HISTORY OF TELEPHONE

In the 1870s, two inventors Elisha Gray and Alexander Graham Bell both independently designed devices that could transmit speech electrically (the telephone). Both men rushed their respective designs to the patent office within hours of each other, Alexander Graham Bell patented his telephone first. Elisha Gray and Alexander Graham Bell entered into a famous legal battle over the invention of the telephone, which Bell won.
The telegraph and telephone are both wire-based electrical systems, and Alexander Graham Bell's success with the telephone came as a direct result of his attempts to improve the telegraph.
When Bell began experimenting with electrical signals, the telegraph had been an established means of communication for some 30 years. Although a highly successful system, the telegraph, with its dot-and-dash Morse code, was basically limited to receiving and sending one message at a time. Bell's extensive knowledge of the nature of sound and his understanding of music enabled him to conjecture the possibility of transmitting multiple messages over the same wire at the same time. Although the idea of a multiple telegraph had been in existence for some time, Bell offered his own musical or harmonic approach as a possible practical solution. His "harmonic telegraph" was based on the principle that several notes could be sent simultaneously along the same wire if the notes or signals differed in pitch.
By October 1874, Bell's research had progressed to the extent that he could inform his future father-in-law, Boston attorney Gardiner Greene Hubbard, about the possibility of a multiple telegraph. Hubbard, who resented the absolute control then exerted by the Western Union Telegraph Company, instantly saw the potential for breaking such a monopoly and gave Bell the financial backing he needed. Bell proceeded with his work on the multiple telegraph, but he did not tell Hubbard that he and Thomas Watson, a young electrician whose services he had enlisted, were also exploring an idea that had occurred to him that summer - that of developing a device that would transmit speech electrically.
Model of Alexander Graham Bell's Telephone
This model of Bell's first telephone (right) is a duplicate of the instrument through which speech sounds were first transmitted electrically (1875).
While Alexander Graham Bell and Thomas Watson worked on the harmonic telegraph at the insistent urging of Hubbard and other backers, Bell nonetheless met in March 1875 with Joseph Henry, the respected director of the Smithsonian Institution, who listened to Bell's ideas for a telephone and offered encouraging words. Spurred on by Henry's positive opinion, Bell and Watson continued their work. By June 1875 the goal of creating a device that would transmit speech electrically was about to be realized. They had proven that different tones would vary the strength of an electric current in a wire. To achieve success they therefore needed only to build a working transmitter with a membrane capable of varying electronic currents and a receiver that would reproduce these variations in audible frequencies.
On June 2, 1875, Alexander Graham Bell while experimenting with his technique called "harmonic telegraph" discovered he could hear sound over a wire. The sound was that of a twanging clock spring.
Bell's greatest success was achieved on March 10, 1876, marked not only the birth of the telephone but the death of the multiple telegraph as well. The communications potential contained in his demonstration of being able to "talk with electricity" far outweighed anything that simply increasing the capability of a dot-and-dash system could imply.
Alexander Graham Bell's notebook entry of 10 March 1876 describes his successful experiment with the telephone. Speaking through the instrument to his assistant, Thomas A. Watson, in the next room, Bell utters these famous first words, "Mr. Watson -- come here -- I want to see you."
Born on March 3, 1847, in Edinburgh, Scotland, Alexander Graham Bell was the son and grandson of authorities in elocution and the correction of speech. Educated to pursue a career in the same specialty, his knowledge of the nature of sound led him not only to teach the deaf, but also to invent the telephone.
Bell's unceasing scientific curiosity led to invention of the photophone, to significant commercial improvements in Thomas Edison's phonograph, and to development of his own flying machine just six years after the Wright Brothers launched their plane at Kitty Hawk. As President James Garfield lay dying of an assassin's bullet in 1881, Bell hurriedly invented a metal detector in an unsuccessful attempt to locate the fatal slug.
Alexander Graham Bell - Biography In 1876, at the age of 29, Alexander Graham Bell invented his telephone. Bell might easily have been content with the success of his invention. His many laboratory notebooks demonstrate, however, that he was driven by a genuine and rare intellectual curiosity that kept him regularly searching, striving, and wanting always to learn and to create.
Alexander Graham Bell - First Patent: #174,465 Read and see the original patent for the Alexander Graham Bell telephone.
General Telephone History and Understanding Telephone Technology
Caller ID, Telephone Books, Yellow Pages, 911, Pay Phones
Next page > Alexander Graham Bell - Biography

