0* THE MICROSCOPE. 39 



knows, it is often of great importance that both polarizer and 

 analyzer should be kept stationary, while the object itself 

 rotates between them. 



The Inverted Microscope. Some years ago, Professor 

 J. Lawrence Smith devised a microscope specially adapted to 

 chemical investigation. In this instrument the stage is placed 

 over the objective, which is inverted, and the body connected 

 with it at an angle. A prism reflects the image of the object, 

 and causes it to pass up the body to the eye of the observer. 

 For some purposes it is a very useful instrument. Nachet 

 seems to be the only maker that keeps this form in stock. 



Tlie Binocular Microscope. More than two hundred 

 years ago, attempts were made to construct binocular micro- 

 scopes, and yet a good and efficient binocular is a thing of 

 yesterday. Professor Riddel of this country, M. Nachet of 

 Paris, and Mr. Wenham of London, seem to have been most 

 prominent in the efforts that have been made of late years to 

 perfect this instrument, and to Mr. Wenham is due the credit 

 of having produced a method which is at once efficient and 

 easily made. Indeed, so little does the binocular feature now add 

 to the expense of even good microscopes, that a London made 

 stand, which in its monocular form costs $90, can be had as a 

 binocular of the most excellent quality for $100. Mr. Wenham 

 has, therefore, laid all microscopists under deep obligations, 

 not only by devising such simple and efficient means of accom- 

 plishing a most desirable result, but by giving the use of his 

 invention freely to the world. 



Of the value of the binocular, there is a wide difference of 

 opinion, some regarding it as a mere toy, and altogether 

 beneath notice as an instrument of scientific research, while 

 others consider it a most important addition to our means of 

 investigation. Since, however, it will almost always be found 

 that those who place a high value on the binocular are those 

 who have used it most, while those who decry it know abso- 

 lutely nothing of its merits, and are even ignorant of the man- 

 ner of using it, the reader will have but little difficulty in de- 

 ciding on which side the truth lies. In England, where cheap 



