Radar;Radar is an acronym for Radio Detecting and Ranging. It refers to a method of locating something or measuring motion by sending out a beam of electromagnetic radiation and receiving the signals rebounded from distant objects. Radio telescope;Instrument used to detect radio waves emanating from celestial bodies. Raffard;Raffard, Jules: 1824 to 1898, physicist Raman;Raman, Sir Chandrasekhara Venkata: 1888 to 1970, Indian physicist Ramelli;Ramelli, Agostino, c. 1530 to 1590, engineer Ramjets;Ramjets are high-pressure reaction engines, in which inrushing is compressed in an expanding duct (supersonic diffuser) and is then forced through the combustion chamber. Ramsay;Ramsay, William Sir: 1852 to 1916, chemist Ramsden;Ramsden, Jesse, 1735 to 1800, precision engineer and optician Rankine;Rankine, Wlliam John Marquorn: 1820 to 1872, engineer Ranney;Ranney, Leo: 1884 to 1950, engineer Rateau;Rateau, Auguste: 1863 to 1930, engineer Raydt;Raydt, Wilhelm: 1842 to 1908, engineer Rayleigh;Rayleigh, Lord (to 1873 John William Strutt): 1842 to 1919, physicist Reaction effect;The force, exerted on an object, when it expels or repels a mass with a given force. Réaumur;Réaumur, René-Antoine Ferchault de: 1683 to 1757, physicist and zoologist Reber;Reber, Grote (* 1911), American astronomer Rectifier;A rectifier is an electronic device or a circuit used to convert, i.e. to rectify, alternating current into direct current. Redtenbacher;Redtenbacher, Ferdinand: 1809 to 1863, engineer Reflecting telescope;Special type of telescope, in which incident light is first reflected by a concave main or primary mirror and is then deflected. Reflector;Designation for a reflecting telescope, in which light is focused by a concave mirror. Refractor;Designation for a refracting telescope, in which light is focused by lenses. Regiomontanus;Regiomontanus (real name Johannes Müller): 1436 to 1476, mathematician and astronomer Regnasult;Regnasult, Henri Victor: 1810 to 1878, chemist and physicist Reichenbach;Reichenbach, Georg Friedrich von: 1771 to 1826, instrument and machine manufacturer Reis;Reis, Johann Philipp (1834-1874), German inventor Reithmann;Reithmann, Christian: 1818 to 1909, clockmaker Remmington;Remmington, Philo: 1816 to 1889, engineer Renard;Renard, Charles: 1847 to 1905, engineer Renault;Renault, Louis: 1877 to 1944, engineer and industrialist Ressel;Ressel, Josef Ludwig Franz: 1793 to 1857,engineer Reuleaux;Reuleaux, Franz: 1829 to 1905, engineer Rey;Rey, Jean: 1861 to 1935, engineer Reynold;Reynold, Osborne: 1842 to 1912, physicist Richardson;Richardson, Owen Williams: 1879 to 1959, physicist Richter;Richter, Johann Benjamin: 1762 to 1807, chemist Riggenbach;Riggenbach, Nikolaus: 1817 to 1899, engineer Righi;Righi, Augusto: 1850 to 1920, physicist Rines;Rines, Robert H.: (* 1922), inventor and lawyer Ritter;Ritter, Johann Wilhelm: 1776 to 1810, physicist Rittinge;Rittinge, Peter von: 1811 to 1872, engineer Roberts;Roberts, Richard: 1789 to 1856, engineer Rochon;Rochon, Alexis Marie du: 1741 to 1817, astronomer and theologist Rockets;Space vehicles propelled by a rocket that creates upward thrust by expelling burnt fuel. Roentgen;Roentgen, Gerhard Moritz: 1795 to 1852, engineer Rois;Rois, Mirko: 1879 to 1961, civil engineer Rømer;Rømer, Ole Christensen: 1644 to 1710, astronomer Röntgen;Röntgen, Wilhelm Conrad (1845-1923), German physicist, first Nobel prize winner for physics (1901) Rosing;Rosing, Boris Lvovich: 1869 to 1933, physicist Rosinski;Rosinski, Edward J.: (* 1921), engineer Rotational speed;Rotational speed is a determinant of the mechanical performance of a machine. It describes how many revolutions a rotating object completes in a given period. Rowland;Rowland, Henry Augustus: 1848 to 1901, physicist Royce;Royce, Sir Frederic Henry: 1863 to 1933, engineer Rubin;Rubin, Benjamin A.: (* 1917), microbiologist Ruhmkorff;Ruhmkorff, Heinrich Daniel: 1803 to 1877, engineer Rukop;Rukop, Hans: 1883 to 1958, physicist Rumford;Rumford, Count (Sir Benjamin Thompson): 1753 to 1814, physicist Runge;Runge, Friedlieb Ferdinand: 1795 to 1867, chemist Runge;Runge, Wilhelm: 1895 to 1987, physicist Ruska;Ruska, Ernst August Friedrich (1906-1988), German physicist, Nobel prize for physics 1986 Russel;Russel, John Scott: 1808 to 1882, engineer Rutherford;Rutherford, Ernest (Baron Rutherford