174 Brunonian or Particle Movements. 



actual experiment that it could be heard at a distance of two 

 miles, though the words could not be distinguished. He died 

 in 1806. He was the preacher among the "Four Johns." 



The Ettrick Shepherd said of him : — " The good John 

 Fairley, a man whom I knew and loved. I think I see him 

 now, with his long white hair and his look, mild, eloquent, and 

 sagacious. He was a giver of good counsel, a sayer of wise 

 sayings, with wit at will, learning in abundance, and a gift in 

 sarcasm which the wildest dreaded." — (Tales and Sketches of 

 Ettrick Shepherd, vol. ii., p. 354.) 



23rd Aiiril, 1909. 



Chairman — Professor Scott-Ei.liot, P. 



Brunonian or Particle Movements. By Mr J. M. 

 Romanes, B.Sc.(Edin.). 



The subject which I bring to your notice is but a small one, 

 a microscopic one. But if it is infinitesimal in size, it is almost 

 of infinite vogue. In time and in place it is of the very widest 

 extension. When the Silurian was laid down it was in opera- 

 tion. And whether we try to ascend Rowenzori, or descend to 

 the depths of the Atlantic, we shall come in contact with it. 



When the first drop of liquid water came in contact with 

 Mother Earth it was bom. When the last drop of water solidi- 

 fies into ice or evaporates into steam then alone will Brunonian 

 movements cease on the earth. 



Brunonian movements are the motions of small particles of 

 matter held in suspension in a liquid medium, such as water. 

 They were first noticed and mentioned some seventy or eighty 

 years ago by an eminent English botanist hailing from Scotland 

 — Robert Brown. As to Brown belongs the honour of their 

 discovery, so they were called by the Latin form of his name, 

 hence Brunonian. They are also known as Brownian, and they 

 are often called molecular movements. The latter name is 

 used as opposed to molar, and when so used it is appropriate. 

 But the word molecular has entered so firmly into science in its 



