William Crookes

WILLIAM CROOKES
1832-1919

English chemist and physicist; His investigations of the photographic process in the 1850s motivated his work in the new science of spectroscopy. Using its techniques, Crooks discovered (1861) the element thallium, which won him election to the Royal Society. His efforts in determining the weight of thalium in an evacuated chamber led to his research in vacuum physics.

Crooks invented the radiometer in 1875 and, beginning in 1878, investigated electrical discharges through highly evaculated "Crookes tubes." These studies laid the foundation for J. J. Thomson's research in the late 1890's concerning discharge-tube phenomena. At the age of 68, Crookes began investigating the phenomenon of radioactivity, which had been discovered in 1896, and invented a device that detected alpha particles emitted from radioactive material. Crookes maintained an interest in agriculture and warned in 1898 that the world's population would face starvation unless new fertilizer sources were discovered. He was also interested in psychic phenomena. He was knighted in 1897.

The English physicist William Crookes (1832-1919) had devised, by 1875, a still better evacuated tube (a Crookes tube), in which the electric current through a vacuum could more easily be studied. It seemed quite clear that the electric current started at the cathode and traveled to the anode, where it struck the neighboring glass and created the glow of light. Crookes demonstrated this by placing a piece of metal in the tube and showing that it cast a shadow on the glass on the side opposite the cathode. (The electrical experimenters of the eighteenth and nineteenth centuries, beginning with Benjamin Franklin, had assumed that the current flowed from the concentration arbitrarily named positive to that named negative. Crookes had now shown that, in actual fact, the assumption was wrong and that the flow was from negative to positive.)

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CHARLES DARWIN

CHARLES DARWIN
( 1809 - 1882 )

“Survival of the fittest” and “Struggle for existence” whenever we talk about Charles Darwin we remember these words. Charles Darwin was the British naturalist who laid the foundation of the modern theory of evolution.

Darwin was born at Shrewsburg on Feb 12, 1809. Even as a child he developed a passion for collecting insects and minerals. Though he went to Edinburg university to study medicine it was a great failure. So in 1828 he went to Cambridge to dtudy Theology. But there also he neglected studies and spent much of his time in the pursuit of beetles. However he got the degree in 1831. There was a call for a naturalist who could accompany a scientific expedition. It was planned to sail around the world in the ship HMS Beagle. Darwin got it. He made a good lot of collections of bones of extinct animals and also that of the existing. He studied the difference between the two. This helped him to get a clear picture on evolution. He wrote an account of his travels sitting in London after he returned from voyage. In 1859 he explained his theory of evolution in his famous book “The origin of species by natural selecton.” The book became a popular one. He has said in the book that all the varied form of life on earth could in the course of time, have evolved from a common ancestry. At this juncture he said “Fittest Survive.”

The variation of animals and plants under domestication is second book published in 1868. he had his own typical method of collecting information.

Darwin died on April 19, 1882 and was buried near the tomb of Sir Issac Newton. Darwin had ten children. But seven only survived of which four were scientists and three of them were fellows of the Royal Society. The theory of evolution as proposed by Darwin still holds. In his book “The Descent of Man” he has described the evolution of man from apes.

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CHARAKA

CHARAKA

We know nothing about Charaka as a person. But his studies in the field of physiology, etiology and embryology have been made known. His monumental work “Charaka Samhita” an Ayurvedic treatise has gained popularity. It is believed that Charaka was the son of a sage who walked from place to place to cure the sick. Charaka lived 20 centuries ago.

Charaka says the body functions because it contains three dosha or humours namely bile (pitha), phlegm (Kafa) and wind (Vata). According to him, these doshas are produced when dhatus such as blood, flesh and marron act up on the food eaten. When the balance among the three dosha is disturbed there will be illness. To cure illness he prescribed medicinal drugs.

Charaka studied the anatomy of human body and various organs. He found that there are 360 bones in human body including teeth. He regarded heart as a controlling centre and it is connected to the entire body through 13 main channels. If there is any obstruction in these channels the result is disease. He gave a correct picture about the concept of digestion, metabolism and immunity.

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SIR JOHN FREDERICK WILLIAM HERSCHEL

SIR JOHN FREDERICK
WILLIAM HERSCHEL
(1792 - 1871)

He alone could have offered all that was needed for the invention of photography but this multi talented scientist needed it much less than all the others. He had many talents including drawing very well. In 1819 he had already discovered the ability that “hypo” had to fix the photographic images and he is the one who solved the “fixing” problem of pictures that his friend Talbot had. He was the one who first used the terms “photography” “negative” “positive” and “snapshot”. He was the first to photograph glass negatives and in the end he discovered a different photographic method called cyanotype. His contact with other important scientists of his time in Europe and his new ideas in many scientific fields made him without a doubt the leading figure in the English scientific community.

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BRAHMAGUPTA

BRAHMAGUPTA
( B.598)

Brahmagupta was the Scientist to tell first that it is the nature of the earth to attract bodies as it is the nature of water to flow.

Brahmagupta, the eminent Indian mathematician was born at Bhillamala in Gujrat. He was the court astronomer to King Vyagnramukha of the dynastry.

He first framed the ruler of operation for zero. He founded the numerical analysis. He gave a solution to indeterminate equations like ax2 + 1 = y2. He declared that addition or subtraction of zero to or from any quantity, negative or positive, does not affect it. He concluded that the product of any quantity with zero is zero and division of any quantity by zero is infinity.

