From changes in shape to changes in production

The production of the microscope was also determined by its practice and by the particular needs expressed by scholars for features, morphology and improvements.

Notably, the shape of microscopes influenced the kind of position taken for observation, the style of science practiced, and, indirectly, the demand of scholars for microscopes.

It is indeed difficult to draw morphological and even more, physiological conclusions about animalcules from the flickering images observed through a hand microscope. In this respect, the death of Leeuwenhoek marked the end of an era and helped to

determine the fate of the practices of the microscope up to the 1740s. In his will

Leeuwenhoek had bequeathed 26 of his microscopes to the Royal Society which arrived in England in 1723. As a kind of eulogy read before the Society, Martin Folkes

introduced the microscopes, each of which had a particular object fixed with glue, though several objects had broken off, during the travel. Registers from the hand of Leeuwenhoek were added to the gift that enabled the fellows “to examine many of those objects, on which he had made the most considerable discoveries”.⁴⁸⁸ Among the objects were blood globules and desiccated animalcula in semine masculino. The rest was composed of tiny parts of insects, animals or plants: eyes of gnats and flies, fibres

487 Cavazza 1995, 717.

488 Folkes 1723, 447.

of fish and tongues, hairs of various origins, parts of bones, organs of spiders, vessels of plants, and so on. Folkes balanced the qualities of the microscopes with the skill of the observer: “However excellent these glasses may be judg’d, Mr. Leeuwenhoek’s discoveries are not entirely to be imputed to their goodness”.⁴⁸⁹ The judgment, experience and assiduity of the man each played a role, creating a sort of mythical standard for microscopical investigation: “it can be imagined any other person can do, that neither has the experience, nor has taken the pains this curious author had so long done”.⁴⁹⁰ Folkes particularly reminded his audience that the microscopes sent to the Society were proofs of Leeuwenhoek’s skills in preparing objects. But the results of this analysis turned out to be rather deceptive. Folkes recommended his listeners not to

“rashly condemn any of this gentleman’s observations, tho’ even with his own glasses, we should not immediately be able to verify them ourselves”.⁴⁹¹ This passage is highly significant and indicates the status the Royal Society granted to Leeuwenhoek’s

observations. They had to be accepted regardless of the fact that other scholars were unable to repeat them, even if they had Leeuwenhoek’s microscopes in hand. There could hardly be a better description of the elitist microscope.

As a result it sounded more impressive that the man was reliable, rather than that his observations were reproducible, and thus assimilable to the general network of scientific data. This is another sign of the absence of integration of Leeuwenhoek’s works with the scientific network, resulting in the heroisation of the man himself as a kind of reliable curiosity: “There can be no reason to distrust his accuracy in those others [discoveries] which have not yet been so frequently or carefully examin’d”.⁴⁹² If many scholars before and after Leeuwenhoek acknowledged that his method for making and using microscopes were unknown, the solution that Folkes proposed --to accept, despite any repetition, his observations because the man was reliable-- only served to

489 Folkes 1723, 452.

490 Folkes 1723, 452.

491 Folkes 1723, 452.

492 Folkes 1723, 453.

shelve the problem. It is certain that Leeuwenhoek contributed to the formulation of important skills. Still his attitude impeded these skills to be turned into standards, both for making microscopes and for its use. Witnesses for this fact are not lacking: “I had not”, reported Archibald Adams in 1710, “an opportunity of examining Mr

Leeuwenhoek’s glasses particularly, which is a favour he allows to none”.⁴⁹³ Leibniz equally begged Leeuwenhoek to divulge the secret of his microscopes, as well as his method of observation to scholars. No tradition of these skills could thus be transmitted, conserved and improved up by the contemporary and subsequent generations of

scholars.⁴⁹⁴ In a sense, this was a waste of time: “We are under very great

disadvantages for want of the experience he had”,⁴⁹⁵ said Folkes before the Society.

The decrease in microscopical publications in Britain in the period 1700 to 1730, as well as the low number of quotations of Leeuwenhoek in the first part of the century should probably be linked to his resistance to publicising his know-how and knowledge of the microscope. Contrasting with the pathetic appeal from Folkes to “pursue those enquiries”,⁴⁹⁶ the studies on microscopical topics like blood, animalcula or the anatomy of tissues, ceased in Britain between 1723 and 1740. Except for rather episodic

remembrances as opposed to references given by Sloane or others,⁴⁹⁷ the Leeuwenhoek

“legacy” in England was buried by the time of, and probably long before, the scientist’s death. In Britain the years 1723-1725 saw the last breath of seventeenth-century

microscopical research. Leeuwenhoek’s posthumous papers were published in 1723, and Folkes’ paper was actually closer to a funerary address or an apology than an eulogy. Other scholars who used the microscope had similarly their works published before 1725. James Jurin (1684-1750), one of the rare people who had improved the techniques of weighting and measuring blood corpuscles in the late 1710s, did not reply to the criticisms raised in 1722 by the Italian scholar Pietro Antonio Michelotti on the

493 Adams 1710, 24. A similar criticism is in Roffredi 1770a, 9. See also Wilson 1995, 90.

494 In this meaning, which I believe to be the historical one, there is no existing Leeuwenhoek legacy, unless we want to consider a will to be written for people not yet born...

