Abstracts of presentations
Thomas Bartholin and Niels Stensen - Master and pupil
Jesper Brandt Andersen
The Danish Society for the History of Medicine
The relation between Niels Stensen and his master and mentor, the anatomist Professor Thomas Bartholin (1616-1680), was characterized by mutual respect and warmth. Bartholin had an early eye for Stensen's unique skills within natural science, and as the leading professor in medicine at Copenhagen University and a famous anatomist all over Europe, he used his knowledge, influence and connections to secure the young Stensen the best possible educational conditions. These efforts and Bartholin's role as an important source of inspiration was undoubtedly crucial for Stensen's career as a natural scientist. Although mainly an anatomist, Bartholin was a true polymath of his time, and his influence on Stensen even on geological issues should not be neglected. Bartholin´s father, Caspar Bartholin the elder (1585-1629), and his uncle, Ole Worm (1588-1654), both thoroughly dealt with geological topics such as stones, minerals, fossils and natural sources and reflected upon important geological questions later taken up by Stensen. Thus inspired Bartholin during his stays in Napoli and Sicily in the early 1640’s made vulcanological studies on Vesuvio and Etna as well as studies of shellfish fossils and tongue stones (glossopetrae) in the mountain rocks of Basilicata and around Messina. In Malta he carried out intensive studies of the sealed earth (terra sigillata) and the glossopetrae. For further studies and teaching he brought samples home to Worm´s and later his own cabinet of rare natural objects. His unpublished manuscript to a planned book about the glossopetrae was lost in the burning of his manor house in 1670, but in 1661 in the last centuria of his Historiarum Anatomicarum Rariorum he brought a shorter thesis on the contemporary medical use of both the terra sigillata and the glossopetrae. Scattered in his many books and in the different volumes of his medical journal Acta Medica & Philosophica Hafniensia (1673-1680) you find numerous reports of different geological topics, like on amber, natural sources and ice, vulcanos, stones and fossils on Iceland, written by Bartholin himself and by different other contributors.
Nicolaus Steno’s arrival in Italy and mathematics
Johns Hopkins University
Baltimore, MD 21201 USA
When Nicolaus Steno published the Elementorum myologiae specimen (1667) in Florence, he claimed that the study of the muscles had to “become part of mathematics” and that “anatomy has hitherto disdained the laws of mathematics.” Most historians agree that Steno’s move to Florence in 1666 was motivated by his interests in mathematics. But what do we know of Steno’s interests outside of anatomy before arriving in Italy? This paper traces Steno’s interests in mathematics through a close reading of his correspondence and publications until his arrival in Italy. Steno does not explicitly say why he turned towards a geometrical explanation of the muscles, but the scholars he met and his research choices reveal a lasting attraction for geometry. This analysis helps to place Steno’s research in relation to the main intellectual networks of the 17th century and sheds light on Steno’s decision to go to Italy.
Steno and the fossils
Zoological Museum (SNM)
The reasoning of Niels Stensen, or Nicolaus Steno, about fossils is first developed in his essay Canis Carchariae Dissectum Caput, published in 1667, and then better developed in his major work of 1669, the Prodromus to a dissertation on “A solid included in other solid”. In the second he introduced a modern methodology based on observations and a way of thinking arguing by conjectures, — what we would today call hypotheses, evidence being tests of these by observations. The 1667 essay included the famous image of the large (and dried) head of the great white shark, Carcharodon rondeletti, accompanied by two fossil teeth, also known as glossopetrae. This image, and a second one of glossopetrae (tongue stones), were engravings he had borrowed from Michele Mercati’s Metallotheca Vaticana of 1593, at the time yet unpublished. The main mystery was their location in nature far from the sea, high up in the country. Steno already knew such big fossil shark teeth from his teacher Thomas Bartolin, who had collected them himself in Malta, and which were exhibited in the famous Museum Wormianum in Copenhagen. Steno was also aware that some fossils were remains of invertebrates, like mussels, snails, brachiopods and echinoids found high in the mountains, some of which he presumably collected during his journeys in Tuscany. Although he never pictured these type of fossils, he must have been aware of them from illustrations and by visiting Italian museums, such as Adrovandi’s in Bologna (Aldrovandi was also the first to use the word “geology” in 1603). It is interesting to note that Steno’s groundbreaking work concerning the wider field of modern earth sciences originated by analogy to pharmacy and chemistry, disciplines that Steno knew well from also his anatomical work and medical education.
