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Galvanometer

A galvanometer is an electromechanical instrument used for detecting and indicating an electric current. A galvanometer works as an actuator, by producing a rotary deflection, in response to electric current flowing through a coil in a constant magnetic field. Early galvanometers were not calibrated, but their developments were used as measuring instruments, called ammeters, to measure the current flowing through an electric circuit. Galvanometers developed from the observation that the needle of a magnetic compass is deflected near a wire that has electric current flowing through it, first described by Hans Christian Ørsted in 1820, they were the first instruments used to measure small amounts of electric currents. André-Marie Ampère, who gave mathematical expression to Ørsted's discovery and named the instrument after the Italian electricity researcher Luigi Galvani, who in 1791 discovered the principle of the frog galvanoscope – that electric current would make the legs of a dead frog jerk.

Sensitive galvanometers have been essential for the development of science and technology in many fields. For example, in the 1800s they enabled long range communication through submarine cables, such as the earliest transatlantic telegraph cables, were essential to discovering the electrical activity of the heart and brain, by their fine measurements of current. Galvanometers had widespread use as the visualising part in other kinds of analog meters, for example in light meters, VU meters, etc. where they were used to measure and display the output of other sensors. Today the main type of galvanometer mechanism, still in use, is the moving coil, D'Arsonval/Weston type. Modern galvanometers, of the D'Arsonval/Weston type, are constructed with a small pivoting coil of wire, called a spindle, in the field of a permanent magnet; the coil is attached to a thin pointer. A tiny torsion spring pulls the pointer to the zero position; when a direct current flows through the coil, the coil generates a magnetic field.

This field acts against the permanent magnet. The coil twists, pushing against the spring, moves the pointer; the hand points at a scale indicating the electric current. Careful design of the pole pieces ensures that the magnetic field is uniform, so that the angular deflection of the pointer is proportional to the current. A useful meter contains provision for damping the mechanical resonance of the moving coil and pointer, so that the pointer settles to its position without oscillation; the basic sensitivity of a meter might be. Such meters are calibrated to read some other quantity that can be converted to a current of that magnitude; the use of current dividers called shunts, allows a meter to be calibrated to measure larger currents. A meter can be calibrated as a DC voltmeter if the resistance of the coil is known by calculating the voltage required to generate a full scale current. A meter can be configured to read other voltages by putting it in a voltage divider circuit; this is done by placing a resistor in series with the meter coil.

A meter can be used to read resistance by placing it in series with a known voltage and an adjustable resistor. In a preparatory step, the circuit is completed and the resistor adjusted to produce full scale deflection; when an unknown resistor is placed in series in the circuit the current will be less than full scale and an appropriately calibrated scale can display the value of the unknown resistor. These capabilities to translate different kinds of electric quantities, in to pointer movements, make the galvanometer ideal for turning output of other sensors that outputs electricity, into something that can be read by a human; because the pointer of the meter is a small distance above the scale of the meter, parallax error can occur when the operator attempts to read the scale line that "lines up" with the pointer. To counter this, some meters include a mirror along the markings of the principal scale; the accuracy of the reading from a mirrored scale is improved by positioning one's head while reading the scale so that the pointer and the reflection of the pointer are aligned.

The largest use of galvanometers was of the D'Arsonval/Weston type used in analog meters in electronic equipment. Since the 1980s, galvanometer-type analog meter movements have been displaced by analog to digital converters for many uses. A digital panel meter contains an analog to numeric display; the advantages of a digital instrument are higher precision and accuracy, but factors such as power consumption or cost may still favour application of analog meter movements. Most modern uses for the galvanometer mechanism are in control systems. Galvanometer mechanisms are divided into moving coil galvanometers. Mirror galvanometer systems are used as beam positioning or beam steering elements in laser scanning systems. For example, for material processing with high-power lasers, closed loop mirror galvanometer mechanisms are used with servo control systems; these are high power galvanometers and the newest galvanometers designed for beam steering applications can have frequency responses over 10 kHz with appropriate servo technology.

