Carl Kellner (optician)
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Carl Kellner (born March 26, 1826 in Hirzenhain ; † May 13, 1855 in Wetzlar ) was a German developer and manufacturer of telescopes and microscopes . He first gained fame as the developer and producer of the Kellner eyepiece, which is now named after him . His devices were delivered all over Germany and abroad and found recognition in scientific circles for their quality. The Optical Institute he founded in Wetzlar was the nucleus of the Wetzlar optical industry. This workshop had up to 12 employees under waiters. In the almost six years under his leadership, around 130 microscopes and around 100 small and large telescopes and telescopes were produced. For several years Kellner worked closely with his friend Moritz Hensoldt , who founded another optics company in Wetzlar.
Kellner died in 1855 at the age of 29 of pulmonary tuberculosis , which he had contracted the previous year. Shortly before his death he was awarded the gold medal for outstanding commercial achievements by the Prussian king . Kellner was married but left no children.
After Kellner's death, the business was continued by his former employee Friedrich Belthle (1828–1869). After his death 14 years later it was taken over by Ernst Leitz and expanded under the name Leitz to one of the largest microscope manufacturers and optics companies in the world. After this group was split up, the microscope division is now called Leica Microsystems , and the headquarters are still in Wetzlar.
Life
 Stations in the life of Carl Kellner (1826–1855) Other cities |
Kellner was born on March 26, 1826 in Hirzenhain, a place in the western Vogelsberg (East Hesse), which is about 60 kilometers southeast of Wetzlar, where he later worked. He was the second of four children, an older brother Eduard (1824-1851) and two sisters, Mathilde and Wilhelmine. His mother was Johanna Elisabeth, née Rudersdorf (1792–1848), from Haiger . His father Albert Philipp Kellner (according to another source Georg Philipp Albrecht Kellner; 1791-1865), born in Bendorf , was the smelter of the Buderus'schen ironworks in Hirzenhain. He also wrote a commercial arithmetic book. Later the father became the administrator of the Oberndorfer Hütte of the Fürstlich Solms'schen Hüttengeselschaft near Braunfels , west of Wetzlar. Carl Kellner spent his school days there and attended Latin school in neighboring Braunfels until he was 17 . He then became an apprentice to the mechanic (according to another source: cutler) Philipp Caspar Sartorius in Gießen , the eastern neighboring town of Wetzlar. Whether he took mathematical lessons at the same time from the founder of the Giessen secondary school Georg Stein (1810–1884) is controversial in the sources. His adopted daughter Maria Werner later became his wife.
Then Kellner went to Hamburg to A. Repsold & Sons , a company that was known for its high-quality optical, especially astronomical instruments. The length of his stay there is stated differently. While older sources report from May 1845 to the end of 1846 or from 1845 to 1846, newer sources write from four months or from April 15 to August 15, 1846. Repsold had the optics supplied by other manufacturers, they were combined with their own mechanics. It was here that Kellner met his friend Moritz Hensoldt from Sonneberg , who was five years his senior, as a colleague. Then Kellner moved back to his parents, who now lived in Braunfels, and began to study optics himself. Through experiments he checked information from the optical literature. His brother Eduard, a student of camera science , supported him in familiarizing himself with integral and differential calculus . Kellner's main focus was on astronomical telescopes. He recognized ways to improve their spherical aberration and manufactured cemented telescope lenses that were superior to the contemporary two-lens lenses from Fraunhofer , Herschel and others. “Putty” means connecting two optical elements with putty in such a way that they merge seamlessly, without any air gap, so that no reflection occurs. From 1847 at the latest, Kellner was concerned with a significant improvement in contemporary eyepieces. He later wrote about his time in self-study:
“For many years, thanks to the loving care of my good parents, a position which allowed me to devote myself to optics in a happy retirement, following a powerful inner urge in complete devotion, I have both exerted all my strength and the spirit of theory to strive for me, as well as by innumerable unsuccessful attempts do not deter me from penetrating into the secret practical artifacts of this subject.
In the course of this work I had an idea; At first tiny, but soon smiling more and more amiably at me, she showed my delighted gaze a new combination of glasses, which bring the two most beautiful optical instruments, the telescope and the microscope, to a far higher degree of perfection than we had before. "
As he had hoped, the publication of a scientific paper on the eyepiece he had developed in October 1849 led to a notoriety that enabled him to build a successful business, even though he had not completed a formal apprenticeship as an optician or mechanic. At the end of his writing he wrote:
“To the men of science. Dear gentlemen!
[...] I dare to modestly emphasize that the success of your struggles against the still veiled natural phenomena is essentially dependent on the material weapons that you wield, on the instruments with which you observe! I, too, feel the urge to share my weak strengths in your glorious struggle, if not directly, but indirectly. For years I have been exerting all my strength to become capable of serving science by manufacturing optical instruments. […]
I hereby offer you my powers!
I am aware of the demands made by the interests of science; but I am not afraid, for a competent friend is by my side, and I proudly mention that he is determined to carry out the work of optical instruments that fall into the field of mechanics for me for the time being, and that I am thus in the fine position to be able to live undisturbed by the pure optics. [...] "
The friend mentioned is Moritz Hensoldt, who did a lot of mechanical work for him.
