1885.] NEW-YORK MICROSCOPICAL SOCIETY. 55 



A little reflection in regard to the space in which we live, will 

 show us how ignorant we are of the surroundings of our exist- 

 ence ; and how inconceivable are the facts — those things that we 

 know to be facts — around us. We cannot conceive of any 

 atom so small that it cannot be divided, or of any extension 

 of space so great that it has no bounds ; and it is between these 

 infinities that we live, and are trying to push each way into the 

 unknown ; — by the telescope and mathematics into the vast dis- 

 tances outside of this globe, and by the microscope among the 

 minute forms of life, toward the constitution of matter. 



Of the constitution uf matter, we learn only indirectly. We 

 are all familiar with the molecular and atomic theory. Although 

 it is a theory, something like it must be true ; for there is a sub- 

 division that will, if continued, separate all compound substances 

 into their original elements, the atoms of which are smaller than 

 the molecules — such as water into hydrogen and oxygen. Be- 

 yond this, it is quite as much a mystery as the outside confines 

 of space. 



One thing is evident, — the constitution of matter appears to 

 be adapted to beings of about our size. Many inconveniences 

 would attend a man one-sixteenth of an inch high ; every drop 

 of water would be a mountain, and no existence, such as we now 

 have, would be possible. An expansion, instead of reduction, 

 would be equally undesirable, as a moment's thought must show. 

 Still, microscopically, we are far away from either molecules or 

 atoms ; for, according to Sir William Thomson's researches on 

 thin films, a molecule of water must bear the same ratio to a drop 

 the size of a pea, as an orange to a globe the size of the earth. 



The question is often asked, "How much will the best micro- 

 scope magnify ? " Now, it is not a question of magnifying, at all. 

 It is, '* How much can we see when we do magnify ? " The 

 commonest lens of one-inch focus, can make a picture of an 

 object — either on a screen or to be viewed by an eye-piece — of 

 two or three thousand diameters ; but the whole picture will be 

 so imperfect and obscure,'nhat no detail can be seen ; and the 

 eye can see much better when the magnifying power is only 

 sixty or seventy diameters. 



So, in regard to the best homogeneous-immersion lenses, the 

 limit of clear vision is five or six thousand diameters. There- 

 fore, the possibility of seeing a molecule by a lens that would 



