoshenko does not tell us whether Michell or Prandtl 

 .made the first step. 



College of Technology, Tours faithfully, 



Manchester. " JoHN Pbbsoott. 



May 21st, 1922. 



