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Information on the history of the microscope.
History Microscope
Although today the microscope is an accepted weapon in the armamentarium both of the scientist and the industrialist, its advent is relatively new. There seems no doubt that the properties of burning glasses were known to the ancients. The allusion to these in Aristophanes' comedy " The Frogs " would indicate this, but there seems equally to be no doubt that the use of burning glasses presumably flasks filled with water did not lead to the discovery of lenses, for Pliny the younger, in his treatise on eyesight, refers to various ocular diseases and their cures. He mentions presbyopia, but nowhere does he refer to its correction by means of lenses. There is also a mass of other evidence which has been fully explored by Dr. H. Martin, which conclusively debuts any assumptions of the existence and utilization of lenses in any form. The invention, if it may be so called, of spectacle lenses, is generally attributed to Salvino Degli Armati, while Alexander Spina, a monk of Pisa, is said to have divulged the secret of their construction and use. It is stated that on Armati's tomb was the inscription "Here lies the body of Salvino Armati. He invented spectacles; may God forgive his sins." This inscription is claimed to have existed and was seen in the year 1820. Roger Bacon, the English Franciscan of Ilchester, who was a contemporary of Armati, was acquainted with the use of lenses, both convex and concave. There is no evidence whether he arrived independently at this knowledge, or through an acquaintance with Armati. From his Opus Majus it might be assumed that he had employed lenses as simple microscopes and, by stretch of imagination that he was acquainted with the telescope, but as no directions for the construction of such instruments are given, the question must be regarded as mere speculation. From the lack of evidence or of contemporary work, it may be assumed that at this period both microscopes and telescopes had yet to be discovered. From this time onwards spectacles of various types are figured in portraits of individuals and in paintings, and there is no doubt that they came into relatively general use. At the Renaissance with its intense mental stimulus the floodgates of enquiry were opened. It was a period of intellectual adventure and it may seem strange to those acquainted with
the literature of the time the questioning attitude of men's minds, the feeling that mankind stood on the brink of a new revelation that the lenses used for spectacles were not developed further. Although the invention of the telescope and the microscope is generally attributed to the brothers Janssen of Middleburgh in Zeeland, it is only just to quote the following from Dr. Nicholson's essay: "The New Astronomy and English Literature Imagination". So far as England is concerned, there is evidence of the invention of the telescope there, even earlier than on the Continent. It is generally agreed by historians that Leonard Digges, from his study of a manuscript of Roger Bacon, had discovered a principle of the telescope about 1550, although until recently no suggestion has been made that his telescope was designed or used for astronomical purposes. "According to his son, Thomas Digges, ' Bi-concave and convex mirrors and circular and parabolic forms/ Digges" Not only discovered things far off, read letters, numbered pieces of money . .but also seven miles off declared what had been done at that very instant in private places." Certainly Digges' illustrations justify no assumption that he was acquainted with or employed what would have presumably been an anticipation of the Newtonian form of telescope. Borelius, who was Ambassador of the Low Countries, in his treatise "De Vero Telescopii Invent ore” has left on record a notarial declaration that the telescope was invented by the brothers Janssen, who were spectacle lens makers in Middleburgh and the date is approximately 1560. It is stated that one of the brothers, having polished a spectacle lens, decided to examine its surface by the aid of another lens. To his amazement, the church clock appeared, when seen through the two lenses, both enlarged and nearer. Even if not true, it is a pretty tale and pregnant with the age-old fact that mankind sees but does not observe. Historically the period was interesting. Motley's epic, "The Rise -of the Dutch Republic”; provides the necessary background. There is evidence that the Janssens were members of what we to-day call the "Resistance Movement” As spectacle makers they visited all the Provincial and city fairs in the Low Countries, passing news of the anti-Spanish movement and circulating spurious coin so as to undermine confidence in Spanish currency. On the discovery of the telescope, as good patriots, they showed their invention to the Archduke Maurice and he, recognizing its military value, purchased the exclusive right of the use of the instrument for a term of years and it would appear that the Janssens honoured this agreement. The invention of the telescope is, unfortunately, attributed to Lipperchey, but we believe this to be incorrect. At the time of the discovery of the instrument, Lipperchey appears to have been employed by the Janssens as a workman, and not being bound by the undertakings entered into by them, he, on leaving their employ, set up on his own account and commenced the sale of these instruments.
