272 The Microscope. 



present Eastman film roll holder. This camera was merely a 

 cubical box of about four inches square, and without bellows; 

 the focussing being effected by sliding the tube carrying the 

 lens within an outer one. The size of the sensitive plate was 

 2^ x 3| inches, very small, but the lens being adapted to the 

 plate. I had received many pleasant souvenirs of the departed 

 summer's " outing," by its aid; which in the winter's evenings 

 now returned were pleasant to look upon. During one of these 

 evenings whilst working with the microscope an object of such 

 extreme interest came under observation that an irresistible 

 desire to draw or photograph it seized upon me. The former I 

 could not do acceptably; what about the latter? Could my 

 little box be utilized for the purpose ? Would the light of my 

 lamp be sufficient if the camera could be made to answer? 

 Upon carefully examining the latter I found that the outer tube 

 in which the one bearing the lens was slid, exactly fitted on the 

 end or the eye-piece of the microscope, when the cap of the lat- 

 ter was removed. The instrument was inclined at an angle of 

 about 45° just comfortable for convenient use, and the object 

 under observation was brilliantly illuminated by a German stu 

 dent's lamp. Without other change than slipping the cap from 

 off the eye piece, the camera box, (from which the lens and 

 tube had been removed) was made to take its place; and on 

 the ground glass screen a well defined and lighted image of the 

 specimen was seen. A slight alteration of the focus was neces- 

 sary to secure the crispest definition, but there was no doubt 

 thus far of the success of the experiment. A plate holder, con- 

 taining a sensitized plate, was substituted for the ground glass, 

 the light was cut off from the microscope, the dark slide with- 

 drawn from the holder ; all was ready for the exposure. Then 

 the question arose what length of time must be given ? I was 

 absolutely in the dark as to this most important matter ; knew 

 nothing whatever about the relative actinism of sun and lamp 

 light, indeed was so new to photography that I really knew 

 nothing of the subject at all. Manifestly only experiment could 

 determine the proper time. The object was the eyeless flea of 

 the mole ; a rather dense mass of brownish yellow chitine, yet 

 transparent withal, and showing the tracheal vessels within, 

 quite distinctly. The objective was Beck's 1^ inch of the first- 