On December 27, 1852, Kellner married the adopted daughter of his former teacher Stein, Maria Werner (1830–1881). The two had only one child, a son, born on April 13, 1854, who only survived one day. At that time, Kellner was already suffering from pulmonary tuberculosis . One cure was unsuccessful. At the beginning of 1855 he saw the award of the “Gold Medal for Outstanding Commercial Achievements” donated by the Prussian king. He died at the age of 29 on May 13, 1855. He was buried in the now-abandoned historic cemetery, known as the rose garden . His tomb is inscribed.
Act
The waiter's eyepiece
Kellner's best-known optical new development is the eyepiece, which he developed for telescopes and microscopes and which was later named after him as the Kellner eyepiece .
physics
Astronomical telescopes and typical (so-called composite) light microscopes have a two-stage image generation: The objective generates an enlarged intermediate image , which is enlarged a second time by the eyepiece. Eyepieces used in contemporary telescopes or microscopes produced curved images, that is, with a flat specimen, either the center or the edge could be brought into focus, but not both at the same time. This image field curvature could be greatly reduced with Kellner's eyepiece, so that the viewer had a continuously flat, undistorted image even with a large field of view. Kellner therefore called his development "orthoscopic", i.e. correct-seeing eyepiece.
In Kellner's time, eyepieces consisted of two individual lenses , the eye lens and the field lens . They were designed either as Huygens eyepieces (with Kellner “astronomical double eyepiece first class”) or as Ramsden eyepiece (with Kellner “double eyepiece second class”) (see also illustrations). Kellner created a new type, which is considered to be derived from the Ramsden eyepiece, since in both the intermediate image is in front of the first lens, while in the Huygens eyepiece it arises between the two lenses. Kellner replaced the single lens of the Ramsden eyepiece with a pair of lenses with fewer chromatic aberrations, an achromatic lens , so that a total of three lenses were used. The field lens was a biconvex converging lens , in the focal length of which the eye lens pair was located.
Today another construction is called an orthoscopic eyepiece , which contains a member made up of three individual lenses and was developed by Ernst Abbe (1840–1905).
Development and the road to publication
The earliest reference to Kellner's new development was found in a letter from him dated December 1, 1847. In autumn 1848 he decided to publish his results in a separate work, not as a journal article. With this publication he wanted to acquire a good reputation that would make his business easier. In March 1849, he wrote to the publisher Vieweg in Braunschweig about this, but the latter initially suggested an article in the magazine before he consented, presumably after Justus von Liebig , at that time holder of the chair for chemistry at the nearby University of Gießen , advocated waiters would have. Vieweg even suggested to Kellner that the company move to Braunschweig, which, however, was not possible for economic reasons. He also suggested to Kellner to focus on microscope construction instead of the telescope as before. At the beginning of 1849, Kellner asked Hensoldt to move to Wetzlar, also because he had an excellent handwriting to create the fair copy of the manuscript. Hensoldt came at the beginning of July, and on the 18th of the month the manuscript was ready for printing and was sent to the publisher.
At the end of October, “The orthoscopic ocular was published, a newly invented achromatic lens combination, which gives the astronomical telescope, including the dialytic tube, and the microscope, with a very large field of view, a completely uncurved, perspective correct image that is sharp in its entire extent, as well as removes the blue edge of the facial area. ”Kellner describes himself as an“ optician in Wetzlar ”. Hensoldt, "Mechanic", contributed an appendix "To the knowledge of the exact examination of the dragonflies or levels".
Content of the publication
| Preface. | S. V |
| Introduction. | P. 1 |
| I. The ocular. | P. 8 |
| Defects in the astronomical double eyepiece, first class. | P. 9 |
| a. The crooked picture. | P. 9 |
| b. The perspective of the pictures. | P. 11 |
| c. Coincidence of the cone of rays in the axis of this ocular. | P. 12 |
| d. The blue edge of the field of view. | P. 14 |
| Disadvantages of the second class double ocular. | P. 15 |
| Diffraction phenomena when seeing through oculars in general. | P. 16 |
| The orthoscopic ocular. | P. 18 |
| II. The objective. | P. 21 |
| a. The older achromatic lens or the common achromatic lens. | P. 21 |
| b. The newer achromatic lens or the dialytic lens. | P. 31 |
| Necessary circumstances to be considered when using optical instruments. | P. 34 |
| To the men of science. | P. 45 |
| Price Directory. | P. 48 |
| Attachment. About the knowledge and testing of dragonflies by M. Hensoldt, mechanic. | P. 51 |
The almost 70-page “booklet” begins with a two-page preface (see also the quote above) in which Kellner thanks his parents and his friend Moritz Hensoldt and in flowery words describes his urge to contribute to the advancement of science. This is followed by a seven-page introduction on the advantages and history of optics, especially developments in previous decades, before the main part begins with a treatise on eyepieces and their shortcomings.
He goes into detail on the problems of the "first class astronomical ocular", which is the Huygens ocular in today's parlance. Among other things, he discusses “The crooked image” (curvature of the field of view) and the resulting distortion of the image at the edge of the field of view. The subsequent discussion of the errors in the "second class double eyepiece", "developed by Ramsden and significantly improved by Fraunhofer ", is much shorter, but Kellner writes: "This ... ocular generally lags far behind the first class double eyepiece in terms of good properties" and “that the deficiencies of the present oculars are essentially the same as those of the previous one.” After discussing the diffraction phenomena, he finally came to the “orthoscopic” ocular he developed, now known as the Kellner ocular.
