Interesting facts

...word electricity comes from the Greek word "ηλεκτρον" (electron), which means amber. The knowledge about the electricity comes from a period of 600 BC when the Greek philosopher Thales of Miletus described the phenomenon in amber, which if rubbed by wool, attracts light bits of matter. Over time, it has been found that other materials can get electrified: various kinds of resins, hard rubber, glass, porcelain and others.

...the first law on the atmospheric pressure was formulated by Robert Boyle. He and his assistant Robert Hook conducted a series of experiments. They found that in the vacuum pen and a metal object fall at the same speed, and that a sound is transmitted through it. They found also that objects can not burn in the vacuum, and that the animals cannot live in it.

...many philosophers and thinkers have tried to answer the question "What is time?" Saint Aurelius Augustine said: "If you do not ask me what time is, I know, but if you ask me, I do not know!". The first clocks driven by weights and levers emerged in the fourteenth century. Word clock is derived from the French word cloche (bell) because the first clocks did not have hands, but the bell would have announced the hour. Given that the frequency can be measured with the lowest measurement uncertainty, the second most accurately represents the realized unit. For centuries, people were trying to figure out different ways to measure the time, all the way from using the sun to using atomic clocks today. The world is currently working on the development of optical clocks. Latest clocks will be so precise, that if they have begun to tick at the time of the "Big Bang" 13 billion years ago they would still not have lost a single second.

...electricity travels at the speed of light - more than 300 000 km / s. If there was a lamp on the moon and in the house the switch, it would take only 1.28 s to turn on a lamp from 384 403 km distance.

Air pressure can be measured by Torricelli tube. Standard atmospheric pressure at an altitude is the pressure resulting from a column of mercury of 760mm in height at 0 °C. In the atmosphere, the air density changes (decreases) with altitude, so the atmospheric pressure changes with altitude too.

French scientist Denis Papin revealed that, when the pressure above some liquid decreases, and its boiling point is lowered, and when the pressure increases, so does its boiling point too. Boiling point of water at atmospheric pressure of 1000 mbar is 100 °C, while at a pressure of 850 mbar (corresponding to an altitude of about 1500 m above sea level) boiling point is 96 °C, at 750 mbar (corresponding to an altitude of about 3000 m) about 92 °C, and so on.

The third temperature scale, based on the idea of absolute zero, was proposed in 1848 by William Thompson and Lord Kelvin. Kelvin proposed a temperature scale where 0 degrees means the lowest theoretically possible temperature or the temperature of absolute zero. From 1954 Kelvin is defined as a unit for the temperature in the SI system of units.

Gold is a measure of the wealth of a country and especially today when money is only an electronic code in a digital world. Given that the national currencies are unstable, gold price is rapidly increasing because it guarantees the inability of the loss of value. That is why the investment gold is popular today.
The application of the metric system in Montenegro was introduced by a Decree of January the 1st 1888, but based on the available archival records; one can see that the "new (French) meter measurements" were used even in the first half of the XIX century. The term referred to a meter has been mentioned for the first time in the letter of Petar II Petrovic Njegos, from 1835, where he informs district captain from Kotor, about a deal, made by some Montenegrins, for the delivery of "80 pieces of nets and two hundred meters of rope."

...there is an anecdote that tells how Archimedes discovered that a golden crown, made for King Nero II, was not made of solid gold. When the golden laurel leaves shaped crown was made, Archimedes were asked to determine whether a crown was of pure gold or dishonest goldsmith mixed it silver. This was not supposed to damage the crown. The problem was how to determine the volume of the crown, which would along the known mass, help determining the density of gold. The solution came during bathing. He noted that upon lowering himself into the bath the water level raised. He realized that in this way one could calculate the volume of the crown. By dividing the mass of the crown with its volume, the density of the metal in the crown can be calculated. Finding a density lesser than the density of gold would mean that the silver was added. Finding a solution to the problem he got so excited that, forgetting to get dressed, he ran out of the tub onto the street, shouting Eureka! (Greek - "Eyphka") - I found it!

...unique system of measures prescribed by a monarch first appeared in Mesopotamia, which is considered the cradle of civilization. Archaeological excavations have enabled us to find prototypes similar to the ones we use today, and the prototype of length was a long copper rod 110, 35 cm length. Historical records show that in the year 1120, Henry I, King of England, declared a yard as the standard length in his country, which was equal to the distance from the tip of his nose to the end of his outstretched hand. In France, the standard defined as the length was a a foot, equal to the length of feet of King Louis XII. This standard has long been in use, practically until the first definition of the meter in 1799. is believed that in the year 1612 Santorio Santorio applied a scale to an air thermoscope and so invented the first thermometer, a device to measure the temperature. Due to variations in air pressure this thermometer was not beneficial because at that time it was not known that changes in the air pressure influence temperature and thermometer.

...the basic idea that gave birth to the metric system, emerged during the French Revolution. The French Academy of Sciences proposed to overcome existing variable and transient units, by taking the meter as the unit of length and the kilogram as the unit of weight. The French Revolution gave rise to the scientific revolution that led to a unified system of measures because there was a tendency to make the system "for all countries and all peoples." The following image shows the Medal coined on the occasion of the mandatory use of the metric system of units in France since 01.01.1894.godine. Engraving on the medal says that the metric system is compulsory under the law since the 4th of July, 1837. much gold is there in the world? It is assumed that the earth's crust contains about 20 billion tons of gold, while in the sea there is about 8 billion tons more. It is estimated that so far excavated about 100,000 tons, of which about 80,000 tones in the 20th century. Quantities, available for mining, amount only 20,000 tones. The largest gold deposits are in the South Africa where gold is mined in the mines at a depth of 4,000 m, and in the countries of the former USSR where mainly surface is being mined.