Meet our Patron Saint

NICOLAUS STENO (NIELS STENSEN)
(1638-1686)

NICOLAUS STENO was born in Copenhagen on the eleventh of January (by the Julian calendar, the first of January), 1638. His father, Sten Pedersen, a goldsmith, was a well-to-do and prominent citizen. Already as a boy, Niels must have been interested in what there was to see and learn of practical chemistry and physics in the jewelry workshop. This appears from some notes dating from his years at the University of Copenhagen. Here he was among those who heard the inspiring lectures on anatomy and medicine, given in well-phrased Latin by Prof. Thomas Bartolinus he also attended Prof. Bartholinus’s dissections in the Theatrum Anatomicum, and, in all probability, he himself soon began to dissect. It also appears from the above-mentioned notes that early he grappled with serious religious reflections. Steno’s three years of study at the University of Copenhagen were made difficult by the war with Sweden, during which, in February 1659, a catastrophe nearly befell Copenhagen. The city was defended successfully, however, by all the inhabitants, including the students on whose military service list Nicolaus Steno’s name can be found.

As soon as possible after the war, in 1660, Nicolaus Steno left Denmark for several years of study abroad, as was the custom at that time. In The Netherlands he carried out independent research work in anatomy, and pursued other studies as well, i.a. mathematics, which later proved important for his crystallographical investigations. He also experienced a period of religious conflict which paved the way for his later conversion to Roman Catholicism (1667).

Step by step, Nicolaus Steno became alienated from his fatherland, where the University had no place for him as a professor, either during his stay in Copenhagen (1664) or later. And step by step, he was led away from the Lutheran confession in which he had been brought up.

Italy, where Steno arrived in the spring of 1666, became his second fatherland. Here he lived in contact with interesting people with whom he had much in common. And both before and after his conversion in 1667, he had here the best possible working conditions, including the liberal support of the Grand Dukes of Tuscany, who favoured the arts and sciences.

In Tuscany, Steno began to study geology and mineralogy. He was led into these new studies by his investigation of the anatomy of sharks and other fishes.

It happened in 1666, that an unusually large shark was caught off Livorno. The Grand Duke of Tuscany, Ferdinand II, ordered its head brought to Florence so that Steno could study it. The results of this dissection were published in 1667, together with a treatise on muscle physiology and a description of the dissection of a smaller shark from the Mediterranean.

Most interesting in this connection is the study Steno made of the teeth of the larger shark, which showed a remarkable resemblance to the well-known fossil “tongue-stones”, qlossopetrae, found in especially great numbers in the rocks of Malta, where professor Thomas Bartholinus, the teacher of Nicolaus Steno, had examined them.

Opinion was divided on the origin of “tongue-stones”: Were these fossils really teeth of animals that formerly had lived in the localities where the glossopetraeare now found? Or had the tongue-stones only a coincidental similarity to recent sharks’ teeth? Steno in 1667 dared not to decide this question. Or rather: he hesitated somewhat.

Here, as everywhere in Nicolaus Steno’s scientific work, we meet his caution regarding facts not yet absolutely proven, and we meet his exact investigations of nature, unbiased by opinions previously advanced by others. He asked his questions and gave his answers as a scientist of the twentieth century.

Nicolaus Steno had seen the unquestionable resemblance between the qlossopetrae („tongue-stones”) and recent shark’s teeth, and in the light of his own newly performed anatomical studies of the great shark from the Mediterranean, he now placed anew the question of the nature of the glossopetrae and all other animal-like fossils ̶ under discussion “as before a court”. He would as correctly as possible present the facts, observed by himself in the strata of the earth, to the reader ̶ and then let other „more knowledgeable people” decide.

Steno founded this discussion of the nature of animal­-like fossils on the many observations of rocks and earth strata that he had made in nature. He cautiously presented his opinions in the form of suppositions, (conjecturae). Step by step, Steno came to the assertion, that the fossils which have a resemblance to parts of animals “may be supposed in reality to be parts of animals”. “And as the form of the tongue-stones resembles the recent shark’s teeth as one egg another I must suppose that the scientists who declare the great tongue-stones to be the shark’s teeth are not far from the truth”. He built up his conjecturae point by point, and proposed them with the clarity and logic which is found again and again in Steno’s works, both scientific and theological. This method makes his train of thought easy to follow, but hard to give in extract, as the material has already been condensed to its shortest possible form.

