Marvels of the Universe 



393 





I'hotn by'] 



\_A. E. fimilli. 



A CIRCULAR DIATOM. 



This photograph is nearly fifty times larger than the natural 

 size of the Diatom, which is shaped like a watch-glass, and 

 beautifully sculptured, every dot under a still higher magnifica- 

 tion resolving itself into a six-sided figure. 



be remembered, too, that these markings are 

 not themselves visible until the cloak of green 

 integmnent is removed. 



The mind is appalled also when one comes 

 to think that the dimensions of these mark- 

 ings lie in the region of thousandths or even 

 hundreds of thousandths of an inch ! Then, 

 too, imless one is familiar \\ith such small 

 quantities as microscopists are accustomed to, 

 the mind seems unable to grasp what magni- 

 fication is required to be able to see objects of 

 these dimensions. 



To make this clear the following attempt 

 has been carried out. Our first illustration 

 on page 390 is a photograph of an ordinary 

 microscope " slip " — a small piece of glass 

 three inches long and one inch wide. In 

 the centre is seen a ring of black varnish 

 which attaches to the shp a little " cover- 

 glass " made of extremely thin glass about 



.17 milhmetre in thickness. Under this have 



been placed a Uttle scattering of Diatoms ; 



but they are quite invisible to the naked eye. The only appearance capable of being seen under 



the cover-glass is what looks hke a little accumulation of dust more in one part than another. 



In the second photo we are looking at a portion of the space enclosed by the black ring, but 

 more magnification has been employed, and we now see a little, long and thin Diatom lying parallel 

 to a black band running from the top to the 

 bottom of the circle. This band is a human 



hair of the head. It has been so placed to 

 educate the mind to appreciate the size of the 



Diatom in question. The e.xact Diatom is in- 

 dicated by an arrow pointing to it. 



Apply considerably more magnification and 



we now see, as at the foot of the same page, 



the same little Diatom much amplified in size, 



and we notice Unes are now visible running 



across from side to side the whole way down 



its extent. If now we come to higher magnifi- 

 cation stiU, using microscopic objectives of the 



finest quaUty and employing the utmost re- 

 finement of the microscopist's art, we find that 



these lines are really capable of being resolved 



into dots (see upper photo on page 392), and, 



moreover, we discover if we measure them that 



they are so small as to require one hundred 



thousand to be placed side by side to reach 



across a halfpenny ! The mind UteraUy reels 



at an assertion of this kind — it is a statement 



that is at once staggering and appalling. The 



Photo bv] 



IE. J. Sjntta. 



ANOTHER CIRCULAR DIATOM. 



In this form the ornamentation is entirely different from the 

 above, the markings making more than twenty concentric circles 

 cut by thirty radiating lines from the clear centre. (Nearly fifty 

 times larger than life size.^ 



27 



