I have discovered some manuscript drawings relating to Leibniz's Protogaea manuscript, which are hitherto unpublished, so far as I am aware. Two of these apparently correspond to the contents of Protoaea chapter 8, referring to the underground distribution of mineral deposits. They reveal Leibniz's map-making programme for the subterranean world. Considering the influence of Steno upon Leibniz, we can point to Leibniz as a "historian" of the Earth, rather than a "theorist" in a Cartesian manner.

    In reading the Japanese translation of Protogaea published in 1991, I found a drawing contained in the photo-version of the Protogaea manuscript of the Niedersachen State Library which was inserted into the translation (1). This was a conic section representing strata in cone-shaped mountain, but neither translator nor editor  mentioned the significance of the drawing. With an opportunity to visit the publishing company Kousakusha company which published the Japanese edition of Leibniz's Works, I was fortunately able to consult the manuscript by kind courtesy of the general editor Ms. Harue Sogawa. There were other drawings too. However, although I have investigated two Latin versions, two French and one German translation of Protogaea (2), I found no other figures equivalent to these drawings.

    Leibniz was evidently endeavoring to describe mineral deposits and strata geometrically. He says in chapter 8 of Protogaea:

    A vein is like as a leaf or a layer of indifferent thickness, long and extending widely under the Earth, containing a peculiar kind of earth, rock or metal, distinct from the surroundings. A vein is illustrated by using the analogy of conic sections (3).

Valleys are also seen everywhere, that are broken open or hollowed out by the power of water or by some other agency [impetus] and show variegated sorts of layers at each opposite side of walls of mountains. I remember that a suspended vein of cooer-slate called ardosia was uncovered with iron(tools) in Osterode in the Harz [Mountains] not so long ago and its continuation was seen   on the opposite side of the valley (4).

This scene or situation is represented in Leibniz's hand in the marginal space of the Protogaea manuscript. [see Figure 2]. The two drawings present both an idea and an example of Leibniz's way of describing underground laminar entities by geometrical means.

    According to Ernst Hamm, Leibnitz aimed to represent underground topography or to make a "scenography" of the subterranean world (5). Hamm was presumably unaware of the above-mentioned drawings in the manuscript, but they show remarkable evidence of the Leibniz's thinking. We might even claim the drawing of the conic section as an indication of emergence of geological cartography in a modern sense (6). Certainly we can admire the priority of Leibniz in this field, so far as we can tell from surviving documentary sources.

    On the other hand, however, it is important to think about the possible influence of Steno upon Leibniz , which Hamm does not discuss. Broadly speaking, the concept of vertical sections indicating "strata-objects" in the Earth's interior had been adopted in the fourth part of Descartes's Principles (1644) and in Steno's Prodromus (1669). Steno went farther. He gave drawings of Moncodeno grotto in his letter to Cosimo III of 1671, which tell us the inner shape of grotto with longitudinal and cross sections (7). He also gave a description of columnar bodies in the cave.

    Turning our attention to the published version of Leibniz's Protogaea, we can easily find the longitudinal section of Baumann Cavern. Leibniz also made figure of sample materials that he had picked up in the cavern, which are described in Chapter 36 and 37. Here we should remember that Steno and Leibniz were together as colleagues in the court of Duke Johann Friedrich (1625-1680) from 1677 to 1680. As Scherz has shown, the two men discussed a great range of contemporary topics, naturally including geological ones (8). Indeed, we can find many points in the Protogaea that reveal influence of Steno on Leibniz , implicitly as well as explicitly.

    Why is the exact description of mineral deposits or strata necessary? Because it is useful and indispensable not only to develop mines but also to reconstruct history of nature. In fact, in Chapter 44 of Protogaea, Leibniz suggested environmental change of a region, pointing to the evidences of fossil plants in strata. In this way, he clearly followed the method of Steno. Although some scholars characterize Leibniz in the Protogaea as a diductivist (9), or a theoretician (10) in a Cartesian manner, we can conclude that Leibniz treated terrestrial bodies as a historian of nature, which attitude Descartes had neglected but Steno had adopted.