Nicolaus Steno built his geological and palaeontological understanding on a long series of investigations, particularly performed in Tuscany.

He gives as an introduction to the conjecturae a short description of the different types of rocks and strata: hard stone, tuff, clay, sand, etc. and he refers to the different states of preservation of the „enclosed bodies, resembling parts of animals” found therein: while some crumbled into dust when touched, others could be studied just like the shells of living animals.

He considers the orientation of the strata, whether horizontal or inclined, and he discusses how the enclosed fossils must have come there. Without calling it “geology”, Steno in his conjecturaegives an outline of scientific earth history arrived at through inductive reasoning.

The most important principle in Steno’s geological thinking, is that the strata are sediments, deposited in water, covering the earth surface, and later hardened to a greater or lesser degree (con­jecturae III- V). If the sediments do not always lie in their original horizontal position, a later disturbance is responsible. The earth can have been „shaken and violently disturbed and broken, giving the strata a new position. It should not be difficult to demonstrate the effects of earth quakes.”

Steno’s studies of both marine and fresh-water deposits led him to a consideration of the effect of the „juices” circulating in the strata of the earth. He compares and illustrates the processes in the earth strata with chemical and physical processes in the laboratory and uses in this connection experiments made in the chemical laboratory of his teacher in Copenhagen, the skilled chemist Ole Borch. As for the remains of plants and animals, both marine and fresh-water, which are found in the sediments, these must have become part of the sediment while it was newly deposited and still soft. Shark’s teeth and other similar fossils now found high up in Malta’s chalk cliffs bear witness to a geological change at an early period in the earth’s history.

“Who knows the history of Malta’s youth?” says Steno. “Perhaps the island formerly was submerged in an ocean with sharks whose teeth after death were buried in the mud of the bottom. But suddenly an explosion of subterranean air may have altered the position of the bottom-layers which now are found as dry land on the island”.

Steno’s first short presentation of his beginning geological theories in the shark’s-head treatise (1667) is filled with the thrill of inquiry and joy of comprehension which he experienced so fully during the short span of time ̶ less than two decades ̶ when he did his scientific work. He could speak from experience of “the wonderful life and work of Nature which day by day is filling us with admiration”. The dissertation, in spite of its concise, almost schematic form, is so vivid that the reader can almost feel Steno’s geological theories becoming clearer and clearer to himself as the treatise progresses.

At the last moment, just as the treatise was going to press, Steno added a few words about a conversation he had had with one of his learned friends, Manfredo Settala of Milano, who came through Florence and remarked, that among the rarities in his museum were many things which supported the theories of Steno.

In the dissertation on the dissection of the shark’s head Nicolaus Steno gives his “geology” in a preliminary form (“verisimilitudes”) “and would not blame those who had perhaps another opinion”. He himself continued his geological studies in Tuscany and in the other parts of Italy to which he traveled.

After the first burst of enthusiasm, when he thought, as he himself writes, that these investigations “were the work of a very short time”, he came to realize that the problems were more complicated than at first supposed. He felt like a man traveling in an unknown, remote realm with a summit city as his goal. It often happens that the traveler when first he sees the city, thinks that it is very near to him, and yet manifold turnings of the way will wear down his hope even to weariness. For he sees only the nearest peaks, while the things which are hidden beyond them ̶ whether heights of hills, or depths of valleys, or level plains ̶ far and away surpass his guesses, since he measures the intervening distances by his desire. “So, and not otherwise, it is with those who proceed to true knowledge of Nature by way of experience. As soon as a little part of the unknown truth has become clear, then he thinks that he shall at once disclose the whole matter”.

Observations accumulated. It was Steno’s plan to use them for a work of large dimensions, written, for the benefit of Steno’s patron, the Grand Duke, in the Italian language, which the Danish scientist had mastered in an amazingly short time. The work was to have as one of its aims the exploitation of Tuscany’s mineral resources; this aspect of the matter was especially emphasized to the Grand Duke by the engineer Vicentio Viviani (b. 1622). Viviani was a friend of Steno’s, and one with whom he could discuss both scientific and religious questions. From his travels as an engineer he had an extensive knowledge of Tuscany’s geology. Undoubtedly Gustav Scherz is right in saying that Viviani had a considerable share in Nicolaus Steno’s geological development; as well, he had a great share in Steno’s conversion to Catholicism.

