El Anton Van Leeuwenhoek Microscope It was a simple single-lens apparatus, it had good clarity and magnification compared to compound microscopes of its time. Designed around 1668, the microscope was completely hand-made, including screws and rivets. Learn more about this story in this post!
Anton Van Leeuwenhoek and his Microscopes
Leeuwenhoek designed and built several hundred microscopes that were all very small and very similar in design and function, the dimensions of his microscopes being fairly constant at about two inches long and one inch wide.
The main body of these microscopes consists of two thin, flat metal plates (usually brass) riveted together, between the plates was a small bi-convex lens capable of magnification ranging from 70x to over 250x, depending on the quality. of the lens.
The operation of Leeuwenhoek microscope it is simple, the sample is placed on a pin that is manipulated by means of two screws, one to adjust the distance between the sample and the lens and the other to adjust the height of the sample.
The sample translator screw and rod are located at the bottom of the microscope, where they pass through a right angle bracket, which secures it to the microscope and then stops on a metal block located in the middle of the plates. of the microscope body.
The specimen support pin is connected to the other side of this block, so that when the translator screw is turned, it moves the specimen up or down, another screw, placed in the block perpendicular to the microscope plates, It serves as a height adjustment screw, when this screw is turned it pushes against the metal plates and moves the sample towards or away from the lens, acting similar to a focus knob.
At the rear of the microscope, another screw holds the stand at right angles to the metal body plates and also serves as a pivot point for moving the specimen from side to side.
Leeuwenhoek spent a considerable amount of time perfecting the manufacture of lenses for his microscopes, and was able to grind and polish biconvex lenses to an incredibly high quality, it is also suspected that Leeuwenhoek used blown glass lenses and that these lenses were responsible for the incredible magnifications of their simple microscopes.
Leeuwenhoek produced these lenses by removing excess glass from the thick glass gob that forms at the bottom of a blown glass light bulb, these amazing lenses were approximately one millimeter thick and had a radius of curvature of 0,75 millimeters, they had superior magnification and resolution compared to the other microscopes of the time, the Utrecht museum has one of the Leeuwenhoek microscopes in your collection.
Van Leeuwenhoek's method of making the microscope generated a lot of interest, he loved demonstrating his microscopes and while his lens making techniques were not unique, the precision with which he made his lenses was incredibly enthusiastic for the day.
With over 500 different microscopes to his credit, van Leeuwenhoek apparently made a microscope for every specimen he examined, fewer than 10 are still intact and in museums, but many more of his lenses survive to this day.
The frames for the van Leeuwenhoek microscope were made of copper, bronze, or occasionally silver, the frame was actually two plates that held the single lens between them in line with a small hole, a static specimen was mounted on a pin that was mounted on a block in the field of view of the lens, two screws adjusted the distance between the specimen and the lens and also the height of the specimen in the field of view.
To examine liquids, a small glass tube was held behind the lens in your field of view, less than four inches long, practice was required to use the microscope properly.
The microscope had to be kept as close as possible to the unblinking eye and the small lenses had a high degree of curvature which made for a short focal length, with their strongest lenses the sample had to be 4/100 of an inch from the microscope. lens.
The usual viewing method for the van Leeuwenhoek microscope was to rest it on the viewer's cheek or forehead and turn the focus screws until the specimen could be seen in full detail, then by turning the body and changing the angle of the microscope , adequate light focused on the sample.
The different designs of Leeuwenhoek microscope they were similar in size and display methodology, but some had up to three lenses mounted side by side and were slightly wider to accommodate the lenses.
His life
The son of a basket weaver, van Leeuwenhoek was not privileged like most Important Scientists, his education was basic, but he was driven by curiosity and had a gift for recording his observations, as a cloth merchant by trade, his first experience with microscopy was examining threads and cloth with a magnifying glass, he gained skill in making his own lenses and then build the microscope frame to hold them.