There he describes in detail the advantages that result for the user, but not how the eyepiece was actually built. So the text was of interest to the user without revealing trade secrets that would have been helpful to competitors. This part begins:
“Certainly none of my dear readers will expect that here, ruthlessly revealing my invention, I will get involved in a dissection of the arrangement of this ocular and the development of the basic principles on which the good success is based, but rather willingly Forgive me if I only report what the new Ocular can do. "
But then he goes into the construction in a limited way, because he worries that the reader might think that the eyepiece would consist of many individual lenses. This would mean that reflection would occur at every air-glass interface , which could greatly reduce the brightness of the image. Hence he notes:
"That my ocular, although it consists of three glass lenses, has only four reflective surfaces, so it is not darkened by any such abuses"
The knowledgeable reader will understand that two of the lenses must be cemented together in order to meet this condition, but not whether it was the eye lens (which it actually was) or the field lens, also known as the collective lens. P. Harting wrongly assumed in 1866: "According to Kellner (The orthoscopic ocular, a newly invented achromatic lens combination, etc. Braunschweig 1849) the bottom glass of his ocular, ie the biconvex collective glass, consists of two interconnected lenses."
After a detailed discussion of the advantages of the new eyepiece in list form with nine points, Kellner finishes the section on his eyepiece:
“Finally I consider myself entitled to be able to remark here that I have exhausted the matter of this subject through extensive, thorough calculations and often modified experiments, and believe that I have given my Ocular the maximum of its virtues, which result from the manifold intersecting conditions of the Be able to excel in theory and practice; unless, through new discoveries in the field of physics or through the achievements of glass smelters, the current position of the optician is shifted. "
This is followed by a treatise about the same length of time on lenses, their structure and construction, as well as possible quality tests. This section is not directly related to Kellner's Okular, but shows the author's expertise. Finally, there follows a chapter on the use of optical instruments, intended to “show the uninformed the way on which he, exercising his powers, can progress to the knowledge of the most advantageous application and closer acquaintance with the method of treatment of the instruments mentioned.” Kellner concludes with the above already partially quoted appeal to the "men of science", which ends with the following paragraph:
"I am herewith opening my business with confidence, hoping that the words with which my friend and I often comforted and encouraged each other: general recognition will be worth our years of effort, may not have been entirely meaningless."
A price table for eyepieces, telescope lenses and entire telescopes and ordering instructions follow before the appendix by Moritz Hensoldt begins.
Admission and further development
Kellner's eyepieces quickly found recognition in specialist circles. For example, Carl Friedrich Gauß praised a Kellner eyepiece in a letter:
“The eyepiece is enlarged 96 times when attached to the Merz telescope and is therefore in this respect completely the same as an existing Merz eyepiece. In the clarity and colorlessness of the picture I could not notice any decisive inequality. But your eyepiece has a 27'36 "diameter field of view, the Merz'sche only 18'25". The area of the field of view with your eyepiece is therefore more than twice as large as under the same magnification with Merz's. The clarity of vision with your eyepiece is equally good up to the edge of the field of view, if not completely, then certainly almost completely. I wish to keep the same for the observatory. "
Optics textbooks from the 20th and 21st centuries write that Kellner eyepieces are typically used in binoculars or certain telescopes and low-magnification microscopes, but are seldom used in conventional microscopes. Until the second half of the 20th century, Kellner eyepieces were part of the basic equipment of many amateur astronomers because they were comparatively inexpensive with acceptable imaging performance. Furthermore, Kellner eyepieces were often used in prism binoculars .
Even in the 20th and 21st centuries, Kellner eyepieces were and are still used as measuring eyepieces in microscopy. It is dealt with accordingly in more recent textbooks.
Telescope lenses
Kellner was initially more inclined to telescopes than microscopes. His eyepiece could be used on both. In parallel to his work on the eyepiece, he is also working on improvements to telescope lenses. Through calculations and experiments he succeeded in reducing the spherical and chromatic aberration . His objective with cemented (glued) lenses allowed significantly higher magnifications than comparable achromatic telescopes. Together with his eyepiece, an enlarged field of view could be observed. The suggestion to cement objective lenses originally came from Hensoldt. In order to manufacture several telescopes, he initially lacked a suitable amount of optical glass , so in 1847 he asked Hensoldt to buy crown and flint glass for him from Friedrich Körner (1778–1847) in Jena on his way from Hamburg to his native Sonneberg . Kellner would have liked to have manufactured his telescope lenses exclusively on the basis of calculations. However, this was not yet possible for him. Trying out after trial and error, called probing for optical elements, was necessary in this case.
Company foundation in Wetzlar
| Kellner's microscope no.79. |
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| Kellner's little tripod. This 79th microscope from the workshop was built in 1854 and sent to Prof. Dr. Wernher sent in Giessen. (Presumably Adolph Wernher ). It cost 50 thalers and 10 silver groschen. |
While they were together in Hamburg, Kellner and Hensoldt decided to found a company together. While Kellner continued his education at home, Hensoldt initially stayed with Repsold. Their correspondence shows that they were considering Frankfurt am Main and Mainz as locations. However, acquiring the civil rights required for settlement was too expensive for them. Ultimately, Hensoldt's hometown of Sonneberg was chosen. Today it is in the south of Thuringia, on the border with Bavaria and near the Franconian town of Coburg.
