Do not forget that it was with the help of a slide rule that a man first set foot on the moon.
William Oughtred, a graduate of Eton and King's College of Cambridge, pastor of Alsbury Church in Surrey, was a passionate mathematician and enjoyed teaching his favorite subject to numerous students from whom he did not charge any fees. “Small in stature, black-haired and black-eyed, with a penetrating look, he was constantly thinking about something, drawing some lines and diagrams in the dust,” one of the biographers described Otreda. “When he came across a particularly interesting mathematical problem, it happened that he didn’t sleep or eat until he found a solution.” In 1631, Oughtred published the main work of his life - the textbook Clavis Mathematicae ("Key of Mathematics"), which withstood several reprints for almost two centuries. Once, while discussing "mechanical calculations" with the help of Gunther's ruler with his student William Forster, Oughtred noted the imperfection of this method. In the meantime, the teacher demonstrated his invention - several concentric rings with logarithmic scales printed on them and two arrows. Forster was delighted and later wrote: “It was superior to any of the instruments that were known to me. I wondered why he hid this most useful invention for many years ... "Ottred himself said that he "simply bent and folded the Gunther scale into a ring", and besides, he was sure that "the real art [of mathematics] does not need tools..." , he considered their use permissible only after mastering this art. However, the student insisted on publication, and in 1632 Oughtred wrote (in Latin) and Forster translated into English the pamphlet Circles of Proportion and the Horizontal Instrument, which described the slide rule.
The authorship of this invention was disputed by another of his students, Richard Delamaine, who published in 1630 the book Grammology, or the Mathematical Ring. Some argue that he simply stole the invention from a teacher, but it is possible that he arrived at a similar solution independently. Another contender for authorship is the London mathematician Edmund Wingate, who proposed in 1626 to use two Gunther rulers sliding relative to each other. The instrument was brought to its present state by Robert Bissaker, who made the ruler straight (1654), John Robertson, who provided it with a slider (1775), and Amede Mannheim, who optimized the arrangement of the scales and the slider.
The slide rule has made complex calculations much easier for engineers and scientists. In the 20th century, before the advent of calculators and computers, the slide rule was the same symbol of engineering professions as the phonendoscope is for doctors.
Device and principles of use
The principle of operation of the slide rule is based on the fact that the multiplication and division of numbers is replaced by the addition and subtraction of their logarithms, respectively. The first version of the ruler was developed by the English amateur mathematician William Oughtred in 1622.
Circular slide rule (slide circle)
The simplest slide rule consists of two slide scales that can move relative to each other. More complex rulers contain additional scales and a transparent slider with several risks. On reverse side rulers can contain any reference tables.
In order to calculate the product of two numbers, the beginning of the movable scale is aligned with the first factor on the fixed scale, and the second factor is found on the movable scale. Opposite it on a fixed scale is the result of multiplying these numbers:
To divide the numbers, a divisor is found on the movable scale and combined with the divisible on the fixed scale. The beginning of the moving scale indicates the result:
With the help of a slide rule, only the mantissa of a number is found, its order is calculated in the mind. The accuracy of calculating ordinary rulers is two to three decimal places. To perform other operations, use the slider and additional scales.
Despite the fact that the slide rule does not have the functions of addition and subtraction, it can also be used to perform these operations using the following formulas:
It should be noted that, despite the simplicity, quite complex calculations can be performed on a slide rule. Previously, quite voluminous manuals on their use were issued.
Slide rule today
All over the world, including in the USSR, slide rules were widely used to perform engineering calculations until about the beginning of the 1980s, when they were supplanted by calculators.