Some people refer to him as the father of the microscope, although compound microscopes had been around for 50 years before van Leeuwenhoek's birth, due to his discovery and classification of microorganisms, he could rightly be called the father of microbiology, his research it earned him membership in the Royal Society of London in 1680.
Lens Discovery
The van Leeuwenhoek microscope lens gave it an advantage over compound microscopes of that time period, those microscopes had distortion and aberration problems that resulted in a usable 30X or 40X magnification, the Ultrecht Museum in the Netherlands has a van microscope Leeuwenhoek in his collection at 275X magnification.
He spent an inordinate amount of time perfecting his lens making and used the three basic methods of grinding, blowing, and drawing.
In polishing the lens van Leeuwenhoek would polish the lens with finer and finer grain compounds until no blemishes remained in the glass, in van Leeuwenhoek's surviving lenses all but one of them were made by this process, in the method of blown glass, I would use the small piece of glass at the end of a blown glass tube and then polish it.
In the drawing method van Leeuwenhoek would place a flame in the middle of a glass rod and gradually pull it apart as it melted, this resulted in two separate glass rods tapering into fine points, then he inserted the small point of one of the rods in the fire and that created a small glass sphere at its end, this small sphere was used as a lens.
Gravity would make the glass asymmetrical, but by rotating it on the end of the glass rod, Leeuwenhoek could make an almost perfectly spherical lens, the smallest of Leeuwenhoek's surviving glass spherical lenses being only 1.5mm in diameter.
The playback system
For the rest of his career, Leeuwenhoek set out to investigate sexual reproduction and the nutrient transport system in animals and plants, although many others had tried, he was the first to observe sperm, which he identified as "animalcules".
Due to his conviction that motility means life, he thought that mobile animals were the essence needed to create life, in contrast to the immobile egg, which he thought contributed little, this gave Leeuwenhoek a form of the preformation theory .
Leeuwenhoek went on to study and describe reproduction in Animal cell, also made great strides in the study of animal and plant anatomy, during his lifetime, he was respected by scientists and known by laymen, in part because of the letters he sent to the Royal Society of London detailing his discoveries and partly due to the growing role as a public intellectual that he enjoyed.
In 1677 he first described spermatozoa from insects, dogs and men, although Stephen Hamm was probably a co-discoverer. Leeuwenhoek studied the structure of the optic lens, striae in muscles, insect mouthparts, and the fine structure of plants, and discovered parthenogenesis in aphids.
In 1680 he noted that yeasts consist of minute globular particles, he extended Marcello Malpighi's 1660 demonstration of blood capillaries by giving the first accurate description of red blood cells.
«In all the rain that falls, carried from the gutters to the cusps of water, animals can be found; and that in all kinds of water, standing in the open air, animals can appear. For these animals, the wind can carry them, along with the bits of dust floating in the air."
the curious merchant
Anton van Leeuwenhoek was a one-of-a-kind scientist, he initially traded in Delft, Holland following the family tradition, had received no higher education or university degrees and knew no languages other than his native Dutch, this would have been enough to exclude him from the scientific community of his time.
Yet with skill, diligence, boundless curiosity, and an open mind free from scientific dogma, he became the protagonist of some of the most important discoveries in history. History of the Microscope, it was he who discovered bacteria, protists, sperm, blood cells, nematodes, rotifers and much more.
Two peculiarities that distinguished him were his curiosity to observe everything that could be placed under his glasses and his care in describing what he observed, because he was not good at drawing, he hired an illustrator to prepare sketches of what he observed, which would accompany his written descriptions. , his research, which became widespread and made him very famous at the time, brought a new world of microscopic life to people's knowledge.
Leeuwenhoek was born in Delft, the Netherlands, later apprenticed in Amsterdam as a textile merchant, there he worked with magnifying glasses, which were used for quality control of fabrics, to check the density of the wire.
In 1654, he returned to Delft, where he spent the rest of his life, initially becoming a linen merchant, he also worked as a surveyor, wine taster, and minor citizen's officer, in 1676 he served as administrator of the estate of the bankrupt Jan Vermeer, the famous painter, who was born in the same year as Leeuwenhoek and is believed to be his friend.