In spring 1848 Kellner moved to Sonneberg, but after only a short stay he was already living in Wetzlar at the beginning of July of that year. Here his sister Mathilde was married to a local wealthy merchant and porcelain dealer, Johann Hinckel (1814–1874), who supported the waiter financially. Kellner took over the house of two piano makers who had emigrated to America. They took a Kellner telescope with them to the USA. A friend of the two was so impressed that he also ordered such a device from Kellner. At first, Kellner was the only employee in his workshop. The collaboration with Hensoldt initially continued, with Kellner sending lens combinations to Sonneberg, while Hensoldt carried out mechanical work for waiters. Kellner's mother died on December 2, 1848 after a long period of serious lung disease.
As early as the early summer of 1849, shortly before Hensoldt's stay of several months in Wetzlar on July 1, Kellner moved into a larger workshop in the former reformed rectory on Jäcksburg, which he rented for 45 thalers a year. The actual business establishment of the "Optical Institute" took place around July 15, 1849. Hensoldt's presence was probably necessary because, unlike Kellner, he had completed an apprenticeship. However, the waiter was the sole owner. He hoped for fame and business success through the publication of his Okular in the same fall, but planning was difficult due to the political upheavals and Kellner and Hensoldt decided to emigrate to America in case of major problems. At first Hensoldt liked it in Wetzlar, but on November 25th he moved back to Sonneberg. There was little to do due to a lack of orders. The company could only survive with the support of the brother-in-law. The official name was therefore "Optisches Institut Johannes Hinckel" until 1852, after which Kellner appeared in the business name. Kellner's father, retired from autumn 1849, moved to Wetzlar with his younger daughter Wilhelmine, also lived in the former parsonage and took care of the son's bookkeeping.
Hensoldt and Kellner remained on friendly terms. In letters to Hensoldt, Kellner describes how orders for microscopes rose sharply, while astronomical telescopes were hardly in demand. In the documents that have been received by Kellner, the first delivery of a “mycroscope ocular” is noted on December 22, 1849; it went to the Bremen pharmacist and naturalist Georg Christian Kindt , who received another in January 1850.
From telescopes to microscopes
In correspondence with the publisher Vieweg before the publication of his Okular script, this waiter suggested offering microscopes as well. On June 13, 1849, Kellner wrote that his main focus was initially on telescopes. Even if he knows the theory of the microscope completely, he still lacks practical experience. However, Kellner quickly tried to fill this gap. On November 24th of that year he wrote to Vieweg:
“My method of grinding has proven itself to a high degree with the microscope objectives, also to my heartfelt delight. I can now say with a clear conscience that this delicate part of the microscope is carried out to perfection, as Plößl, Schick, Oberhäuser and Chevalier do, but in the other no less important part of the microscope, through my orthoscopic eyepieces, I can see the achievements of the artists mentioned still far outbid. Considering now that the microscope plays such a vital role in the current standpoint of science, […] considering that interest in astronomy has long since reached its culmination point, […] considering all of this, I want the task of our time grossly misjudge if I wanted to turn my strength to the telescope. "
Kellner had already dealt with microscope lenses during his time in Braunfels, but had to give up this work because he did not have a suitable microscope frame for the development. The starting point for his new work was a telescope lens he developed himself, in which he shortened the focal length and enlarged the aperture. His medium magnification lenses had a double cemented front lens and two pairs of lenses behind it. Each of the three parts was achromatic in itself, the spherical aberration was largely corrected in the rear parts. These lenses were among the best that could be manufactured under the conditions of the time. The highest achievable numerical aperture was 0.60. Today's standard 40x objectives have a numerical aperture of 0.65.
The first delivery of a microscope from the Optical Institute is noted in the delivery book on May 9, 1851. This went to a pastor Duby in Geneva, but it was later returned and probably resold in April 1852 to the botanist Gottlob Ludwig Rabenhorst in Dresden.
Economic development
Numerous professors from the nearby University of Giessen are listed in Kellner's delivery books. Kellner also benefited from this proximity through practical suggestions. While the precision engineering of his microscopes and telescopes was simple compared to French or English competitors, the quality of the optics was among the best. The devices therefore also covered longer distances, for example to Matthias Jacob Schleiden in Jena, to Albert von Koelliker in Würzburg, to Justus von Liebig , who moved from Gießen to Munich, and to Tübingen to Hugo von Mohl .
A special sponsor of the workshop was Theodor von Bischoff , at that time professor of anatomy and physiology at the University of Giessen. In Kellner's delivery books, seven microscopes that went to von Bischoff are documented. Appointments from other Giessen professors are probably also due to his advocacy. Furthermore, eight scientists from Marburg and six from Würzburg were Kellner's customers, including Albert von Koelliker , Franz von Leydig and Rudolf Virchow .
