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Dutour (1760)

How to cite this translation

As found by Dutour (1760) rivalry occurs .... (O'Shea, 1999).

...rivalry was found (Dutour, 1760; translated by O'Shea, 1999).

How to reference the original work and this translation

Dutour, E. -F. (1760). Discussion d'une question d'optique [Discussion on a question of optics]. l'Académie des Sciences. Mémoires de Mathématique et de physique présentés par Divers Savants, 3, 514-530.
O'Shea, R. P. (1999). Translation of Dutour (1760). Retrieved from

Discussion on a question of optics

1. When we fixate an object, it is painted on both retinae. The object appears double whenever both its images fall on parts of the retinae situated opposite the optic axes, or at points unequally distant from where the axes abut; in summary: when the images fall on noncorresponding retinal parts. But when the two images are painted on the retinae, either precisely at the extremities of the optic axes, or at equal distances from these points on corresponding parts, the object appears single, despite the two images. In this latter case, does the mind receive the impression of both images at any time, or is it appreciably affected only by one?

2. I have conducted the following experiments to resolve this question. I pasted a disk of blue taffeta of an inch in diameter onto one side of a sheet of cardboard, and on the opposite side, another disk of yellow taffeta of the same size, so that the two were exactly back-to-back. I placed the cardboard against my nose in a vertical plane, and perpendicular to my face. With my right eye I could see only the blue disk and not the yellow, and vice versa for my left eye. Thus each of the disks was painted separately: blue in my right eye, yellow in my left. However I could discern only a single patch from the two images. If my perception were the combined product of simultaneous impressions of both images, should not the patch have seemed to be green? But I was unable to detect even the least tint of green. The single patch I could perceive sometimes appeared blue, sometimes yellow, apparently according to which rays of light reflected by one or the other disks struck my eyes with more energy. Also, sometimes the patch appeared partly blue and yellow. I attribute this further to the fact that certain parts of the blue disk stimulated my sight more strongly than the corresponding places of the yellow disk, while the rest of the blue stimulated my sight less than the corresponding parts of the yellow disk. May we not now conclude that at any instant my mind experiences the impression of half the light reflected by both disks, and that it is not affected simultaneously by two corresponding image points? Otherwise, these two points must be superimposed into one which would be coloured both blue and yellow, and consequently should appear green.

3. Moreover, would there be many difficulties in supposing that of two such simultaneous impressions on the nerve fibers of the eyes, and which are probably going to coincide at the point where the fibers converge, there would be only one impression which would be perceived to the exclusion of the other? All that is necessary for this supposition is that the two impressions do not fuse absolutely equally. As soon as one impression acts on the brain more strongly, it is not surprising that the mind would be affected by it (see [Mariotte, 1717] p. 317, and Mus[s]ch[enbroek, 1739] p. 582), and would either not be affected by, or would not pay attention to, the weaker impression. How many more variables are there of the object, the brain, or the light, which contribute to making simultaneous impressions unequal? And how many combinations are there in which these variables have no effect? Perhaps the case of equal action between two corresponding impressions is infinitely rare, or almost impossible.

4. If one looks with both eyes at point A [Figure 1], four to five inches away, and places on the optic axes LA, RA, short of their intersection at point A, two small pieces of taffeta, one yellow at C, the other blue at D, one will see only a single patch of blue or yellow, or parts of both colours, and never green. The spot will appear to be on line AA, which bisects angle CAD.

5. This experiment is analogous to the former, the effects are the same, they result from the same causes, and one has to draw the same conclusions from it. The first experiment differs in that the coloured objects are precisely at the point of intersection of the optic axes, whereas in the second the coloured objects are separately arranged on the optic axes between their point of intersection and the eyes. There would be a third way to arrange them on the optic axes, that is, beyond the point A [Figure 2] of their intersection, at N and at P for example. The appearances will still be the same, providing one views each object with only one eye. To observe this condition, it is necessary to place between the eyes and the objects a piece of cardboard K, with a hole in it at the point of intersection A of the optic axes LP, RN. By this means one will see only a single patch, either blue, or yellow, providing care is taken to turn the eyes so that the two pieces of taffeta N, P, are each precisely in the direction of the optic axes.

