Lenses, for the purpose of magnifying objects were first used as early as the thirteenth century.  It wasn’t until about 300 years later that scientists discovered that they could use lenses in studying the minute structures of natural objects.  In 1637, the French Philosopher and Physicist Descartes published a diagram of a microscope.  This diagram shows us a device in which light was reflected onto an object by means of a concave mirror.  There were various versions of this instrument, but it is generally accepted that a pair of Dutch spectacle makers, Hans and Zacharias Janssen created the first microscope in 1590.  Of course, the use of the microscope would be of critical importance for the pioneers in microbiology and immunology.

A microscope magnifies an object many more times by using two lenses.  There are essentially three main types of microscopes: Compound, Stereoscopic or Dissecting and Electron.  We will leave the electron microscope to the professionals and focus on the other two.

1. Compound Microscopes - These are slide-viewing microscopes and have at least one eye piece and two or more objectives.  They contain a stage for holding the slides and have some source of illumination.  The idea here is for the light to pass through the object and then through the lenses to the viewer’s eyes.  The total power of magnification can be calculated by multiplying the magnification of the eye piece lens and objective lens.  If an eye piece has a magnification of 10x and the objective lens has a magnification of 20x, then the total magnificatin is 200x.  Then what you see through the microscope is made 200 times larger than you would see with just your own eyes.
2. Stereoscopic Microscopes - These microscopes have dual eye pieces for three-dimensional stereo viewing with one objective lens. Some have illumination and some do not.

What to buy?

• If your child or student is going to be viewing three-dimensional objects such as rocks, minerals, flowers, or insects then the Stereoscopic Microscope is for you.  This microscope is a very good choice for younger children.  Your child will be amazed at what they can see.
• If your "young scientist" has a little more dexterity and wants to see microscopically (objects unseen by our eyes), then a Compound Microscope is your best choice.  With this type of microscope you will be able to see inside cells and some simple organisms.

     Club Scientifics’ Top Ten Microscope Buying Tips

1. Decide if you want a compound or a stereo microscope.
2. Do not buy the poor quality microscopes you find in department or science/hobby stores.  You will be disappointed in their performance and it will soon be discarded.
3. Spend a minimum of $100-200 dollars for a quality beginner student microscope.
4. Make sure that the microscope frame, screw fastners and focusing system are NOT plastic.
5. Purchase a microscope with separate coarse and fine focus adjustments.
6. Obtain a microscope that uses fluorescent illumination, NOT tungsten (incandescent).
7. Look for glass achromatic lenses and a microscope with a slip clutch, which will allow the focus knob to slip (turn in place) without damaging the microscope focus system.
8. As an option, consider a mechanical stage which will help hold the slides in place.
9. You might want to opt for a microscope with an iris diaphram instead of a disk diaphram making it easier to adjust the light.
10. Buy a book!  There are some great books about microscopes which contain lots of useful information and activities.  Certainly your young scientist has to have something to do once they have that microscope in hand.  As a starting point we recommend the following books.

• The Microscope Book by Shar Levine & Leslie Johnston
• The World of the Microscope - A Usborne Science and experiment book.

Shop online for a quality microscope

• Meade microscopes - www.meade.com
• Carolina Biological - www.carolina.com
• Nasco Science - www.enasco.com