370 THE AMERICAN MONTHLY \Tfec. 



measure to the impetus given by Dr. Woodward iu his 

 efforts to obtain the best for use in Photo-Micrography. 

 Indeedj Nobert saw for the first time the lines of his 

 nineteenth band in a photograph made by Dr. Woodward 

 with one of these object glasses. 



But even more marked in their effect upon Photo-Mi- 

 crography, than the improvements in objectives, have 

 been the changes in photographic methods, since Dr. 

 Woodward's day. He worked within his camera itself, 

 his workroom constituting a gigantic camera box, to 

 which no ray of light was admitted during the focussing 

 of the object and exposure of the plate save that which 

 passed through the microscope. 



The source of light varied according to time and cir- 

 cumstances. Usually he employed that of the sun 

 through an immense heliostat, which is still in use at the 

 museum. But as a very large proportion of his work 

 was done at night, he also called in the aid of various 

 artificial illuminants, viz. : magnesium ribbon, the lime 

 light, and toward the end of his work, the electric arc 

 lamp, each with unvarying success. Not being an expert 

 photographer himself, this portion of his work was done 

 by a professional, and it may not be uninteresting to 

 know that colodion or wet plates alone were used. Gel- 

 atine emulsions were as yet unknown, or practically 

 unattainable. 



It will thus be seen that in addition to his own won- 

 derful skill as a manipulator. Dr. Woodward had at his 

 disposal unlimited government resources as aids to his 

 researches and experiments. Indeed, it may be safely 

 said, that no other worker in the same field ever was so 

 liberally provided with the means for prosecuting it. The 

 cost in every direction was deterrent to the most of less 

 fortuuate mortals, and as stated before, but for the many 

 radical changes since made in photographic methods. 



