Archives April 2013

"...when I seek out the massed wheeling circle of the stars, my feet no longer touch the Earth..." Claudius Ptolemy, matematician and astronomer An astrolabe is a device with which astronomers solved problems relating to time and the position of the sun and stars in the sky. Its main element is a two-dimensional circular stereographic projection of the hemispherical sky. The projection was most probably formalized by the Greek astronomer Hipparchus (190-120 B.C.E.), who worked on the island of Rhodes. The astrolabe was suspended vertically and a cross-arm was used to measure the altitude above the horizon of the sun (in the day) and bright stars (at night). The rim of the astrolabe is marked off in months, days, and hours, and most astrolabes have a series of longitude-specific circular main plates each marked off with lines of constant altitudes, azimuths, declinations, and right ascensions. Fitting over the plate is more...

In 1954 George Devol created the first programmable industrial robot. It consisted of a multijointed manipulator arm and a magnetic storage device to hold and replay instructions. More advanced versions worked on assembly lines in the 1960s. In 1978 the PUMA (Programmable Universal  Machine for Assembly) was introduced by Victor Scheinman and quickly became the standard for commercial robots. Dr. Yik San Kwoh..(b. 1946) invented the robot- software interface that allowed the first robot-aided surgery in 1985. "Ole"' was a modified PUMA that could perform a type of neurosurgery. In the surgery, a small probe traveled into the skull, a linked CT scanner provided a 3D picture of the brain, and the robot plotted the best path to the lesion. "Ole" was used for biopsies of deeply located suspected tumors. Before his device could be used on humans, Kwoh needed to test it. Small metal objects were inserted into four more...

There are many views regarding merits and demerits of English and other Indian languages regarding medium of instruction in education at school and college level. As there are many languages in India it becomes difficult to adopt a common language as medium of instruction throughout the country. The argument why English should be the only medium of instruction is that it is spoken all over the world. Being a language of scientific knowledge, we can be benefited from the technological advancement of other countries by reading English. Therefore English is very much suitable as the medium of instruction. But the fact is that we can understand better in our mother tongue. In case of English it is very difficult to master a foreign language. In the mother tongue the student can attain greater efficiency and he can express his thoughts in a better way in his mother tongue. When we more...

Politics is the most common phenomenon in the world today. Politics is the concept which provides the manner and the rules to govern a state and country. Its approach is to provide good governance. The persons who are related to this phenomenon are known as politicians. They are supposed to be the persons with all the qualities needed for the good governance. But the present scenario has completely been changed. Now the person who are in the politics appear to be the criminals. They have a number of criminal cases under trial against themselves. Still they rule the state and the country. They are being elected as public representatives for Assembly and Parliament. Whether they win or snatch victory in elections no one can say. It seems that politics has became synonym for crime. Criminalization is a term which comes of the word 'crime' which appears to be very unpleasant more...

A dynamo is a device that converts mechanical energy into electrical energy. For example, power for bicycle lamps used to be provided by a type of dynamo in which a ribbed cylinder resting against the bike tire was made to rotate as the cyclist pedaled along. The two main components of a dynamo are a system for producing a magnetic field (a stator) and a coil of conducting wire (an armature) that rotates in such a way that the wires continually cut through the magnetic field lines. The end product is an alternating current flowing through the wires. A third component, a commutator (a set of contacts mounted around the machine's rotating shaft) is often used to convert the alternating current into a direct current. There is a close relationship between dynamos and electric motors. One converts movement into electric current; the other, electric current into movement. In fact, traction more...

The principle of bearings has been around for as long as the Pyramids of Giza. Bearings enable easy smooth movement between two objects, and the builders of the pyramids applied this principle by using rolling tree trunks laid under planks to move heavy loads in the construction of these wonders of the ancient world. Early bearings were linear (allowing movement in a straight line, like the opening and closing of a drawer) and were made of wood, stone, sapphire, and glass. However, advances in technology demanded new and improved bearings to allow smoother mechanical movement. In 1907 Swede Sven Wingquist (1876-1953) patented a design for a multi-row self-aligning ball bearing. Made of steel to lower friction, the bearing comprised two rows of balls in a concave raceway. Wingquist's design was structurally superior to earlier bearing designs and was rotary—allowing motion around a center, such as in wheel axles. Self-alignment meant more...

India has four seasons. Winter is one of them. It lasts from the month of November to February. In England Winter is a bad time. Of course some of the days of winter are very chilly and unpleasant in India also. In winter morning is the hardest time. The nights are long. So we wake up in the morning at 5 o'clock. But it is so cold that we do not like to rise and leave the beds. We cover ourselves with the quilt and remain lying comfortably on the warm bed. At last, we have to leave our beds to answer our natural calls. The water is very cold at this time. So we get fresh water from well or tap. But when we have washed ourselves, our hands become numb and we go to fire place to warm our hands and other parts of our body.  Then we more...

Captain George Manby (1765-1854) is perhaps most famous for his invention of the Manby Mortar, which was a device to help rescue people from shoreline shipwrecks. However, he is also heralded as the father of the modern fire extinguisher, which in itself has helped to save many thousands of lives. Fire extinguishers in one form or another predate Manby's invention, and there is some debate over the design of the first, extinguisher, although one of the earliest recorded ones was designed and used in 1723 by Ambrose Godfrey. But Godfrey's device consisted of a receptacle containing a fire-extinguishing liquid and a chamber of gunpowder with a series of fuses attached. When the fuses were lit, the gunpowder exploded and scattered the liquid. They were not widely used, although there is an account of them being used to put a fire out in London in 1729. Captain Manby's 1818 invention was more...

"He is praised as an innovator, yet he is also maligned as derivative and labeled a mere craftsman." Freyda Spira, historian As a decorative technique, etching had been in use for many years before the birth of Daniel Hopfer (1470- 1536), possibly since antiquity. His innovation was to apply the method to printmaking. The etching process begins by covering a metal plate with a waxy material called a ground. Lines are then scratched into the ground with a needle to expose bare metal where the artist wants lines to appear on the print. The plate is then washed with (or dipped into) acid, which cuts into the exposed metal, leaving lines etched in the plate. The longer the plate is submerged, the deeper the incision, and the darker the lines will appear on the print. For a more sophisticated finished print, the process can be repeated to allow for different more...

"If the grace of God miraculously operates, it probably operates through the subliminal door." William James, psychologist In 1859 German doctor Alfred Wilhelm Volkmann (1800-1877) built the first tachistoscope, a device capable of influencing subliminal thought by flashing pictures for as little as ten milliseconds. Using mechanical shutters similar to those used in cameras, Volkmann exposed people to images of emotive words. The people would not notice them consciously, yet subconsciously they would  project the corresponding emotions onto a subsequent image. However, because of their mechanical nature the shutters can't be controlled with perfect precision, and hence flashtube tachistoscopes were developed. Tiese use mirrors in a large box and a small lamp that goes from complete darkness to extreme brightness and back in a few milliseconds. The person looking into the viewing hole gets the impression that every image appears in the same spot, which allows the person conducting the more...