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Difference engines are strictly calculators. They crunch numbers the only way they know how - by repeated addition according to the method of finite differences. They cannot be used for general arithmetical calculation. The Analytical Engine is much more than a calculator and marks the progression from the mechanized arithmetic of calculation to fully-fledged general-purpose computation.

Physical Legacy Aside from a few partially complete mechanical assemblies and test models of small working sections, none of Babbage's designs was physically realized in its entirety in his lifetime. The major assembly he did complete was one-seventh of Difference Engine No. 1, a demonstration piece consisting of about 2,000 parts assembled in 1832. This works impeccably to this day and is the first successful automatic calculating device to embody mathematical rule in mechanism. A small experimental piece of the Analytical Engine was under construction at the time of Babbage's death in 1871. Many of the small experimental assemblies survived, as does a comprehensive archive of his drawings and notebooks. The designs for Babbage's vast mechanical computing engines rank as one of the startling intellectual achievements of the 19th century. It is only in recent decades that his work has been studied in detail and that the extent of what he accomplished becomes increasingly evident.

George Boole (1815–1864) was an English mathematician and a founder of the algebraic tradition in logic. He worked as a schoolmaster in England and from 1849 until his death as professor of mathematics at Queen's University, Cork, Ireland. He revolutionized logic by applying methods from the then-emerging field of symbolic algebra to logic. Where traditional (Aristotelian) logic relied on cataloging the valid syllogisms of various simple forms, Boole's method provided general algorithms in an algebraic language which applied to an infinite variety of arguments of arbitrary complexity.

Starting at the age of 16 it was necessary for Boole to find gainful employment, since his father was no longer capable of providing for the family. After 3 years working as a teacher in private schools, Boole decided, at the age of 19, to open his own small school in Lincoln. He would be a schoolmaster for the next 15 years, until 1849 when he became a professor at the newly opened Queen's University in Cork, Ireland. With heavy responsibilities for his parents and siblings, it is remarkable that he nonetheless found time during the years as a schoolmaster to continue his own education and to start a program of research, primarily on differential equations and the calculus of variations connected with the works of Laplace and Lagrange (which he studied in the original French).

But I am able to recognize that the psychological premises on which the systems based are an untenable illusion.

It is always possible to bind together a considerable number of people in love, so long as there are other people left over to receive the manifestations of their aggressiveness

By 1925, Bryan and his followers had succeeded in getting legislation introduced in fifteen states to ban the teaching of evolution. In February, Tennessee enacted a bill introduced by John Butler making it unlawful "to teach any theory that denies the story of divine creation as taught by the Bible and to teach instead that man was descended from a lower order of animals."  

    Opening statements pictured the trial as a titanic struggle between good and evil or truth and ignorance. Bryan claimed that "if evolution wins, Christianity goes." Darrow argued, "Scopes isn't on trial; civilization is on trial." The prosecution, Darrow contended, was "opening the doors for a reign of bigotry equal to anything in the Middle Ages." To the gasps of spectators, Darrow said Bryan was responsible for the "foolish, mischievous and wicked act." Darrow said that the anti-evolution law made the Bible "the yardstick to measure every man's intellect, to measure every man's intelligence, to measure every man's learning." It was classic Darrow, and the press--mostly sympathetic to the defense--loved it.

    On the seventh day of trial, Raulston asked the defense if it had any more evidence. What followed was what the New York Times described as "the most amazing court scene on Anglo-Saxon history." Hays asked that William Jennings Bryan be called to the stand as an expert on the Bible. Bryan assented, stipulating only that he should have a chance to interrogate the defense lawyers. Bryan, dismissing the concerns of his prosecution colleagues, took a seat on the witness stand, and began fanning himself.     Darrow began his interrogation of Bryan with a quiet question: "You have given considerable study to the Bible, haven't you, Mr. Bryan?" Bryan replied, "Yes, I have. I have studied the Bible for about fifty years." Thus began a series of questions designed to undermine a literalist interpretation of the Bible. Bryan was asked about a whale swallowing Jonah, Joshua making the sun stand still, Noah and the great flood, the temptation of Adam in the garden of Eden, and the creation according to Genesis. After initially contending that "everything in the Bible should be accepted as it is given there," Bryan finally conceded that the words of the Bible should not always be taken literally. In response to Darrow's relentless questions as to whether the six days of creation, as described in Genesis, were twenty-four hour days, Bryan said "My impression is that they were periods."     Bryan, who began his testimony calmly, stumbled badly under Darrow's persistent prodding. At one point the exasperated Bryan said, "I do not think about things I don't think about." Darrow asked, "Do you think about the things you do think about?" Bryan responded, to the derisive laughter of spectators, "Well, sometimes." Both old warriors grew testy as the examination continued. Bryan accused Darrow of attempting to "slur at the Bible." He said that he would continue to answer Darrow's impertinent questions because "I want the world to know that this man, who does not believe in God, is trying to use a court in Tennessee--." Darrow interrupted his witness by saying, "I object to your statement" and to "your fool ideas that no intelligent Christian on earth believes." After that outburst, Raulston ordered the court adjourned. The next day, Raulston ruled that Bryan could not return to the stand and that his testimony the previous day should be stricken from evidence.

Ice was harvested and stored in China before the first millennium. Hebrews, Greeks, and Romans placed large amounts of snow into storage pits and covered this cooling agent with insulating material.