HISTORY OF TELESCOPE

Phoenicians cooking on sand discovered glass around 3500 BCE, but it took about 5,000 years more for glass to be shaped into a lens for the first telescope. A spectacle maker probably assembled the first telescope. Hans Lippershey (c1570-c1619) of Holland is often credited with the invention, but he almost certainly was not the first to make one. Lippershey was, however, the first to make the new device widely known.
The telescope was introduced to astronomy in 1609 by the great Italian scientist Galileo Galilei, who became the first man to see the craters of the moon, and who went on to discover sunspots, the four large moons of Jupiter, and the rings of Saturn. Galileo's telescope was similar to a pair of opera glasses in that it used an arrangement of glass lenses to magnify objects. This arrangement provided limited magnification--up to 30 times for Galileo--and a narrow field of view; Galileo could see no more than a quarter of the moon's face without repositioning his telescope.
In 1704, Sir Issac Newton announced a new concept in telescope design whereby instead of glass lenses, a curved mirror was used to gather in light and reflect it back to a point of focus. This reflecting mirror acts like a light-collecting bucket: the bigger the bucket, the more light it can collect. The reflector telescope that Newton designed opened the door to magnifying objects millions of times--far beyond what could ever be obtained with a lens.
Newton's fundamental principle of using a single curved mirror to gather in light remained the same. The major change that took place was the growth in the size of the reflecting mirror, from the 6-inch mirror used by Newton to the 6-meter (236 inches in diameter) mirror of the Special Astrophysical Observatory in Russia, which opened in 1974.
The idea of a segmented mirror dated back to the 19th century, but experiments with it had been few and small, and many astronomers doubted its viability. It remained for the Keck Telescope to push the technology forward and bring into reality this innovative design.
A binocular is a optical instrument for providing a magnified view of distant objects, consisting of two similar telescopes, one for each eye, mounted on a single frame. The first binocular telescope was invented by J. P. Lemiere in 1825.
The Early History of the Binocular The modern prism binocular began with Ignatio Porro's 1854 Italian patent for a prism erecting system.
The First 300 Years of Binocular Telescopes "What we call a binocular is a binocular telescope, two small prismatic telescopes joined together. When Hans Lippershey applied for a patent on his instrument in 1608, the bureaucracy in charge, who had never before seen a telescope, asked him to build a binocular version of it, with quartz optics, which he is reported to have completed in December 1608."
Telescopes and their Makers "Box-shaped binocular terrestrial telescopes were produced in the second half of the 17th century and the first half of the 18th century by Cherubin d’Orleans, by Pattroni in Milan, and by I.M. Dobler in Berlin; but were not successful because of their clumsy handling and poor quality."
Telescope Facts - James Short The Short Telescope, was made by the Scottish Instrument maker James Short in 1740. An optician and astronomer, James Short invented the first perfect parabolic and elliptic, distortionless mirror ideal for reflecting telescopes. James Short built over 1,360 telescopes. James Short - Biography
Related Innovations Glass & Reading Glasses Light Microscope