of Nelson): 1871 to 1937, physicist Rydberg;Rydberg, Johannes Robert: 1854 to 1919, physicist Sack;Sack, Rudolf: 1824 to 1900, farming machine engineer Saint-Vernant;Saint-Vernant, Adhémar Jean Claude Barré de: 1797 to 1886, mathematician Santos-Dumont;Santos-Dumont, Alberto: 1873 to 1932, aviation pioneer Sarett;Sarett, Lewis Hastings: 1917 to 1999, chemist Satellite;In astronautics an artificial satellite is a spacecraft that orbits a planet (usually the Earth) unpowered, while in astronomy it is any moon. Saturn V rocket;Large booster rocket that launched the Apollo missions into the Earth's orbit before sending it on its way to the Moon. Saussure;Saussure, Horace Bénédict (1740-1799), Swiss naturalist Sauvage;Sauvage, Frédéric: 1785 to 1857, engineer Sauveur;Sauveur, Joseph: 1653 to 1716, mathematician and physicist Savart;Savart, Félix: 1791 to 1841, physician and physicist Savery;Savery, Thomas: c. 1650 to 1715, engineer Scheele;Scheele, Carl Wilhelm: 1742 to 1786, chemist Scheiner;Scheiner, Christoph: 1575 to 1650, scholar Scherrer;Scherrer, Paul: 1890 to 1969, physicist Schichau;Schichau, Ferdinand: 1814 to 1896, engineer Schickard;Schickard, Wilhelm: 1592 to 1635, scholar Schilling;Schilling, Paul von Cannstadt: 1786 to 1837, physicist Schmidt G.;Schmidt, Gustav: 1826 to 1883, mining engineer Schmidt W.;Schmidt, Wilhelm: 1858 to 1924, engineer Schöbein;Schöbein, Christian Friedrich: 1799 to 1868, chemist Schöffer;Schöffer, Peter: c. 1425 to c. 1502, printer Schorlemmer;Schorlemmer, Carl: 1834 to 1892, chemist Schott;Schott, Freidrich Otto: 1851 to 1935, chemist and glass engineer Schottky;Schottky, Walter: 1886 to 1976, physicist Schrödinger;Schrödinger, Erwin: 1887 to 1961, physicist Schröter;Schröter, Fritz: 1886 to 1973, physicist Schubert;Schubert, Johannes Andreas: 1808 to 1870, engineer Schuckert;Schuckert, Johann Siegmund: 1846 to 1895, electrical engineer Schütte;Schütte, Johann: 1873 to 1940, engineer Schweigger;Schweigger, Johannes Salomon Christoph: 1779 to 1856, physicist Schwilgué;Schwilgué, Jean Baptiste: 1776 to 1856,engineer and precision engineer Sculls;A scull is a sports rowing boat, in which each rower moves two oar blades. These boats may be classed as single or double sculls. It may be contrasted with a single-oared boat, in which each rower moves an oar blade with both hands. Seaborg;Seaborg, Glenn Theodore: 1912 to 1999, physical chemist Seasons;Seasons: division of the tropical year into four set periods. Seebeck;Seebeck, Thomas Johann: 1770 to 1831, physicist and physician Seger;Seger, Hermann August: 1839 to 1893, chemist Segner;Segner, Johann Andreas Von: 1704 to 1777, physician and physicist Séguin;Séguin Marc: 1786 to 1875, engineer Seiwald;Seiwald, Robert J.: (* 1925), chemist Semon;Semon, Waldo L.: 1898 to 1999, chemist Sennefelder;Sennefelder, Alois (1771-1834), Austrian inventor Sennert;Sennert, Daniel: 1572 to 1637, physician Senning;Senning, Aake, Swedish physician Sensors;Sensors are devices that react to external conditions such as temperature, light sensitivity, pressure, humidity or acidity in a fluid and convert them into electric signals. Serpollet;Serpollet, Léon: 1859 to 1907, engineer Sertürner;Sertürner, Friedrich Adolf: 1783 to 1841, chemist Server;A server is a computer in a network that performs certain administrative functions, e.g. managing a database or hard drive, administering of the network itself or relaying communications with other networks. Shannon;Shannon, Claude Elwood: (* 1916): mathematician Sheehan;Sheehan, John C.: 1915 to 1992, chemist Shellac;Shellac is a natural, yellowish resin, formerly used to manufacture gramophone records. It is a substance secreted by the female lac insect and is used today for sealing wax or furniture lacquer. Shockley;Shockley, William (1910 to 1989), British-American Physicist, Nobel prize winner for physics 1956 (along with John Bardeen and Walter Houser Brattain) Shukovski;Shukovski, Nikolai Yegorovich: 1847 to 1921, scientist Siedersleben;Siedersleben, Wilhelm: 1835 to 1892, farming machine engineer Siemens E.W.;Siemens, Ernst Werner von (1816-1862), German physicist and engineer Siemens F.;Siemens, Friedrich: 1826 to 1904, engineer and brother of Werner S. Siemens W.;Siemens William Sir: 1822 to 1883, engineer and brother of Werner S. Sigl;Sigl, Georg: 1811 