Acknowledgement: I am most greatful to Ms. Sogawa of Kousakusha Publishing Co. for her kind and helpful support.
 
 

(1)    Translated by Tsutomu Tanimoto, in Japanese version of Gottfried Wilhelm Leibniz Opera omnia (Leibniz Chosaku- shu), 10, Kousakuhsa, Tokyo, 1991, pp. 119 - 207; Leibniz Manuskripte: lhxxiii,23 (a), Niedersaechsische Landesbibliothek Hannover, Handschriften- Abteilung.

(2)     Svmmi polyhistoris, Godefridi Gvilielmi Leibnitii Protogaea, sive de Prima Facie Tellvris et Antiqvissimae Historiae Vestigiis in ipsis Natvrae Monvmentis Dissertatio ex Schedis Manvscriptis Viri Illvstris in Lvcem Edita Christiano Lvdovico Scheido, Goettingae: Svmptibvs Ioh. Gvil Schmidii, Bibliopolae Vniversit., 1749. xxviii+86pp. (Leibniz, 1749)
    Opera Omnia... Ludovici Dutens, vol.2, 2, Genève 1768/ Olms, Hildesheim, 1989, 201-204.  (Dutens, 1768) The figures are contained in 12 pages of the end of vol.1.
    Protogée ou de la formation et des révolutions du globe par Leibniz, Ouvrage Traduit pour la Première Fois avec une Introduction et des Notes Par le Dr Bertrand de Saint-Germain, Paris: L. LAnglois, Libraire-Editeur, Paris 1859, lxiv +138pp. (Saint-Germain, 1859)
    Leibniz Werke, Herausgegeben von W. E. Peuckert, Erster Band, Protogaea, Uebersetzt von W.v. Engelhardt, Stuttgart: W. Kohlhammer Verlag, 1949, 182pp. (Engelhardt, 1949)
    G. W. Leibniz Protogaea, Texte Latin et Traduction Bertrand de Saint-Germain, Edition, Introduction et Notes Jean-Marie Barrande, Toulouse : Presses Universitaires du Mirail, 1993, xxxi+262pp. (Barrande, 1993)

(3)    Leibniz, 1749 (n.2), p.14. : "Vena est velut folium quoddam, sive stratum, sub terra longe lateque procurrens, crassitiei mediocris, in quo peculiare genus terrae,saxi, aut metalli, ab ambientibus divisum ;nec melius quam Conicarum sectionum similitudine illustratur."

(4)    Leibniz, 1749 (n.2), pp.15-16. : "Passim etiam valles aquarum vi, aut alio impetu effractae vel excauatae, ab utroque     latere oppositos parietes montium, simili stratorum genere variegatos ostentant.Meminique cum non ita pridem Osterodae in Hercyniis pendens vena ardesiae aeriferae ferro aperta esset,continuationem in opposito vallis latere notatam.

(5)     E. P. Hamm, "Knowledge from Underground: Leibniz Mines the Enlightenment", Earth Sciences History, 1997, 16, 77-79 (at pp.77-82).

(6)    For history of geological cartography, see David R. Oldroyd, Thinking about the Earth, London: Athlone, 1996, chapters 3 and 5. Oldroyd makes no reference to Leibniz's idea about making geological map.

(7)    Gustav Scherz (ed.), Steno Geological Papers (Acta Historica Scientiarum Naturalium et Medicinalim, 20), Odense, 1969, p.246.

(8)    Gustav Scherz, "Gesprache zwischen Leibniz und Stensen", Studia Leibnitisns Supplementa, 5, (Akten des Internationalen Leibniz-Kongresses Hannover, 14-19. November 1966, 5), 1971, 81-104.

(9)    Kurdvon Bülow, "Protogaea Prodromus", Studia Leibniziana Supplementa, 2, (Akten des Internationalen Leibniz- Kongresses Hannover, 14-19. November 1966, 2), 1969, 197-208 (at p.205).

(10)  Otfrien Wagenbreth, Geschichte der Geologie in Deutschland. Enke im Thieme Verlag, Stuttgart, 1999, p.17.