118 A HALF-HOUK WITH POLARIZED LIGHT. 



rewarm the slide, and apply the opposite edge of 

 the cover to the edge of the balsam, and allow 

 the cover to fall gradually down ; when the 

 glass disc is covered by the balsam, press care- 

 fully until all the superfluous balsam is squeezed 

 out. 



We must now, however, draw our last half-hour 

 to a close. All we have attempted has been in the 

 way of introduction. We have only described those 

 things which are most easily obtained, and we have 

 sought rather to create a desire for further know- 

 lodge, than to impart an exhaustive amount of 

 information on any one subject. 



Those who have properly apprehended our re- 

 marks will see that there is not a distinct science 

 of microscopic objects, but that these objects belong 

 to various departments of science, whose great facts 

 and principles must be studied from works devoted 

 to them. The Microscope is in fact an instrument 

 to assist the eyes in the investigation of the facts 

 of structure and function, wherever they may occur 

 in the great field of nature; and that inquirer 

 must have a very limited view of the nature of 

 science, who supposes either that the Microscope is 

 the only instrument of research, or that any in- 

 vestigation, where its aid reveals new facts, can be 

 successfully carried on without it. 