Nicolaus Steno’s research - Conjectures from incidental observations making organic and inorganic processes measurable
From studies of Steno’s published works in science I conclude that he applied the same method of research throughout; that is, based on incidental observations he put forward conjectures on mechanisms beyond the reach of observation, such as a model of contraction of skeletal muscles and of the interchange of fluids between an inner and an outer body liquid space at the newly discovered so-called capillaries, and, not to forget, anatomical observations in a calf with hydrocephalus enabling his proposal that, rather than being caused by maternal imaginations, deformations in this case was caused by blocking of brain liquids normally flowing from the inner cavities to the surface of the brain through channels to be detected. Also, from occasional findings he gave proposals for unobservable processes back in time on the chemical transformation of live material to fossils in the sea-bed, the transformation of landscapes in Tuscany, and the growth of crystals by accretion to the surface. Knowledge on the formation of teeth could bring “cure for so many sicknesses, and [reduce] the number of those who complain of being toothless”. Throughout he applied a “Galilean foundation for research” making organic and inorganic processes measurable and, in a Popperian sense, refutable. Centuries later his “conjectures” were tacitly integrated in common knowledge when useful, or they were rediscovered backed by a web of evidence when measurable by new technologies, thus in recent time the muscle model. A brief survey is given with emphasis on my main theme, Steno’s geometrical model of muscle contraction.
Leonardo da Vinci’s and Nicolaus Steno’s geology
Gian Battista Vai
Museo Geologico Giovanni Capellini and Department BiGeA
Alma Mater Studiorum, Università degli Studi di Bologna
Recurrences for the two founding fathers of geology occurring on the same year prompted a comparative evaluation of how the two contributed to establish the basic principles of the discipline. To do so passages from their publications, codices and manuscripts have been quoted directly, as far as possible. The three basic Stenonian Principles (Original Horizontality, Original Continuity, and Superposition of Individual Strata) are present in Leonardo’s notebooks amazingly formulated in similar wordings over 150 years earlier, studying the same area. Also alleged Stenonian priority in naming and explaining new geological concepts and processes (e.g., faulting, folding, angular unconformity, relative chronology) are mirrored in Leonardo’s writings and pictorial works. Steno enjoys priority in stepwise restoration of geological history in a given region. Leonardo by far alone excels in the first 3D geological profile representation and geomorphologic map cartography. The final part of the talk focuses on two rather discussed aspects of diverging stance of the two scientists concerning the Noachian Deluge and the age of the Earth. Leonardo had solved the question of marine fossil remains found in the mountains showing their organic origin already 500 years ago, implying a possible deep geologic time by a statement of eternalism. Steno solved again acutely the same question 350 years ago in a different way, retaining a basic role for the Deluge, assuming a short age of the Earth by focusing mainly on short-lived sedimentary and geomorphologic processes.
Steno and the rock cycle
Department of Engineering, Physical and Computer Sciences
Rockville, MD 20850 USA
Geologists categorize the basic types of rock according to their origin – igneous, sedimentary or metamorphic rather than by their physical properties. This is expressed dynamically by the fundamental concept of the rock cycle, which describes how the basic rock types are derived from one another within the Earth system as a result of ongoing geologic processes. In the Prodromus, or De Solido, Steno urges a similar approach to thinking about natural materials, outlining how a substance can be examined “to disclose the place and manner of its production”. He recognizes the roles of erosion, transport, deposition and lithification in the production of sedimentary strata, and his description and diagrams of the geological evolution of Tuscany show a clear cyclicity of process. While Steno does mention the action of subterranean “fires” and the possibility of post-depositional alteration of sedimentary rock, igneous and metamorphic processes are essentially absent from his model. The modern concept of the rock cycle did not emerge until the 19th century.