The original telescope consisted of two bi-convex lenses and objects were seen inverted. The first microscopes were in effect very short focus telescopes. It is understandable that with an extremely limited scientific world, the members of which were in correspondence with each other, information of the telescope would spread and that it would reach Galileo, who was already a well-known and famous mathematician. He did not invent the telescope, but he did substitute a concave for a convex eye lens, as a result of which objects were seen erect instead of inverted. To trace the history of the microscope from this time onwards would necessitate the production of several volumes. The period was one fruitful in ideas and one in which design being in a fluid state, was rich with suggestions for the future. Design was, unfortunately, to become conventionalized in certain channels and the ideas adumbrated during this period of flux were only realized in their ultimate form within the last century. From the early seventeenth century to the middle of the eighteenth century there is a voluminous literature, but the books are scarce.
Passing in rapid review the various developments in design, we would refer to Descartes. This simple microscope designed by Descartes was the forerunner of the Lieberkuhn, which had a great vogue until the 1880's. The principle was applied by Mr. E. M. Nelson to his reflecting magnifier and subsequently appeared again on the microscope in the form of ring illuminators, Ultrapak, etc., and is now in frequent use. The microscope of Campani can be justly termed the precursor of the pocket microscopes, which have been so prominent during the past two decades. It was also the model upon which the Wilson screw barrel and similar instruments were developed. Of still greater interest is Hooke's compound microscope. For the first time coarse and fine adjustments are incorporated, and provision is made for inclination of the body tube, also the object can be orientated for examination at any angle. Admittedly the movements incorporated are rudimentary, but the germ of future design is present. For the first time a lamp with the equivalent of a condensing system is provided, and it will be noted that adjustment to the lamp condensing lens is incorporated. Incidentally, it will be remembered that Hooke was the inventor of Hooke's joint, known to all users of scientific instruments and employed with success up to the present time. Hooke (Secretary of the Royal Society) was a man of amazing mental activity. He made attempts to overcome the chromatic and spherical aberrations in the lens systems of the time. Actually he introduced a field lens to the eyepiece, but while admitting that there was an improvement in performance, he objected that the field of view was reduced. Another attempt was the introduction of water between the objective and the eye lens system. Again he found that the continuous path of light had its advantages, but the method was inconvenient and the gain insufficient to justify this. He also experimented with the use of colour screens. The Capucin Priest, Cherubin d'Orleans, introduced the first binocular microscope. This was a true binocular. Not only were two eyepieces provided, but also two objectives. In his own book, and Zahn, figures of these eyepieces appear and it will be seen that they were provided with inter-pupillary adjustments. No coarse focusing adjustment was fitted for this microscope, objects were focused by moving the stage nearer to or further from the objective surely the forerunner of the stage focusing used so extensively in the next century and employed to-day on metallurgical microscopes. The microscopes of Van Leeuwenhoek have so often been figured and referred to that no illustration is necessary, nor in view of DobelFs publication, in which work the author has been extraordinarily successful in bringing Van Leeuwenhoek to life and making the reader feel that he is actually in mental contact with Dobell's hero is any reference to Van Leeuwenhoek required. The next suggestive design in chronological order is that of Bonani, and nothing can be more suggestive or more in advance of its time. The complete instrument is virtually based upon the principle of the optical bench. There is an attempt at rigidity. The microscope body is fitted with coarse and fine adjustments, the coarse being by rack and pinion. The sub-stage or lamp condenser is provided with focusing motion, surely the prototype of the microscope used so successfully for metallurgical research, photomicrography, etc., up to within the last twenty years. The microscope by Joblot, incorporates the first objective slide. Joblot mounted his objective in thin, brass, dovetailed slides, and these, some of them incorporating one, others two, objective lenses, were interchangeable and were, what would be known as, objective changers on the microscope. The first revolving nosepiece was introduced either by Adams or by Martin. These two designers were contemporaries and it is sometimes difficult to attribute the various designs for which they are responsible in correct priority the one to the other. It is perhaps convenient at this point to interpolate a note on the first Scientific Society. This, under the name of " The Academy of the Lynx," was founded in Rome and met at the house of the Prince Cesi. Stelluti, Galileo and many others were members. The new knowledge obtained by means of the microscope and the telescope was of such enthralling interest and fitted in with the new outlook of the thinking section of mankind, resultant from the Renaissance. The Church had not fully determined her attitude. The Pope Urbino he who was interested in Galileo's work occupied the Papal throne,and both as a compliment and to placate him, the first monograph ever published was on the honey bee. This was selected for study because the bee figured in the papal coat of arms. It will be remembered that Milton made the Grand Tour. From his subsequent essay " Aeropagitica " it is known that he met Galileo (M. N.), and the whole of his poetry subsequent to that meeting is instinct with awe of a new knowledge of space. It is interesting to speculate upon the possibilities of Milton having attended meetings of the
Academy of the Lynx and subsequently meetings of the Royal Society, through which there is then a continuous link from the first Scientific Society to the present day, for the Royal Society has the longest continuous history of any scientific society in the world.
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