NOTES AND MEMORANDA. 



Eelation between the Limit of the Powers of the Microscope 

 and the TTltimate Molecules of Matter.^ 



The subject which I have selected for my address is the 

 relation between the limit of the powers of the microscope, 

 and the ultimate molecules of organic and inorganic matter. 

 I think I may at all events claim for this question sufficient 

 novelty. Until the last few years the subject could scarcely 

 have been attempted, and even now so many necessary facts 

 are imperfectly known, that nothing more can be done than 

 to fill the gaps with plausible assumptions. This neces- 

 sarily imparts more or less of a speculative character to some 

 of my remarks ; but it appears to me that in his annual 

 address the president of a society cannot do better than 

 endeavour to point out the general bearings of what is 

 already known on some great question, even if for no other 

 object than to prove the need of further inquiry. 



Though fully impressed with the imperfect state of our 

 knowledge, yet, even now, the facts are sufficiently definite 

 to indicate, if not to prove, the existence of as wide a world 

 of structure beyond the limit of the power of the microscope, 

 as what has been revealed to us by it is beyond the powers of 

 the unassisted eye. 



I propose to divide my subject into three heads — 



1. The limits of the power of the microscope. 



2. The size of the ultimate molecules of organic and inor- 

 ganic matter. 



3. Conclusions to be drawn from the general facts. 



In considering the limits of the power of the microscope, 

 I shall assume that the instrument itself is perfect, and that 

 the invisibility of the objects examined is in no way depen- 

 dent on the want of the necessary characters. The point 



' Abstract of the Anniversary Address of the President of the Royal 



Microscopical Society, H. C. Sorby, F.E..S., &c. With corrections com- 

 municated by the Author. 



VOL. XV NEW SER. P 



