STENO, NICOLAUS (Niels Stensen; 1638–1686)

STENO, NICOLAUS (Niels Stensen; 1638–1686), Danish anatomist, paleontologist, and geologist. Born 11 January 1638 to a Copenhagen goldsmith, Steno attended the University of Copenhagen from 1656 to 1660, where he studied medicine and anatomy with Thomas and Erasmus Bartholin. Moving on to Amsterdam and Leiden from 1660 to 1664, he made several important discoveries concerning glands, which were a new field of investigation. Inspired by René Descartes's Treatise on Man (published posthumously in Leiden in 1662), Steno began studying the physiology of the heart, and he came to argue, against both Descartes and William Harvey, that the heart was not a specially endowed organ but merely a muscle. Failing to secure a position at the University of Copenhagen, Steno traveled to Paris, came under the patronage of Melchisedec Thevenot, and continued his anatomical studies. He gave a lecture on the brain in 1665 in which he took further issue with Descartes's theories of brain function, and he argued that ideas about brain physiology should be grounded in the results of detailed dissection. This lecture was published four years later as Discourse on the Anatomy of the Brain and was the most influential of his anatomical works.

Continuing his slow journey south, Steno spent some time in Montpelier in 1665, and in 1666 he arrived at Pisa and the summer court of the Medici family of Florence. He was invited to join the circle of the Accademia del Cimento, and he readied for publication a study of muscle anatomy. His career abruptly changed course when he was given the head of a giant white shark to dissect by the grand duke, Ferdinand II. Steno was indeed interested in the muscle anatomy of the shark, but he was even more fascinated by its teeth, which closely resembled the fossil objects known as glossopetra or tonguestones. Tonguestones, and nearly all other fossils, were commonly regarded as mineral objects that grew in the rocks where they were found and were not thought to have an organic origin. Steno considered the problem and offered compelling reasons why tonguestones must have once been sharks' teeth. When he published his Elements of Myology in 1667, he appended to it a short treatise, "The Dissection of the Head of a Shark." This essay marks the beginning of the science of paleontology.

Steno then addressed the more general problem of ascertaining the history of rock formations by examining the clues within them. He formulated principles by which he could determine if formations had been moved or altered after they had been laid down and which formations had been deposited first. Within eighteen months, he had completed his major geological treatise, Prodromus to a Dissertation on Solids Naturally Contained Within Solids. Steno argued here that rock strata are like the pages in a book of history, and that proper understanding of the principles of stratigraphy will allow that book to be read. The Prodromus marks the beginning of historical geology.

Steno resumed his travels in 1668, touring much of central Europe; he returned to Florence in 1670 for two years and then was invited back to Copenhagen in 1672, where he was royal anatomist until 1674. But his interest in anatomy had been waning for some time. Steno had converted to Catholicism in 1667, and he gradually turned his attention to religious and churchly matters. He returned to Florence in 1675 to be ordained a priest; in 1677 he was appointed apostolic vicar of the northern missions (Germany), and shortly thereafter became the titular bishop of Titiopolis. He spent the last nine years of his life in Hanover, Münster, and Hamburg, trying to bring the followers of Luther back into the Catholic Church. He died on 5 December 1686 in Schwerin. The grand duke of Florence, Cosimo III de' Medici, had Steno's body brought back to Florence, where he was buried in the cathedral of San Lorenzo. About three hundred years later, on 23 October 1988, Steno was beatified by Pope John Paul II.

See also Anatomy and Physiology ; Descartes, René ; Florence ; Geology ; Harvey, William ; Scientific Revolution .

BIBLIOGRAPHY

Primary Sources

Steno, Nicolaus. Discours sur l'anatomie du cerveau. Paris, 1669.

——. Elementorum Myologiae Specimen . . . cui Accedunt Canis Carchariae Dissectum Caput. Florence, 1667.

——. De Musculis & Glandulis Observationum Specimen. Paris, 1664.

——. De Solido Intra Solidum Naturaliter Contento Dissertationis Prodromus. Florence, 1669.

——. Steno: Geological Papers. Edited by Gustav Scherz. Translated by Alex J. Pollock. Odense, 1969.

Secondary Sources

Kardel, Troels. Steno: Life, Science, Philosophy. Copenhagen, 1994.

Scherz, Gustav, ed. Dissertations on Steno as Geologist. Odense, 1971.

