178 



PKACTICAL PHOTO-MICKOGKAPHY 



But it will be found that, if properly made with due regard 

 to the mechanical principles involved, some such spring 

 support is perfectly efficient. 



A further method, which the writer has not seen in 

 operation but which he understands has been tried, is to 

 float the whole apparatus in a tank of water. This obviously 

 presents many difficulties, and is only to be regarded as a 

 suggestion of a possible experimental method worth trying 

 when everything else has failed. 



It is not easy to overrate the effect of vibration when 



work of a critical nature 

 is being attempted in 

 an ordinary laboratory 

 or a house, and many 

 a photograph over 

 which great care has 

 been expended in other 

 respects, has been 

 spoilt by the want of 

 attention to the elimi- 

 nation of this very 

 troublesome factor. 



Light - excluders 

 between the Camera 

 and Microscope. The 

 microscope and camera 

 are for all essential 

 purposes two separate 



pieces of apparatus, but a connection must be made between 

 the eye-piece end of the microscope and the front of the camera 

 by some arrangement that will effectually prevent the entrance 

 of extraneous light. This may be simply effected by having 

 a velvet or cloth tube with an elastic band at either end which 

 slips over the microscope tube and over a short tube protruding 

 from the front of the camera. While this is quite efficient, it 

 has the disadvantage that in the actual connecting up of the 

 microscope to the camera there is considerable danger of the 

 adjustments of the instrument being altered. The almost 

 universal method is now to have a light-excluding device, as 

 Fig. 62. This has the advantage of great simplicity in use, 



FIG. 62. Appliance for excluding Light. 



