(1666-1673)

сокр. от Saunders' King's Bench Reports

SUBJECT AREA: Horology

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Huygens was born into a cultured and privileged class. His father, Constantijn, was a poet and statesman who had wide interests. Constantijn exerted a strong influence on his son, who was educated at home until he reached the age of 16. Christiaan studied law and mathematics at Ley den University from 1645 to 1647, and continued his studies at the Collegium Arausiacum in Breda until 1649. He then lived at The Hague, where he had the means to devote his time entirely to study. In 1666 he became a Member of the Académie des Sciences in Paris and settled there until his return to The Hague in 1681. He also had a close relationship with the Royal Society and visited London on three occasions, meeting Newton on his last visit in 1689. Huygens had a wide range of interests and made significant contributions in mathematics, astronomy, optics and mechanics. He also made technical advances in optical instruments and horology.

Despite the efforts of Burgi there had been no significant improvement in the performance of ordinary clocks and watches from their inception to Huygens's time, as they were controlled by foliots or balances which had no natural period of oscillation. The pendulum appeared to offer a means of improvement as it had a natural period of oscillation that was almost independent of amplitude. Galileo Galilei had already pioneered the use of a freely suspended pendulum for timing events, but it was by no means obvious how it could be kept swinging and used to control a clock. Towards the end of his life Galileo described such a. mechanism to his son Vincenzio, who constructed a model after his father's death, although it was not completed when he himself died in 1642. This model appears to have been copied in Italy, but it had little influence on horology, partly because of the circumstances in which it was produced and possibly also because it differed radically from clocks of that period. The crucial event occurred on Christmas Day 1656 when Huygens, quite independently, succeeded in adapting an existing spring-driven table clock so that it was not only controlled by a pendulum but also kept it swinging. In the following year he was granted a privilege or patent for this clock, and several were made by the clockmaker Salomon Coster of The Hague. The use of the pendulum produced a dramatic improvement in timekeeping, reducing the daily error from minutes to seconds, but Huygens was aware that the pendulum was not truly isochronous. This error was magnified by the use of the existing verge escapement, which made the pendulum swing through a large arc. He overcame this defect very elegantly by fitting cheeks at the pendulum suspension point, progressively reducing the effective length of the pendulum as the amplitude increased. Initially the cheeks were shaped empirically, but he was later able to show that they should have a cycloidal shape. The cheeks were not adopted universally because they introduced other defects, and the problem was eventually solved more prosaically by way of new escapements which reduced the swing of the pendulum. Huygens's clocks had another innovatory feature: maintaining power, which kept the clock going while it was being wound.

Pendulums could not be used for portable timepieces, which continued to use balances despite their deficiencies. Robert Hooke was probably the first to apply a spring to the balance, but his efforts were not successful. From his work on the pendulum Huygens was well aware of the conditions necessary for isochronism in a vibrating system, and in January 1675, with a flash of inspiration, he realized that this could be achieved by controlling the oscillations of the balance with a spiral spring, an arrangement that is still used in mechanical watches. The first model was made for Huygens in Paris by the clockmaker Isaac Thuret, who attempted to appropriate the invention and patent it himself. Huygens had for many years been trying unsuccessfully to adapt the pendulum clock for use at sea (in order to determine longitude), and he hoped that a balance-spring timekeeper might be better suited for this purpose. However, he was disillusioned as its timekeeping proved to be much more susceptible to changes in temperature than that of the pendulum clock.

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SUBJECT AREA: Medical technology, Photography, film and optics

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He was the son of a basketmaker, Philip Tonisz Leeuwenhoek, and Grietje Jacobsdr van den Berch, a brewer's daughter. After the death of his father in 1637, his mother married the painter Jacob Jansz Molijn. He went to school at Warmond and, later to an uncle who was Sheriff of Benthuizen. In 1648 he went to Amsterdam, where he was placed in a linen-draper's shop owned by William Davidson, a Scottish merchant. In 1652 or 1653 he moved back to Delft, where in 1654 he married the daughter of a cloth-merchant, Barbara de Mey. They had five children, only one of whom survived (born 22 September 1656). At about this time he bought a house and shop in the Hippolytus buurt and set up in business as a draper and haberdasher. His wife died in 1666 and in 1671 he married Cornelia Swalmius, a Reformed Church minister's daughter. Lacking self-confidence and not knowing Latin, the scientific language of the day, he was reluctant to publish the results of his investigations into a multitude of natural objects. His observations were made with single-lens microscopes made by himself. (He made at least 387 microscopes with magnifications of between 30x and 266x.) Among the subjects he studied were the optic nerve of a cow, textile fibres, plant seeds, a spark from a tinderbox, the anatomy of mites and insects' blood corpuscles, semen and spermatozoa. It was the physician Reinier de Graaf who put him in touch with the Royal Society in London, with whom he corresponded for fifty years from 1673. One of his last letters, in 1723, to the Royal Society was about the histology of the rare disease of the diaphragm that he had studied in sheep and oxen and from which he died. In public service he was a chamberlain to the sheriffs of Delft, a surveyor and a wine-gauger, offices which together gave him an income of about 800 florins a year. Leeuwenhoek never wrote a book, but collections were published in Latin and in Dutch from his scientific letters, which numbered more than 250.

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SUBJECT AREA: Chemical technology, Photography, film and optics

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George's father James was a successful lawyer and merchant, engaging in overseas trade.