——. Nicolaus Steno and His Indice. Copenhagen, 1958.

William B. Ashworth, Jr.

Nicolaus Steno

The Danish naturalist Nicolaus Steno (1638-1686) established the law of superposition and the law of constancy of interfacial angles.

Nicolaus Steno, originally Niels Stensen, the son of a goldsmith, was born in Copenhagen on Jan. 10, 1638. He entered the University of Copenhagen in 1656 to begin studies in medicine which he continued in Amsterdam and Leiden. After studying anatomy in Paris in 1664, he went to Florence in 1665. He became court physician to the Grand Duke of Tuscany, Ferdinand II, who subsidized Steno's scientific interests.

During this period Steno investigated the geology of Tuscany with its related mineralogical and paleontological problems. His De solido intra solidum naturaliter contento dissertationis prodromus (1669; Introduction to a Dissertation concerning a Solid Body Enclosed by Process of Nature within a Solid) was one of the most fundamental contributions to geology because of Steno's qualities of observation, analysis, and inductive reasoning at a time when scientific research was nothing but metaphysical speculation. Contrary to many other works of the 17th century, it had an impact on contemporary scientists through three Latin editions and its translation into English by Henry Oldenburg in 1671.

The Prodromusis divided into four parts. The first contains an investigation on the origin of fossils. The second part analyzes the following fundamental problem: "given a substance having a certain shape, and formed according to the laws of nature, how to find in the substance itself evidences disclosing the place and manner of its production." The third part discusses different solids contained within a solid in relation to the laws discovered and presented in the previous part. This is the section dealing mostly with crystallography. The fourth part is largely a consideration of the geological changes which Steno was able to interpret from his observations throughout Tuscany.

A fundamental part of Prodromus concerns the aspects and the mechanism of the growth of crystals, which are also solids within solids. In that respect Steno discovered the fundamental law of crystallography known as the "law of constancy of interfacial angles," which states that regardless of the variations in shape or size of the faces of a crystal, the interfacial angles remain constant. At the end of Prodromus, Steno in a series of diagrams illustrates the geological history of Tuscany. These sections, the earliest of their type ever prepared, fully substantiate the claim that Steno is one of the founders of stratigraphy and historical geology and perhaps the first geologist in the modern sense.

Steno, in his general concept of the universe, adopted the doctrine of the four Aristotelian elements: fire, earth, air, and water. However, his concept of matter was Cartesian, since he considered a natural body as an aggregate of imperceptible particles subject to the action of forces as generated by a magnet, fire, and sometimes light.

In paleontology, Steno clearly understood the organic origin of fossils and their importance as indicators of different environments of deposition. Assuming that strata had been deposited in the form of sediments from turbid waters under the action of gravity, Steno established some of the fundamental principles of stratigraphy: deposition of each bed upon a solid substratum, superposition of younger strata over older ones, and occurrence of all beds except the basal one between two essentially horizontal planes. In structural geology, Steno visualized three types of mountains: mountains formed by faults, mountains due to the effects of erosion by running waters, and volcanic mountains formed by eruptions of subterranean fires.

In 1672 Steno became professor of anatomy in Copenhagen. As a Catholic, he encountered so much religious intolerance from the Protestant community that he returned to Florence, where he was put in charge of the education of Cosimo III, the son of the Grand Duke. In 1675 Steno took Holy Orders, and a year later Pope Innocent XI appointed him bishop of Titopolis and apostolic vicar of northern Germany and Scandinavia. He died in Schwerin on Nov. 26, 1686.

Further Reading

The most comprehensive biography of Steno, including the translation of all his geological works, is in Steno: Geological Papers, edited by Gustav Scherz and translated by Alex J. Pollock (1969). Some biographical information on Steno is in Gustav Scherz, ed., Historical Symposium on Nicolaus Steno (1965). Other accounts of his life and contributions to geology are in Sir Archibald Geikie, The Founders of Geology (1897); Karl von Zittel, History of Geology and Palaeontology (1901); and Frank D. Adams, The Birth and Development of the Geological Sciences (1938).

Additional Sources

Moe, Harald, Nicolaus Steno: an illustrated biography: his tireless pursuit of knowledge, his genius, his quest for the absolute, Copenhagen: Rhodos, 1994.

