**Banknotes of Switzerland 10 Swiss Franc note**

**Swiss National Bank**

Schweizerische Nationalbank - Banque Nationale Suisse - Banca Nazionale Svizzera - Banca Naziunala Svizra

Obverse: Portrait of

**Leonhard Euler**(15 April 1707 – 18 September 1783) was a pioneering Swiss mathematician and physicist. He made important discoveries in fields as diverse as infinitesimal calculus and graph theory. He also introduced much of the modern mathematical terminology and notation, particularly for mathematical analysis, such as the notion of a mathematical function. He is also renowned for his work in mechanics, fluid dynamics, optics, astronomy, and music theory. Euler is considered to be the pre-eminent mathematician of the 18th century and one of the greatest mathematicians to have ever lived. He is also one of the most prolific mathematicians; his collected works fill 60–80 quarto volumes. He spent most of his adult life in St. Petersburg, Russia, and in Berlin, Prussia.

Reverse: Water turbine, solar system and scheme of propagation of rays of light passing through lenses.

Watermark: portrait of Leonhard Euler.

Colors: red, green.

Size: 137 x 66 mm.

Artists: Ernst Hiestand und Ursula Hiestand.

Printer: Orell Füssli Arts Graphiques S.A.

In circulation from 05.11.1979 to 01.05.2000.

Cancelled from 01.05.2020.

**Banknotes of the Swiss franc**

**10 Swiss Franc 20 Swiss Franc 50 Swiss Franc 100 Swiss Franc**

The Swiss National Bank introduced the sixth series of Swiss banknotes in 1976 with the issuance of its updated 100 franc note. It was not until November 5, 1979 that the 10 franc banknote of the sixth series was put into circulation. Commissioned by the SNB to print the note was Orell Füssli in Zürich. A competition was held to determine the designs of the sixth series, and the submissions sent in by artists Ernst (1935–) and Ursula Hiestand (1936–) were selected, although they did not officially win the competition. The banknote was produced from 1979 to 1992, and was recalled beginning on May 1, 2000. It is expected to be demonetized on May 1, 2020. The note, like the others of the sixth series, is unique in that one side – the obverse – has horizontal orientation while the other – the reverse – has vertical orientation. Also, although Romansh was recognized as a national language in Switzerland in 1938, no banknote series until the sixth series included the language. The 10 franc note has a width of 137 millimeters and a height of 65 millimeters when held horizontally. It is predominantly orange-brown or red-brown in color and printed on white paper. Certain, less prominent design elements are printed in other colors of ink, such as green or light blue.

Featured at the center right of the note's obverse is a large, left-facing illustration of Leonhard Euler (1707–1783), a well-known Swiss mathematician and physicist, similar in appearance to the 1753 Portrait of Leonhard Euler by Jakob Emanuel Handmann (1718–1781). The numeral "10" superimposes a portion of the image at the lower right corner of the banknote. To the left is a partially green and orange background consisting of Euler diagrams captioned with "A", "B", and "C", and drawings of several lines coming from a single point and concluding at a curved boundary. One of the "C" items is white in color. A large, three-dimensional numeral "10" is displayed at the top center of the note, inside the area of the background. Its shadow is printed in orange-brown or red-brown ink while the number is a light in color, and the designs on the background underneath are visible through the "10". The caption "Leonhard Euler" is printed in blue below the large numeral, and below that is "1707–1783", signifying the lifespan of Euler. Printed in an upward direction in purple at the bottom center of the note is the German value "ZEHN FRANKEN", and written to the right of it in a similar manner, but with blue and red ink, is the Romansh value "DIESCH FRANCS". Directly outside of the area with the background, near the left of the large "10", is a small, touch-perceptible red/orange dot that can be used by the visually-impaired for identifying the value of the note. Printed vertically and upward in orange or red ink at the left edge of the obverse is the German bank title "SCHWEIZERISCHE NATIONALBANK". Accompanying it to the right is the Romansh "BANCA NAZIUNALA SVIZRA", written in the same manner. A small Swiss cross in red or orange is present above the Romansh text, to the immediate right of the "K" in the German "NATIONALBANK". The area between the bank titles and the aforementioned touch-perceptible dot is deliberately empty. When held against the light, a watermark of Leonhard Euler becomes visible in this portion of the note.