Nicolaus Steno had not in any way finished his geological investigations. Special circumstances were necessary, however, to make him publish more than what he had stated provisionally in the shark’s head paper.

In the autumn of 1667 ̶ the year of Steno’s conversion ̶ these circumstances arrived. Nicolaus Steno then received an official communication dated October, 1667, from the Danish King, Frederik the Third, bidding him return to Denmark as „Royal anatomist”, anatomicus regius.

Had this occurred earlier, Steno would not have hesitated to comply with his King’s wishes. Now, however, he felt dubious about it. The ties between Nicolaus Steno and Italy were very strong. How could he, a convert, be permitted to live in the narrow-minded, orthodox Lutheran Denmark? And how about the completion of the geological research work he had begun?

Finally, Steno decided to obey the Danish king’s summons. But before he took leave of Italy, he felt himself duty-bound, both to his patron, the Grand Duke Ferdinand II of Tuscany, and to science itself, at least to publish a „forerunner”, a prodromus, of the great geological work. This provisional treatise was to present the results Steno had attained so far in his studies of rock strata and other deposits, with their content of ̶ so runs the title of the book ̶ “Solid bodies enclosed by the process of nature within a solid”. By this he meant, plant and animal fossils, and now, in addition, the mineral crystals to which Steno had only alluded in his dissertation of 1667. The booklet, now a classic and great rarity, is only seventy-six pages long, but filled with an enormous amount of material concerning the geological history of the earth.

Before he left Italy, Steno entrusted the manuscript to his friend Viviani, who was to supervise its publication. Viviani had, as already noted, a first-hand knowledge of the progress of Nicolaus Steno’s geological investigations. It also was Viviani who, in connection with the church censor’s endorsement (August 30, 1668), described the work as „having far-reaching significance for all science”.

Viviani had a transcript made of De Solido for use in the printing office. This document, so interesting in respect to the history of geology, was found a few years ago by Gustav Scherz in the Biblioteca Nazionale in Florence. On the first page the manuscript has a notice (by Viviani?) saying that De Solido was printed under his supervision. “Questofu stampato sottolamia cura”. The original manuscript from Steno’s own hand is not known .

The dissertation: De Solido (1669) is a continuation and amplification of the geological parts of the treatise on the dissection of the shark’s head (1667), reporting further observations and drawing far-reaching conclusions from them regarding the history of the earth. As a beginning Steno describes again his point of departure:

whether or not the „tongue-stones”, glossopetrae, from Malta were real shark’s teeth from past time. In connection with this problem many others arose: e.g. if all other bodies “which are similar to marine bodies”, and which now are found far from the sea, were once produced in the sea. And how is one to understand the bodies which are similar to bodies, produced in fresh water? Is this a coincidental resemblance? Or how else can it be explained? And the mineral crystals in rocks – how were these bodies formed? The investigation which began with the „tongue-stones”, glossopetrae, from Malta eventually became a problem embracing the whole earth and its geological history. When one question was solved, others were created. “I might compare those doubts to the heads of the Lernean Hydra, since when one of them had been got rid of, numberless others were born”.

Steno’s basic geological assumption was expressed in De Solido (as well as in his former dissertation) in the sentence: “The strata of the earth are due to deposits of a fluid”.

In concise sentences he characterized sediments as opposed to other kinds of rock, e.g. lava. He also distinguished between geologically older and younger formations, and recognized that layers with enclosed fragments of other layers revealed something about the successive sedimentation. He distinguished between marine deposits (which contain a marine fauna, ship timbers and „a substance which resembles the sea floor”) and fresh water sediments containing plant remains, formed for example during floods etc. Traces of volcanic activity were also recognized in the strata, and the effects of transgression and regression of the sea considered. Now there is no longer any doubt on Steno’s part that the plant- and animal-like bodies in the earth-layers have an organic origin.

