THE WONDERS OF MICROSCOPY 



THE use of a lens for magnifying purposes is ancient, but 

 the first "compound microscope" was probably made in 

 1590 by a Dutchman, Zacharias Jansen, whose invention 

 was followed up by Galileo a few years later. But it did not be- 

 come an effective instrument till towards the middle of the 

 eighteenth century. In a "simple" microscope we look at the 

 object directly through a lens or through several lenses. This 

 kind of instrument is often used for microscopic dissection. But 

 in the "compound" microscope we look through an eye-lens or 

 ocular at an inverted image of the object formed inside the tube 

 of the instrument by an object-lens or objective. In all ordinary 

 microscopes there are two lenses in the eye-piece and three lenses 

 in the objective, and all sorts of ingenious devices have been in- 

 vented for making the most of the magnifying power without 

 losing clearness and definition. 



An Invisible World of Life 



In the early days of microscopy the instrument was to a large 

 extent a scientific toy. The observers magnified objects and often 

 drew them very beautifully, but without making them more in- 

 telligible. There is not much gain in seeing a minute object loom 

 large unless we understand it better. This was a necessary stage. 

 Soon, however, great steps were taken, and one of these may be 

 called the discovery of the invisible world of life. The pioneer 



299 



