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The Simple Microscope in the Hands of Van Leeuwenhoek and Huygens

Spinoza’s Microscopology: a prospective comparison of context

It strikes me that there is a subtle, yet important contrast between the single lens microscope that Christiaan Huygens ended up offering by the Fall of 1678 and the design which was consistently used by Van Leeuwenhoek, a contrast that points up a branching out of conception of the relationship between instrument and observation, one that perhaps help position Spinoza’s own view of lens use. 

At the end of 1678 the Huygens, Rømer, Hartsoeker microscope resulted in this design:

Its “strength” is that it was that it was equipted with a revolving wheel, into which six different preparations could be placed, enabling a kind of frame by frame, one might even say, nearly cinematic comparison specimens which could be flipped before a small grain of a lens. This designed was very quickly put into widened production by the instrument maker Herbert Butterfield. When compared to Van Leeuwenhoek’s essential model, there is a notable difference:

For Van Leeuwenhoek the specimen is placed fixed, suspended [atop the pictured needle], in the most elementary of relations. Further, in his use of the microscope Van Leeuwenhoek seemed to express a very different idea of the relationship of the device to what is seen. For instance, of the 26 samples that were sent to the Royal Society upon his death, they consisted of a pairing: each microscope came with a matched specimen which was placed ready to view. The device was not conceived apart from the staging of the observed. (And these devices were for Van Leeuwenhoek private, personal, not conceived to be widely reproduced.)

This contrast is a small point, but I think that the kind of looking that Van Leeuwenhoek was famous for, the intensified examination and preparation of the moment of witness, came out of his conception of device and specimen. And Huygens’s incredibly rapid development and “improvement” of this device, marks a difference in the act of looking, a mechanized and rotational expression of specimen interface, one where the device stands as a kind of medium between the facts of the world (and not a particular event) and an investigating mind. I make no judgment of course between these two conceptions, other than to say that their contrast perhaps provides a backdrop upon which Spinoza’s conception of lensed observation may be made more clear. He looked somewhat obliquely at Huygens’ complex machinery of automated ends (again, Letter 32), perhaps sensing that the means of witnessing color and shape help establish the quality of what is seen. The Huygens “enhancement” of the Van Leeuwenhoek design, the speeding up of the relation between the witness of one specimen and another, and they bodily experience of an intricate, mechanized interface with various phenomena, marks out a significant difference. 

These thoughts are a continuation from an originary thought begun here: Van Leeuwenhoek’s View of Technology

Huygens Appropriation Further Notes and Complications

More Notes on Huygens’s New Microscope

Having now read Marian Fournier’s “Huygens’ Designs for a Simple Microscope” (1989) the extended hypothesis that Christiaan Huygens was somehow aided in his quick production of a “new microscope” by the grinding techniques that may have been found in the purchase of equipment from Spinoza’s estate, suffers complication. This is largely due to the remission of any detail as to the grinding of lenses in this rather through report. Indeed, there is text citation as to the blowing of lenses [cited is a manual OC viii, Part II, 683-4 and OC viii, 89 letter dated 30 July 1678 ]. Having not read these passages I cannot say for sure how exclusive these descriptions are, since they are taken to be refinements of the blowing techniques themselves. It is possible, at least from this distance, that such blown lenses were then ground, but as there is no existent discussion of such a process, it is hard to embrace that this formed a decisive aspect of the process. Instead it seems that Christiaan and Constantijn were absorbed with nearly every other aspect of the microscope model, trying multiple configurations of the frame, the eyepiece, diaphragm, specimen holding means, etc. This relative silence as to the lens could I suppose suggest that by June 1668 the technique of lens grinding (if assumed) was settled on, and all that remained for improvement was the apparatus.

Christiaan Huygens first design

Be that as it may, Ms. Fournier presents clearer a timetable presentation of the unfolding of the microscope’s conception and production, some of which exposes the possibility of further questions. I reprint here some of the relevant events:

Christiaan Huygens is in The Hague, returned from Paris due to illness, from June 1676 to July 1678.

Feb 21 1677 – Spinoza dies in The Hague.

Unknown date – Christiaan translates Van Leeuwenhoek’s letter to the Royal Society dated Feb 15 1677 into French.

Aug. 1677 – Van Leeuwenhoek discovers the animalcules in semen, spermatozoa. (May have informed Huygens: Fournier)

Nov. 4 1677 – The Huygenses possibly purchase the grinding dishes and other equipment from the Spinoza Estate.

