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| A Short History of the
Microscope |
Historians disagree as to who invented the microscope.
Spectacles were known in Florence, Italy in the late 1200's.
In the late 1500's, Dutch spectacle-makers began experiment with
lens. In 1608, Hans Lippershey, applied for a patent on his
magnifying tube which enlarged distant objects. He reported also
used variations of it to enlarge subjects near at hand. A few
months later, Italian instrument maker Galileo made his own magnifying
tube, and reported, "I have seen flies which look as big as lambs,
and have learned that they are covered over with hair and have very
pointed nails by means of which they keep them selves up and walk on
glass, although hanging feet upwards, by inserting the point of their
nails in the pores of the glass." He discovered, to his
dismay, that while a telescope focused on the stars need to be only two
feet long, to magnify small objects nearby required a tube two or three
times that length.
As early as 1625 a member of the Academy of the Lynxes, the
physician-naturalist John Faber had a name for the new device.
"the optical tube... it has please me to call, after the model of
the telescope, a "microscope," because it permits a view of
minute things."
Although many were very suspicious of the
"artificial image" produced by the telescope, it was
observable that it did enlarge distant objects. It was
immediately useful. This was not the case the microscope.
Although a greatly enlarged image of everyday things was
fascinating, no one could see any practical purpose for the
microscope. |
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| In 1665, Robert Hooke published
Micrographia, an enticing miscellany expounding his theory of
light and color, and his theories of combustion and respiration.
It included a description of the microscope and its uses.
But the widespread suspicion of optical illusion would
plague him. At first the "new world" he claimed to see
through his lenses were the butt of ridicule, but what Galileo did
for the telescope Hook did for the microscope. Fifty-seven
amazing illustrations drawn by Hooke himself revealed for the
first time the eye of fly, the shape of bee's sting organ, the
anatomy of a flea and louse and much more. When his
discovered the honeycomb structure of cork, he said it was made of
"cells," thus coining the word. |
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| Three pictures from
Micrographia:
stinging hairs on a nettle, a flea, and corks "cells."
At Left: his microscope. Light provided by candle and directed by
a lens on to the subject. |
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Antonie van Leeuwenhoek |
| As the years passed, an international community of
science began to grow. In 1668, the Philosophical Transactions
of the Royal Society of London published an extract from an Italian
learned journal telling how an Italian lens-maker, Eustachio Divini,
using a microscope, had discovered "an animal lesser than any of
seen hitherto." Five years later, Henry Oldenburg, who was in
London publishing the Philosophical Transactions received a
letter from the Dutch anatomist Regnier de Graaf describing the
work of a Dutchman, Antonie van Leeuwenhoek, who "has devised
microscopes which far surpass those which we have hitherto seen.
Antonie sold wool, cotton and other textiles and also
worked as the inspector of weights and measures. He often used low-power
magnifying glasses to inspect the quality of cloth, and this awakened an
interest in other things. He began grinding his own
lens. |
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Unlike Hooke and others, who used a
compound microscope that combined two or lenses, Leeuwenhoek used
a simple microscope, such as that shown at right. The specimen was
mounted on the top of the pointer. Just above it is a tiny lens.
The specimen was viewed by holding the microscope and looking at the
specimen through the other side. Leeuwenhoek eventually ground some five hundred fifty
lens of which the best had a linear magnifying power of 500 and a
resolving power of one-millionth of a meter. Over a period of
years, he reported his findings to the Royal Society through letters -
one hundred and ninety of them. In 1674, he filled a glass
vial cold water from a nearby lake, and found" many small
animalcules. He then turned his microscope on a drop of pepper water |
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"I now saw very plainly that these were little eels, or worms,
lying all huddled up together and wriggling just as if you saw, with the
naked eye, a whole tubful of very little eels and water, with the eels
squirming among one another; and the whole water seemed to be alive with
these multifarious animalcules. This was for me, among all the
marvels that I have discovered in nature, the most marvelous of all; and
I must say, for my part, that no more pleasant sight has every yet come
before my eyes that these many thousand of living creatures seen all
alive in a little drop of water, moving among one another, each several
creature having its own proper motion." |
| In his famous Letter 18 to the Royal Society
(October 9, 1678), he concluded that "these little animals were, to
my eye, more than ten thousand times smaller than the animalcule
which Swammerdam has portrayed, and called by the name of
Water-flea, or Water-louse, which you can see alive and moving in water
with the bare eyes. Having discovered the world of bacteria,
Leeuwenhoek declared that each had its full complement of bodily organs
needed for life. He opened the doors to microbiology, embryology,
histology, entomology, botany and crystallography. |
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