His famous magnifying glasses
Leeuwenhoek is known to have made more than 500 "microscopes," of which fewer than ten have survived to the present day. In basic design, probably all of Leeuwenhoek's instruments, certainly all that are known, were simply powerful magnifying glasses, not compound microscopes of the type used today, shown at left is a drawing of one of the Leeuwenhoek microscopes.
Compared to modern microscopes, it is an extremely simple device, using a single lens, mounted in a small hole in the brass plate that forms the body of the instrument, the specimen being mounted on the sharp point protruding in front of the lens and its position and focus could be adjusted by turning the two screws, the entire instrument was only 3-4 inches long and had to be held close to the eye.
For many years, Leeuwenhoek made his lenses in the shape of lentils, called "microscopes", the lenses were essentially magnifying glasses, they were small, sometimes smaller than a nail, but enlarged 100 or even 300 times, observing with these lenses required skill and patience.
There are no data to establish for sure when Leeuwenhoek began his research, he was far from thinking about making a discovery, the microscope for him, an adult and respectable person, was just a favorite toy, but it was impossible to get out.
Examining thin slices of meat under a magnifying glass designed by him, Leeuwenhoek discovered that meat, or more precisely, muscles, consist of microscopic fibers, in this case, the muscles of the limbs and trunk (skeletal muscles) consist of microscopic fibers. cross-striated, for which they began to be called striated, in contrast to smooth muscles, which are found in most internal organs and in the walls of blood vessels.
Leeuwenhoek examined his own samples
Leeuwenhoek also started advanced parasitology using a microscope, in 1681, he examined his own stool samples in times of diarrhea, in his liquid stool, he found small animals. Leeuwenhoek described "Giardia" as a slow moving animal, but capable of making quick movements with its "legs".
Today, we know that this is a helical movement caused by flagella. Van Leeuwenhoek saw that these motile parasites were in the trophozoite stage of his.
Leeuwenhoek not only discovered Giardia in diarrhea feces, but also discovered Opalina and Nyctotherus in the intestines of frogs and their "waste", discovered a species of Trichmonas, Enterobius vermicularis (roundworm), and studied Balantidium coli, a ciliated parasitic protozoan of the colon according to Dobell in 1932.
Leeuwenhoek described Giardia as a slow moving animal, but capable of making quick movements with its "legs". Today, we know that this is a helical movement caused by flagella. Van Leeuwenhoek saw that these motile parasites were in the trophozoite stage of his.
The "legs" Van Leeuwenhoek saw in Giardia had four pairs of these little tails, or eight flagella, and it wasn't until 1880 that biologists realized there were other stages in Giardia that didn't contain flagella.
Visitors to Leeuwenhoek
Leeuwenhoek's scientific achievements were recognized during his lifetime by both his colleagues and the public, in 1680 he was elected a member of the Royal Society of London, in 1699 he was a correspondent of the Paris Academy of Sciences and in 1716 the College of Sciences. Leuven teachers awarded him a silver medal, in addition to the pension they gave him, the municipality of Delft awarded him special prizes after the publication of several of his books.
The growing number of finds caused Leeuwenhoek to demand letters of introduction, his guests included kings and princes, including Peter the Great, James II, Frederick the Great, Elector August II of Saxony, and Grand Duke Cosimo III of Tuscany, in his old age. , Leeuwenhoek became a legend, his fellow citizens referred to him with reverence as a magician.
His legacy
Mainly because it was so difficult to learn how to use, the Leeuwenhoek microscope was never used by other scientists in their Interesting science topics.
However, its magnification and resolution were so advanced that it would be the middle of the XNUMXth century before the compound microscope could open the door to the world of microbiology as Van Leeuwenhoek had done.
Each microscope was handcrafted and one of a kind and in designing them Van Leeuwenhoek had to overcome the problems of magnification, resolution and visibility using his own ingenuity.