Feb 1678 – Christiaan studies spermatozoa through a microscope of unknown kind, taking notes (OC viii. Part 2. 698 )

March 1678 – already in close contact, Hartsoeker sends Christiaantwo microscopes and instructions for their use. Two attributes are noted: 1). a 1 to 1½ ft tube used to restrict ambient light on the specimen, and 2). a movable glass, polished or plain, behind the object to control the beam of light (dating letters 14 and 25 March, 4 April . [Ruestow adds that Hartsoeker did not only mail these, but also at the end of March came to The Hague to show the spermatozoa of a dog in person].

26 March 1678 – Christiaan orders a single lens microscope from the renowned Van Musschenbroek workshop.

May 1678 – Christiaan completes the first drawn version of the design his microscope.

An Article on the authorship of the microscope is published in the Journal des Sçavans, crediting Harksoeker with primary credit for the control of specimen lighting, and Huygens for that of the sandwiching of the speciment between glass and mica discs.

Christiaan Huygenss third design 29 August

Christiaan Huygens's third design 2.9.78

Fournier, quite differently than Ruestow, paints Huygens in Paris as being very reluctant for the recognition of his microscope. Ruestow is quite convinced that Huygens attempted to cheat Hartsoeker of some credit. Given that Huygens was returning to Paris after a two year absence, and that the credit he probably wished was from the society members he made his presentations to, and intercoursed with daily. It seems unlikely that issues of priorty and publication are those that defined Huygens sense of identity and self-esteem.

And Fournier brings out more than any other source the ubiquity of this kind of lens scope, confirming my suspicion it was not at all the lens beading technique which Hartsoeker supplied to Huygens. In fact it seems that Huygens “recently” had visited the house of the master of the small lens, Van Leeuwenhoek (581). Given that over time Huygens’s design would move away from the distinct component that Harksoeker is credited with contributing, as Fournier reports, “the development proceeded from a very long tube to a simple perferation directly behind the object, which served to limit the amount of stray light” (589), one wonders just where Hartsoeker’s fingerprint on the device remains.

As for my chain of inferences which link the production of this microscope with the possible acquisition of the grinding equipment of Spinoza’s estate, it remains tenuous. Until I or another go over the cited material describing the production of the lenses used. Most certainly it seems that the ball-bead lenses were employed in the new design, but the experimentation with the melting method may suggest dissatisfaction with this rather quick and easy method of making lenses. Given that the rate of Huygens’ microscopic observations balloon to daily notes in June of 1678, lasting until early ’79, it may be that Huygens himself used lenses of a kind different that more ubiquitously distributed. Such a view may be supported by Ruestow’s citation of OCCH xiii 522-7, which in retrospect provides the possibility of both a bead lens and a ground lens being used (26). What is provocative is that the very thing which Huygens found disconcerting about the bead lens in April 1665, the depth of field, is that which is addressed to some degree by grinding the bead lens into a convex/convex shape, opening up the aperture, drawing out more detail. Fournier sums up Huygens’ objection to Hudde as:

He particularly deplored their very limited lack of depthof field. He foundit inconvenient that with such a small lens one could not see the upper andunderside of an object, a hair for instance, at the same time (“Huygens’ Design…” 579).

Why Spinoza’s Method of Lens Polishing Might Have Been Integral

How The Clouded Glass Sphere Becomes Opened up to Light

Al Shinn has given me a link to work being done by Alvaro Amaro de Azevedo, which might explain why a hypothesized Spinoza lens polishing expertise could prove decisive in employing a single lens technique. First, Amaro de Azevedo approximated a simple, thread-melting techique thought to have been used by Van Leeuwenhoek, and achieved practical results of about x500 magnification and more, reaching those even achieved by Van Leeuwenhoek himself (x266 is I believe the highest magnification of an existing Leeuwenhoek lens, but Ruestow estimates that x500 could not have been “unusual” (14), noting that a recommended lens by Hartsoeker would “entail a magnification of x770”). Amaro de Azevedo even reached a magnification level of x1000 using soley the melted beads of glass thread, whose proximity to the specimen challenged most 17th century specimen staging capacities. If nothing more, this established the ease of dramatic single lens, beaded magnification achievement. Here his experiments are detailed.

Yet Mr. Amaro de Azevedo later learned that nearly all of existent Leeuwenhoek lenses had been ground lenses, and not simply beaded from melted glass. He set to grounding equally powerful lenses. As I have said, Johannes Hudde is reported to have ground his bead lenses (in salt), and Hooke too ground his bead lenses. It has consternated some modern analyzers of this method as to why a rather effective, tiny glass globule lens should prove insuffient? Why grind glass? The answer to this might help establish why an additional and otherwise guarded means of grinding technique might pave the way towards a more effective beaded lens.

