Backwash is the flow of water down a beach under the influence of gravity after the breaking of a wave and its associated swash. As this water returns to the breaker zone it carries beach material with it. Steep waves, which break almost vertically on to a beach, have an extremely powerful backwash and move much material out to sea. Backwash contributes to longshore drift. Research Backwash
In mathematics, a brachistochrone is the curve between two points through which a body moves under the force of gravity in a shorter time than for any other curve, that is the path of quickest descent. Research Brachistochrone
Etymologically a hypothesis is a supposition, and the term is popularly used to denote something not proved, but assumed for the sake of argument. In scientific and philosophical usage the term hypothesis denotes either a probable theory of phenomena not yet fully explained, or a strictly scientific theory which accounts for all the known facts of the case, and which only needs the verification of subsequent observations and deductions to become a certainty. Thus the conjecture of Isaac Newton that the force of gravity, as exemplified on the earth, might extend to the moon, was in its first stage a probable hypothesis; but when it was found to account for all the facts, it became a scientific hypothesis or theory. Research Hypothesis
A neutron star is a star that has collapsed under its own gravity. It is composed solely of neutrons, has a mass of between 1.4 and about three times that of the sun, and a density in excess of 107 kilograms per cubic metre. Research Neutron Star
The Renaissance was that change in the outlook of Europe which took place during the centuries from the fourteenth to the sixteenth. In its broadest sense the Renaissance affected every department of human life. But in its narrower sense it refers to the revival of the learning of ancient Greece, and to the effects of that revival on the arts and literature of modern peoples. The Church in the Middle Ages had taught men to revere authority and to find in her teaching an answer to all the problems of life, whereas the Greeks taught men to inquire and to explore rather than to accept, and to enjoy rather than to suffer. It was this attitude of mind, more than anything else, which shook the medieval world to its foundations. The views of the ancient Greeks, now re-born into the world, were in sharp contrast with the ideals of the Middle Ages. From these ideals many men for a time turned with a feeling of contempt.
The Renaissance was a many-sided movement: it deeply influenced learning and education, art and architecture, science and invention, geography and exploration, and, above all, religion. After the fall of Rome, a knowledge of Greek had rapidly died out in the West and no provision was made for its teaching similar to that made for Latin. In Italy, owing to the closeness of its relations with the East, the number of scholars, monks, and others, who learnt some Greek was greater than elsewhere. It is not, surprising, therefore, that the revival of learning received its main impulse from Italy. From the time of Petrarch and Boccaccio, Italian scholars became more and more devoted to ancient studies, and they began to visit Constantinople, where Greek learning had been preserved. There they hunted out, copied, and eagerly studied the precious manuscripts of the past, and these opened up a new world of thought. Further, from the time that the Turks' crossed from Asia into Europe, some of the Greeks themselves began to travel westwards and to accept well-paid teaching posts in the wealthy Italian cities. And, though the revival began in Italy, the new ideas were rapidly circulated by the new printing presses invented at the time, and every nation in due course played its part in the Renaissance.
The great and wealthy city of Florence was the centre of the Italian Renaissance. Cosimo de Medici, a merchant prince who became ruler of the city, was a patron of the New Learning, and he encouraged Greek scholars to settle in Florence. His grandson, Lorenzo de Medici, known as The Magnificent, loved to gather round him the learned men of the day; he spent 60,000 pounds a year on books; and he caused 200 rare manuscripts to be brought from the East to the Medici library. Rome was second only to Florence as a centre of the New Learning. The Popes themselves became great patrons of learning. Nicholas V founded the Vatican Library. When the son of Lorenzo de Medici became Pope as Leo X, the Renaissance in Rome reached its highest point. Leo made Rome, as he said, ' the capital of the world in literature, as it is in everything else'. He provided a hundred professors for his Greek college in Rome, and he brought his father's library to the Holy City. The library was afterwards restored to Florence by his cousin Clement VII, another member of this remarkable Medici family. The New Learning influenced England from the time of Edward IV, and it made great headway in the reigns of Henry VII and Henry VIII when the scholars known as the Oxford Reformers were flourishing.