Nicolaus Steno arrived at these ideas through independent observation, but his studies in Copenhagen, as well as his acquaintance with the literature, must surely have brought him in contact with the geological-paleontological problems which he later was to study in Italy. Steno must, for example, have known professor Ole Worm’s museum, which was one of the sights of Copenhagen in the middle of the seventeenth century. In the printed description of the museum (Museum Wormianum, 1655) we can find geological, palaeontological and mineralogical problems considered. Above all, it can be assumed that Steno met geological problems in the instruction given by Prof. Thomas Bartholinus, who, while in Italy for several years, discussed the problem of the nature of fossils, the past distribution of land and sea, vulcanism, mountain grottos, etc. This side of Steno’s scientific life and development is still in need of careful study.

Since the strata were deposited in water, the original position, on the whole, Steno declares, must have been horizontal; the lowest stratum in the series must be the oldest, deposited and perhaps hardened before the overlying stratum was formed. Each stratum, then, except the lowest, is limited by two planes parallel to the ho­ rizon. This can be seen, for example, in open sections. The originally horizontal planes of sedimentation can be recognized, even where the stratification is now divergent from the horizontal.

The disturbed position of strata so often observed, is explained as due to the influence of different forces (underground fire, burning of subterranean gases, water) after the formation of the sediments. We must, Steno says, here think upon “the spontaneous slipping or downfall of the upper strata after they have begun to form cracks, in consequence of the withdrawal of the underlying substance, or foundation. Hence by reason of the diversity of the cavities and cracks the broken strata assume different positions; while some remain parallel to the horizon, others become perpendicular to it, many form oblique angles with it, and not a few are twisted into curves because their substance is tenacious. This change can take place either in all the strata overlying a cavity, or in certain lower strata only, the upper strata being left unbroken”. If we take such disturbances into account, Steno continues, we have an explanation for the diversity of the earth’s surface: mountains and valleys, upland lakes, high plains, lowlands, etc. These forces are not something of the past, but continue even now to change the surface of the earth.

Here Steno came to the much discussed problem of the origin of mountains.

At a time when views were based on mere speculation, rather than on observation, it was commonly thought that mountains had been formed at the time of the earth’s creation, and had not changed essentially in the time which had elapsed since ̶ a few thousand years, according to Genesis.

But Nicolaus Steno could not agree with this. He observed the mountains of Tuscany, and of the other countries he visited on his travels. On the basis of these observations he could assert that “all present mountains did not exist from the beginning of things”, and that “mountains can be overthrown … peaks of mountains can be raised and lowered … the earth can be opened and closed again”.

Several different mountain types were distinguished by Nicolaus Steno in De Solido. Some were built as the result of volcanic activity, others as a result of fluvial erosion ̶ in which case the same strata could be found on both sides of the valleys. He had observed mountains composed of sediments where the strata were parallel to the horizon, and other mountains where the strata were inclined; and he knew of mountains where the beds were folded. Although he did not fully understand the scope of this last observation, he had thus approached the problems of mountain folding.

On the length of the geological periods in comparison with historical chronology, Steno had, of course, only the most imperfect notion, although he touched on the problem. Among other things he tried to establish a connection between the (Pleistocene) elephant bones found near Arezzo in a valley of Arno, and accounts of Hannibal’s march through Italy nineteen hundred years before. Furthermore Nicolaus Steno, like his contemporaries, felt himself obliged to accept the Biblical tradition about a Common Inundation in Noachian times, the Flood, “some four thousand years ago”.

Nicolaus Steno did not limit himself to merely theoretical geological considerations. He made an attempt to solve a concrete problem.

The geological history of Tuscany was outlined by Steno in the light of his interpretation of geological observations. He wrote on this subject: “In what way the present condition of any thing discloses the past condition of the same thing is above all other places clearly manifest in Tuscany; inequalities of surface observed in its appearance to-day contain within themselves plain tokens of different changes”. And then Nicolaus Steno presented the first attempt to understand regional geological development in the light of surface phenomena. He illustrated his interpretation with the help of some schematic drawings (Fig. 6,20-25).