The workshop was fully utilized from autumn 1850, and its products were able to assert themselves against other leading microscope manufacturers of the time such as Simon Plössl in Vienna, Friedrich Wilhelm Schiek in Berlin, Georg Oberhäuser and Charles Chevalier in Paris. Carl Zeiss had already opened his workshop in Jena in 1846, but did not manufacture assembled microscopes until 1857. From the beginning, Kellner often had financial problems, also because of workshop expansions and personnel costs, from which his brother-in-law Johann Hinckel helped him several times. One author writes that the main cause of the financial troubles was the extravagance of Kellner's wife, without specifying what that assumption was based on. In 1850 and 1851 Kellner tried repeatedly in letters to bring Hensoldt to another move to Wetzlar. Finally, he came from June 27, 1851 to June 12, 1852 for almost another year and then returned to Sonneberg. Hensoldt's great-granddaughter Christine Belz-Hensoldt and her co-author suspect the reason for the return that he “felt increasingly pushed into the corner of the pure mechanic”, which he was not and did not want to be. Kellner, on the other hand, wanted to concentrate on the optics. After a few more letters, the contact seems to disappear, possibly because Hensoldt decided to build microscopes himself.
production
In the six years before his death, Kellner's workshop produced around 130 microscopes, which were also delivered to Austria, Holland, England, Sweden and Norway, as well as at least 5 large astronomical telescopes and several small telescopes. Kellner had up to twelve assistants and apprentices.
The exact number of devices produced differs from one another by different authors, although all refer to Kellner's delivery books. 28 microscopes were delivered to Berg in 1852, 39 in 1853, then 50 in 1854, while in 1855 the number fell to 44. According to Belz-Hensoldt, the following table and graphic results:
| year | Eyepieces | Telescopes | Microscopes |
|---|---|---|---|
| 1850 | 20th | 2 | - |
| 1851 | 22nd | 33 | 3 |
| 1852 | 8th | 36 | 27 |
| 1853 | 4th | 15th | 36 |
| 1854 | 13 | 1 | 42 |
| 1855 | - | 10 | 34 |
In addition to individual pieces that were adapted to special customer requirements, series of microscopes were also offered:
“I make 3 types of microscopes. The smaller type costs 50 thaler , has two systems and two oculars and the enlargement runs 90. 180. 360 720. The middle type costs 75 thaler, has two systems and three oculars and the magnifications 90. 180. 360 720 .u. 1000. The tripod allows the oblique lighting and the rough adjustment is done by means of a drive instead of the spring sleeve. The larger type costs 120 Thaler, has three systems and four oculars. The strongest magnification is 1200. The tripod is made of very solid metal and has a removable screw micrometer at the ocular end of the tube. [...] I would only be able to place an order for an instrument of the smaller type in 5 to 6 months, for an instrument of the medium type in 6 - 7 and for one of the larger types only (in) 9 months. "
In the 19th century, 'system' or 'lens system' was a name for lenses that are made up of several lenses, and the magnifications given are the total magnifications of the eyepiece and lens together. Up until the 20th century it was customary to change not only the objective but also the eyepiece to change the magnification. When making comparisons with today's microscopes, it must be taken into account that Kellner only manufactured dry objectives, i.e. those that were used without immersion liquid . Today's dry objectives usually have a magnification of 40x or less, so that in combination with a typical 10x eyepiece, a total magnification of 400x is achieved. With optimal lighting with a condenser , a resolution of almost 300 nanometers can be achieved today with the best dry objectives ( numerical aperture 0.95) .
Of the 108 microscopes delivered by the end of 1854, 22 were medium-sized and two were larger.
The composition, position and shape of the optical elements in Kellner's instruments were calculated in advance on a scientific basis in order to minimize chromatic aberration and spherical aberration. His journeyman and successor Belthle described “that after precise determination of the refraction and dispersion conditions, Kellner precisely calculated the radii for the first approximation of his first objective according to the usual form, etc. these calculated radii in practice also exactly executed u. removed the residual both chromatic and spherical aberration by correction ”.
The quality of Kellner's instruments
In the few years between the opening of the business on July 15, 1849 and the beginning of his illness in 1854, which ended with his death on May 13, 1855, Kellner managed to establish himself among the top ranks of optical equipment manufacturers. This can be concluded indirectly, on the one hand, from the list of well-known customers, some of whom are named above. On the other hand, it is also mentioned in contemporary literature. Pieter Harting , who wrote a hundred-page textbook on microscopy in 1859, also described instruments from the most important manufacturers in it. The report on Kellner from the second edition from 1866 is quoted here, which is also found in the first edition, linguistically slightly different:
“Carl Kellner has made a name for himself in Wetzlar as a microscope manufacturer since 1849. I got to see three of his smaller microscopes which are excellent in optical terms; only they have too little change in magnification because only one objective and two oculars are required.
The objective of the one I examined more closely consisted of two achromatic double lenses and had a focal length of 7.9 millimeters. The aberrations, especially the spherical, were so completely improved that far stronger oculars could be connected to them than is usually the case. When the same test objects were used, the optical power seemed to be equivalent to an Oberhauser lens system of 3.22 millimeters and a Nachet system of 4.8 millimeters focal length; in this respect it was only inferior to the Amici system of 8.7 millimeters focal length. ...