6. I stood about a dozen feet from a picture with a width of eight feet, and placed a sheet of cardboard KJ between my eyes, holding it vertically and perpendicular to the picture. The optic axes of my eyes, LO, RO, [Figure 3] crossed towards the middle O of the picture AT. Then, alternately closing one eye and the other, without changing the direction of the open eye, I could see with the left eye only portion AC of the picture and QT with the right. Instead of the remaining parts of the picture AQ and CT, screened by the cardboard, I could see the surface of the cardboard turned towards the open eye. On opening both eyes, still keeping them in the same direction, I could then see only the picture in its entirety, and not the cardboard, which I continued to hold between my eyes. The cardboard seemed to have disappeared. In this last case, the surface S of the cardboard KJ would be painted on the retina of my right eye at BH. Portion AQ of the picture, however, would be painted only in my left eye (the cardboard hiding this portion of the picture from my right eye) at DE on the part of the retina corresponding to BH, relative to the optic axes LO, RO. Thus, since I could see this part AQ of the picture, and nothing of surface S of the cardboard KJ, it must necessarily be that of the two simultaneous impressions that these different objects produce conjointly on the same portion of the brain, it is only the impression made by image DE of the portion AQ of the picture which is effective and by which my mind is affected. DE would eclipse and nullify the impression of the corresponding image BH of the card, and undoubtedly does so because DE is more conspicuous than BH. Indeed, under these circumstances, the bundle of light rays that leave from each point of the object AQ, would reunite precisely on the retina, whereas the bundle of rays that leave from each point of the cardboard KJ, being too close to the eyes, reunite beyond the retina.

7. The facts I have reported establish that of two objects which paint themselves in the eyes, there is only one which affects the mind when their images fall on corresponding retinal points. If this is accepted, then would we need any stronger reason to admit that a single object can produce only a single effective impression on the mind, despite being painted simultaneously in both eyes? I thought however that it would be appropriate to attempt to clarify this question as much as I can, by discussing another related fact on which Physicists do not agree at all: If one looks with one eye L [Figure 4] at object S, it seems to be situated at C. If by winking, one looks at it with eye R, the object seem to be at B. When both eyes are opened on the same object S, M. Musschenbroek ([e.g., 1739], Essay on Physics no. 1225) says that one judges the object to be at F, equally distant from points B and C. However, M. Leclerc, in the account of M. Polinière [(e.g., 1734,] Exp. 95, p. 506]), claims that one would see it only at B or at C, in one of the two places that it seems to occupy when looked at it with one eye. Nothing seems more contrary than these two observations. Thus, convinced that one could not be accepted without excluding the other, I gave myself the task of establishing which must be preferred, to verify the disputed fact. I am going to give an account of what I have come to in this respect, below. First, consider M. Musschenbroek's statement of the fact: that when one considers the object with both eyes, the mind makes a different judgment on its position from when the object is painted in a single eye. It seems that this difference can only be taken as support for the combined action of two images. This leads to the suspicion that the mind receives simultaneous corresponding impressions from both images. Therefore, in seeking to verify the fact in question, I was examining the validity of an objection made in advance against an hypothesis which in other respects seemed very likely.

8. I placed horizontally, and end to end, three pieces of ribbon, each about two feet in length. One was red AB [Figure 5a], another green BC, and the third yellow CD; I stood facing them from about twelve feet away, with a vertical rod held at the point of intersection S of my optic axes of my eyes so that the right ended at point B, the left at point C. I placed a small disk of white paper at each end of the green ribbon, B and C. When I opened one eye directed towards the object S, I judged the three ribbons and the paper disks arranged as they actually were. The object S appeared to be placed on point B or C, according to whether I would use the right or left eye.

9. Having fixated S with both eyes together, I judged it at F, precisely opposite me and in the middle of the green ribbon. Behind object S, I saw two paper disks. I could see a third disk to the left, and a fourth to the right. These last two seemed to at each end of the green ribbon, which appeared to have doubled in length while still bounded by the red and yellow ribbons. It was as if there were two green ribbons one on the other (both bounded by paper circles) which detached themselves, one approacing the right, the other towards the left, until they touched only at their extremities. The two paper disks met precisely behind object S.

10. I am refraining [until] here-after from giving the explanation of this phenomenon, and new evidence of its reality: meanwhile, let us pause here to consider that it absolutely settles the difficulty that M. Musschenbroek's observation could contribute against my hypothesis, and that it follows that the diversity of judgments brought to our mind in the two specific cases on the position of the object S at B, at C or at F, will not be adduced as an indication that the mind can be affected by simultaneous impressions of two images formed on corresponding parts of both retinae.