Printed horizontally in red ink at the top of the reverse is the French bank title "BANQUE NATIONALE SUISSE", and written in the same format on a line below is the Italian "BANCA NAZIONALE SVIZZERA", followed by a small Swiss cross identical in appearance to the cross presented on the obverse. Directly below the Italian title is a blank area in which a watermark becomes visible. The signatures of the President of the Bank Council and a member of the Board of Directors are featured in orange/red in the order listed below the blank area, the former captioned above by the French "Le président du Conseil" ("The President of the Council") and the latter accompanied by "Un membre de la Direction générale" ("A member of the Board of Directors"). Both of these captions are printed on two lines, the first separated between "president" and "du" and the second between "la" and "Direction". The signature of Edmund Wyss is present under "Le président du Conseil" on notes printed from 1979 to 1986; pieces produced in 1987 bear the signature of François Schaller (1928–2006), while notes printed from 1990 to 1992 carry the signature of Peter Gerber (1923–2012). Over the ten years of production, the signatures of six individuals have appeared under the caption "Un membre de la Direction générale". Of these, Jean Zwahlen's signature, which is present on some notes made from 1987 to 1992, comes in two varieties: one measuring 15 millimeters and the other 18 millimeters. Written in black ink to the right of the signatures is the seven-digit serial number, preceded by the last two digits of the date and a letter. Below all of the aforementioned elements is a colored area in which the prominent features of the reverse are located. This area, decorated at portions with several wavy lines, features a large illustration of a water turbine that was initially sketched by Leonhard Euler, signifying Euler's contributions to fluid physics. Next to the turbine, and even superimposing parts of it, is a depiction of a ray diagram with an object in front of five converging lenses and the object's resultant image. Such a depiction represents Euler's work with optics. Featured in the center of the reverse, superimposing the turbine but covered partially by the ray diagram, is a representation of a model drawn by Euler of the solar system, showing the planets of Mercury (not accompanied by a symbol on the note), Venus (♀), Earth, Mars (♂), Jupiter, and Saturn, as well as Halley's Comet, in their respective orbits around the sun. Also displayed in the illustration is the Moon orbiting around Earth, the four known moons of Jupiter during Euler's lifetime – Io, Europa, Ganymede, and Callisto – traveling around the planet, and the five known moons of Saturn of Euler's time – Tethys, Dione, Rhea, Titan, and Iapetus – circling Saturn. Erroneously, a fifth moon is shown in Jupiter's orbits. In between the orbits of Mars and Jupiter is a white oval, which corresponds to the location of the white "C" item on the note's obverse. The inclusion of the solar system identifies Euler's contributions to astrology. The numeral "10" is printed in a large font at the upper right corner of the colored area, the shadow colored red and the remainder showing the designs of the background underneath. The French value "DIX FRANCS" is printed in a downward direction at the upper left corner of the background, whereas the Italian "DIECI FRANCHI" is inscribed upward at the lower right corner of the note. The serial number is printed once again in blue ink over the image of the water turbine. Written in small, orange or red print at the very bottom of the note, outside of the colored area, is "E + U HIESTAND" followed by "© Banque Nationale Suisse" and "Orell Füssli Arts Graphiques S.A. Zurich". Such text signifies the designs were made by Ernst and Ursula Hiestand and the note is owned by the Swiss National Bank and was printed by Orell Füssli.

Leonhard Euler

**Leonhard Euler**, (born April 15, 1707, Basel, Switzerland — died September 18, 1783, St. Petersburg, Russia), Swiss mathematician and physicist, one of the founders of pure mathematics. He not only made decisive and formative contributions to the subjects of geometry, calculus, mechanics, and number theory but also developed methods for solving problems in observational astronomy and demonstrated useful applications of mathematics in technology and public affairs.