The first Englishman to bring Greek manuscripts to England was William Selling. One of his pupils was Thomas Linacre, who went to Florence and shared the instruction given to the young Medici princes; he read in the Vatican Library, and made the acquaintance of Aldo at Venice. Another Oxford teacher who drew his inspiration from Italian sources was William Grocyn, one of the first men to give lectures on Greek literature at his University.
One of Grocyn's pupils was John Colet, who visited Italy in 1496 and returned to lecture on the Gospels in the Greek original at Oxford. He and Sir Thomas More, were friends of Erasmus, a Dutch scholar of international fame. Lady Margaret Beaufort, mother of Henry VII, was herself a patroness of the New Learning. She founded two Cambridge colleges, Christ's and St. John's, and two Lady Margaret Professorships of Divinity, one at Oxford and one at Cambridge. The Revival of Learning was one aspect of the Renaissance; the outburst of artistic energy in the fifteenth and sixteenth centuries was another. The painters of the new period broke away from the conventional art of the Middle Ages and began again to draw from living models. As with the artists, so with the sculptors. Donatello 'went straight with his mighty chisel to original sources - to youth and manhood, and the love of living'. The great figures of that age - Botticelli, Leonardo da Vinci, Michelangelo, Raphael, Titian - still dominate the history of European art. Examples of their works, and of many other Italian artists of the Renaissance, as well as of the Northern artists - Holbein, Durer, and others - are to be seen in the magnificent collection at the National Gallery.
It was natural that men who sought their inspiration from the Greeks should turn with renewed interest to classical architecture. The ruins of ancient Rome provided examples ready to hand; and soon churches planned like classical temples were rising in every city in Italy. St. Peter's, Rome, was designed by Bramante, and the famous dome added by Michelangelo. But great as was the enthusiasm for this architecture Renaissance architecture did not establish itself in England until the end of the reign of Queen Elizabeth I, though Henry VII's tomb at WestminsterAbbey is an example of the Florentine art of the period.
The Renaissance period, filled as it was with a love of experiment, naturally produced a renewed interest in science. With the exception of isolated geniuses like Friar Roger Bacon, there were no medieval scientists worthy of the name. Practically no scientific discoveries had been made for centuries. Modern Science begins its history with the Renaissance and owes a good deal to Leonardo da Vinci. He was the first of a long line of experimenters whose work has continued to the present day. The greatest shock to the medieval notions of the universe was given by Copernicus. For two thousand years mankind with few exceptions had believed that the earth was the centre of the universe, and that the sun revolved round our planet every twenty-four hours. Such had been the teaching of Ptolemy, the Greek scientist. Another Greek, Pythagoras, had questioned it, and advanced the extraordinary notion that the sun, not the earth, was the centre of the universe; but there were few who accepted his theory until Copernicus turned his attention to the 'solar system'. Through slits cut in the walls of his house, Copernicus watched the movements of the planets. Just before he died in 1543 he published a book - 'The Revolutions of the Heavenly Bodies' - giving to the world the results of his observations.
Twenty years later the famous Galileo was born at Pisa, and it was he who perfected the telescope. He lived to popularise the theory of Copernicus, but he was nearly put to death for his pains and was forced by the Court of Inquisition to recant. The Italian Galileo, and the English Newton who discovered the laws of gravity, were the two greatest scientists of the seventeenth century. In the realm of geographical discovery, no age in the world' s history was more momentous than the Age of the Renaissance. Columbus, who discovered America; Vasco De Gama, who found the Cape Route to India; Cabot, Cartier, and Cortez, the discoverers of Newfoundland, Canada, and Mexico; Balboa, who first sailed on the Pacific; Magellan, whose ship was the first to sail round the world - all these and many more make the fifteenth and sixteenth centuries an era without parallel in the annals of discovery.
The new ideas which came surging into the world during the Renaissance acted in many respects as disruptive forces. This was particularly true in the realm of religion. An unquestioning acceptance of authority - i.e. of the teaching of the Catholic Church - was the keynote of the medieval attitude to life, but an eager, inquiring generation began to question this attitude. Men, too, were shocked by the moral decay of the Church and of the Papacy; voices were raised demanding reforms. Some reformers, like Colet and Erasmus, tried to reconcile the new ideas with the Church of Rome and worked to reform it; others, of whom Luther was the greatest, rejected altogether its authority.
