Have you ever looked at some of the tiny things in nature and wished you had a way to see them more clearly? By using a microscope, we can enlarge the images of these objects and living beings, making it possible to find out more about their structures and the way they function.

Microscope: How to Use It and Enjoy It describes the history and use of the microscope. Before the microscope was invented, people thought there was nothing smaller than the smallest things that could be viewed with the human eye. Then early microscope designers like Robert Hooke changed all that. Robert Hooke made a microscope out of two lenses placed at opposite ends of a long tube. The tube was attached to a stand, and an oil lamp provided light. Hooke also added a mirror to focus the light onto the object being examined. He used his microscope to magnify visible things like fleas. Other scientists began examining living things, called microorganisms, that were never seen before.

Today, most microscopes are called compound microscopes, and use two lenses for greater magnification. The upper lens is called the ocular lens or eyepiece, and the lower lens (or lenses, as there may be a choice of sizes) is called the objective lens. When an image is formed it is actually magnified twice. First, the image is formed at the bottom by the objective lens. Then the image is projected through a tube and magnified again by the eyepiece at the top. The image is always upside down, so what you see through a microscope shows up as the opposite of what you are doing. Any movement of the object also shows up in the opposite way. When you move an object to the right, it appears to move to the left, and when you move it up, its image moves down.

The book also explains how to use microscopes. To use a microscope, you need to place a slide or a specimen on the stage. You should make sure that it is sitting over the hole in the stage. The mirror below will reflect the light source you are using to light up your specimen. For safety reasons, you should never use a microscope in direct sunlight. This could hurt your eyes. Look through the eyepiece to see the specimen. If your microscope has more than one objective lens, then use the lens that shows you the clearest and largest view of the specimen. You can also turn the adjustment knobs until the image is clear. Try rotating the slide to see the specimen in different ways. Remember that you always need to keep both eyes open while looking into the microscope, because this will help you to avoid a painful condition called eyestrain.

Try the Microscope: How to Use It and Enjoy It Activity to examine some of the microorganisms that you can only see by looking through a microscope.