652 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Class 1. — Simple. {To illustrate the Early Type of Simple 



Microscope.) 



LEEUWENHOEK. (Copy,) About 1673. 

 Type — Simple Microscope. 



Two thin metal plates are fastened together by rivets. Between 

 these plates a very small double convex glass lens is mounted between 

 two concavities provided with minute apertures. The object is held in 

 front of the lens on the point of a short pin, the other end of which 

 screws into a small block or stage of brass, which is riveted on the end 

 of a long coarse-threaded screw acting through a socket angle-piece 

 attached behind the lower end of the plates. It is with such instru- 

 ments, of the rudest kind mechanically, that Leeuwenhoek astonished 

 the world with his discoveries of Infusorians, Bacteria, and other 

 microscopic forms of life. 



Described and figured in Mayall's Cantor Lectures, 1885, p. 20, and 

 in Journ. R.M.S.,, 1886, pp. 1047-9. 



Lent by Sir Frank Crisp. 



MUSSCHENBROEK. Date, about 1690. 

 Type — Simple Microscope. 



Consists of a hollow handle, through the length of which slides a 

 tube, which is controlled by a knob at the base. Various forms of 

 object-holders can be inserted in the tube, whilst the handle is provided 

 with hinge-joints set at right angles, and by means of two thumb-screws, 

 acting against springs, the object can be moved laterally and adjusted to 

 the focus of the lens. The small biconvex lenses are mounted between 

 two thin plates of brass, fitted to slide in metal grooves in the carrier, 

 over which slides a metal box, with a pivoted sector of diaphragms. This 

 is the first time this system of changing diaphragms occurs, and it is 

 the precursor of the modern wheel of diaphragms. The carrier is con- 

 nected to the handle by means of a strong brass wire bent to two right 

 angles ; this arrangement gives considerable scope for movements 

 forward or backward, and laterally. 



Described and figured in Zahn's Oculus Artificialis, 2nd ed., p. 783, 

 and in Mayall's Cantor Lectures, 1885, p. 24. 



Lent by Sir Frank Crisp. 



LIEBERKUHN. About 1738. 



Type — Simple Microscope. 



Lieberkuhn devised a combination of a simple biconvex lens, mounted 

 in the central aperture of a polished metal reflector, which formed a 

 small hand Microscope for the special purpose of viewing opaque objects. 

 This construction, in an improved form and applied to achromatic 

 object-glasses, is in use at the present day. 



The present model shows this form as made by Adams. See Adams' 

 Micrographia Illustrata, 1747, p. 16. 