11. I begin by admitting that, according to the observation of M. Musschenbroek, the mind forms, in the two specific cases, different judgments; but I will add at the same time that the impressions which it receives and which they cause, are not the same, and that thus there is not the occasion to attribute here the diversity of these judgments to precisely the fact that the image is painted in a single eye, or single in the first case, and printed in both eyes, or double in the second case.

If in both cases the objects represented in the eyes would not produce the same impressions on the mind, it is not surprising that there would be a difference between the judgments which it brings in respect of these objects, the cause presents itself in the variety of impressions: why would one look for it elsewhere? One is thus not obliged to make it consistent in that the image is single or double; and since then [therefore] the conclusion that one might want to draw from this last reason, in favour of the efficacy of simultaneous impressions of two corresponding images, is false.

12. Thus it really only remains to demonstrate that when one looks at the object S [Figure 5] with one eye, the impression that the image which paints itself there produces in the mind is quite different from the impression of which it is affected by images which are formed in both eyes [when] fixed together on the same isolated object S. In the first case, the impression which the mind receives is that of the image abgm, or the image npcd, which differ from each other only in that the object S appears in one [to be] situated between the red ribbon and the green, and in the other between the green ribbon and the yellow: but in the second case, and when both eyes are fixed together on the object S, the impression by which the mind is affected, is that of the image npc/bgm [Figure 5b], where the green ribbon has more length than in the first two, and where the object S appears to occupy the middle of the green ribbon, [and] become double in appearance.

13. Since the experiment tells us that the mind experiences different impressions in the two cases in question, it is undoubtedly natural to derive from this diversity of impressions the diversity of judgments that it [the mind] makes on the site of object S; it would judge it in comparison to the apparent position of points B and C which meet in the direction of the optic axes. When one looks at object S with one eye, point B, or point C appears situated as is natural to it, to the left or to the right, relatively to the eye [depending on which eye is used]; and the object S, which the mind still judges on one of these points on the optic axes, would consequently also appear to the left or to the right to the regard of our eye, and it is there that we see it.

But [what about when] one looks at object S with both eyes? In that case, as we have noticed it above from the experiment, space BC included between the two optic axes becomes double, and it exists as two apparent spaces BC, arranged one against the end of the other, and of which the ends that touch, and the circles of paper that one has attached there, coincide at the same point; this indicates that points B and C, on which the circles of paper have been attached, also both coincide there: thereupon the mind can suppose that for one to be reconciled with the other, they are advanced equally and jointly; by means of which, the point of reunion of points B and C will be judged to be placed directly towards and opposite the Observer, and object S will also appear at the same point, because the apparent position of points B and C cannot miss [mask] deciding that of object S [the apparent positions of B and C specify that of S].

14. It follows that the observation of M. Musschenbroek and that of M. Leclerc differ less that I had first thought. Both these authoritative physicists have considered things from different points of view, and one can almost reconcile them. Indeed, it is certain that at the moment one looks at an isolated object S, with both eyes, and that points B and C are in the direction of the optic axes [Figure 4], one would never know, in the same way as M. Leclerc advances it, object S placed elsewhere than on points B or C, or, more exactly, than on both {tous [sic] les deux} at once, since the two points B and C are mobile and would reunite themselves apparently behind object S, or, which is the same thing, since the two optic axes still appear to have a common direction. Further, it is equally true that, following the observation of M. Musschenbroek, the optic axis that one would judge directed obliquely to the line BC, when one would look at object S with one eye, seems directed perpendicularly to the same line BC, when one comes to fix both eyes at once on object S. M. Musschenbroek had presumed that this phenomenon was contrary to that which M. Leclerc reported; but the experiment, in which we learn that points B and C then are apparently mobile, allows us to understand why these two phenomena can exist together.

15. To ascertain the mobility of points B and C in an even more convincing way, it is only necessary to do the experiment at night, and place a lighted candle at one of the points where object S is attributed [when] looked at alternatively with one of the two eyes, at B, for example; and at the moment that one will fix both eyes on the object S, one will believe [that one] see[s] two lights, one at the same point B, and the other at point F, where one then judges object S [to be]. Thus the light, or, this which is the same thing [in other words], apparently moves itself from point B to point F.

