THE PHOTO-MICKOGKAPHIC CAMERA 129 



influence likely to cause relative movement of any of the 

 parts. 



An arrangement of practically the same design as the 

 above is made by the Bausch and Lomb Optical Company of 

 Eochester, U.S.A. It embodies all the main principles of 

 the Zeiss apparatus, but is supported somewhat more strongly, 

 and admits of the microscope and the optical accessories being 

 lowered sufficiently for the instrument to be used in a vertical 

 position. In essential respects this apparatus differs but little 

 from the one by Zeiss, already described. 



Nearly all firms supplying microscopes now make an 

 apparatus for photo-micrography which embodies most of the 

 points already enumerated. The large apparatus made by 

 Messrs. Swift is after a model designed by Mr. Andrew Pringle, 

 and therefore, it is needless to say, founded on the result of 

 very wide and long experience. The whole apparatus is 

 carried on one base, and the only point which is not mentioned 

 in some previous type of instrument, is that the front portion of 

 the microscope, when it is thrown into the horizontal position, 

 is supported on a triangular trunnion. Therefore, the weight 

 of the body-tube of the instrument is not taken entirely by its 

 own tripod base ; nor is the tendency to vibration or flexure 

 of the apparatus so great when the microscope is of a very 

 heavy and substantial design. 



In most modern instruments this addition is not necessary ; 

 in fact, it should not be necessary, as the design should be such 

 that the instrument is well balanced in either the horizontal 

 or vertical position. Further, as the tendency of late is to 

 simplify and reduce microscopes in weight and size, any 

 additional means of support for the body-tube is not advisable. 

 In other respects this apparatus is substantially made, and 

 is capable of doing work of the highest order. 



Similar types are also made by Messrs. W. Watson & Sons, 

 Charles Baker, and E. & J. Beck ; but as none of these embody 

 points that are entirely novel or peculiar to themselves it would 

 not appear to be necessary to set out a detailed description of 

 them here, but reference should in each case be made to the 

 makers' catalogues. 



The type of apparatus used by the writer differs in many 

 particulars from any of those hitherto described, and as it 