The Kellner microscopes are particularly characterized by their large and flat field of view ... Regardless of this large size, it is almost free of curvature. "
"The microscope and its application" by Leopold Dippel was published in 1867, twelve years after Kellner's death, so only the microscopes of his successor Belthle are discussed there. However, the section begins with a mention of Kellner:
“After the death of the founder of the Wetzlar optical institute, C. Kellner, who was unfortunately torn away too early from his art and science, whose microscopes have found well-deserved recognition in Germany and England, albeit sporadically, Belthle headed the institute some time for the account of Kellner's widow. "
The large microscope for von Bischoff
In 1851, Kellner planned to relocate the company to Gießen, where von Bischoff was his most important academic advisor. However, this should no longer happen. At around this time, Kellner also commissioned Bischof to manufacture a special large microscope, the construction of which was also no longer possible. Kellner wrote about it to Hensoldt:
“A few days ago I met Prof. Dr. Bischoff in Giessen, to whom I owe the greatest gratitude for his help in word and deed, submitted a detailed essay on my investigations and an instrument that can be regarded as a representative of the results achieved, and he has now carried out the same for me Invoice from the Physiological Institute in Giessen commissioned. You must not imagine a microscope here, as the present ones are, but this is an instrument that, in terms of its mechanical and optical equipment, does not have the slightest resemblance to these. It is, casually speaking, an instrument made of brass and iron that will weigh several hundredweight, with which magnifications, of which one has no idea up to now, are to be achieved, and on which I will still have to struggle for at least ten months and more will. If all this succeeds, which I cannot doubt, for all the principles on which this is based have been carefully developed through numerous extremely precise and comprehensive experiments and confirmed by experience, then microscopic observations are about to undergo a similar redesign as this met the observatories from Munich. "
Together with Justus Liebig, von Bischof organized the amount of 1,500 thalers. Further details about the project are not known, and construction did not take place.
It should be taken into account that the physical limitation of microscopic resolution due to diffraction was not yet known in Kellner's time. The maximum possible resolution was also only reached a few decades later, after further technical improvements.
Kellner's kinship and legacy: the optical industry in Wetzlar
Kellner's mother, Johanna Elisabeth (1792–1848), née Rudersdorf, was the youngest of ten children; she had three sisters. The eldest, Catharina Elisabeth (1777–1828), married to Johann Philipp Neumann (1783–1852) from 1810, was the mother of Katharina (1813–1893), married to Peter Seibert (1813–1870). Katharina, in turn, was the mother of the brothers Wilhelm and Heinrich Seibert. The second sister, Katharina Jakobina (1786–1850), married Abraham Engelbert (1784–1827) in 1807. Their son was Ludwig (Louis) Engelbert (1814–1887). The third oldest sister was Sara Philippine Helene (1789-1856). In 1816 she married Jacob Ohlenburger (1787–1863) and their daughter Christine (1829–1903) became Moritz Hensoldt's wife in 1854 .
- Belthle microscopes similar in design to Kellner's. From Dippel, 1867.
Big microscope
Small microscope
Smallest tripod
Before his death, Kellner discussed his experiences with his most important colleague and cousin, the master carpenter Ludwig Engelbert, and wrote down his findings in order to ensure the continued operation of the workshop. Kellner appointed Engelbert plant manager, and he took over management of the company during Kellner's illness and after his death on May 13, 1855, until Kellner's widow and Friedrich Belthle (1828–1869) married on December 6, 1856. Belthle had in November In 1853 he made metalwork for waiters and worked for the workshop from February 8th to April 28th and again from June 20th, 1855, five weeks after Kellner's death on May 13th. Now he took over the workshop on behalf of his wife. With an annual production of around 70 microscopes, Belthle was able to keep the company running. The optical quality was judged differently by contemporaries, from "the best waiters almost the same" and "... excellent for the finer histological examinations .......... not surpassed by any of the equally powerful newer systems" to "stand behind those of his in the sharpness and clarity of the image Previously decided to go back ”. Ernst Leitz joined the company on New Year's Day 1864 . In 1865 he became a partner and in 1869 the sole owner. The company was also renamed Leitz and became one of the largest manufacturers in the optical industry worldwide. The two successor companies Leica Microsystems and Leica Camera are still based in Wetzlar today.
Engelbert left the workshop at the wedding of Kellner's widow and initially founded his own workshop in nearby Oberndorf. In 1861 he began a collaboration with Hensoldt, which was ended again in 1865, whereupon both of them moved their workshop to Wetzlar. Engelbert sold his devices until his death in 1877 under the name “Engelbert and Hensoldt”. His son Fritz limited himself to microscope lenses and eyepieces.
Hensoldt specialized in geodetic instruments. He died on October 10, 1903. Under his sons Waldemar and Karl, the Hensoldt-Werke enjoyed a significant upswing. Today you are still based in Wetzlar as Carl Zeiss Sports Optics .
The Wetzlar optics company W. & H. Seibert also goes back to Kellner's Optical Institute. The founders were the brothers Wilhelm (* 1840) and Heinrich Seibert (* 1852). Her mother was a niece of Kellner's mother and had lived with Kellner's parents for six years as a teenager. She lived in poor conditions and waiter promised to train her sons. In 1854 Wilhelm began an apprenticeship in the company, and Heinrich did the same after Kellner's death.
Other optics companies have settled in Wetzlar over the years. These include Wilhelm Will and the successor company Helmut Hund GmbH, Minox and Wilhelm Loh KG Optikmaschinenfabrik .
