MICROSCOPIC OBJECTS, 



CHAPTER I. 



NOTES ON THE RECENT IMPROVEMENTS IN 

 MICROSCOPES. 



" The Divine laws work on the minutest and the grandest scale indifferently ; in fact, 

 there is no such thing as great and small in nature, but world spaces are as a hair- 

 breadth, and a thousand years as one day." — Explanations, Vestiges of Creation, p. 6. 



So rapid have been the discoveries by the Achromatic 

 Microscope, that no treatise on animal or vegetable 

 physiology of twenty years' standing can be depended 

 upon as containing a correct account of organic 

 structures. It is therefore unnecessary to offer any 

 remarks on the utility of that instrument. A few 

 details relating to the causes which led to the modem 

 improvements in the Microscope, and the consequent 

 discoveries in science, may, however, be introduced here 

 with advantage. 



About the year 1757 the refracting telescope was 

 made achromatic by the introduction of a concave lens 

 of flint glass, to. connect the errors arising from the 



D 