Closed-loop mirror galvanometers are used in similar ways in stereolithography, laser sintering, laser engraving, laser beam welding, laser TVs, laser displays and in imaging

Cathcart District Railway

The Cathcart District Railway was proposed to serve the arising demand for suburban residential travel on the south side of Glasgow, Scotland. It was planned as a loop running to and from Glasgow Central station, but at first only the eastern arm, to Cathcart via Queens Park, was built, opening in 1886; the western arm was opened in 1894 and trains operated round the loop. A frequent passenger train service was operated, there was a limited goods and mineral operation; the passenger trains were popular but the company was never profitable, tramcar competition hit it hard. A decline set in through the twentieth century until electrification in 1962, which revived the line, which served onward routes to Newton and Neilston as well; the line continues in use today. The trunk railways of central Scotland developed from 1850 onwards. Other railways south of the River Clyde led to specific locations outside Glasgow; as the city grew, the notion of daily residential passenger travel arose, at first by the middle classes but by all levels of the community.

Suburban railway facilities were limited, they were inhibited by the inconvenient location of the Glasgow passenger terminals. Bridge Street station was on the south side of the river close to Glasgow Bridge, it served the Paisley lines. South Side station was located further from the city, south of Cumberland Street. Buchanan Street station, located on the north-east side of the city at Cowcaddens Street led by a circuitous railway route to the Motherwell and Carlisle line, as well as the Stirling direction; this unsatisfactory situation was resolved by the construction of two central passenger terminal stations: St Enoch station, opened by the G&SWR in 1876, connecting to the G&SWR line to Ayr via the Paisley joint line, to Kilmarnock over the Glasgow and Kilmarnock Joint Railway, opened in 1873. This "magnificent terminal" was centrally situated in the city, it gave access to all the G&SWR south side lines. In 1879 the Caledonian opened its Glasgow Central station well situated, accessible for all the Caledonian's south side routes.

So from 1 August 1879 both large railway companies had commodious new stations serving their south side network. On 15 November 1879 three suburban railways to the Cathcart area were announced in the press, they all planned turning south-east. Two proposed a loop. In fact the G&SWR rebuffed the approach of one of the contenders, this was made known to the others, who reconsidered the St Enoch part of their schemes; the most ambitious proposal was the Cathcart District Railway and this was favoured by the Caledonian, which offered to work the line at cost if it were connected only to their lines. As the Glasgow Barrhead and Kilmarnock Joint Railway, managed independently, was objecting to the running powers application over their line. Accordingly, the CDR withdrew the proposal for those running powers, their Parliamentary Bill was unopposed as a result. On 7 September 1880, the Cathcart District Railway Act was passed; the share capital was to be £175,000. The route was the present-day Cathcart Circle, leaving the connecting line between Central station and the GB&KJR line at a proposed Cathcart Junction, near Albert Road, running in a loop via Cathcart and returning to a junction near Strathbungo station.

Prior to this the Caledonian Railway had intended to apply for powers to subscribe for shares in the CDR and to work it, but a difference of opinion about the connection to the G&SWR lines resulted in the Caledonian withdrawing for the time being. In the 1881 session, however the Caledonian relented and the Caledonian Railway Act empowered it to subscribe 50% of the share issue, to manage and work the line. Only now, on 7 December 1881, did the company issue a prospectus inviting public subscription; the Caledonian would maintain the line for 45 % of gross receipts. Share subscription proceeded satisfactorily, but on 22 November 1882 the company asked the Caledonian to agree to a proposal to construct only the eastern arm of the circle, "due to a lack of support in the district"; this meant building only the section from Cathcart Junction via Queens Park and Mount Florida to Cathcart. The Caledonian agreed to this. Tenders for construction were obtained, Alex Coghill & Co were awarded the contract in the sum of £76,571 on 10 January 1883.