Until the dissolution of the Holy Roman Empire of the German Nation in 1806, Wetzlar was the seat of the Imperial Chamber Court, the highest court in the empire and, as such, also the scene of Goethe's famous “ The Sorrows of Young Werther ”. In the middle of the 19th century, Wetzlar threatened to slide into insignificance with only about 5000 inhabitants. The emergence of the optical industry made a significant contribution to making it an important business location.
Honors
- Gold medal for outstanding commercial achievements, donated by the Prussian King and awarded by the Minister for Trade, Industry and Public Works, 1855
- At the beginning of the 20th century, Wetzlar named the then new Karl-Kellner-Ring after him.
- The Braunfels comprehensive school, the Carl-Kellner-Schule, is named after him.
reception
As the founder of the optical industry in Wetzlar and of a company that from the end of the 19th century as " Ernst Leitz Wetzlar " was to be among the world market leaders in the optical industry, Kellner was certainly the subject of biographical writings to a greater extent than comparable opticians of his time. Accordingly, the majority of the biographies arose from the Ernst Leitz works and the family. The oldest biography comes from Julius Hinkel, grandson of Kellner's brother-in-law, and was published by the Wetzlar History Society. On the occasion of the 100th anniversary of the Leitz-Werke, counting from the official establishment of Kellner's optical institute, Alexander Berg wrote a 120-page book in 1949, in which a chapter also deals with waiters. To mark the 100th anniversary of Kellner's death, he wrote a brochure exclusively about waiters, which was published by the "Optical Works Ernst Leitz in Wetzlar". In 2010 a book about Ernst Leitz I was published that was edited by his great-grandson Knut Kühn-Leitz. There is also a chapter on waiters here. It was co-authored by Christine Belz-Hensoldt, a great-granddaughter of Moritz Hensoldt and thus also great-great-niece of Carl Kellner. Three years earlier, she had published an annotated edition of Kellner's letters to Hensoldt. Those from Hensoldt to Kellner have not been preserved. In addition, Kellner is also a topic in company-independent presentations of the history of microscopy.
literature
- Alexander Berg: Carl Kellner. On the centenary of the death of the founder of the optical industry in Wetzlar. As a memorial to the centenary of the death of its founder, published by the optical works Ernst Leitz in Wetzlar. Edited by Dr. med. habil. et phil. Alexander Berg, Hildesheim, 1955. pp. 7-25.
- Dieter Gerlach: History of Microscopy . Verlag Harri Deutsch, Frankfurt am Main 2009, ISBN 978-3-8171-1781-9 , pp. 355-366 .
- Christine Belz-Hensoldt, Gerhard Neumann: Carl Kellner and the Optical Institute . In: Knut Kühn-Leitz (Ed.): Ernst Leitz I From Mechanic to Entrepreneur of World Reputation . Lindemanns Verlag, Stuttgart 2010, ISBN 978-3-89506-287-2 , p. 44-62 .
Web links
- Literature by and about Carl Kellner in the catalog of the German National Library
- Early microscope by C. Kellner in Wetzlar in the "Museum of Optical Instruments".
- Small microscope from Ms. Belthle in Wetzlar , successor to C. Kellner in the “Museum of Optical Instruments”.
Individual evidence
- ↑ a b c d e f g h i j k l m n o p q Dieter Gerlach: History of microscopy . Verlag Harri Deutsch, Frankfurt am Main 2009, ISBN 978-3-8171-1781-9 , pp. 355-366 .
- ↑ a b c d e f g h i j k l m n o p q r s Alexander Berg: Carl Kellner. On the centenary of the death of the founder of the optical industry in Wetzlar. As a memorial to the centenary of the death of its founder, published by the optical works Ernst Leitz in Wetzlar. Edited by Dr. med. habil. et phil. Alexander Berg, Hildesheim, 1955. pp. 7-25.
- ^ A b c d e Siegfried Rösch : Kellner, Carl. In: New German Biography (NDB). Volume 11, Duncker & Humblot, Berlin 1977, ISBN 3-428-00192-3 , p. 475 f. ( Digitized version ).
- ↑ a b c d e f g h i j k l m n Christine Belz-Hensoldt, Gerhard Neumann: Carl Kellner and the optical institute . In: Knut Kühn-Leitz (Ed.): Ernst Leitz I From Mechanic to Entrepreneur of World Reputation . Lindemanns Verlag, Stuttgart 2010, ISBN 978-3-89506-287-2 , p. 44-62 .
- ↑ a b c Julius Hinckel: Carl Kellner, the founder of the optical industry in Wetzlar . In: Messages from the Wetzlar History Association . tape 3 , 1910, pp. 71-80 .
- ↑ a b c d e f Alexander Berg: Carl Kellner . In: Ernst Leitz Optical Works Wetzlar 1848–1949 . Umschau Verlag, Frankfurt am Main 1949, p. 17-36 .
- ↑ a b c d e f g Carl Kellner: The orthoscopic ocular, a newly invented achromatic lens combination, which gives the astronomical telescope, including the dialytic tube, and the microscope, with a very large field of view, a completely uncurved, perspective correct the whole extent to a sharp image, as well as eliminating the blue border of the visual space. Friedrich Vieweg and Son, Braunschweig 1849 (two copies are available online at Google Books: one , two ).
- ↑ a b Horst Riesenberg: Optical system of the microscope . In: Horst Riesenberg (Hrsg.): Handbuch der Mikoskopie . 3. Edition. VEB Verlag Technik, Berlin 1988, ISBN 3-341-00283-9 , p. 100-101 .
