you remember a little girl from a fairy tale, Thumbelina?You never thought about the origin of its name?Let's talk about this.
about the word "inch»
Translated from the Dutch word "inch" means "thumb".It is a measure of length equal to the width of the average human thumb (though someone says that it is about the length of the upper phalanx).But, on whatever part or in question, it turns out that Thumbelina - a girl the size of a finger.
By the way, in a fantastic epic known another hero of the same size.It turns out that our beloved Boy Thumb could also be called by analogy Dyuymovchikom.The joke, of course.However, the fingers of people are different, so all the same it would be desirable to clarify how many mm per inch?
Magnitude inches
determine what constitutes an inch in mm, it is not so simple.The fact that this unit, which for hundreds of years, has repeatedly changed even within the same system of measures, not to mention different.Vienna inch equaled 2.6340278 cm or 26.3 mm;Spain Local inch (pulgada) was 23.2 mm;in Mexico, where he also called pulgada, inch size in mm was equal to about 23.3.
This list can be replenished almost indefinitely.In each of the German states had their own, different from the other kind of said measures of length: Baden, Bavaria, Saxony and Prussia, and the Confederation of the Rhine inch.In the Baltic provinces, respectively, were Courland, Riga and Revel.In the territories of the Commonwealth existed Old Polish and novopolskie inches and Wroclaw, Breslau, Silesia, the old Lithuanian.France had a measure of length.There were similar units even in Japan and China.So, 1 cun (Chinese inch) in mm was 33.3.There are also the so-called vidikonovsky inch, most commonly used in the measurement matrix digital camera.It is equal to 16.93 mm.
About the Metre Convention and the metric system
May 20, 1875 in Paris, at the Ministry of Foreign Affairs of France, was signed m. N.Metre Convention - a treaty designed to ensure uniformity of the international metrological standards.By this agreement, and now Russia - on behalf of the Emperor agreement was signed Okunev counselor of the embassy.The adoption of the convention served as a major impetus in the development of the metric system and the start of development of standards meter and the kilogram.Later it was introduced the basic unit values in the fields of electricity and optics.By the Metre Convention for the time being attached to more than 50 countries, including all of the most industrialized.
Two important observations.First inch - an old unit, generally unrelated to the metric system.Moreover, OIML (International Organization of Legal Metrology) strongly recommends the speedy removal from circulation, where it is still used for measurement (the reason, I think, is clear).Note the second.Biggest highly developed country and the United States, although it has signed the Metre Convention, still it does not consider itself bound to use the metric system of measures.Inch is widely used as a local unit as in the rest of the world to follow the recommendations seriously hampers the OIML.
of the English inch
So what is all the same is this unit how to express in mm 1 inch?Currently, with the mention of the term usually refers to the English or imperial measure of length.Its value is also changed several times, but since 1958, translating inches 25.4 mm will result in a single unit.So the size of our fantastic characters today would amount to 2.54 cm. In fact, the crumbs!
way in England inch referred inch, it recognized the sign - quotation marks: eg: 17 ". So the man decided to, say, buy a TV, one should not confuse a double bar or mention in next to the figures on the size of the screen. It isall about the same SI units.
In the United States, as in England, since 1958, is considered equal to an inch 2.54 cm. It is the unit used in various fields, and quite widely - for example, when you specify the caliber of small arms. In Americaweapon caliber (inner diameter of the barrel) is measured in hundredths of an inch. Accordingly, the famous Colt .45 is a weapon with a trunk diameter of 0.45 inches (11.43 mm).
Where Used inch
There is a legitimate question.Why is a person living in a country that uses the metric system of measures (Russia), should worry about US indicators length or, for example, how to convert mm to inches? But things are not so simple. In recent years, due to the expansion of American technology and the emergence of new technicalterms Inches began to be used in the Russian language more often.And before there were whole industries, wherein said value is considered to be the basic unit of measurement.So, generally measured in inches caliber artillery shells.However, it should be to understand otherwise.For example, in the UK, unlike the US, gauges show a few thousandths of an inch.A famous Russian "trehlineyka" - is referred to 3 units (7.62 mm).
Inches are also used in the automotive industry: they measure the diameters of the wheels of the car.Since the existence of the Soviet automobile industry began with foreign technology and license it to a large extent, and foreign terminology used.For example, one of the firstborn of the domestic automotive industry, KIM-10, the cylinder diameter is 2 1/2 "(63.5 mm). As well as specify inches diameter lens telescopes, and even this unit of measure used for marking pipes.
About Pipe inch
long tradition is the use of the quantity when working with gas and water pipes, as well as to refer to cut into their threads. But it should be noted: Pipe inch mm - this is not the same as an ordinary inch.