Alvaro Amaro de Azevedo in his second round of experiments actual unveils some of the possibilities for these techniques (improvised on modern equipment), and produced results suggestive of the necessity of the additional polishing means. Here is his article, “The Challenge of Grinding Lenses for Single Lens Microscopes” (keeping a close eye upon the aspects that were feasible in the 17th century).

The first thing I notice is that the grinding abrasive required the use of mills, as Alvaro decides to use sand:

Anyone who has ever read about lens grinding techniques is aware that the main resource for succeeding is the grinding powders…I honestly have no idea where such powders could be found locally but the article mentions that Leeuwenhoek might have employed sand and graded it by levigation. So that was what I did. The sand was collected from a nearby beach and then washed thoroughly. After it had dried, the sand was put into a mill where it was crushed for one hour. The resulting flour was then suspended in water and through levigation six fractions were collected. I named them from 1 (the coarsest) to 6 (the finest).

As an simple point of correspondence, bought at the auction of Spinoza’s estate were various “mills” (molens):

and various instruments for grinding (‘en verscheidene slypgereedschap’) like mills (‘molens’, also plural!) and great and small metal dishes serving for them (‘groote en kleine metale schotels daartoe dienende’) and so on” (en so voort).

The plurality of mills suggests a gradation of grits produced, such as perhaps those used by Amaro de Azevedo. Whether these were of salt as Hudde is said to have used, or of sand, these mills speak to a particular technique of grinding and polishing, something that could be passed on through the equipment alone.

Next I noticed his search for a polishing agent:

For polishing purposes, I tried to find the jewelry rouge (iron oxide) but it was in vain. Then I tried to smash a hematite stone and I got a powder that was too coarse for a good polishing powder. Then I made many attempts to find a good substitute and at the end of the day I made a polishing tool that doesn’t need powder to carry on polishing.

His solution is certainly not one that Spinoza would use, though the iron oxide powder may have been something that Spinoza picked up in Amsterdam when he learned to grind glass, given the plethora of gem and diamond polishers that may have florished in his community (it was one for the few non-Guild regulated buisnesses available to Jews). Robert Hooke used “tripoli” (a diatomaceous material, getting its fineness from the remains of microscopic organisms). This was long used by Venetian spectacle makers, its use forwarded by instructional manuscripts written by Sirturus and then Rheita. Because Van Leeuwenhoek put tripoli under his microscope to examine it, it is quite likely that he used this as well.


Lastly though, as Amaro de Azevedo ground his smaller and smaller lenses, leaving behind a cut glass blank, and eventually grinding melted beads of glass themselves, as did Hooke and Hudde (and likely Van Leeuwenhoek), achieving greater and greater limits of magnfication, he comes to the vital point, illumination and focal distance:

The main advantage of ground lenses are that they can focus at longer distances compared to the same magnification from ball lenses and thus, I could capture images from already mounted slides that wasn’t possible before. I also noticed that ground lenses allow wider apertures and as consequence, the images seemed to be brighter and higher in resolution.

A modern maker of the two comparable lenses, that is, of the simple beads of glass spheres, and their tiny ground counterparts might not readily notice the distinct advantage that Amaro de Azevedo brings out here. The reason is, the quality of glass that is readily available to us simple was not makeable then. Glass, even the best of it, was bubbled, marred with striations, and considerably darker, tinged with colored. Any advantage in opening up the aperture and letting in more light was not simply a convenience, but rather probably marked the difference between being able to see a specimen or not. For instance, when Robert Hooke says that the single bead lens is simply too small, and that he fears for his eyesight, he means not only too small, but too small and too dark.

Aligned with this point was the techniques of lighting the specimen would prove most important. Ruestow infers that Hudde’s microscopic observations may have been impaired for many years for it did not occur to him to look directly at a light source, with the specimen in between, an improvement attributed to Van Leeuwenhoek (22, n.85). Is this why Hudde did not come up with any astounding discoveries despite owning the beading technique for more than decade before Van Leeuwenhoek comes upon the scene?

These three factors, rather poor occluding glass, just discovered techniques in lighting and specimen preparation, and in some cases guarded secrets in grinding and polishing techniques, all point to the difficulty of microscopic discovery, when using bead-lenses. What is suggested is that the best polishing of these tiny melted spheres would open up the aperture and clarity of an otherwise murky ball glass lens, when pushed to the greatest of magnifications. Thus the state of the technology may have demanded an adequate polishing means, one provided by the purchase of Spinoza’s equipment by the Huygenses.