Eötvös, Loránd

Loránd Eötvös (Baron) was the son of the well-known Hungarian writer, political scientist and politician, József Eötvös. He began his studies in the Piarist Grammar School in Pest then he studied mathematics and physics at the University of Heidelberg.

During his university years his masters were Ányos Jedlik in Pest, and among others Gustav Kirchhoff, Robert Bunsen and Hermann Helmholtz in Heidelberg. He also took his Ph. D. degree there in 1870 with a thesis which studied problems of Fizeau on the relative motion of a light source, which was one of the first steps towards relativity theory..

His interests turned to the phenomenon of capillarity in the field of experimental physics, and within a short time he determined the relationship, later named after him as the Eötvös rule, between the surface tension, the molecular volume of fluids and temperature.

Following this he began to carry out methodological research in the phenomenon of gravity. He constructed a new instrument, the torsion balance (or Eötvös pendelum) for gravitional investigations which met the requirements of the measurement procedures he had developed to the highest degree. The first version of the device was completed in 1891 and was a human-sized measuring device.

He started to study the geographical micro structure (changes at different locations) of the gravitational field of the earth with the use of his torsion balance. A method in field work was developed, by means of which the visible and invisible distribution of material - unevenness of distribution according to the density of surrounding masses - could be mapped, which made the Eötvös balance an effective means of raw material exploration. This procedure arrived for applied geophysics at just the right time, because at that time interest in crude oil and natural gas had increased tremendously.

The Eötvös balance became more and more significant in basic research. By use of the balance it was successfully proved that the so-called heavy mass featuring the gravitational nature of a material and the so-called inertial mass featuring the inertia of a material are generally proportional (independently of the chemical composition of bodies), i.e. the two masses are equal in a proper measuring system. By means of his balance Eötvös proved this equivalence with record accuracy (he measured that the ratio of the deviation of the two masses and the mass, so the relative deviation, was less than 1/2,000,000). This result was 3 to 4 times more accurate than earlier measurements. This is called the equality independent of the chemical composition of heavy and inertial mass.

At the beginning Einstein did not know Eötvös' result, though the Hungarian scientist was just on the top with his work when Albert Einstein developed his general theory of relativity.

In 1906 the international geodetical society, the Internationale Erdmessung, held its XV. congress in Budapest. Eötvös presented his measurements on gravity and also demonstrated in field application of his balance. The success of his presentation resulted in a grant of annually 60,000 crowns of the Hungarian government from 1907 onwards for his gravitational and geomagnetic research. By this decision the first applied geophysical institute in the world was established under Eötvös's direction. The institute later was named after him.

In the meantime, between 1910 and 1918, Eötvös continued his investigations in gravity and earth magnetism. He proved that the weight of the bodies moving on the surface of the Earth (the resultant of the gravitational effect and the centrifugal force resulting from the rotation of the Earth) is not constant but in case of objects moving towards the west, it increases and in case of objects moving towards the east, it decreases as compared to those standing on the Earth (Eötvös effect).

After the death of Eötvös, his former assistant, Dezső Pekár carried on the torsion balance measurements.

From 1873 he was correspondent member of the Hungarian Academy of Sciences.

In 1983 full member and in 1889, he was elected President and he performed this duty in several terms till 1905.

From 1871 he lectured theoretical physics at the Budapest University of Sciences,

in the next year professor and in1891-92 he became its rector. During this interval he organized the Mathematical and Physical Society. From 1878 he led the Institute of Experimental Physics.

In 1894 and 1895 he filled a governmental post as Minister of Religion and Education. In 1895 he established the Eötvös College in memory of his father.

Representatives of the international scientific world regard him even today as the master of classical physics. In 1909 he received the Benecke prize in Göttinga for his gravity measurements. Two years later the Royal Prussian Academy of Science, the Jagello University of Krakow and the Norwegian Royal University conferred the title of honorary doctor upon him.

capillarity
Surface tension of liquids (also known as capillary action or motion) is the ability of a narrow tube to draw a liquid upwards against the gravitional force. It occurs when the adhesiv intermolecular forces between the liquid and a solid are stronger than the cohesive intermolecular forces within the liquid. The liquid for which this effect is most commonly seen is water, because water is capable of surface interactions and it is ubiquitous.
The effect causes a concave meniscus to form where the liquid is in contact with a vertical surface. The same effect is what causes porous materials to soak up liquids.
A common device used to show capillary action is the capillary tube placed in a liquid. The narrower the tube, the higher the liquid will climb, because a narrow column of liquid weighs less than a thick one and a concave meniscus forms.
On the other hand, molecules of some materials such mercury are more attracted to each other than they are to glass, so a convex meniscus forms and capillary action works in reverse.

