52 THE MICROSCOPE. 



being of light weight, can be carried in the coat-pocket : the cost com- 

 plete is 21. 10s. 



The following useful remarks on the microscope are extracted 

 from the Juries' Reports of the Great Exhibition, 1851 : " The powers 

 varying from one-inch to a quarter-inch focus, inclusive, are by far the 

 most generally useful in the whole range of microscopic combinations, 

 especially for educational purposes. It must be remarked, that the 

 angle of aperture of the combinations should not be extended to its 

 utmost possible limit when destined for the general purposes of natural 

 history or anatomical investigation. Combinations of high power, and 

 extremely extended angle of aperture, are excellent in developing one 

 class of test objects, viz. minute lines or dots on plane surfaces, and 

 admirably demonstrate the high perfection to which such glasses are 

 capable of being carried by scientific opticians; but such combinations, 

 with a less angle of aperture and more penetrating power, are far more 

 generally useful and valuable to the minute anatomist and the naturalist. 

 In regard to the brass-work, the qualities especially requisite in the 

 stand of a microscope are simplicity of construction, portability, com- 

 bined with sufficient weight to ensure safety and steadiness, with smooth- 

 ness and accuracy of action in all the working parts, and such a con- 

 struction as to distribute any tremor that may be communicated to the 

 instrument equally over its body, stage, and other working parts." 



