On a microscope, the iris diaphragm controls the amount of light.
Zacharias Janssen
You place your slide on the stage of a microscope.
100x with oil immersion
telescope, micrscope, barometer and thermometer
It's big under the micrscope
Anton Van Leewenhoek
it is called the diaphram.
The diaphragm is not made out of bone, but the diaphragm is a muscle.
The muscle you are referring to is the diaphragm. It also separates the thoracic cavity from the abdominopelvic cavity.
antonie van leeuwenhoek
The distance in front of and behind the focal point that is in relative focus
the diaphragm is the muscle separating the chest and the abdomen