DR. L. SMITH S INVERTED MICROSCOPE. 



$5 



in such a limited compass that space is still left for the Objectives 

 and Accessory apparatus most useful to the working Naturalist. 

 This instrument may be specially recommended to those who, 

 already possessing a superior Microscope, desire neither to en- 

 cumber themselves with it whilst travelling, nor to expose it to 

 the risk of injury, but wish to utilize its Objectives by means of 

 a simple and portable arrangement. * 



59. King's Pneumatic Aquarium Microscojie. — The purpose of 

 this instrument is to enable such as possess an Aquarium to apply 

 the Microscope to the examination of the structure and habits of 

 the living animals it may contain, without disturbing or interfer- 

 ing with them in any way. It is simply a Microscope especially 

 adapted for use with very low powers (a 2-inch and a 4-inch com- 

 bination will be found most serviceable), which can be attached 

 by a kind of sucker to the glass of the Aquarium, whether round 

 or flat.; the needful exhaustion being made by turning a screw. f 



60. Dr. Lawrence Smith' s Inverted Microscope.-— A very ingeni- 

 ous arrangement has been devised by Dr. J. Lawrence Smith, of 

 Louisiana, U.S., whereby objects may be viewed from their under 

 instead of from 

 their upper sur- 

 face ; and thus Heat 

 or Reagents may be 

 applied to them , 

 without any risk of 

 dimming or more 

 seriously injuring 

 the object-glass by 

 the vapours thus 

 raised. The gene- 

 ral plan of this in- 

 strument, as con- 

 structed by MM. 

 Nachet, is shown in 

 Fig. 42 ; whilst 

 Fig. 43 explains 

 the principle of its 

 action. The Body 

 is screwed obliquely 

 into a kind of box 

 which is attached 



Fig. 42. 



Dr. Lawrence Smith's Inverted Microscope. 



to the base of the instrument, and which contains a Prism 

 of the form shown in Fig. 43, its angles being respectively 55°, 

 107^°, 52^°, and 145°. The Objective is screwed erect into this 



* An instrument nearly resembling the above is made by Messrs. 

 Murray and Heath. 



t The Aquarium Microscope is made by Mr. Collins, at the price of 

 8 guineas. 



