Anton van Leeuwenhoek was born on October 24, 1632. To earn a living, he was a merchant, and then a cashier, and a store keeper. However, what he is best known for is his microscope.
To be sure, devices to magnify had been invented or rather discovered before, but Leeuwenhoek’s microscope had unusually high magnifying power. His microscopes used but one lens, and yet with it he achieved wonders. He had people believe that he laboriously ground the lenses into shape with a secret method, but more research has indicated that such a feat would have been impossible. Come to find out, by carefully heating a glass rod, a tiny ball of glass with enormous magnifying power can be produced. It was thus that he made his lenses.
Leeuwenhoek studied all sorts of interesting things, including hair, muscle fibers, nerves, blood, and entire insects; but he gained most of his renown for his discovery and research of protozoa. He sent his protozoa discoveries to the Royal Society of London. However, they refused to believe in the existence of protozoa, until upon Leeuwenhoek’s persistence, they sent a team of doctors, jurists, and a vicar to visit him and see for themselves the results of his research. When the team looked through his microscope, they were amazed at what they saw. The team reported back, and the Society insisted that he work for them. For fifty years thereafter, Leeuwenhoek made observations with his microscope and sent them to scientific institutions including the Royal Society of London. He continued to research in spite of serious illness, and refused to stop until his death in 1723.
Modern microscopes use multiple lenses to achieve superb magnification. For every lens added, the microscope’s magnification multiplies. For example, if the eyepiece has a magnification of 15 times, and the objective lens (which is the lens that focuses on the object being studied) has a magnification of 40 times, the result is 600 times of amplification (the two numbers being multiplied). The eyepiece (No. 1 shown in the illustration to the right) usually does have a magnification of around 15 times, while the objective piece (No. 3) varies enormously. Often enough, a bank of objective lenses of different values are attached to a rotating disk (No. 2), allowing the magnification to be changed. A light source (No. 7) under the object illuminates it, providing a sharp image. To focus on an object, adjustments are provided which bring the object being studied closer to or farther from the objective lenses.
As for Leeuwenhoek’s microscope, it doesn’t look much like anything you see today. A large copper plate held the tiny eyepiece, while a needle was used to hold the specimen before it. The needle was adjusted as needed. However, to change the magnification, Leeuwenhoek had to build a whole new microscope! The instrument was crude, but highly effective compared to anything else available at the time.
As can be seen, Leeuwenhoek’s microscope revolutionized the field of microscopes. It proved that large magnifications were possible, and opened the door to detailed study of living things significantly smaller than the period at the end of this sentence. That study is what we now call microbiology.
Further Investigation
Anton Van Leeuwenhoek
A biography from PBS.
Tiny Lenses
All about the lenses used in Leeuwenhoek’s microscope.
History of the Microscope
Brief history that also includes a photo of a van Leeuwenhoek microscope.
The Microscope – Parts and Specifications
Diagram with explanations.
Amoeba
Information from Enchanted Learning.
Ron’s Pond Scum
A vast series of images taken through a microscope. “An Adventure in Protozoan Art.”
Activities
Let’s Make an Antoni van Leeuwenhoek’s Microscope
Not particularly practical, but very interesting!
Van Leeuwenhoek’s Surprise
Lesson plan for learning how microbes were first discovered.
Microscopic Experiments and Labs
18 options with instructions including one on protozoa.
Amoeba Coloring
Information and labeling diagram worksheet.
Virtual Electron Microscope
Interesting interactive that lets you use an electron microscope to identify samples.
Books
The World of the Microscope
Usborne Science and Experiments title that includes basic information such as the history of the microscope, types of microscopes and how a microscope works, but also helpful resources such as how to use a microscope, first projects (to become familiar with slide preparation), drawing what you see, making sections, staining, and mounting and measuring. Activities include examining cells, fungi, simple organisms, microscopic water life, plants, insects, rocks and minerals, and crystals. Perfect for a do-it-yourself science course!
How to Know the Protozoa by Theodore Jahn
Definitive classic on the subject with extensive illustrations. Works very well as part of an older student’s biology course.
Greg’s Microscope by Millicent E. Selsam
Simple text but interesting for early reader. Illustrated by Arnold Lobel.
The Microscope by Andrew Ross
Public domain work for the older student, describing in relatively easy to understand language how the instrument works.
Notebooking Helps
Standard Microscope
Microscope part labeling diagram for notebook.
Label Amoeba Diagram
From Enchanted Learning.
Microscope Data Sheet
For recording observations.
Microscope Lab Sheet
Another option for the younger student from Guesthollow.com.
Complete Book of the Microscope Notebooking Pages
29-page download for everything microscope.
Microscope Notebooking Pages
Primary-lined and regular.
Our own unit studies, book studies and investigations that encourage research and independent learning.
