The two following =drawing eye-pieces= Nos. 92 and 93, have quickly found favor among those having frequent occasion to make drawings from microscopic preparations and are now largely used in educational institutions as an aid to students in the study of their specimens. In both eye-pieces the prism is so adjusted as to accomplish total reflection of the image, thus doing away with loss of light and with secondary reflections, such disturbing features of those forms of drawing apparatus of which a mirror forms an essential part. [Illustration] 92. This =drawing eye-piece= is employed with the stand in the vertical position. The reflected image lies at the side of the microscope, the rays passing off at an acute angle from the reflecting prism near the top of the eye-piece. The eye-piece slips into the tube of the microscope like any ordinary eye-piece and is held in position by a thumb-screw. The drawing field is at once visible without further adjustment, and the picture is clear and sharp. The brightness of the drawing field may be regulated by smoked glass plates mounted in two moveable metal arms =8.--= [Illustration: Drawing eye-piece for drawing with inclined stand.] 93. This =drawing eye-piece= is similar in construction to that just described, but is so arranged as to throw the image vertically downwards behind the microscope when the latter is inclined at an angle of 45 degrees. In this case also the picture reflected is clear and sharp, devoid of all disturbing secondary images. As the image is reflected vertically downwards upon the table, no special drawing stand is necessary as there is no distortion of the picture. The intensity of the light may be modified by smoked glass plates mounted in two moveable metal arms =10.--= For a description of these drawing eye-pieces and of the principles involved in their construction reference may be had to the Zeitschrift für wissenschaftliche Mikroskopie, XII, 1895. [Illustration: Abbe's Drawing Apparatus.]