Eötvös rule
Eötvös worked out a new way of determining surface tension of different liquids called the reflection method. During his experiments Eötvös found that there was a relationship between the surface tensions of liquids, their molar weight and temperature.
The Eötvös rule states: as the temperature increases the surface tension will go linearly to zero at a critical temperature. In case of liquids this constant is so fundamental as the universal gas constant in case of gases.

torsion balance
The operation based on the concept that the forces exerted by various underground materials on two masses or weights suspended on a lever were different. One weight hung 20 cm lower than the other one. Weights were made of gold or platinum, because materials of high specific density needed to be used for measurements.
The angle of turn was indicated by a needle moving in front of a dial. In the beginning, the device was protected by a simple case; later its thickness was tripled to prevent the balance from being affected by air movements, temperature changes and electric effects caused by moving metal particles during the measurements.
The device had wide application in oil exploration until the mid-1930s. For one and half decades it was displaced by new instruments, but since 1950 it has regained its use in geophysical measurements.

Eötvös effect
In the early 1900s German researchers carried out gravity measurements on moving ships in the Atlantic, Indian and Pacific Oceans. While studying their results Eötvös noticed that the data were lower when the boat moved eastwards, higher when it moved westward. He identified this as primarily a consequence of the rotation of the Earth. In 1908 new measurements were made and the results proved him. Since then geodesists correct measurements according to the Eötvös effect.
The gravitational force of the Earth is the resultant of two forces: the principal one caused by the attraction according to Newton's law, the additional one the centrifugal force caused by the Earth's rotation. Since the distribution of the masses on the Earth's surface and the speed at which the Earth rotates are constant, the weight of objects on the Earth's surface is also constant. The situation is different, however, in the case of moving objects. As the Earth rotates from west to east, the centrifugal force on a moving object is greater if its motion on the Earth is towards the east than towards the west. As a result of this phenomenon the weight of a body moving eastwards will decrease, while that moving westwards will increase.
In 1915 Eötvös constructed a special instrument to demonstrate this phenomenon. The device is basically a balance with horizontal axis, where instead of pans, weights are attached to the end of the arms. The balance stands on a tripod, which rotates evenly. When the balance is rotated the weight moving towards the west will become heavier, the one moving towards the east lighter. The balance will, therefore, deflect from its state of equilibrium. If the balance is rotated at such a speed that the rotation period equals the period of its oscillation the impulses occurring during the rotations will cause the arms to make ever greater oscillations.

Eötvös College
As a teacher at the end of the 19^th century Loránd Eötvös perceived that a great number of talented students break their studies, due to lack of financial support. To solve this problem in 1895, during the time he was minister of education, he established a scientific residential college, which was named the József Eötvös College, after his father. Within the framework of the college future secondary school teachers received excellent tuition and took part in special tutorials to promote individual scientific work. It was the first action towards creating further programs in higher education which were needed for the systematic large-scale training of young scholars in the following decades .
To support the poorest students no fees were required for thirty of the one hundred places.
Students working in various academic fields were successfully mixed in interdisciplinary discussion groups which facilitated confronting of diverse views.
To promote natural sciences, Eötvös advised, Andor Semsey, a great patron of Hungarian science, to establish a scholarship for young graduates who wished to devote themselves to scientific studies. This tradition of careful scholarship – like for graduates of Oxford and Cambridge, or of Harvard and Yale - was maintained during the first decades of 20^th century.

Piarist Grammar School
Eötvös, Loránd It is the oldest operating secondary school in Budapest, operating even today. It was established by the council of the city of Pest under the name of Collegium Pestinense in 1717. The teaching was left to the members of the Piarist Order (order of pious schools - Ordo Scholarum Piarum). The teaching started with two Piarists and 155 students in 1717. Among its teachers, Bernát Benyák began to teach philosophy in the Hungarian language in 1777 and István Szablik, teacher of physics, launched the first balloon from the courtyard of the Piarist building in Hungary in 1783. In the teaching at the school special attention was paid to the teaching of the sciences and the Hungarian language. To help this school theatrical performances were performed in the Hungarian language, even from 1718. The theatre hall of the Piarist Secondary School was the first permanent theatre in Pest from 1719 till 1745. After 1848, the school was transformed into college and it is here that the first matriculation examinations were held in Pest, in 1851. As of 1924, it continued its operation as a grammar school, which was closed in 1948 when all schools were nationalised. It was reopened in 1950 and since then it has been continuously operating. Over the years students have left this school to become world famous, such as Loránd Eötvös, Nobel Prize winner George Hevesy, and George Oláh.