112 



PRACTICAL PHOTO-MICROGRAPHY 



make an effort to build or to design and have built an apparatus 

 according to their own ideas, and the writer is strongly of the 

 opinion that such an arrangement, crude though it may be, 

 usually gives the best results in the hands of an intelligent 

 worker. Each one will have ideas which as the result of 

 experiment they would like to carry into practice, and an 

 apparatus built up as the result of practical experiment is 

 usually most satisfactory. 



The designs for an apparatus may be divided very broadly 

 into two well-defined types. In one 

 arrangement, and probably the one which 

 is most generally used and has the 

 most to recommend it, the microscope 

 and camera are supported on one very 

 stiff and solid base, so that no alteration 

 of either part in relation to the other 

 can take place. In the other type the 

 microscope and camera are supported 

 and treated as two separate pieces of 

 apparatus, the idea in this design being 

 that where any outside influence tends 

 to disturb the position of either of the 

 components, it would then only affect one 

 of them. For instance, if in the course 

 of focussing the image on the screen of 

 the camera, in inserting the dark-slide 

 or in withdrawing the shutter, some 

 alteration takes place in the position of 

 the camera, the microscope and its adjust- 

 ments will not be affected. It is claimed for this method 

 that the greatest evil would result from any movement of the 

 microscope and such is unquestionably the case therefore 

 that the microscope should as far as possible be isolated and 

 so arranged that it is free from such disturbing influences. 

 One of the greatest troubles usually met with where the work is 

 carried out in an ordinary room or laboratory is vibration or 

 tremor. Well-defined shaking of the apparatus is rarely a factor, 

 as any worker would usually take reasonable precautions against 

 any dislocation of the apparatus,' but it is the ordinary tremors 

 that are the most difficult to provide against. It would appear 



FIG. 36. Simple Form 

 of Photo-micrographic 

 Camera. (J. Swift & 

 Son.) 



