Janssen microscope

A replica of the Janssen microscope, circa 1595.

Photo courtesy of Lucent Books Inc.
c. 1595
Replican Microscope
© CHIN 2001


Hans and Zacharias Janssen are thought to have made one of the first microscopes (a compound model, using two lenses) in Middleburg, Holland, around the year 1595.

The 18th century was a period of several mechanical improvements to the microscope, such as mechanisms for focussing, changeable objective lenses, specialized stages to accommodate different types of specimens, and raised stages for better illumination of specimens from below. By the end of the 18th century, there were mechanical stages that allowed moving the specimen in two directions.

Microscope makers during the early 19th century made two important improvements to the quality of the optical image. One improvement in lens-making corrected chromatic aberration, an optical effect resulting in images with coloured edges. The other corrected spherical aberration, an optical effect resulting in blurred images. By the 1830s large clear images were being produced, instead of large blurry images.
Hans and Zacharias Janssen are thought to have made one of the first microscopes (a compound model, using two lenses) in Middleburg, Holland, around the year 1595.

The 18th century was a period of several mechanical improvements to the microscope, such as mechanisms for focussing, changeable objective lenses, specialized stages to accommodate different types of specimens, and raised stages for better illumination of specimens from below. By the end of the 18th century, there were mechanical stages that allowed moving the specimen in two directions.

Microscope makers during the early 19th century made two important improvements to the quality of the optical image. One improvement in lens-making corrected chromatic aberration, an optical effect resulting in images with coloured edges. The other corrected spherical aberration, an optical effect resulting in blurred images. By the 1830s large clear images were being produced, instead of large blurry images.

© CHIN 2001

Culpeper-type microscope

A microscope characteristic of the 18th century

Manufacturer unknown
University Health Network Artifact Collection
c. 1800
1942.4.1
© CHIN 2001


Benjamin Martin microscope

A compound/drum microscope characteristic of the mid 19th century

Benjamin Martin
Canada Museum of Science and Technology
c. 1850-1870
UNITED KINGDOM
720429
© CHIN 2001


The most widely used microscopes are optical microscopes, which use visible light to create a magnified image of an object. The simplest optical microscope is comprised of one double-convex lens with a short focal length.

The compound microscope uses two lenses, an objective lens and an ocular lens, mounted at opposite ends of a closed tube, to provide greater magnification than is possible with a single lens.

The total magnification of a compound microscope is determined by the focal lengths of the two-lens system. This magnification can be more than 2000 times.
The most widely used microscopes are optical microscopes, which use visible light to create a magnified image of an object. The simplest optical microscope is comprised of one double-convex lens with a short focal length.

The compound microscope uses two lenses, an objective lens and an ocular lens, mounted at opposite ends of a closed tube, to provide greater magnification than is possible with a single lens.

The total magnification of a compound microscope is determined by the focal lengths of the two-lens system. This magnification can be more than 2000 times.

© CHIN 2001

How the Compound Microscope Works

The compound microscope uses two (or more) lenses to increase the size of the image focused on the viewer's retina. Light rays (A) travelling outward from an object (B) bend as they pass through the first lens (C). The rays converge at a focal point (D). The rays cross and spread out until they create an image known as the first image (E). The light rays making up this enlarged image are allowed to spread out further before they are bent inward by a second lens (F), the eye-lens. The rays passing through the eye-lens enter the eye at an angle, so they appear to be coming from a much larger object (G), the virtual or final image.

Courtesy of Lucent Books Inc.

© CHIN 2001


Schematic of the magnification of the optical microscope

Sizes of cells drawn on a logarithmic scale indicating the range of readily resolvable objects in the light microscope.

Graphic by David C. Kasserra

© CHIN 2001


Italian scientist Marcello Malpighi was one of the first great microscopists, and today is considered the father of embryology and histology. In 1661, Malpighi used a microscope to identify and describe the tiny blood vessels called capillaries, which link arteries to veins. This provided important support for William Harvey’s theory that the blood circulated from the heart to the extremities of the body and back again.

Antoni van Leeuwenhoek, with his simple, single lens microscope was capable of magnifying specimens from fifty to over two hundred times. The specimen was impaled on a pin, behind the lens, and the whole apparatus was held vertically to the eye.

Leeuwenhoek made remarkable observations with his very simple instrument, reporting his discoveries in letters to the Royal Society of London. In 1673, Leeuwenhoek described what were later recognized as blood corpuscles (red blood cells). His reports caused a sensation: he described ""animalcules,"" small moving creatures that appeared to be present in everyday matter!

In the 19th century the microscope allowed for observations of bacteria, and greatly facilitated Read More
Italian scientist Marcello Malpighi was one of the first great microscopists, and today is considered the father of embryology and histology. In 1661, Malpighi used a microscope to identify and describe the tiny blood vessels called capillaries, which link arteries to veins. This provided important support for William Harvey’s theory that the blood circulated from the heart to the extremities of the body and back again.

Antoni van Leeuwenhoek, with his simple, single lens microscope was capable of magnifying specimens from fifty to over two hundred times. The specimen was impaled on a pin, behind the lens, and the whole apparatus was held vertically to the eye.

Leeuwenhoek made remarkable observations with his very simple instrument, reporting his discoveries in letters to the Royal Society of London. In 1673, Leeuwenhoek described what were later recognized as blood corpuscles (red blood cells). His reports caused a sensation: he described ""animalcules,"" small moving creatures that appeared to be present in everyday matter!

In the 19th century the microscope allowed for observations of bacteria, and greatly facilitated the development of the germ theory of disease. This was the dawn of medical bacteriology, and the identification of specific bacteria responsible for many communicable diseases. In 1882, Robert Koch discovered a staining technique that enabled him to see Mycobacterium tuberculosis. What excited the world was not so much the scientific brilliance of Koch’s discovery, but the certainty that now the fight against one of humanity’s deadliest enemies could really begin.

The microscope has aided many Canadian scientific discoveries. This is the microscope from Dr. James Collip’s laboratory at McGill University. Between 1927 and 1947, Collip, a renowned Canadian biochemist, worked with Hans Selye at McGill, undertaking a wide-range of histological and biochemical studies of the endocrine glands.

© CHIN 2001

Leeuwenhoek microscope

Reproduction of a Leeuwenhoek microscope

Bausch and Lomb Optical Company
University Health Network Artifact Collection
c. 1933
Leeuwenhoek microscope (reproduction)
1972.10.1
© CHIN 2001


Tubercule bacillus slide

Present-day image of tuberculosis bacteria (red-staining rods) in sputum from a patient with tuberculosis, stained with an ´acid-fast´ stain.

Photo courtesy of Department of Microbiology and Immunology, Queen´s University

Slide
© CHIN 2001


Microscope from Dr. Collip´s laboratory

A binocular microscope used by James Collip

Manufacturer unknown
Museum of Health Care at Kingston
Date unknown
Collip microscope
997039002
© CHIN 2001


Learning Objectives

The learner will:

  • Identify and appreciate the way history and culture shape a society’s science and technology
  • Provide examples of how science and technology have influenced the diagnosis and treatment of human illness, and have made medical technology an integral part of our lives
  • Describe scientific and technological developments, past and present, and appreciate their impact on individuals and societies
  • Describe how Canadians have contributed to science and technology on the global stage

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