 

The six sketches suggest six stages in Tuscany’s development. Steno gave the following legend to the figures: “Figure 25 shows the vertical section of Tuscany at the time when the rocky strata were still whole and parallel to the horizon. ̶ Fig. 24 shows the huge cavities eaten out by the force of fires or waters while the upper strata remained unbroken. ̶ Fig. 23 shows the mountains and valleys caused by the breaking of the upper strata. ̶ Fig. 22 shows new strata, made by the sea, in the valleys. ̶ Fig. 21 shows a portion of the lower strata in the new beds destroyed, while the upper strata remain unbroken. ̶ Fig. 20 shows the hills and valleys produced there by the breaking of the upper sandy strata”.

In the text itself Steno explained more fully that Tuscany’s surface had been covered with water twice, had twice been “even and dry”, and twice “uneven”. Steno tried to bring this geological history into agreement with (or least not in opposition to) the Bible. He thought that when Tuscany was covered for the second time with water it was in the days of the Flood. This was in Tuscany’s “fourth stage”. Later the water fell away again, carrying much sediment to the sea, where new land was formed. The sixth and last stage in the geological history of Tuscany we see going on before our eyes, with geological forces still at work changing the landscape.

Steno made the first attempt to treat geological problems by inductive reasoning, and he was convinced that the history of the earth could be read from examination of the rocks. He sketched the outlines of a new, exact science: geology. The way to new fields of research was shown; new paths were opened up when Steno began to read the tale of the earth layers and their content of fossils. But it was not alone scientific paleontology and stratigraphy with their allied disciplines, that were founded by Nicolaus Steno. He also was the first scientist who made the crystals of minerals an object of exact research.

When Steno wrote or talked about “solid bodies, enclosed by the process of nature within other solids”, he did not mean fossil plants and animals alone; to him the term “solid” included mineral crystals (angulata corpora) as well. In this field, too, his accomplishments were so extraordinary that the year 1669, when De Solido was published, has rightly been described as the date of birth of scientific crystallography. Steno must share the credit to a certain degree, however, as will be described below, with his countryman Professor Erasmus Bartholinus of Copenhagen.

In the seventeenth century, only a little was known about the technically important ores, the precious stones and other minerals used for medical and other purposes. A little was known about mineral crystals, for example the cubic crystal of pyrites. But, as it has been said, in Steno’s time more thought was given to the philosophy of crystals, and crystal symbolism, than was given to an exact study of the crystals themselves. Their multiplicity of forms was thought to be an incidental caprice of nature, even when attention was paid to a single noticeable crystal form.

While traveling, especially in the mountains of Tuscany, Steno often had the opportunity to observe crystallized minerals in veins, cavities, fissures etc. With his own hands he hewed the crystals from the rocks, trying to find out how mineral crystals are formed, and how they get their shape.

It was a common belief in Steno’s time that quartz crystals (“rock crystal”, Si02) grow in cavities in the rock like a plant. Just as a living plant draws up nourishment from the ground through its roots, so a rock crystal on the wall of a cavity draws the juices which make it grow, from the rock substratum. The mineral particles were supposed to move up inside, by intussusception. Steno could not share this belief. From analogies with crystals precipitated from watery solutions in the laboratory he adopted the opinion that quartz crystals in the rocks were formed in a similar way­ perhaps from a watery solution, perhaps from a quite different, yet unknown fluid.

Steno was aware that mineral veins with their contents were formed later than the surrounding rock. “The most of the minerals for which man’s labor is spent did not exist at the beginning of things”, he writes, He therefore rejected many of the old mining superstitions regarding the location of rich mineral deposits, their detection, etc. On the contrary, he emphasized that it is necessary to study the very rock which surrounds the mineral vein, “seeing that it is more probable that all those minerals which fill either the clefts or expanded spaces of rocks had as their matter the vapor forced from the rocks themselves”.

Nicolaus Steno, unlike many of his predecessors and contemporaries, was not willing to confine himself to speculations over the primary origin of crystals. Instead, he wished to study the crystals themselves as he found them.

Here again we meet Steno’s desire for realities. He realized the necessity of entering into close observation and diligent study of nature, and nevertheless he did not lose sight of the total picture of which the facts were part.

Steno subjected rock-crystal (quartz) to an exact investigation, and succeeded in establishing certain definite, hitherto unknown laws for the growth and form of the, e and other crystals.