to 1887, machine manufacturer Sikorsky;Sikorsky, Igor Ivanovich: 1889 to 1965, aeronautical engineer Simpson;Simpson, James Young: 1811 to 1870, physician Singer;Singer, Isaac Merrit: 1811 to 1873, engineer Single-oared boat;In a single-oared boat each rower holds and moves an oar blade with both hands. They may be contrasted with sculls, in which the rower moves two oar blades. Sinin;Sinin, Nikolai Nikolayevich: 1812 to 1880, chemist Sinsteden;Sinsteden, Wilhelm Josef: 1803 to 1891, physician Skladanowsky;Skladanowsky, Max: 1863 to 1939, film pioneer Skoda;Skoda, Emil von: 1839 to 1900, engineer Slaby;Slaby Adolf: 1849 to 1913, engineer Slavyanov;Slavyanov, Nikolai Gavrilovich: 1854 to 1897, electrical engineer Smeaton;Smeaton, John: 1724 to 1792, engineer Smith F.P.;Smith, Sir Francis Petty: 1808 to 1874, engineer Smith J.;Smith, James: 1779 to 1850, engineer Snell;Snell, Wilbrord: 1591 to 1626, physicist Soddy;Soddy, Fredric: 1877 to 1956, physicist and chemist Solvay;Solvay, Ernest: 1838 to 1922, chemist and entrepreneur Somerset;Somerset, Edward (2nd Marquess of Worcester):1601to 1667, inventor Sommerfeld;Sommerfeld, Arnold: 1868 to 1951, physicist Sömmering;Sömmering, Samuel Thomas: 1775 to 1830, physician and natural scientist Space probe;A spacecraft propelled by a multistage rocket at an escape velocity, required to escape the Earth's gravitational pull. Space vehicle;Motion of an artificial object in space. Spectroscope;An appliance used to measure the wavelength of electromagnetic radiation. Spectrum;Splitting of light into its constituent components (wavelengths). Speed of light;Speed at which light travels in a vacuum. Its value is 300,000 km/s. Sperry;Sperry, Elmer Ambrose: 1860 to 1930, engineer Spoke;A spoke is one of many relatively thin radial rods that join the hub of a wheel with the rim. Early wheels were simply solid discs. Sputnik;"Sputnik" was the Earth's first artificial satellite. It was launched on October 4th, 1957 by the former Soviet Union and was the first artificial satellite ever that accompanied the Earth in its orbit around the Sun. Stahl;Stahl, Georg Ernst: 1755 to 1830, chemist and physician Stanhope;Stanhope, Charles: 1735 to 1816, engineer Stanley Jr;Stanley Jr., William: 1858 to 1916, engineer Staudinger;Staudinger, Hermann: 1881 to 1965, chemist Stefan;Stefan, Josef: 1835 to 1893, physicist Steinheil;Steinheil, Carl August von: 1801 to 1870, physicist Steinmetz;Steinmetz, Carl: 1865 to 1923, electrical engineer Stelzer;Stelzer, Alfred: 1840 to 1895, geologist and mineralogist Stephenson G.;Stephenson, George (1781-1848), British engineer Stephenson J.;Stephenson, John (1809-1893), Irish-American engineer Stephenson R.;Stephenson, Robert: 1803 to 1859, engineer and son of George S. Stern;Stern, Otto: 1888 to 1969, physicist Stevens J.;Stevens, John: 1749 to 1838, engineer and industrialist Stevens R.;Stevens, Robert Livingstone: 1787 to 1856, engineer Stevin;Stevin, Simon: 1548 to 1620, mathematician, master builder and physicist Stibitz;Stibitz, George R.: 1904 to 1995, mathematician and physicist Stokes;Stokes, George Gabriel: 1818 to 1903, mathematician and physicist Stoletov;Stoletov, Aleksander Grigoryevich: 1839 to 1896, physicist Straßmann;Straßmann, Friedrich (Fritz) Wilhelm (1902-1980), German chemist Stringfellow;Stringfellow, John: 1799 bis1883, engineer Sualem;Sualem, Rennequin: 1645 to 1708, engineer Sulzer-Hirzel;Sulzer-Hirzel, Jean-Jacques: 1806 to 1883, machine manufacturer Sumerians;The Sumerians were the earliest inhabitants of Mesopotamia recorded in history and were mentioned from around 3100 BC. They are of uncertain origin. Sundback;Sundback, Gideon, Swedish electrical engineer Swan;Swan, Sir Joseph Wilson: 1829 to 1914, engineer Swash Plate;A swash plate is a disc aligned at an oblique angle to its axis of rotation. It is used in helicopters and can adjust the pitch of the rotor blades with the aid of a control rod. Symington;Symington, Wlliam,: c. 1763 to 1831, engineer Synchronized cameras;A synchronized camera is employed in cinematography, when lip movements need to be exactly synchronized with the sound track. It can record sound directly along with moving pictures rather than on separate magnetic tapes. Synge;Synge, Richard Lawrence Millington: (* 1914) Szilard;Szilard, Leo: 1898 to 1964, physicist