. The microscope : an introduction to microscopic methods and to histology. Microscopes. 72 LIGHTING AND FOCUSING [ CH. II It frequently happens that the upper surface of the back com- bination of the objective becomes dusty. This may be removed in part by a brush, but more satisfactorily by using a piece of the soft paper loosely twisted. When most of the dust is removed some of the paper may be put over the end of a pine stick (like a match stick) and the glass surfaces carefully wiped. CARB OF THE EYES § 127. Keep both eyes open, using the eye-screen if necessary {Fig. 67); and divide the
. The microscope : an introduction to microscopic methods and to histology. Microscopes. 72 LIGHTING AND FOCUSING [ CH. II It frequently happens that the upper surface of the back com- bination of the objective becomes dusty. This may be removed in part by a brush, but more satisfactorily by using a piece of the soft paper loosely twisted. When most of the dust is removed some of the paper may be put over the end of a pine stick (like a match stick) and the glass surfaces carefully wiped. CARB OF THE EYES § 127. Keep both eyes open, using the eye-screen if necessary {Fig. 67); and divide the labor between the two eyes, i. e. use one eye for observing the image awhile and then the other. In the beginning it is not advisable to look into the microscope con- tinuously for more than half an hour at a time. One never should â work with the microscope after the eyes feel fatigued. After one. Fig. 67. Adjusting Eye-Shade. This is prepared by covering a card about 6 x 12 centimeters with black velveteen. A copper wire about 5 mm. (Y% in.) and of the right length is curved as shown in the figure. Its ends are rounded, and finally it is put under the cloth and sewed carefully all around. The card and cloth are then cut as shown. The flexible wire makes it possible to put the screen on the tube at any level. becomes accustomed to microscopic observation he can work for several hours with the microscope without fatiguing the eyes. This is due to the fact that the eyes become inured to labor like the other organs of the body by judicious exercise. It is also due to the fact that but very slight accomodation is required of the eyes, the eyes remaining nearly in a condition of rest as for distant objects. The. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Gage, Simon Henry, 1851-1944. Ithaca, N. Y. : Coms
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