MICROSCOPIC DRAWING AND ENGRAVING. 



determines the form of the characters, and the motion in the direc- 

 tion of the axis at right angles to that surface determines the depth 

 of the incision, if it be engraving, or the thickness of the stroke, if 

 it be writing. 



33. Having thus explained the principal results of the art of 

 microscopic engraving, it remains to offer some notice of the not 



Ffc. 27. 



APPEARANCE AS SEEN IN THE FIELD OF THE MICROSCOPE, THE OUTER CIRCLE BEING 

 ONLY THE 30TH OF AN INCH IN DIAMETER. 



less interesting methods of delineating microscopic objects, or trans- 

 ferring to paper, metals, or wood fac-similes of the appearances 

 presented in the microscope: The methods of accomplishing this 

 have varied with the varying resources presented to art, by the 

 progress of the sciences. 



34. The first attempts at delineation of this kind were made by 

 dividing the field of the microscope into a system of squares, by 

 74 