In fact Coghill was unable to progress the work properly, left certain buildings alongside railway cutting earthworks in a dangerous situation. A major disagreement over payments arose and on 14 November 1883 Coghill discontinued work on the line. Amid demands for compensation from Coghill, the Company relet the contract to Morrison and Mason in the sum of £76,407; the Company had lost a considerable sum in employing Coghill, his own company went into liquidation. In April 1885 the Pollok Estates asked if the Company would wish to extend the line to the west of Cathcart, if offered the land at agricultural values; this appears to reinstate the intended circle route, was provisionally accepted by the CDR. Major General Hutchinson inspected the line on 11 February 1886 and approved it for opening as far as Mount Florida subject t

1936 Florida Gators football team

The 1936 Florida Gators football team represented the University of Florida during the 1936 college football season. The season was Josh Cody's first as the new head coach of the Florida Gators football team; the highlights of the season included a 32–0 shutout of the Stetson College Hatters, a Homecoming game win over the Maryland Terrapins, the Gators' only conference victory over the Sewanee Tigers, but the season was remembered for the Gators' three disappointing 0–7 shutout losses to the South Carolina Gamecocks, Kentucky Wildcats and Mississippi State Bulldogs. Cody's 1936 Florida Gators finished 4–6 overall and 1–5 in the Southeastern Conference, placing tenth of thirteen SEC teams in the conference standings—Cody's worst SEC finish in four seasons as the Gators football coach. Primary source: 2015 Florida Gators Football Media Guide. Mayberry earned second-team All-Southeastern Conference honors at the conclusion of the season

Minardi M198

The Minardi M198 was the car with which the Minardi Formula One team used to compete in the 1998 FIA Formula One World Championship. It was driven by Shinji Nakano, who had moved from Prost, rookie Esteban Tuero; the M198 had a Ford V10 engine, allowing representative horsepower after several years using V8s, but many of the chassis component designs had not been changed from previous seasons, prompting former designer Gustav Brunner to start work on the team's 1999 car, the Minardi M01, within a month of rejoining the team. Despite their problems, the team was able to hang onto the rest of the field and was involved in a season-long battle with Tyrrell, beating the British team on occasion. However, the team was still unclassified in the Constructors' Championship, with no points. AUTOCOURSE 1998-99, Alan, Hazleton Publishing Ltd. ISBN 1-874557-43-8

Lake Hart, Indiana

Lake Hart is an unincorporated community and former town in Monroe Township, Morgan County, in the U. S. state of Indiana. As of the 1990 census, the town had a total population of 213. Incorporated in the 1970s with a population of 231, the town was degraded to an unincorporated community on September 23, 1998. Residents are now part of the unincorporated community of Morgan County. On September 13, 1985, the former town was declared a legal Conservancy District per the Indiana Conservancy District Act in Morgan County Circuit Court under Cause # C84 C 443; the name of the community and of the Conservancy District has since been Hart Lake. Lake Hart is the name of the former town, disbanded; the purpose for the Hart Lake Conservancy District was amended in Morgan County Circuit Court on January 16, 1987 to include the legal purposes of procuring water and sewage service for the community. While not an incorporated town, a Conservancy District is a legal governmental entity with a duly elected board of directors.

Hart Lake is located at 39°34'3" north, 86°25'54.9840" west, southwest of Mooresville

Blacktown Girls High School

Blacktown Girls High School is a government-funded single-sex academically selective secondary day school for girls, located in Blacktown, a suburb of western Sydney, New South Wales, Australia. Established in 1956 as the co-educational Blacktown High School, the school enrolled 750 students in 2018, from Year 7 to Year 12, of whom three percent identified as Indigenous Australians and 85 percent were from a language background other than English; the school is operated by the NSW Department of Education in accordance with a curriculum developed by the New South Wales Education Standards Authority. The school's brother school is Blacktown Boys High School; the school was established in January 1956 as Blacktown High School. However, owing to a growing local population and in accordance with government policy, it was decided that the schools would be split into two single sex schools: Blacktown Boys and Blacktown Girls High Schools. Both were split by 1959. List of government schools in New South Wales List of girls' schools in New South Wales List of selective high schools in New South Wales Education in Australia Official website NSW Schools website