The order of things: Steno's experience of nature in Tuscany
Museo di Storia Naturale
Università degli Studi di Firenze
Steno's experience of the natural world in Tuscany was many-sided, based as it was on a wide range of outdoor observations as well as on his work in creating a museum. His scientific career was at that time at its height, after he had spent the period between 1659 and 1666 in Copenhagen, Amsterdam, Leiden, Paris and Montpellier. In Tuscany, Steno could compare the remains of existing marine animal species with fossils dug up in the same region. He compared the nature and geometry of the tabular strata of turbidite Apennine sandstones, which lacked visible fossils, with the richly fossiliferous sandstones and mudstones at the core of the Tuscan hills. After the publication of the Prodromus in 1669, he worked to create a museum in Florence. The underlying museological concepts can be partly reconstructed from letters and the list of specimens that he chose from the granducal collection in Pisa. Following the Prodromus order, the Indice lists 38 quartz specimens, 76 groups of minerals including marcasite and pyrite, 24 shells, 51 stones with fossil shells, 5 fossil bones, 31 heterogeneous objects and 40 corals. Steno's intention was not to form a collection of curiosities, but rather a cabinet of naturalia following an order unseen in previous museums. His search for a match between Nature and Scripture, pursued since his student years, was perfected in Tuscany, where the historical order of biblical events could be geometrically demonstrated, on a large scale by strata of mountains and hills, on a small scale by fossils.
How do crystals grow? Steno’s approach
Department of Earth Sciences
Università degli Studi di Firenze
Steno (1638-1686) operated in a historical context rich in previous discoveries and observations such as those of Vannoccio Biringuccio, Georg Bauer (Agricola), Johannes von Kepler, Christiaan Huyghens, Erasmus Bartholin, and others, but he also had to fight against some irreducible dogmatic and "mythological" beliefs, such as the vis formativa of the naturalist Michele Mercati and the succus lapidescens of the gemmologist Boetius de Boot. In "De solido intra solidum naturaliter contento dissertationis prodromus", Steno deals with almost all aspects of earth sciences and not just "solid inclusions" as it might seem from the title. Obviously, we will deal only with those related to crystallography and minerals in general. The most famous is highlighted by the sentence "non mutatis angulis", which referred to quartz crystals and is a very clear reference to constancy of dihedral angles, generalized as a law for all minerals by Romé de l'Isle only a century later. Less well known, but of great importance, is the assertion that crystals grow thanks to the addition of particles that come from an external fluid and are not "fed" from the inside like the vegetables; moreover, the speed of growth is not the same for all faces. For example, the faces of the "pyramid" in quartz can grow more or less rapidly than those of the prism (thicker or more elongated crystals). It can therefore be argued that Steno has greatly contributed to the concept of anisotropy in the solid state, typical of all crystals.
Crystalline Stenonian time features from Earth and beyond
Desmond E. Moser
Department of Earth Sciences
University of Western Ontario
London, ON, CANADA
In his 1669 Prodromus Steno used spatial features such as internal crystal zoning and the orientation of boundaries between crystals and strata to infer outward, radial crystal growth as well as genesis from deep-crustal fluids in fissures. These remarkable insights identified spatial markers of moments in Earth history over a range of spatial scales which led to a novel, dynamic model of the evolution of the continental crust near Florence. With recent advances in microscopy, similar Stenonian time features are now being found to persist in minerals at microscopic to atomic scales, and are being used, particularly by geochronologists, to measure and reconstruct the rate and evolution of the crusts of Earth and neighbouring planets. Beyond Steno’s crystal (quartz) the new findings are from sand-size grains of highly resilient, Zr-rich minerals such as zircon (ZrSiO4) which occur widely in rocks and can be accurately dated using U-Pb isotope ratios. Some zircon grains are >4.3 billion years old making them the oldest known Earth solids. Their Stenonian time features include luminescent growth zoning indicative of the environment of crystallization (e.g. fluid vs. solid), and lattice planes that, like sedimentary strata, record deformation events due to tectonic plate movements or shock waves from giant meteorite impacts. Such metamorphisms can cause the isotopes themselves to form novel Stenonian features. Results will be presented from samples of early Earth, meteoritic and returned (Apollo) samples of the Moon, and the highlands of Mars, with implications for the timing of habitability.