Ch. Ill] ROYAL MICROSCOPICAL SOCIETY STANDARDS 



103 



continental microscopes is excellent for high powers and preparations 

 of moderate dimensions, but for the study of serial sections and large 

 sections and preparations in general, a form of mechanical stage which 

 gives great lateral, forward, and backward movement, and which is 

 easily removable, is desirable. Such removable mechanical stages 

 are now produced by all the microscope manufacturers. The latest 

 and best forms enable one to explore the serial 

 sections on slides from 25 x 75 to 50 x 75 mm. 



Royal Microscopicai, Society Standards 

 § 175. Society screw. — Owing to the lack 

 of uniformity in screws for microscope objec- 

 tives, the Royal Microscopical Society of 

 London, in 1857, made an earnest efiort to in- 

 troduce a standard size. 



In order to facilitate the introduction of 

 this universal screw, or, as it soon came to be 

 called, "The Society Screw," the Royal Micro- 

 scopical Society undertook to supply standard 

 taps. From the mechanical difficulty in mak- 

 ing these taps perfect there soon came to 

 be considerable difference in the " Society 

 Screws," and the object of the society in pro- 

 viding a universal screw was partly defeated. 

 (See Edward Bausch, Trans. Amer. Micr. 



Fig. 64. Royal Mic- 

 roscopical Society's 

 Standard Screw for 

 Objectives. 



(From the Jour. Roy. 

 Micr. Soc, Aug. 1896). 



Soc, 1884, p. 153.) 

 In 1884 the American Microscopical Society appointed Mr. Edward 

 Bausch and Prof. WiUiam A. Rogers upon a committee to correspond 

 with the Royal Microscopical Society, with a view to perfecting the 

 standard " Society Screw," or of adopting another standard and of 

 perfecting methods by which the screws of all makers might be truly 

 uniform. Although this matter was earnestly considered at the time 

 by the Royal Microscopical Society, the mechanical difficulties were 

 so great that the improvements were abandoned. 



Fortunately, however, during the year 1896 that society again took 

 hold of the matter in earnest and the " Society Screw " is now accu- 

 rate, and facilities for obtaining the standard are so good that there 