16. I am retracing my steps, and I am going to give a reason for the phenomenon that I have reported in no. 9, that is, the apparent lengthening of the green ribbon BC, in the case where the optic axes which fall on points B and C, [and] cross each other at S in the interval which separates the ribbon from the eyes. Referring to [Figure 5a] for this subject, one sees there why each of three ribbons paint themselves in each eye: in the left eye, images dc, cp, pn represent from left to right the yellow ribbon CD, green BC, and red AB; and in the right eye, images mg, gb, ba represent again from left to right the three ribbons, yellow CD, green BC, and red AB.

Images cp, ba are corresponding. (In Fig[ures 5a and 7a], I have distinguished the portions of the retinae which are corresponding, by designating them with similar numbers. The shaded arcs indicate portions of the images of which the impression is effective.)

Images dc, gb, are [corresponding] in like manner.

Consequently if, according to the hypothesis which I have stated, one is willing to admit that of the two images which fall on corresponding retinal parts, there is only one of them which appreciably affects the mind, that of the other being ineffective in this respect, one will conclude from it that in each of these two pairs of images, that is, of one part cp and ba, and the other dc and gb, there would be one of them which should be visible, and the other not.

The results of [these] observations teach us that the impression which communicates itself effectively to the mind, [arises from] images cp and gb, and that the impression from the corresponding [images] ba, dc is null.

Indeed, if the impression of images ba, dc would affect the mind as the two others do, it follows, from [the fact] that these two images ba, dc correspond to images cp and gb, relatively to the optic axes, that the mind has to judge the two images dc, cp applied on the two images ab, gb, that is, [the mind has to] see yellow and green applied on green and red; but we see only two green bands without any mixture of red and yellow, which indicates that images ba, dc are not appreciably affecting the mind.

It is nevertheless true that to the left of the green band one distinguishes a red band, and to the right a yellow band; but it is independently of these images ba, dc, that the red AB, and yellow CD ribbons, produce in our eyes, and of which the impressions are ineffective, [since] the same yellow and red ribbons still paint themselves elsewhere, specifically, the yellow ribbon in the right eye at mg, and the red ribbon in the left eye at pn, and it is by virtue of the impression of these images mg and pn that the yellow and red ribbons become apparent.

Thus it is necessary to consider that in these circumstances the mind receives impressions of images cpn from the left eye, and mgb from the right eye.
cp represents the green ribbon
pn represents the red ribbon
mg represents the yellow ribbon
gb represents the green ribbon

The green therefore appears two times, it is double. These two images cp, gb of the green ribbon are put together and are continuous in the perception of the mind, because the end c of one of the images and the end b of the other meet on the optic axes.

Image cpn being painted to the right of the optic axis, must, according to the usual optical laws, be judged to the left, and is indeed judged to the left; to the contrary, image mgb is painted to the left of the optic axis Bb, and must, according to the same laws, be sensed, and is sensed, on the right.

It further follows that the perception of the mind must then be of the image npc/bgm, consistent with that which gives the observation, and which is composed of two parts, of which one npc is painted in the left eye, and the other bgm is painted in the right eye.

17. I will note however on the point of the lengthening of the green band which I could see between the red band and the yellow, that I have not always judged the appearances as consistent with the theory as it seemed to me they should have been: I would not clearly see a double extension of reality in the green band; but could not this arise from the eyes being fixed on point S, which is a considerable distance from the ribbons, [so that] the images are never absolutely clear? they [the images] present themselves only confusedly to sight, which could easily influence the judgment the mind makes in respect of their respective extents. Moreover, some slight changes made to the procedure of my experiment have procured, in the new results, the complete proofs that then the appearance of the green ribbon must be double [that] of reality.

18. 1st. I attached to the green ribbon a circle of white paper, of an inch in diameter; and when I directed my eyes on object S, so that their crossed optic axes ended at points B and C, the circle of paper appeared doubled to me; from which it follows that the green ribbon should become the same, for it would be [the same] for all parts of the green ribbon as that where the circle of paper was attached.