495 Folkes 1723, 452.

496 Folkes 1723, 453.

497 Sloane 1733, 100.

separation of bodily fluids.⁴⁹⁸ The works by Patrick Blair on vegetable physiology and the compilation of naturalia that included microscopical works by Richard Bradley (1688-1732) had also been published in 1720 and 1721, respectively. Moreover, the microscope by Culpeper (1660-1738), said to have been promoted in 1725,⁴⁹⁹ did not actually produce particularly obvious echoes, and no one ventured to speak of

animalcula any more. Except for Stephen Hales whose 1727 Vegetable Staticks was also very quiet on the subject of microscopes, it is not before the mid-1730s that new perspectives on using the microscope appeared.

Both simple and compound microscopes presented certain problems related to the vibration, venue of light, fine adjustment screw, and to fitting the objects. At high magnifications, the very small distance between the specimens to be observed and the objective or lens caused problems in lighting the object, and both Wilson and

Culpeper’s microscopes did not allow the alive setting of parts of taller creatures.⁵⁰⁰ For instance still in December 1761 Albrecht von Haller, who could not observe parts of a full egg being disturbed with the tripod of his Culpeper microscope, asked Charles Bonnet for other solutions.⁵⁰¹ New microscopes invented since the middle of the thirties, and by Cuff later, solved these two problems. But here astronomical research influenced the 1740s development of microscopy. A telescope using mirrors had been invented in the 1610s by Father Zucchi, a Jesuit from Parma,⁵⁰² and later, in 1672, Newton designed his catoptric microscope, believing that the optical limitations of the lenses could not been overcome. In 1728 the French instrument maker, Jacques

Lemaire, presented a new catoptric telescope to the Académie des sciences. This kind of project was taken up and applied to the microscope, because Robert Barker, in 1736,

498 Michelotti 1721. For a biography of Jurin, see Rusnock 1996, 8-22.

499 Culpeper’s leaflet does not give a date. See C&C 1932, 108-115.

500 It must be remembered that, for eighteenth-century instrument makers, the objective glass must be a segment of a small sphere. The smaller the sphere, the higher the magnification, and the nearer it is from the object.

501 Sonntag 1983, 250-251.

502 According to Pézenas (1767, 420-421), Niccolò Zucchi stated in his 1652 Optica philosophica to have used metal mirrors for telescopes since 1616. See ISIS on telescope

and Robert Smith in 1738, claimed to have improved the catoptric microscope, using two mirrors. Newton’s reflective microscope needed only one metal mirror, while those of Barker and Smith had two.⁵⁰³ Both fitted a large concave mirror in which an ocular with two lenses had been set in the middle, the light, therefore, being reflected in a second smaller mirror (Fig. L).⁵⁰⁴ In Barker’s, the distance between the object and the

mirror was between nine and 24 inches, leaving enough space for manipulation,

changes in light and larger objects. Barker first submitted the principles of the catoptric microscope to the Royal Society in 1736, but the instrument was judged to be not very efficient.⁵⁰⁵ A second model released in 1740 was much better, and this microscope continued to be sold for some years.⁵⁰⁶ It had three advantages over the common microscope: first, the object could be exposed to any degree of light and not be

503 Barker 1736a, pl.; Barker 1736b, 432; An. 1740, 165.

504 Barker 1736b, 433-434; Smith 1767, 124.

505 In 1740 the editor of the Bibliothèque Britannique wrote that when it was presented before the Royal Society in 1736, the microscope was but “an essay of a construction, to which one should come back to improve it”, An. 1740, 166. Later, an improved microscope was presented (An. 1740, 168).

506 The double reflecting microscope was used at least until 1745 (Parsons 1745, 260-261) and probably by Needham 1750. Another microscope of that time was the smaller simple hand microscope for opaque objects, which had a concave mirror before the lens to reflect light.

perturbed by the small distance of the objective to the object as was the case for the refracting microscope. Second, the object did not need to be transparent. Even opaque objects could be highly magnified. Third, this technique allowed the magnification of small details of whole creatures, and allowed one to observe the circulation of the blood, and any kind of motion in a live animal.⁵⁰⁷ Among the different steps in the history of increasing freedom of form and function of the microscope, the catoptric microscope gave way to the possibility of experimenting on live beings and improved the flexibility in light use.

Two new microscopes were also invented in the late 1730s. In 1738, during the English leg of his grand tour of Europe, the German MD Johann Nathaniel Lieberkhun (1711-1756) demonstrated the concave mirror which carries his name, and two new

microscopes, the solar microscope and the simple microscope for opaque objects before certain craftsmen and other members of the Royal Society.⁵⁰⁸ A few years later

improved versions of these microscopes were being sold by Cuff and by other British manufacturers. Along with the catoptric microscope which signaled the revival of the market for microscopes, the two new models brought to England by Lieberkhun allowed the instrument maker to sell a minimum of five different types of microscopes in the early 1740s. As a consequence the microscope acquired better visibility in the titles of leaflets and in certain microscopical research. A period of fifteen to twenty years had therefore been necessary to clear away the outdated context of dealing with and producing the microscope.

4.5. Social and political cultures of the microscope: Two styles of producing