- ^ A b c Eugene Hecht: Optics . 5th edition. Oldenbourg, Munich 2009, ISBN 978-3-486-58861-3 , pp. 350-351 .
- ↑ Kellner, Das orthoskopische Ocular, 1849, p. 49
- ↑ P. Harting: The microscope. Theory, Uses, History and Present State of the same. Volume 3 . 2nd Edition. Friedrich Vieweg and son, Braunschweig 1866, p. 190 .
- ↑ Alexander Berg: Carl Kellner. On the centenary of the death of the founder of the optical industry in Wetzlar. As a memorial to the centenary of the death of its founder, published by the optical works Ernst Leitz in Wetzlar. Edited by Dr. med. habil. et phil. Alexander Berg, Hildesheim, 1955. p. 16.
- ↑ Francis A. Jemkins, Harvey E. White: Fundamentals of Optics . Third ed. McGraw-Hill Book Company, Inc., New York 1957, pp. 183 .
- ^ W. Burrell's MRI: Microscope Technique . Fountain Press, London 1977, ISBN 0-85242-511-2 , pp. 86 .
- ↑ Rolf Riekher: Telescopes and their masters. 2nd edition, Verlag Technik, Berlin 1990 ISBN 3-341-00791-1 p. 246.
- ↑ a b Wolfgang Gloede: From reading stone to electron microscope . VEB Verlag Technik, Berlin 1986, ISBN 3-341-00104-2 , p. 137 .
- ↑ Jörg Haus: Optical microscopy, functionality and contrasting methods . John Wiley & Sons, 2014, ISBN 978-3-527-41286-0 , pp. 63 f . ( limited preview in Google Book search).
- ↑ Gerhard Göke: Modern methods of light microscopy. From transmitted light brightfield to laser microscopes . Kosmos Gesellschaft der Naturfreunde Franckh'sche Verlagsbuchhandlung, Stuttgart 1988, ISBN 3-440-05765-8 , p. 72 .
- ↑ Alexander Berg: Carl Kellner. On the centenary of the death of the founder of the optical industry in Wetzlar. As a memorial to the centenary of the death of its founder, published by the optical works Ernst Leitz in Wetzlar, Hildesheim, p. 48.
- ↑ Dieter Gerlach: History of microscopy . Verlag Harri Deutsch, Frankfurt am Main 2009, ISBN 978-3-8171-1781-9 , pp. 359 .
- ^ A b Rolf Beck: The Leitz works in Wetzlar . Sutton Verlag GmbH, Erfurt 1999, ISBN 978-3-89702-124-2 , p. 9 .
- ↑ Christine Belz-Hensoldt, Gerhard Neumann: Carl Kellner and the optical institute . In: Knut Kühn-Leitz (Ed.): Ernst Leitz I From Mechanic to Entrepreneur of World Reputation . Lindemanns Verlag, Stuttgart 2010, ISBN 978-3-89506-287-2 , p. 59 .
- ↑ P. Harting: The microscope. Theory, Uses, History and Present State of the same. Volume 3 . 2nd Edition. Friedrich Vieweg and son, Braunschweig 1866, p. 189-190 .
- ↑ Leopold Dippel: The microscope and its application . Friedrich Vieweg and son, Braunschweig 1867, p. 148 .
- ↑ Dieter Gerlach: History of microscopy . Verlag Harri Deutsch, Frankfurt am Main 2009, ISBN 978-3-8171-1781-9 , pp. 363 .
- ^ Siegfried Rösch .: Early history and genealogy of the Wetzlar optical industry. In: sheets for German national history . tape 98 , 1962, pp. 159-164 ( online ).
- ↑ Hermann Welcker: About the storage of microscopic objects . Giessen 1856, p. 40 . , quoted from Harting, 1859
- ↑ Leopold Dippel: The microscope and its application . Friedrich Vieweg and son, Braunschweig 1867, p. 153 .
- ↑ Harting: The microscope. Theory, Uses, History and Present State of the same. Volume 3 . 2nd Edition. Friedrich Vieweg and son, Braunschweig 1866, p. 191 .
- ↑ Wetzlarer Kreis- und Anzeige-Blatt dated February 23, 1855, illustrated in: Alexander Berg: Carl Kellner. On the centenary of the death of the founder of the optical industry in Wetzlar. As a memorial to the centenary of the death of its founder, published by the optical works Ernst Leitz in Wetzlar, Hildesheim, p. 75.
- ↑ Who was Carl Kellner? Carl-Kellner-Schule website, accessed January 1, 2019.
- ↑ Christine Belz-Hensoldt: Two pioneers of optics. Carl Kellner's letters to Moritz Hensoldt 1846–1852. In three parts . Kempkes, Gladenbach 2007, ISBN 978-3-88343-046-1 (638 pages).
| personal data | |
|---|---|
| SURNAME | Waiter, Carl |
| ALTERNATIVE NAMES | Waiter, Karl |
| BRIEF DESCRIPTION | German optician and inventor |
| DATE OF BIRTH | March 26, 1826 |
| PLACE OF BIRTH | Hirzenhain |
| DATE OF DEATH | May 13, 1855 |
| Place of death | Wetzlar |
