One of the most important instruments used in biology is the microscope. This tool allows us to see that which is imperceptable by the naked eye. History has it, that around 1 AD the Romans undertook the task of investigating the properties of glass and how these properties helped magnify objects when one looked through glass. It took roughly another 12 centuries before the understanding of glass led to the production of the first eye glass. Salvino D'Armate of Italy, would become known as the first person to produce the eye glass, providing the wearer with the power of magnification in one eye. Fast forward nearly 3 centuries and we get the first compound microscope. Around the late 1500's, Zacharias Jansen and his father, Hans used thier knowledge of spectacle making and placed several lenses in a tube, today this tube is known to contain two types of lenses, at the top, the ocular lens or eyepiece (what we look through) and at the bottom, the objective lens, which produces the primary magnified image, which in turn is then amplified by the ocular lens. This two-stage magnification is the principle and basis of the compound microscope.

-O. James

The drawing on the right represents the compound microscope. To view enlarged image in a new window, simply click on image (drawing by Orin James).

1. Ocular Lenses or Eyepiece - Used to view specimen.
2. Head - Provides support for objective lens and oculars.
3. Arm - Connects base and head.
4. Power Switch- Provides power to light source.
5. Light Control - Increases or decreases the amount of light on specimen.
6. Coarse Adjustment Knob - Allows for focusing in on the specimen.
7. Fine Adjustment Knob - Allows for fine tuning the focus on the specimen.
8. Base - This structure supports the entire microscope.
9. Substage Light - Primary light source for viewing specimen.
10. Iris Diaphragm Lever - Regulates the amount of light passing through the condenser (see condenser).
11. Condenser - Small lens that concentrates the light on the specimen.
12. Stage - Platform for the specimen being viewed.
13. Mechanical Stage / Clippers - This apparatus helps secure and manipulate the specimen, using the rotary knobs.
14. Objectives or Objective Lenses- These lenses vary by power. They provide initial magnification of the specimen.
15. Rotating Nose Piece- This is used to rotate the objective lenses.

-O. James