This concept can not be called scientific, and yet it has a well-defined meaning. Pipe inch is considered to be the outer diameter of a pipe, in which the internal diameter corresponds to the usual inch. The value of this to some degree arbitrary: pipes have different thicknesses, which, of course, affects thediameter ratio. Yet to some uniformity on this issue failed to arrive.
Conditional pass
Speaking of settings made (rolled) pipe, usually mean diameter outside.Of course, under the same values of the exterior, but with a different wall thickness, the internal dimensions of different products may differ significantly.Therefore, the notion of conditional transfer tube: a special internal diameter, which may correspond to a specific external value.For example, in a pipe, which passage is 40 mm, the real inner diameter may be any number of sufficiently similar.
Why do you need to know?Then, that the main index, which is calculated by the passage of water is the internal diameter of the pipe.In practice, water use as steel products which are marked in inches, and copper, aluminum, stainless steel, produced on metric standards.Therefore, a correct translation: inches mm pipe (reference of the quantity to metric values).There are special tables (GOST 3262-75), establishing a correspondence between the different types of pipes and their parameters.In them as a base and take the value of the nominal diameter (passage) of the pipe.
About the threads
pipes often have to connect.With diameters of more than 6 inches is generally used welding, smaller products are braided by a thread, whose parameters are usually expressed in inches.Step pipe threads - the number of threads posted on one such unit.There also exist correspondence table moves in mm thread count of threads per inch.There is also a table summarizing, linking inch size cylindrical pipe thread with its metric parameters.In accordance therewith, in particular, the threading 3 inch 87.884 mm corresponds to the values;86.405 and 84.926 (nominal figures the outer, middle, inner diameters, respectively).Generally NPT - is a science, plus a considerable group of different standards, the objectives of which - the right mix of elements and structures that have a thread.The standards are based on those figures inch system of units.
Again inches of
name "inch" and its derivatives can often be found in the description of other production processes.For example, the word "dyuymovka" sometimes refers to a board thickness of an inch or as long nail (in these cases again becomes relevant transfer inches mm).But that's not all.Until now, the concept of "inch" when referring to a popular fixture and many other metal products.And yet, that word would be enrolled into an anachronism, if not for the rapid development of computer technology, which led to our turnover of new terms.Resolution of the printer, and some other devices are generally defined in dots per inch (dpi).There is also the concept of pixels per inch (ppi), used when specifying the resolution of the device, administering or outputting graphics.Concepts dpi or ppi technologically identical.
measured in inches as mobile phone screens, monitors, TV screens (formerly in the Soviet Union, this value is expressed in centimeters).On the screens should talk a little bit more.
About pixels and image
lot, talking about television or other screens, considered the most important indicator of its size.They strongly translate into more usual for a long diagonal measures (for example, 21 inches in mm), trying to figure out if there is enough for them to this value.However, there are equally important indicators on which buyers of such equipment often do not pay attention.
Pixel - this is a technical term that migrated in everyday use.If you move away from the complicated definition, the pixel can be called the smallest indivisible object image of a certain color.Raster image is a collection of computer pixels, arranged in rows and columns.Principles of television bit different, but here to talk about the resolution of the device, ie. E. About his ability to represent the largest number of parts (units) exhibited pictures.Of course, any image even more beautiful and high quality, the higher the number of pixels per unit area of the screen.This is the already mentioned figure ppi (dots per inch display).The value ppi is very important to get a clear bright picture quality, so it is sure to look for when buying the appropriate equipment.
However, not only in pixels happiness - well, at least according to many experts.The pursuit of high-resolution leads to a serious increase in the load on the graphics card.That is, buyers of television and other such equipment should carefully weigh the "pros" and "cons" and stay at the best option for themselves devices.
inches, inches ...
In computer practice, we are reminded of this magnitude even when we specify the parameters of hard drives, disk drives, DVD-drive characteristics.In inches, and indicates the size of the matrix of digital cameras.What is the matrix and what impact it has on the size of the picture quality?This is a very interesting and important question, but for another discussion.
How to remember the size of an inch?
man does not differ a good memory for numbers, it is worth to know the following: 4 inches in mm amount to 2.54 * 4, t. E. A little more than 1 cm. In cases when special accuracy is not needed, such a scheme it is possible to usein some domestic situations.
Conclusion
If in any search engine to write the query "inch" as the answers and certainly would be a reference to the story of James Aldridge "The Last Inch".This small, but really worthwhile work, which has become a classic of world literature, more than once filmed.Deeply tragic story of human courage, the complex relationship of father and son, the quirks of fate.
But the interesting title of the story.Why "The Last Inch"?In the story of teen, had never fly a plane, it was possible not only to drive the car hard routes, but also to put it in difficult and even dangerous conditions.The child managed.Last inches before planting began abroad, turning it into another person - an adult who is responsible, it is highlighted and a new face in the future relationship of father and son.So it is not always the right to express inch mm - sometimes this value requires a completely different approach and equivalents.
