20 4 Mr. C. Tomlinson on the Formation of 



when the visual line is lowered 45°, the horopteric line becomes 

 perpendicular to that plane and at the same time expands into a 

 surface. Below 45° the horopter again becomes aline, but now 

 inclined in the contrary direction, i. e. the upper end nearer the 

 observer. 



(8) In inclining the visual plane upward or toward the brows, 

 if the optic convergence be strong the inclination of the horop- 

 teric line increases ; but if the optic convergence be small it de- 

 creases, but does not reach zero or become perpendicular*. 



(9) In looking downward 45°, for all distances the horopter 

 is a surface passing through the point of sight and perpendicular 

 to the median line of sight; but the form of the surface I have 

 not attempted to determine. In looking straight forward at in- 

 finite distance, the horopter is also a surface passing through the 

 point of sight ; but the inclination of this surface I am unable to 

 determine. 



(10) It is possible that in some eyes which would be consi- 

 dered normal there is, in convergence, a rotation of the eyes 

 imvard, probably from greater power in the superior oblique. In 

 such cases the position of the horopter would be different. 



Columbia,, S.C., 

 November 16, 1868. 



XXI. On the Formation of Bubbles of Gas and of Vapour in Li- 

 quids. By Charles Tomlinson, F.R.S., F.C.S.f 



IN the fifth Number of PoggendorfPs Annalen for the present 

 year, dated May 31, and published, I suppose, early in 

 June, is a paper by Herr Schroder on the conditions under 

 which bubbles of gas and of steam are formed in liquids J. The 

 paper is dated " Mannheim im December 1868," and a conti- 

 nuation is promised for a future Number. In paragraph 4, 

 which is devoted to the history of the subject, the author does 

 me the honour of referring to two papers of mine which appeared 

 in the Philosophical Magazine just two years ago§, although he 

 says he was not aware of the existence of my papers nor of those 

 of M. Gernez||, until he had completed the greater part of his 

 researches on this subject. Still he does not think it super- 

 fluous to publish his paper, since he believes it will add new re- 

 sults to those obtained by M. Gernez and myself. 



* See this statement modified in note on p. 202. 



\ Communicated by the Author. 



% " Untersuchungen liber die Bedingungen, von welchen die Entwick- 

 lung von Gasblasen und Dampfblasen abhangig ist, und iiber die bci ihrer 

 Bildung wirksamen Krafte/' p. 76> 



§ " On the so-called ' Inactive ' Condition of Solids," Phil. Mag. for Au- 

 gust and September 1867. 



|| Comptes Rendus for 1866 and 1867. 