19. 2nd. Instead of making the optic axes which cross at S fall on points B and C, which separate the green ribbon from the red and the yellow, I stationed myself so that they ended, one on the red ribbon, the other on the yellow ribbon, at P and H [Figure 6a], at two or three inches away from the respective points B and C. The appearances which I obtained are given in [Figure 6b]. Object S appeared, as usual, placed opposite: to the right and all against object S I saw a red patch, at the side of which extended a green band, and beyond this latter a yellow band: to the left of object S another patch presented itself, but yellow, from which proceeded a green band, followed by a red band. It is evident that both the red and yellow patches arose from {rendoient} both parts of the ribbons of these colours PB and CH; and since one distinguished a green band to the left of the yellow band, and a second green band to the right of the red patch [band], is not this a sign that the green ribbon which paints itself in one and the other eye, makes [an] impression on the mind by each of its two images which fall on non corresponding parts of the retinae? This must make it appear double.

20. 3rd. Having placed lighted candles at points B and C, where they would intercept the optic axes crossed at S [Figure 4], and another between the first two towards F, I saw, in turning my eyes [so that they were] directed towards the isolated object S, five lights. The three candles were painted in my right eye, that is, one at the point of the retina where the optic axis falls, and the two others to the left; and they being also in my left eye, that is, one at the point of the retina intercepted by the optic axis, and the two others to the right, one ought to have, it seems, seen six lights; but the two which fall on the points of the retina where the optic axes terminate, can only produce from them a single [image] in the perception of the mind, since these retinal points are corresponding.

21. And indeed, having placed the three lit candles on three points of the line BC, other than [at] points B and C, so that the image of each of the candles could not fall on points of the retinae where the optic axes abutted, I distinguished six lights. These observations complete the confirmation that the space enclosed by the two optic axes, in the circumstances mentioned above, is seen double, and [is] attributed by the mind at two different places and arranged end to end.

22. It would appear to follow from the detail to which I have just alluded, that the explanation which I am proposing, and which is based on the non efficacy of the impression of one of two corresponding images formed on the retina, applies itself generally and naturally to all circumstances of the observation expressed in no. 9. Moreover the appearances of this observation made with the care {attentions} which I have specified, are constant and always represent themselves the same [occur in the same way]; and it evidently follows from it [no. 9] that it is [it represents an example] of the cases where a space BC [Figure 5a], enclosed between points B and C, where crossed optic axes terminate, and to which one would attribute the situation of object S, [space BC] must appear double; but on the other hand {en revanche} there are other cases where the same space BC annihilates itself, so to speak, and disappears from the regard on the Observer, of whom the eyes are however still directed as they were in the first observation [it is clear that there are some cases in which BC appears double, yet others in which BC disappears without any change in the position of the eyes]. A slight change in the procedure of my experiment procured this new phenomenon, which is precisely the opposite of the first.

23. The arrangements made for my first experiments continuing to be the same, I added only two strips of cardboard N, M [Figure 7a], the first of white, the second coloured brown, which I placed between the ribbons and my eyes, so that the interior edge of each of these strips of cardboard would be shaved by one of the optic axes, and that these would mark [mask], that is strip N [would mask] the red and green ribbon[s] from my left eye, and strip M [would mask] the green and yellow ribbon[s] from my right eye. Therefore I could see only the yellow ribbon with the first [eye], and only the red ribbon with the second [eye].

Having both eyes fixed on object S in this manner, I judged it at F, at which point the two red and yellow ribbons appeared connected {réunis}, I could discern between them neither the green ribbon nor any other object which separated them. The end of the red ribbon was, apparently, immediately set onto {appliqué au} the end of the yellow ribbon: to the right of this latter extended the cardboard M, and to the left of the red ribbon extended the cardboard N. See [Figure 7b], which gives this perception of the mind: it did not conform to either of the two images formed in my eyes.

It follows from these results, that in these circumstances all of the space BC which the green ribbon occupies, and which is enclosed between the points where the optic axes Bb, Cc fall, is suppressed {supprimé} from the regard of the Observer, since the extremity B of the red ribbon coincides with the extremity C of the yellow ribbon. It is true that, according to the arrangement of things, the green ribbon is hidden to one and the other eye by the cards N, M; but since in this second experiment the image of the green ribbon is replaced in each eye by the cards N, M, which fall on the same portions of the retinae bg, cp, where the green ribbon painted itself in the first experiment, and that in this latter the green ribbon was supposed [to be] interposed between the red ribbon and the yellow, one must, it seems, in the second [experiment] see the cards N, M interposed in the same way {de même} between the red ribbon and the yellow: it is however completely otherwise, and we are going to examine from where this diversity in appearance derives.

24. In the right eye, card M, the red ribbon AB and card N are painted from left to right, and in this same order, on contiguous parts mgb, ba, an of the retina.

