2. Look through the eyepiece with the low power objective in place and identify the ocular micrometer, check by turning the eyepiece. Note the number of gradations between numbers.
3. Focus the stage micrometer scale and note the gradations that are 0.01 mm apart and those which are 0.1 mm apart (if present). Adjust the two scales so that they are parallel and partially superimposed.
4. Align an ocular micrometer line with a stage micrometer line at the left side of the field. Look for another ocular micrometer line toward the right side of the field which is aligned similarly with a stage micrometer line.
5. Count the number of graduations between the two aligned marks. Count the number of ocular micrometer divisions which span the observed number of mm.
6. Divide the distance by the number of divisions to determine the distance between each two ocular micrometer divisions. Record the results on the chart provided.
7. Repeat the procedure using the high dry objective and the oil immersion objective. Note that with the higher magnifications the stage micrometer lines look thick. It is necessary at these magnifications to align an ocular micrometer line along one edge of a stage micrometer line and choose a second ocular micrometer line also lying along the corresponding edge of a stage micrometer line.
8. Record on the board the calibration of your assign microscope using the oil immersion objective.
9. Measure the diameter of the microscope field on low power, high dry, and oil immersion using the stage micrometer.
10. Return the stage micrometer to its case after carefully wiping off the oil.
11. Measure a rod-shaped bacterium, a coccus, a yeast cell, a protozoan,
and a human red blood cell. Record the results.
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