HISTORY OF TELESCOPE

Phoenicians cooking on sand discovered glass around 3500 BCE, but it took about 5,000 years more for glass to be shaped into a lens for the first telescope. A spectacle maker probably assembled the first telescope. Hans Lippershey (c1570-c1619) of Holland is often credited with the invention, but he almost certainly was not the first to make one. Lippershey was, however, the first to make the new device widely known.
The telescope was introduced to astronomy in 1609 by the great Italian scientist Galileo Galilei, who became the first man to see the craters of the moon, and who went on to discover sunspots, the four large moons of Jupiter, and the rings of Saturn. Galileo's telescope was similar to a pair of opera glasses in that it used an arrangement of glass lenses to magnify objects. This arrangement provided limited magnification--up to 30 times for Galileo--and a narrow field of view; Galileo could see no more than a quarter of the moon's face without repositioning his telescope.
In 1704, Sir Issac Newton announced a new concept in telescope design whereby instead of glass lenses, a curved mirror was used to gather in light and reflect it back to a point of focus. This reflecting mirror acts like a light-collecting bucket: the bigger the bucket, the more light it can collect. The reflector telescope that Newton designed opened the door to magnifying objects millions of times--far beyond what could ever be obtained with a lens.
Newton's fundamental principle of using a single curved mirror to gather in light remained the same. The major change that took place was the growth in the size of the reflecting mirror, from the 6-inch mirror used by Newton to the 6-meter (236 inches in diameter) mirror of the Special Astrophysical Observatory in Russia, which opened in 1974.
The idea of a segmented mirror dated back to the 19th century, but experiments with it had been few and small, and many astronomers doubted its viability. It remained for the Keck Telescope to push the technology forward and bring into reality this innovative design.
A binocular is a optical instrument for providing a magnified view of distant objects, consisting of two similar telescopes, one for each eye, mounted on a single frame. The first binocular telescope was invented by J. P. Lemiere in 1825.
The Early History of the Binocular The modern prism binocular began with Ignatio Porro's 1854 Italian patent for a prism erecting system.
The First 300 Years of Binocular Telescopes "What we call a binocular is a binocular telescope, two small prismatic telescopes joined together. When Hans Lippershey applied for a patent on his instrument in 1608, the bureaucracy in charge, who had never before seen a telescope, asked him to build a binocular version of it, with quartz optics, which he is reported to have completed in December 1608."
Telescopes and their Makers "Box-shaped binocular terrestrial telescopes were produced in the second half of the 17th century and the first half of the 18th century by Cherubin d’Orleans, by Pattroni in Milan, and by I.M. Dobler in Berlin; but were not successful because of their clumsy handling and poor quality."
Telescope Facts - James Short The Short Telescope, was made by the Scottish Instrument maker James Short in 1740. An optician and astronomer, James Short invented the first perfect parabolic and elliptic, distortionless mirror ideal for reflecting telescopes. James Short built over 1,360 telescopes. James Short - Biography
Related Innovations Glass & Reading Glasses Light Microscope

HISTORY OF CAMERA

5th-4th Centuries B.C.Chinese and Greek philosophers describe the basic principles of optics and the camera.
1664-1666Isaac Newton discovers that white light is composed of different colors.
1727Johann Heinrich Schulze discovered that silver nitrate darkened upon exposure to light.
1794First Panorama opens, the forerunner of the movie house invented by Robert Barker.
1814Joseph Nicéphore Niépce achieves first photographic image with camera obscura - however, the image required eight hours of light exposure and later faded.
1837Daguerre’s first daguerreotype - the first image that was fixed and did not fade and needed under thirty minutes of light exposure.
1840First American patent issued in photography to Alexander Wolcott for his camera.
1841William Henry Talbot patents the Calotype process - the first negative-positive process making possible the first multiple copies.
1843First advertisement with a photograph made in Philadelphia.
1851Frederick Scott Archer invented the Collodion process - images required only two or three seconds of light exposure.
1859Panoramic camera patented - the Sutton.
1861Oliver Wendell Holmes invents stereoscope viewer.
1865Photographs and photographic negatives are added to protected works under copyright.
1871Richard Leach Maddox invented the gelatin dry plate silver bromide process - negatives no longer had to be developed immediately.
1880Eastman Dry Plate Company founded.
1884George Eastman invents flexible, paper-based photographic film.
1888Eastman patents Kodak roll-film camera.
1898Reverend Hannibal Goodwin patents celluloid photographic film.
1900First mass-marketed camera—the Brownie.
1913/1914First 35mm still camera developed.
1927General Electric invents the modern flash bulb.
1932First light meter with photoelectric cell introduced.
1935Eastman Kodak markets Kodachrome film.
1941Eastman Kodak introduces Kodacolor negative film.
1942Chester Carlson receives patent for electric photography (xerography).
1948Edwin Land markets the Polaroid camera.
1954Eastman Kodak introduces high speed Tri-X film.
1960EG&G develops extreme depth underwater camera for U.S. Navy.
1963Polaroid introduces instant color film.
1968Photograph of the Earth from the moon.
1973Polaroid introduces one-step instant photography with the SX-70 camera.
1977George Eastman and Edwin Land inducted into the National Inventors Hall of Fame.
1978Konica introduces first point-and-shoot, autofocus camera.
1980Sony demonstrates first consumer camcorder.
1984Canon demonstrates first digital electronic still camera.
1985Pixar introduces digital imaging processor.
1990Eastman Kodak announces Photo CD as a digital image storage medium.