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See what "Slide Rule" is in other dictionaries:
logarithmic ruler- slide rule - Topics oil and gas industry Synonyms slide rule EN slide rule ... Technical Translator's Handbook
- (slide ruler) a calculating tool for simplifying calculations, with the help of which operations on numbers are replaced by operations on the logarithms of these numbers. It is used in engineering and practical calculations, when an accuracy of 2 3 digits is sufficient ... Big Encyclopedic Dictionary
LOGARITHMIC RULER- SLIDE RULER, a device that allows you to quickly, although not very accurately, perform mathematical calculations (multiplication, division, raising to a power, extracting a root, finding the logarithm of a number, calculating the value of the sine and tangent by ... ... Big Medical Encyclopedia
LOGARITHMIC RULER- (counting ruler) a counting tool for quickly performing a number of mathematical operations (multiplication, division, raising to a power, extracting a root, trigonometric calculations, etc.), while operations on numbers are replaced by operations on ... ... Great Polytechnic Encyclopedia
SLIDE RULER, a counting instrument consisting of two rulers with logarithmic scales of numbers, one of which slides along the other. Before the advent of computer technology, such rulers were indispensable when performing ... ... Scientific and technical encyclopedic dictionary
Slide rule or slide rule- a computing device that allows you to perform several mathematical operations, including multiplication and division of numbers, exponentiation (most often in a square and a cube) and the calculation of square and cube roots, the calculation of logarithms, potentiation, the calculation of trigonometric and hyperbolic functions and other operations. Also, if you break the calculation into three steps, then using the slide rule, you can raise numbers to any real power and extract the root of any real power.
Don't be scared! You do not need to calculate bases and logarithms, cosines and arctangents every day. In most cases, slide rules built into watches are not equipped with scales for calculating the values of trigonometric functions.
A number of watches are equipped with calculating rulers, the functions of which are close to everyday life.
By the way, Mark Carson, the head of the theoretical department at the nuclear center, USA, was the first to come up with the idea of putting the logarithmic school into the clock.
So the clock Citizen Promaster Sky– already from the symbols on the calibrated scale it is clear that they are perfectly suited for calculating fuel consumption when traveling by car or traveling by motor boat.
Let's start with the simplest. The circular slide rule consists of a ruler on the bezel and a ruler on the dial. Turn the bezel until the value on the bezel ruler lines up with the desired mark on the dial.
In order to divide 150 by 3, the number 15 (=150) on the outer scale should be set against the number 30 (3) on the inner scale. The result is counted on the internal scale opposite "10" and is equal to 50.
You can find an example on the internet triple rule, or calculating the rate of descent using the circular ruler on the watch.
A pilot in a glider at 3,300 meters determines that he is losing altitude at a rate of one meter per second, i.e. 60 meters per minute. How much time does he have until the end of the flight? In order to know the answer, you should set the number 33 (=3300) on the outer scale against the number 60 on the inner scale. The result is against the "10" sign on the internal scale and is 55 minutes.
But let's leave aviation problems alone and apply this rule for calculations in a closer sphere. How far will you need 40 liters of gasoline with a fuel consumption of 8 liters per 100 kilometers? We set the number 40 opposite the number 8. We get 50, taking into account the scale of 1 to 10 - at 500 km.
On various watches there are many symbols that facilitate the conversion of measures of length.
STAT means English mile, NAUT- nautical mile M- American mile, and on the clock Citizen Promaster Sky-KM- which in both Latin and Russian transliteration means kilometers.
The first slide rules were invented by the British - mathematician and teacher William Otred and mathematics teacher Richard Delamain. In the summer of 1630, Ottred was visited by his friend and student William Forster, a mathematics teacher from London.
Friends talked a lot about mathematics, about the correct method of teaching it. When the conversation turned to Gunther's scale, Oughtred was critical of it. He noted that a lot of time is spent manipulating two compasses, while the accuracy is low.
The logarithmic scale used with two circular measuring instruments was built by the Welshman Edmund Günther. The scale invented by him was a segment on which divisions were applied, they corresponded to the logarithms of numbers or trigonometric quantities. Using compasses, it was possible to determine what is the sum of the lengths of the scale segments or their difference, and accordingly, according to the properties of logarithms, it was possible to find the product or quotient. The now generally accepted notation log, as well as the terms cotangent and cosine, were introduced by Edmund Günther.