A devout but necessarily circumspect Catholic, James sent his sons to the English College at Douai, now in northern France. Leaving there in 1651, George began to learn his father's business and spent some fifteen years in Venice. He took an increasingly important part in it, doubtless dealing in Venice's leading products of lace and glass. By 1666 he was back in England and, perhaps because the supply of Venetian glass was beginning to decline, he started to manufacture glass himself. In 1673 he set up a glassworks in the Savoy in London and succeeded so well that in the following year he petitioned the King for the grant of a patent to make glassware. This was granted on 16 May 1674, stimulating the Glass Sellers' Company to enter into an agreement with Ravenscroft to buy the glassware he produced. Later in 1674 the company allowed Ravenscroft to establish a second glasshouse at Henley-onThames. At first his ware was beset with "crizzling", i.e. numerous fine surface cracks. The Glass Sellers probably urged Ravenscroft to cure this defect, and this he achieved in 1675 by replacing crushed flint with increasing amounts of lead oxide, rising finally to a content of 30 per cent. He thereby obtained a relatively soft, heavy glass with high refractive index and dispersive power. This made it amenable to deep cutting, to produce the brilliant prismatic effects of cut glass. At about the same time, the Duke of Buckingham, a considerable promoter of the glass industry, agreed that Ravenscroft should manage his works at Vauxhall for the making of plate glass for mirrors. Ravenscroft terminated his agreement with the Glass Sellers in 1678, the date of the last evidence of his activities as a maker of crystal glass, and the patent expired in 1681. His new glass had immediately rivalled the best Venetian crystal glass and has been a valued product ever since.

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Ляйбніц, Готфрид Вільгельм (1646, Ляйпциг - 1716) - нім. філософ, вчений В. ивчав філософію та право в Ляйпцизькому ун-ті, математику в Ієнському. Після закінчення Ляйпцизького філософського ф-ту захистив у 1666 р. дис. "Про комбінаторне мистецтво", в кінці того ж року в Альтдорфі - дис. на ступінь докт. права. Л. створив першу обчислювальну машину, яка, крім арифметичних дій, могла добувати квадратні корені; після її успішної демонстрації у Парижі був обраний до Паризької академії, а в 1673 р. став членом Королівського тов-ва у Лондоні. Першу статтю про диференційне числення Л. опублікував у 1684 р., а про інтегральне - у 1686 р. Л. виступив ініціатором створення Академії наук у Берліні (1700), був обраний (пожиттєво) першим її президентом. Протягом життя Л. багато подорожував (певний час перебував у Франції, Англії, Італії, зокрема у Римі). Постійним місцем роботи Л. (від 1686 р. і до смерті) було опікування бібліотекою герцогів Ганноверських. Власна філософська система задумувалась і створювалась Л. як спроба синтезу досягнень античної, середньовічної та "нової філософії"; в історію світової філософської думки вона увійшла як завершення європейської філософії XVII ст. і як попередниця нім. класичної філософії. Основними імперативами раціоналістичної за своїм характером методології Л. постають універсальність і чітка доказовість філософських міркувань. Вихідними методологічними засадами, що уможливлюють дотримання означених імперативів, є наступні принципи буття і мислення: 1) несуперечливість будь-якого можливого або мислимого буття (закон суперечності); 2) логічна первинність можливого над дійсним (можливість незліченної множинності несуперечливих світів); 3) достатнє обґрунтування, що існує саме даний світ, відбувається саме ця подія, а не будь-які з можливих (закон достатньої підстави); 4) довершеність чи досконалість даного світу як достатня підстава його існування. Досконалість дійсного світу Л. розумів як гармонію сутності та існування Н. а відміну від попередніх мислителів, які вважали анахронізмом такі поняття античної та схоластичної філософії, як "ентелехія", "монада", "мета" (або кінцева причина) та "субстанція" (субстанційна форма), Л. залучає їх, докорінно переосмисливши, як основоположні і продуктивні засоби філософського пізнання. Першочергове місце тут належить поняттю "монада". Л. радикально відходить від ототожнення матерії і протяжності та тлумачення простору як субстанції (Декарт), позаяк такий підхід, на його думку, передбачає нескінченну подільність. Натомість він вводить поняття частки, наділеної силою (на тій підставі, що цього вимагають закони руху). Прості субстанції, або монади, не мають протяжності і тому не можуть ділитися іще на щось простіше; вони є осередками сили і, отже, почуття, сприйняття (перцепції) і прагнення (апетиції). Кожна монада є мікрокосмосом, що "віддзеркалює" увесь універсум. Із тези, що монади - це прості субстанції, випливає, що вони не мають вікон, через які щось має "входити і виходити". Звідси - ідея Л. про напередвизначену гармонію, адже інакше неможливо пояснити взаємозв'язок монад поміж собою. Подібно до того як два хори можуть співати за однією партитурою, так і монади взаємодіють на підставі первинного Божественного вибору щодо їхнього співіснування. Існування Бога Л. обґрунтовує, виходячи із принципу достатньої підстави; оскільки поняття Бога можливе, то він існує. Тільки Бог спроможний, "віддзеркалюючи" свою власну природу, нівелювати відмінність між випадковим та необхідним; але це не означає, за Л., що зникає людська свобода. Людині, як монаді, також притаманні сприйняття, апетиції і спонтанність, але у формі мислення, волі і свободи. Свобода (включно зі свободою вибору) полягає у слідуванні велінням розуму згідно із принципом достатньої підстави.

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Осн. тв.: "Принцип індивідуації" (1663); "Роздуми про знання, істину та ідеї" (1664); "Теорія руху" (1671); "Міркування про метафізику" (1686); "Про походження речей" (1697); "Теодицея" (1710); "Монадологія" (1714).