24+0=24, 24-0=24 or -24-0=-24, 24x0=0
He solved equations like ax+b=0 and ax2+bx+C+0. He is the first mathematician to treat algebra and arithmetic as two separate branches of mathematics.

Brahmasphutasiddhanta and Karanakhandakhadyaka are the two threatises of Brahmagupta. The former contains chapters on arithmetic and algebra. The latter is a hand book on astronomical calculations.

Brahmagupta was an orthodox. He believed that the earth was round. He effectively used algebra for the first time in calculations.

Bhaskara said Brahmagupta is the gem of the circle of mathematicians.

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DMITRI IVANOVICH MENDELEEV

DMITRI IVANOVICH MENDELEEV
( 1834 - 1907 )

Mendeleev was a Russian Chemist who was the first to propose that the seemingly different chemical elements can be sorted out according to certain similarities in their properties. The arrangement he proposed is called the PERIODIC TABLE. His table proved to be a unifying principle in chemistry and led to the discovery of many new chemical elements.

Mendeleev studied chemistry at the university of St.Petersburg. He became a professor of general chemistry in 1867 after he received his Ph.D in 1865. He participated in the early development of oil fields in Southern Russia. He went to USA in 1876 and studied the petroleum industry there. Then he returned to St.Petersburg and resigned his job at university in 1890 in order to support for a group of student activists in their unrest against conservative academic policies.

Mendeleev wore for most of his life a large and baggy jacket without a belt, made of dark grey cloth, that too being his own creation.

In his table Mendeleev found that if elements are arranged in order of increasing atomic weights, elements with similar physical and chemical Properties occur at periodic intervals.

In the periodic table Mendeleev ordered the elements according to their atomic weights. It is an arrangement of the chemical elements in order of increasing atomic number into vertical columns and horizontal rows in such a way that elements with similar properties occupy the same columns. The vertical columns are known as groups and the horizontal rows are known as periods. The groups in the modern periodic table are numbered from 1 to 18 rather I to VIII and 0 in the old classification.

Mendeleevium is a transuranic chemical element belonging to group 3 (a) Old classification III (b) Its atomic number is 101. This element has been named after Mendeleev.

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S. CHANDRASHEKAR

S. CHANDRASHEKAR
(1910)

Subramanyam Chandrashekar was the third Indian to win the Nobel Prize in science. The others earlier were C.V.Raman and Hargovind Khurana.

S.Chandrashekar was born on October 10, 1910 in Lahore. He studied at Madras. He was a book worm and read many books. He did his B.A. at the Presidency college, Chennai. By that time he had many papers to his credit. He went to Cambridge as fellow of Trinity college. He was in USA at the age of 27 becoming an astrophysicist. Otto Struve, Director of Yerkes observatory and an astronomer offered him a job at the Chicago University.

Chandrashekar worked in yerkes observatory also. He had two students Trung Dao Lee and Chen Ning Yang at Chicago.

They wanted Subramanyam as their teacher. In 1997 they were awarded the Nobel Prize in Physics.

Chandrashekar studied the stars. He is best known for “Chandrashekar’s limit”. The fact is that this imposes a limit on the size of a highly dense star known as the white Dwarf. If this type of star has mass in excess of the limit it explodes to become a very bright star called “super nova”. Until all the excess matter is shed into space. Later it was confirmed that all the white dwarf stars in the sky have masses withing this limit. Chandrashekar calculated his limit based on mathematical equations. He also described the formation of “black holes”.

They are super heavy objects. A spoon of which may weigh several thousands of tons. His work on rotating fluid masses and blueness of the sky is highly commendable.

He got the Noble Prize in physics in 1983. He wrote few books and are found valuable.

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JOHANN HEINRICH SCHULZE

JOHANN HEINRICH SCHULZE
(1687 - 1744)

German professor at the University of Altdorf. With experiments, proved that silver nitrate becomes dark due to sunlight and not by temperature. He is the first that created photograms with paper masks, which unfortunately could not last due to lack of paper fixer. His observations that opened the path, for the creation of photography became know after his death

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EDMUND HALLEY

EDMUND HALLEY
( 1656 - 1742 )

Edmund Halley was a British astronomer and a mathematician. He was noted for his work on comets. Comets are formed by the collection of dust and gas. Halley calculated the orbit of a comet he observed in 1682. He proved that the comet was the same one astronomers had seen in 1531 and in 1607. He also predicted that it would return in 1758. This comet has been named after him. It is a bright, periodic comet; its average orbital speed is 76 years. The comet’s size, activity and favourably placed orbit makes it visible to the naked eye at each apparition. It is the only comet to be observed at close range by as many as three space crafts. Giolto Space craft was launched on 2 July, 1985 to study the Halley’s comet. The space craft traveling at a speed of 68 kil metres per second, passed within 500 km of the comet’s nucleus.

Halley was a contemporary of Issac Newton. Infact he was responsible for the publication of Newton’s famous work ‘prinicipia mathematica’. Halley studied the comets with the help of Newton’s Laws of motion. The unfortunate thing is that Halley didn’t live to see the comet. The same comet made its appearance again in 1986. Halley also produced the first accurate map of the stars visible from the Southern HemiSphere. Halley died in the year 1742.

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