Otred's first ruler had two logarithmic scales, of which one easily shifted relative to the other, which was fixed. The second tool was a ring, inside of which there was an axis, and a circle rotated on it. On the outer surface of the circle and inside the ring, one could see logarithmic scales "folded into a circle." Both rulers could be used without resorting to compasses.
In the book of Otred and Forster called "Circles of Proportions", published in London in 1632, a description was given of a circular slide rule, although then there was a different design. In A Supplement to the Use of the Tool Called Proportional Circles, published the following year, Forster described Oughtred's rectangular slide rule in detail.
The right to make Orthred's rulers was given to Elias Allen, a well-known London mechanic. The ruler, which was a ring with a rotating circle inside, was invented by Richard Delamain (Ottred's former assistant). A detailed description of it was given in 1630 in the brochure Grammology or Mathematical Ring.
Delamain described several variants of slide rulers containing up to 13 scales. Other designs have also been proposed. Delamain presented not only the descriptions of the rulers, but also the graduation technique. They were offered ways to check the accuracy, as well as examples where he used his devices.
Most likely, Richard Delamaine and William Oughtred became the inventors of their slide rules independently of each other. And in 1654, the Englishman Robert Bissaker proposed the construction of a rectangular slide rule. Its general appearance has survived to our time.
Inventor Story by: William Oughtred and Richard Delamaine
A country: England
Time of invention: 1630
The inventors of the first logarithmic are the British mathematician and teacher William Oughtred and mathematics teacher Richard Delamaine.
The son of a priest, William Oughtred studied first at Eton and then at King's College, Cambridge, majoring in mathematics. In 1595 Oughtred received his first degree and entered the college council. He was then a little over 20 years old. Later, Ootred began to combine mathematics with the study of theology, and in 1603 he became a priest. Soon he received a parish in Albury, near London, where he lived most of his life. However, the real vocation of this man was the teaching of mathematics.
In the summer of 1630 Ottred was visited by his student and friend, the London mathematics teacher William Forster. Colleagues were talking about mathematics 
ke and, as they would say today, about the methodology of its teaching. In one of the conversations, Oughtred was critical of the Gunther scale, noting that manipulating two takes a lot of time and gives poor accuracy.
The Welshman Edmund Günther built a logarithmic scale, which was used in conjunction with two measuring compasses. Gunther's scale was a segment with divisions corresponding to the logarithms of numbers or trigonometric quantities. With the help of measuring compasses, the sum or difference of the lengths of the scale segments was determined, which, in accordance with the properties of logarithms, made it possible to find the product or quotient.
Gunther also introduced the now generally accepted notation log and the terms cosine and cotangent.
Is it the first 
Otred's neck had two logarithmic scales, one of which could be shifted relative to the other, fixed. The second tool was a ring, inside which a circle rotated on an axis. On the circle (outside) and inside the ring, “rolled into a circle” logarithmic scales were depicted. Both rulers made it possible to do without compasses.
In 1632, Otred and Forster’s book “Circles of Proportions” was published in London with a description of a circular logarithmic (already different design), and a description of Otred’s rectangular slide rule is given in Forster’s book 
“An addition to the use of a tool called Proportion Circles, released the following year. Otred transferred the rights to manufacture his rulers to the famous London mechanic Elias Allen.
The ruler of Richard Delamain (who was at one time Oughtred's assistant), described by him in the pamphlet Grammology, or the Mathematical Ring, which appeared in 1630, was also a ring within which a circle revolved. Then this brochure with changes and additions was published several more times. Delamain described several variants of such rulers (containing up to 13 scales). IN 
In a special recess, Delamaine placed a flat pointer capable of moving along a radius, which made it easier to use the ruler. Other designs have also been proposed. Delamain not only provided descriptions of the rulers, but also gave a calibration technique, suggested methods for checking accuracy, and gave examples of the use of his devices.
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