COMPUTER

There are a variety of terms used to describe the educational use of computer and each has a slighlty different meaning. Computer Assisted Learning (CAL) is an all encompassing term to describe any educational use of computers. Such uses can be divided into three main groups: (1) when the computer is used as a tool (word processor, data base, spread sheet, and graphics application); (2) when the student 'teaches' the computer, for example, by issuing a set of instructions to the computer through a programming language such as Logo, and (3) when the computer delivers some instructional material (Taylor 1980). This latter situation is termed Computer Based Instruction (CBI) or Computer Assisted Instruction (CAL) which is an older term than CBI. This paper will only deal with the third aspect of the use of computers in education, computer based instruction.
Computer Based Instruction has traditionally been composed of four main components, Drill and Practice, Tutorials, Games and Simulation and Modelling. Modern technologies have added to these Hypertext, Hypermedia and Multimedia. These new technologies will be deal with in detail later in the paper.
Drill and Practice was probably the most extensively used CBI application in the early days of the educational use of computers. It can be argued that there were two main reasons for this; (1) they were comparatively easy to program, which was important as there was little available commercial software and so teachers who wished to use computers had often to write much of the software themselves; (2) the programs could show off effectively the capabilities of the computer and this was important for the computer-enthusiast teacher as it could help to win over colleagues to the cause, and hopefully, result in more money being spent on computers in schools.
A drill and practice program typically deals with material that has already been taught. The student is presented with a task, often selected randomly, and feedback is offered immediately it is completed. A well constructed program of this type should be able to keep pace with the student by offering remedial or advanced level if and when they become necessary (Hannafin and Peck 1988, 4). There is a place for drill and practice mainly for the beginning learner or for students who are experiencing learning problems. Their use, however, should be kept to situations where the teacher is certain that they are the most appropriate form of instruction.
Tutorials attempt to teach new materials. Typically they present information and then question the user to ascertain the level of learning achieved. The program should be able to monitor the student's progress and to present remedial or advanced levels if and when required. The tutorial is based on the Socratean model but Merrill (Twitchell 1991, 35) cautions that "Socrates is highly over-rated. We give too much credit to tutoring as a model".
From a practical point of view, the computer tutorial is very limitted in its ability to assess the level of understanding of the student. In the classroom situation, when teachers ask questions, they can assess the level of understanding of the topic, the degree of comfort with the material, etc., by not only listening to the answer given, but also by observing the speed with which it is given, the degree of hesitation, the body language of the student, and so on. The computer, however, is only capable of responding to the answer given, usually by typing characters on a keyboard. A teacher can accept a slightly wrong answer and probe deeper to get the correct one. The computer can normally only respond to a small number of possible answers and often cannot cope with a slightly incorrect answer; for example, if the expected answer is apples and the student enters apple, the computer will frequently reject it which can result in a considerable degree of frustration on the part of the student. There is also a problem from the designer's point of view; after a screen of information has been presented, it is difficult to determine which question will demonstrate an understanding of all the information that has been given. Research is being conducted in the production of Intelligent Tutoring Systems which should overcome this problem, but these will depend upon artificial intelligence (AI), however, some people state that the true meaning of AI is always impossible.
Educational games are normally placed in a group of their own, but in practice it is often difficult to differentiate between games, drill and practice programs or simulations. It is possible to have a game and a drill and practice program that contain the same content, but which have a different end result For example, the game Maths Invaders has the same content as a drill and practice program in that users are asked to complete a number of sums, but the outcome is different as when a question is answered correctly, as in the game the student gets to shoot down an alien. A game can also have the format of a simulation but the major difference between the two is that a simulation normally models a real life situation whereas a game can model an imaginary one. Games also have a place to play in the classroom especially as a way of increasing the motivational levels of students. However, they should be used with care. Many students, especially boys, spend a lot of time playing computerised games and it is important that the classroom computer is not seen solely as another games machine.
Simulation programs normally model some real life situation and they enable students to manipulate and experiment with it. The normal justification for using them is in situations where the real thing is too expensive, too dangerous or too time consuming. For example, students would not normally be able to observe the evolution of a species as it would take too long but the whole process could be observed in a very short period of time on a computer simulation. While simulations have a potential to be useful in the classroom, they do have some draw backs. These will be considered in more detail later.