Scherz, Gustav, Niels Steensen (Nicolaus Steno), 1638-1686: the goldsmith's son from Copenhagen who won world fame as a pioneering natural scientist but who sacrificed science to become a celebrated servant of God, Copenhagen: Royal Danish Ministry of Foreign Affairs, 1988. □

Nicolaus Steno

1631-1687

Danish Anatomist, Naturalist, and Physician

Nicolaus Steno was one of the great scientists of the seventeenth century. Best known today for his views on fossils and as the founder of stratigraphy, he was trained as a physician and did important work in anatomy, crystallography, geology, and paleontology.

Steno, whose real name was Niels Steensen (sometimes spelled Stensen), was born on January 1, 1631, in Copenhagen, Denmark. Raised a devout Lutheran, he entered the University of Copenhagen in 1656 to study medicine. He continued his studies at the University of Leiden (1660-1663), receiving his M.D. in absentiawhile in Paris (1664). After making important anatomical discoveries he traveled to Italy, where in 1666 he was appointed court physician to Ferdinand II, Grand Duke of Tuscany (1610-1670). His most significant geological and paleontological results were developed during his stay in Florence. He converted to Catholicism in 1667 and returned to Copenhagen in 1668 to accept the position of royal anatomist. After becoming a priest in 1675 he abandoned science completely and devoted his remaining years to the Catholic Church. He died in acute pain from gallstones at Schwerin, Germany, on November 25, 1686.

In 1660 Steno discovered the parotid gland (Steno/Stensen's duct)—the oral cavity's principal source of saliva. His further investigations led to a basic understanding of the lymphatic system as a whole. In Observationes anatomicae (1662) and De musculis et glandulis (1664) Steno presented his new discoveries, describing the structure and function of other glands including the lachrymal apparatus, which facilitates the movement and cleansing of the eye, the nasal duct, the earwax duct, ducts of the cheek glands, smaller ducts under the tongue, and the glandular ducts of the epiglottis and palate.

Beginning in 1662 Steno conducted research on muscles from which he developed a comprehensive view of their structure. He showed that muscle tissue contains arteries, veins, and nerves, and is composed of closely woven fibers. Steno described the function of the diaphragm during respiration, classified the tongue as a muscle, and advanced the then-novel idea that the heart is nothing more than a muscle with contractions controlled by muscle fiber. From 1665 to 1667 he worked on brain anatomy, embryology, and comparative anatomy. During this period he demonstrated that animals possess a gland resembling the pineal gland of humans. This undermined René Descartes' (1596-1650) claim that the pineal gland was the seat of the uniquely human soul.

The catalyst for Steno's paleontological, geological, and mineralogical discoveries was his dissection of a huge shark caught near Leghorn, Italy (1666). His examination of the shark's teeth revealed their similarity to glossopetrae (tonguestones, so called because of their resemblance to petrified serpent or bird tongues) found on Malta and elsewhere. These and other fossils were widely believed to be either direct productions of nature or God. Steno challenged these views in De Solido intra Solidum naturalites contento dissertionis Prodromus (1669), maintaining the organic origins of fossils.

Prodromus contains the outlines of modern geology. Steno argued that fossils are animal remains that had become embedded in sea-floor strata and then petrified by the concreting action of chemical forces, heat, and compression over time. He suggested that strata are deposited horizontally in layers from aqueous fluids with occasional crustal collapses accounting for diversities of topography. In explaining this stratification he established the principle of superposition—underlying sedimentary layers are older than those overlaying them—upon which modern geochronology is based. To accompany his explanations, Steno produced what are considered the earliest geological cross sections. In this same treatise, attempting to account for crystallization, he propounded Steno's law—angles formed by corresponding faces of quartz crystals remain constant for a given mineral.

STEPHEN D. NORTON

Nicolaus Steno

1638-1686

Danish anatomist and geologist, also known as Niels Steensen (or Stensen), whose landmark treatise The Prodromus of Nicolaus Steno's Dissertation Concerning a Solid Body Enclosed by Process of Nature Within a Solid (1669) advanced the study of geology and helped establish the science of crystallography. Steno described the structure of quartz crystals, suggested that fossils were the remains of ancient organisms, and that the study of the earth's strata could provide a history of the planet. His most famous anatomical contribution was the discovery of the parotid salivary duct, which is also known as Stensen's duct.