|
Joseph Henry
Joseph Henry (December 17, 1797– May 13, 1878) was an American scientist who served as the first Secretary of the Smithsonian Institution. He was the secretary for the National Institute for the Promotion of Science, a precursor of the Smithsonian Institution. He was highly regarded during his lifetime. While building electromagnets, Henry discovered the electromagnetic phenomenon of self-inductance. He also discovered mutual inductance independently of Michael Faraday, though Faraday was the first to make the discovery and publish his results. Henry developed the electromagnet into a practical device. He invented a precursor to the electric doorbell (specifically a bell that could be rung at a distance via an electric wire, 1831) and electric relay (1835). His work on the electromagnetic relay was the basis of the practical electrical telegraph, invented by Samuel F. B. Morse and Sir Charles Wheatstone, separately. In his honor the SI unit of inductance is named the hen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spencer Fullerton Baird
Spencer Fullerton Baird (; February 3, 1823 – August 19, 1887) was an American naturalist, ornithologist, ichthyologist, herpetologist, and museum curator. Baird was the first curator to be named at the Smithsonian Institution. He eventually served as assistant Secretary of the Smithsonian from 1850 to 1878, and as Secretary from 1878 until 1887. He was dedicated to expanding the natural history collections of the Smithsonian which he increased from 6,000 specimens in 1850 to over 2 million by the time of his death. He published over 1,000 works during his lifetime. Early life and education Spencer Fullerton Baird was born in Reading, Pennsylvania in 1823. His mother was a member of the prominent Philadelphia Biddle family; he was a nephew of Speaker of the Pennsylvania Senate Charles B. Penrose and a first cousin, once removed, of U.S. Senator Boies Penrose and his distinguished brothers, Richard, Spencer, and Charles. He became a self-trained naturalist as a young man ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Institute For The Promotion Of Science
The National Institution for the Promotion of Science organization was established in Washington, D.C. in May 1840, and was heir to the mantle of the earlier ''Columbian Institute for the Promotion of Arts and Sciences''. The National Institution for the Promotion of Science was later renamed the ''National Institute'' and eventually became a part of the Smithsonian Institution. The National Institute was the initial repository for collections of artifacts brought to the US by the United States Exploring Expedition, as well as various other object accumulated by the government, such as items owned by early American politicians, patent models, and natural objects. Housed in the Patent Office Building, these were the precursor to the Smithsonian Institution collection. The cabinet was managed by a group of scientists in 1840 and others to secure control of the Smithson bequest and create a National Museum in Washington. Among those who were elected as corresponding members were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hudson River
The Hudson River is a river that flows from north to south primarily through eastern New York. It originates in the Adirondack Mountains of Upstate New York and flows southward through the Hudson Valley to the New York Harbor between New York City and Jersey City, eventually draining into the Atlantic Ocean at Lower New York Bay. The river serves as a political boundary between the states of New Jersey and New York at its southern end. Farther north, it marks local boundaries between several New York counties. The lower half of the river is a tidal estuary, deeper than the body of water into which it flows, occupying the Hudson Fjord, an inlet which formed during the most recent period of North American glaciation, estimated at 26,000 to 13,300 years ago. Even as far north as the city of Troy, the flow of the river changes direction with the tides. The Hudson River runs through the Munsee, Lenape, Mohican, Mohawk, and Haudenosaunee homelands. Prior to European ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surveying
Surveying or land surveying is the technique, profession, art, and science of determining the terrestrial two-dimensional or three-dimensional positions of points and the distances and angles between them. A land surveying professional is called a land surveyor. These points are usually on the surface of the Earth, and they are often used to establish maps and boundaries for ownership, locations, such as the designed positions of structural components for construction or the surface location of subsurface features, or other purposes required by government or civil law, such as property sales. Surveyors work with elements of geodesy, geometry, trigonometry, regression analysis, physics, engineering, metrology, programming languages, and the law. They use equipment, such as total stations, robotic total stations, theodolites, GNSS receivers, retroreflectors, 3D scanners, LiDAR sensors, radios, inclinometer, handheld tablets, optical and digital levels, subsurface locat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silversmith
A silversmith is a metalworker who crafts objects from silver. The terms ''silversmith'' and ''goldsmith'' are not exactly synonyms as the techniques, training, history, and guilds are or were largely the same but the end product may vary greatly as may the scale of objects created. History In the ancient Near East the value of silver to gold was lower, allowing a silversmith to produce objects and store these as stock. Ogden states that according to an edict written by Diocletian in 301 A.D., a silversmith was able to charge 75, 100, 150, 200, 250, or 300 ''denarii'' for material produce (per Roman pound). At that time, guilds of silversmiths formed to arbitrate disputes, protect its members' welfare and educate the public of the trade. Silversmiths in medieval Europe and England formed guilds and transmitted their tools and techniques to new generations via the apprentice tradition. Silver working guilds often maintained consistency and upheld standards at the expense of i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Watchmaker
