IW. F. D. Adams an.l Dr. -I. T. ffi 



:i to be spectral green. But in this case the physical stimulus is 

 complex. On adding to the magenta a yellow glass, to cut out the 

 violet, or using candle light, the violet reappears in the complementary 

 inn, while if a blue glass is added instead, the violet vanishes, 

 and red stands out brightly in the spectrum. It may be thus shown 

 that the colour which has green for its complementary is not spectro- 

 scopically simple, and since the spectral elements of it have each a 

 different and independent effect upon the spectrum of the comple- 

 mentary colour, I conclude that the green sensation has no special con- 

 nection with the red, or indeed with any single colour sensation. 



It would, of course, be easy to arrange the apparatus so as to use 

 pure spectral colours for the backgrounds, but the phenomena are 

 sutticiently distinct for ordinary purposes with coloured glasses. 



A portion of the apparatus used has been paid for out of the sum of 

 10 allotted to me by the Royal Society from the Government Grant. 



" An Experimental Investigation into the Flow of Marble." By 

 FRANK D. ADAMS, M.Sc., Ph.D., Professor of Geology in 

 McGill University, Montreal, and JOHN T. NICOLSON, D.Sc., 

 M.Inst.C.E., Head of the Engineering Department, Municipal 

 Technical School, Manchester. Communicated by Pro; 

 H. L. CALLENDAR, F.Pt.S. Received June 12, Read June 21 . 

 1900. 



(Abstract.) 



That rocks, under the conditions to which they are subjected in 

 certain parts of the earth's crust, become bent and twisted in the most 

 complicated manner is a fact which was recognised by the earliest 

 geologists, and it needs but a glance at any of the accurate sections of 

 contorted regions of the earth's crust which have been prepared in 

 more recent years to show that there is often a transfer or " flow " of 

 material from one place to another in the folds. The manner in which 

 this contortion, with its concomitant " flowing," has taken place is, how- 

 ever, a matter concerning which there has been much discussion, and a 

 wide divergence of opinion. Some authorities have considered it to le 

 a purely mechanical process, while others have looked upon solution 

 and redeposition as playing a necessary rule in all such movements. 

 The problem is one on which it would appear that much light might 

 be thrown by experimental investigation. If movements can be 

 induced in rocks under known conditions, with the reproduction of the 

 structures found in deformed rocks in nature, much might be learned 

 concerning not only the character of the movements, but also con- 