Euler’s mathematical ability earned him the esteem of Johann Bernoulli, one of the first mathematicians in Europe at that time, and of his sons Daniel and Nicolas. In 1727 he moved to St. Petersburg, where he became an associate of the St. Petersburg Academy of Sciences and in 1733 succeeded Daniel Bernoulli to the chair of mathematics. By means of his numerous books and memoirs that he submitted to the academy, Euler carried integral calculus to a higher degree of perfection, developed the theory of trigonometric and logarithmic functions, reduced analytical operations to a greater simplicity, and threw new light on nearly all parts of pure mathematics. Overtaxing himself, Euler in 1735 lost the sight of one eye. Then, invited by Frederick the Great in 1741, he became a member of the Berlin Academy, where for 25 years he produced a steady stream of publications, many of which he contributed to the St. Petersburg Academy, which granted him a pension.

In 1748, in his Introductio in analysin infinitorum, he developed the concept of function in mathematical analysis, through which variables are related to each other and in which he advanced the use of infinitesimals and infinite quantities. He did for modern analytic geometry and trigonometry what the Elements of Euclid had done for ancient geometry, and the resulting tendency to render mathematics and physics in arithmetical terms has continued ever since. He is known for familiar results in elementary geometry—for example, the Euler line through the orthocentre (the intersection of the altitudes in a triangle), the circumcentre (the centre of the circumscribed circle of a triangle), and the barycentre (the “centre of gravity,” or centroid) of a triangle. He was responsible for treating trigonometric functions—i.e., the relationship of an angle to two sides of a triangle—as numerical ratios rather than as lengths of geometric lines and for relating them, through the so-called Euler identity (eiθ = cos θ + i sin θ), with complex numbers (e.g., 3 + 2√(−1)). He discovered the imaginary logarithms of negative numbers and showed that each complex number has an infinite number of logarithms.

Euler’s textbooks in calculus, Institutiones calculi differentialis in 1755 and Institutiones calculi integralis in 1768–70, have served as prototypes to the present because they contain formulas of differentiation and numerous methods of indefinite integration, many of which he invented himself, for determining the work done by a force and for solving geometric problems, and he made advances in the theory of linear differential equations, which are useful in solving problems in physics. Thus, he enriched mathematics with substantial new concepts and techniques. He introduced many current notations, such as Σ for the sum; the symbol e for the base of natural logarithms; a, b and c for the sides of a triangle and A, B, and C for the opposite angles; the letter f and parentheses for a function; and i for √(−1). He also popularized the use of the symbol π (devised by British mathematician William Jones) for the ratio of circumference to diameter in a circle.

After Frederick the Great became less cordial toward him, Euler in 1766 accepted the invitation of Catherine II to return to Russia. Soon after his arrival at St. Petersburg, a cataract formed in his remaining good eye, and he spent the last years of his life in total blindness. Despite this tragedy, his productivity continued undiminished, sustained by an uncommon memory and a remarkable facility in mental computations. His interests were broad, and his Lettres à une princesse d’Allemagne in 1768–72 were an admirably clear exposition of the basic principles of mechanics, optics, acoustics, and physical astronomy. Not a classroom teacher, Euler nevertheless had a more pervasive pedagogical influence than any modern mathematician. He had few disciples, but he helped to establish mathematical education in Russia.

Euler devoted considerable attention to developing a more perfect theory of lunar motion, which was particularly troublesome, since it involved the so-called three-body problem—the interactions of Sun, Moon, and Earth. (The problem is still unsolved.) His partial solution, published in 1753, assisted the British Admiralty in calculating lunar tables, of importance then in attempting to determine longitude at sea. One of the feats of his blind years was to perform all the elaborate calculations in his head for his second theory of lunar motion in 1772. Throughout his life Euler was much absorbed by problems dealing with the theory of numbers, which treats of the properties and relationships of integers, or whole numbers (0, ±1, ±2, etc.); in this, his greatest discovery, in 1783, was the law of quadratic reciprocity, which has become an essential part of modern number theory.

In his effort to replace synthetic methods by analytic ones, Euler was succeeded by J.-L. Lagrange. But, where Euler had delighted in special concrete cases, Lagrange sought for abstract generality, and, while Euler incautiously manipulated divergent series, Lagrange attempted to establish infinite processes upon a sound basis. Thus it is that Euler and Lagrange together are regarded as the greatest mathematicians of the 18th century, but Euler has never been excelled either in productivity or in the skillful and imaginative use of algorithmic devices (i.e., computational procedures) for solving problems.