A watchmaker is an artisan who makes and repairs watches. Since a majority of watches are now factory-made, most modern watchmakers only repair watches. However, originally they were master craftsmen who built watches, including all their parts, by hand. Modern watchmakers, when required to repair older watches, for which replacement parts may not be available, must have fabrication skills, and can typically manufacture replacements for many of the parts found in a watch. The term clockmaker refers to an equivalent occupation specializing in clocks. Most practising professional watchmakers service current or recent production watches. They seldom fabricate replacement parts. Instead they obtain and fit factory spare parts applicable to the watch brand being serviced. The majority of modern watchmakers, particularly in Switzerland and other countries in Europe, work directly for the watchmaking industry and may have completed a formal watchmaking degree at a technical school. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galway (village), New York
Galway is a village in the town of Galway in Saratoga County, New York, United States. The population was 200 at the 2010 census. The village is north of Schenectady. Galway Lake, a vacation area, is west of the village. History The first settlers in the town established themselves south of Galway village. In 1838, the village of Galway was incorporated. The charter was amended in 1869. Geography According to the United States Census Bureau, the village has a total area of 0.3 square mile (0.7 km2), all land. Galway is at the junction of County Road 45 (East Street/West Street) and New York State Route 147 (North Street/South Street) in the central part of the town. Demographics As of the census of 2000, there were 214 people, 82 households, and 71 families residing in the village. The population density was 834.4 people per square mile (317.8/km2). There were 85 housing units at an average density of 331.4 per square mile (126.2/km2). The racial makeup of the v ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Henry (unit)
The henry (symbol: H) is the unit of electrical inductance in the International System of Units (SI). If a current of 1 ampere flowing through a coil produces flux linkage of 1 weber turn, that coil has a self inductance of 1 henry. The unit is named after Joseph Henry (1797–1878), the American scientist who discovered electromagnetic induction independently of and at about the same time as Michael Faraday (1791–1867) in England. Definition The inductance of an electric circuit is one henry when an electric current that is changing at one ampere per second results in an electromotive force of one volt across the inductor: :\displaystyle V(t)= L \frac, where ''V''(''t'') denotes the resulting voltage across the circuit, ''I''(''t'') is the current through the circuit, and ''L'' is the inductance of the circuit. The henry is a derived unit based on four of the seven base units of the International System of Units: kilogram (kg), metre (m), second (s), and ampere (A). Expre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Wheatstone
Sir Charles Wheatstone FRS FRSE DCL LLD (6 February 1802 – 19 October 1875), was an English scientist and inventor of many scientific breakthroughs of the Victorian era, including the English concertina, the stereoscope (a device for displaying three-dimensional images), and the Playfair cipher (an encryption technique). However, Wheatstone is best known for his contributions in the development of the Wheatstone bridge, originally invented by Samuel Hunter Christie, which is used to measure an unknown electrical resistance, and as a major figure in the development of telegraphy. Life Charles Wheatstone was born in Barnwood, Gloucestershire. His father, W. Wheatstone, was a music-seller in the town, who moved to 128 Pall Mall, London, four years later, becoming a teacher of the flute. Charles, the second son, went to a village school, near Gloucester, and afterwards to several institutions in London. One of them was in Kennington, and kept by a Mrs. Castlemaine, who wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Samuel Morse
Samuel Finley Breese Morse (April 27, 1791 – April 2, 1872) was an American inventor and painter. After having established his reputation as a portrait painter, in his middle age Morse contributed to the invention of a single-wire telegraph system based on European telegraphs. He was a co-developer of Morse code and helped to develop the commercial use of telegraphy. Personal life Samuel F. B. Morse was born in Charlestown, Massachusetts, the first child of the pastor Jedidiah Morse (1761–1826), who was also a geographer, and his wife Elizabeth Ann Finley Breese (1766–1828). His father was a great preacher of the Calvinist faith and supporter of the Federalist Party. He thought it helped preserve Puritan traditions (strict observance of Sabbath, among other things), and believed in the Federalist support of an alliance with Britain and a strong central government. Morse strongly believed in education within a Federalist framework, alongside the instillation of C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrical Telegraph
Electrical telegraphs were point-to-point text messaging systems, primarily used from the 1840s until the late 20th century. It was the first electrical telecommunications system and the most widely used of a number of early messaging systems called ''telegraphs'', that were devised to communicate text messages quicker than physical transportation. Electrical telegraphy can be considered to be the first example of electrical engineering. Text telegraphy consisted of two or more geographically separated stations, called telegraph offices. The offices were connected by wires, usually supported overhead on utility poles. Many different electrical telegraph systems were invented, but the ones that became widespread fit into two broad categories. The first category consists of needle telegraphs in which a needle pointer is made to move electromagnetically with an electric current sent down the telegraph line. Early systems used multiple needles requiring multiple wires. The first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electromagnet
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire wound into a coil. A current through the wire creates a magnetic field which is concentrated in the hole in the center of the coil. The magnetic field disappears when the current is turned off. The wire turns are often wound around a magnetic core made from a ferromagnetic or ferrimagnetic material such as iron; the magnetic core concentrates the magnetic flux and makes a more powerful magnet. The main advantage of an electromagnet over a permanent magnet is that the magnetic field can be quickly changed by controlling the amount of electric current in the winding. However, unlike a permanent magnet that needs no power, an electromagnet requires a continuous supply of current to maintain the magnetic field. Electromagnets are widely used as components of other electrical devices, such as motors, generators, electromechanical s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
_crop.jpg "Click for more on -> Surveying")