In the left eye, card M, the yellow ribbon CD and card N are also painted from left to right, and in this order, on contiguous parts md, dc, cpn of the retina.

If, according to the hypothesis which I have espoused, one conceives that of two images printed on corresponding retinal parts, there is only one of them which appreciably affects the mind, it will be easy to explain why the appearance seized by the mind in these circumstances differs {diffère} from images drawn in the eyes, in saying that of each of four pairs of portions of corresponding images,
md, mg,
dc, gb,
cp, ba,
pn, an,
there are only portions md, dc, ba, an, of which the mind experiences the impression, and that those of corresponding portions mg, gb, cb, cp, pn are null. Thus the impression of which the mind is affected in these circumstances is formed of two partial and simultaneous impressions, that is, from image mdc in the left eye, and from image ban in the right eye.
md, represents the cardboard M.
dc, represents the yellow ribbon CD.
ba, represents the red ribbon AB.
an, represents the cardboard N.

Points b and c of the images which specify {rendre} points B and C of the ribbons, are united {joints} in the perception of the mind which is nab/cdm [Figure 7b], because they meet each other on the optic axes. Image cdm which represents the yellow ribbon and the cardboard M, is painted to the left of the optic axis Cc, and is seen to the right corresponding to reality, and according to the known laws of optics: likewise image ban which represents the red ribbon and cardboard N, is painted to the right of optic axis Bb, and is judged to the left, according to the same optical laws.

25. One has, in my first and second experiment, two procedures of which the effects are quite opposite, one apparently doubles the length enclosed between two visual rays, and the other makes it completely disappear, although these visual rays form the same angle BSC in one and the other cases. This is not, moreover, the only point on which the two observations differ: one was able to distinguish that in one the mind was struck only by objects painted on retinal halves cn, bm which, relative to the optic axes which they share, are turned to the side of the nose, and that the images which fall on the opposite halves cdh, ban, fall there in vain and do not affect it [the mind]; whereas in the other of these observations objects painted in retinal halves cpn, bgm, situated inside, or in closest proximity to the nose, make for their part not the least perceptible impression on the mind, which only experiences that of the images which meet themselves on halves cbn [cdn], ban situated outside [of the optic axes].

If I may be permitted [I wish], in finishing my Address {Mémoire}, to rule in favour of my hypothesis on the nonefficacy of one of two impressions stimulated {excitées} by the images painted on corresponding portions of the two retinae, the advantages which I have drawn from it [the hypothesis] offer {pour rendre} a reason, of a plausible sort and without the least farfetched assumption, for these two phenomena, of which the[ir] apparent contradictions would seem to proclaim much difficulty in reconciling them. I will note that there is some sort of agreement between this hypothesis and that of some Physicists who have claimed that we never see but with one eye, and that even though they are both open, there is one of them which is without action and as at rest [:

While the retina of one eye is concentrated, the retina of the other is relaxed, and so one acts while the other is idle ... one of the eyes is always concentrated and shoulders the principal labour of vision, that is, it is concentrated on viewing something clearly, while the other in the meantime is at leisure and views only in a blurred manner and, in fact, perfunctorily and carelessly. Gassendi, [(e.g., 1658-75] Phys[ics] lect[ure] 3, book 7, chap[ter] 7)

But although I presume that of two complete images which one object produces in our eyes, there is ordinarily only half of them of which the impression would be effective, I do not allow less than both eyes together can contribute to vision, and that the mind can be affected in the same instant by the two images painted in one and the other eye, nevertheless provided that they would not be on corresponding portions of the retinae. For example, on the subject of the observation of no. 23, I have made apparent, and I almost venture to say proved, that the perception of the mind on this occasion was the product of simultaneous impressions of the image mdc [Figure 7b] from the left eye and image ban from the right eye.

[Dutour's references

Gassendi, P. (1658-75). Opera omnia in sex tomos divisa.... Lvgdvni: Sumptibus Lavrentii Anisson & Ioan. Bapt., Devenet.

Mariotte, E. (1717). Oeuvres de Mr. Mariotte, de l'Academie royale des sciences.... (Rev. & cor. de nouveau. ed.). Leide: P. Vander.

Musschenbroek, P. v. (1739). Essai de physique.... A Leyden: S. Luchtmans.

Polinière, P. (1734). Experiences de physique (4th rev. et augm.). Paris: Gissey.

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