The revolution in European history known as the Reformation was an indirect result of the Renaissance - of the New Learning which invited comparison between the present and the past; of the invention of printing which scattered broadcast the new ideas; and again, of the growing idea of the Nation and with it the supremacy of the State. Research Renaissance
A stamp mill is a machine used for the fine crushing of mineral ore. The stamp mill consists of a cast iron rectangular box provided with a feed slot at the back and screens in the front. A number of stamps consisting of heavy stems with a steelshoe at the bottom work in each box. The stamps are raised by means of cams and falling by gravity crush the ore on the steel dies placed in the bottom of the box. Water flowing through the boxes carries the crushed ore through the screens. Research Stamp Mill
In its narrow, everyday use, vegetable is a word indicating any herb that is cultivated specially for table use in whole or part, such as the turnip (root), cabbage (leaves), broccoli (flowers), peas and beans (fruit). In its widest sense it includes all living things that are not animals - trees, shrubs, herbs, ferns, mosses, seaweeds, fungi, and the microscopic diatoms.
The unit of structure, the cell, is essentially the same in both animals and plants, but the combination of the cells into tissues and organs shows marked differences.
All animals depend for their food upon material originally elaborated by plants. The green plants alone have the power to construct this basic food material from elemental substances, and physiological processes different from those of animal assimilation are rendered necessary. The fungi approach the animals in this respect: they must feed upon material that has already done service as part of the structure of other plants or of animals.
The fine divisions of roots explore the soil in search of water in which are dissolved the salts of sodium, iron, potassium, phosphorus, calcium, sulphur, etc. The hairs with which the rootlets are clothed absorb this fluid by osmosis, and it is passed upward through the long vessels of the wood bundles until it reaches the cells of the leaf. These cells contain green bodies (chloroplasts) in their protoplasm, and it is these that impart the green colour to leaves and soft shoots. In the leaf-skin (epidermis) there are innumerable pores or stomata through which surplus water from the roots is evaporated and through which atmospheric air is admitted to the spaces between the leaf-cells.
The chloroplasts in these cells have the power to utilise solar energy in decomposing the carbon dioxide of the air, and the cells retain the carbon, setting free the oxygen. Water from the roots is broken up also into its elements, hydrogen and oxygen, and with these plus carbonstarch is formed. This, converted into grape sugar, is passed from cell to cell to parts of the plant whore it is needed for the production of new cells, wood, bark, leaves, or fruit. Starch is the material from which are made all the organic substances produced by the plant.
The surplus over present requirements is stored up as reserves in seeds, enlarged roots or stems, bulbs, or tubers for renewed growth or floral display at a later season. Waste products are converted into resins, oils/wax, or alkaloids - many of these being of considerable economic value to man. Part of the water stream from the roots passes by osmosis from cell to cell, where it is necessary in order to keep the protoplasm in an active condition; any insufficiency is followed by a flagging of the tissues, the drooping of leaves and young shoots. In addition to the absorption of carbon by the protoplasts for building purposes, the leaf-cells also take up oxygen from the atmosphere and give off carbon much as animals do.
As the plant respires without lungs and assimilates without digestive organs, so also it can effect movements without a muscular system and react to external stimuli without a nervous system. It is sensitive to light and heat; many plants have distinct night and day positions for their leaves. It responds positively and negatively to the force of gravity, the root going down into the earth and the stem rising into the air. The growing tip of a stem or shoot commonly nutates, i.e. moves from side to side or in a circle or ellipse. The plant can orientate itself, i.e. take up a definite position in regard to the incidence of light or other external stimulus. These movements appear to be controlled largely by alterations in the position of the mobile chloroplasts.
The reproductive process is, in essentials, similar to that of animals, the ovules or seed-eggs in the ovary requiring to be fertilised by male sperms represented by the pollen grains produced in the anthers. The result of such fertilisation is to cause the ovule to develop into an embryo capable of further development under suitable conditions into a plant resembling the parent. Research Vegetable
Abbreviations
Research Backwash