First Steno demonstrated that the growth of a quartz crystal is not (as mentioned above) analogous with that of a plant. A crystal, he says, “grows while new crystalline matter is being added to the external planes of the crystal already formed”. This accretion of material, however, is not always equal on all the faces of the crystal.

A quartz crystal’s simplest form is, according to Steno, hexagonal pyramides and an intermediate prism likewise hexagonal; in reality the hexagonal dipyramid consists of two rhombohedra, but this Steno could not know. This ideal form can vary greatly during the growth of the crystal. The size of the faces can vary,. and the prism may be entirely absent; new faces, and step-like unevennesses can be found, he writes, and so forth. But amid all the differences, Steno could always demonstrate this law: regardless of the size and reciprocal distance of the crystal faces, the interfacial angles are constant.

In the text of De Solido Nicolaus Steno does not formulate the law of constancy of interfacial crystal angles in definite words. He speaks of it most directly in the legend to the accompanying figures “Figures 5 and 6 belong to the class of those which I could present in countless numbers to prove that in the place of the axis both the number and the length of the sides are changed in various ways without changing the angles”. And further: “Figure 13 shows how sometimes the length and number of the sides are changed in various ways without changing the angles, on the plane of the base, while new crystalline matter is being placed upon the planes of the pyramids”.

If one reads carefully what Steno writes in De Solido (1669) on the morphology of different crystals, especially quartz, hematite and pyrites, time after time one will meet statements which assume the new-found law of the constancy of angles. That Nicolaus Steno did not communicate all of his observations pertaining to constancy of angles and did not pronounce it as a universal 1aw, can be blamed on the haste with which De Solido (1669) was written. He wrote “In as much as the brevity of my hurried writing has left not a few things insufficiently explained, especially where the treatment concerns angular bodies (i. e. crystals) and the strata of the earth, in order to afford some sort of remedy for that defect, I have decided to add … figures”.

Knowing Nicolaus Steno’s cautiousness in making broad generalizations, it is easy to imagine that he had wished to study more crystals, before he pronounced the law universal. Reading Steno’s description of his research on crystals, one cannot help feeling that behind his condensed remarks, there lies an extensive knowledge, waiting to be presented to the scientific world in the main work for which De Solido (1669) was only a forerunner.

Rock crystal was not the only mineral which Nicolaus Steno subjected to a crystallographical examination. One can not doubt that he had studied many others. In De Solido (1669) he communicates, for example, his results concerning the more complicated crystals of hematite from the classical iron ore mines of the island of Elba, and of the crystals of pyrites. He compared these crystals with the quartz crystals and discussed mineralogical and crystallographical problems.

Nicolaus Steno did not undertake any actual measuring of crystal angles, and in connection with this some criticism has been raised regarding his share in the finding of the law of constancy of angles.

It has been proposed that the name “Steno’s Law” (the law of the constancy of interfacial angles) should be changed to: Steno­ Romé de l’Isle’s Law or only “Romé de l’Isle’s Law”, because the French mineralogist, working a hundred years after the lifetime of Nicolaus Steno, established the law’s universality on the basis of a large number of measurements of crystals with his goniometer.

It must, however, be remembered that Steno actually was the first to point out the constancy of interfacial angles, directly stating it in the case of the quartz crystal and leaving it understood in his description of several other mineral crystals. We therefore must continue to assert that it is correct to speak of Steno’s Law, the first of the fundamental laws of crystallography. But aside from this Nicolaus Steno occupies a distinguished place in the history of crystallography. With him began the scientific description of crystal morphology, the first step forward on the way to exact crystallography.

Unfortunately Nicolaus Steno never published the great geological-mineralogical work he had begun, and which was constantly in his thought in the years after the publication of De Solido. The material must, unfortunately, be regarded as lost.

Nicolaus Steno, who had taken Holy Orders in 1675, died in Schwerin, Germany, in 1686, as a prominent Catholic churchman; by then he had long ceased to work with the natural sciences. His grave is in Firenze (Basilica di San Lorenzo.)

Source:

“Nicolaus Steno” by Axel Garboe, trans. M.S. Bryan [in:]

Geological Survey of Denmark. IV. Series. Vol. 3. No.9.

(Danmarks Geologiske Undersegelse. IV. Reekke. Bd. 3. Nr. 9.)