Mathematicians Yost Byurgi and John Napier made tables of logarithms. They performed long-term laborious work. Considerably facilitated work of thousands of calculators who used these tables.

In the sixteenth century navigation rapidly developed. Therefore observations of celestial bodies were improved. For simplification of astronomical calculations at the end of 16 – the beginning of 17 centuries there were logarithmic calculations. The value of a logarithmic method consists in data of multiplication and division of numbers to addition and subtraction. To actions by less labor-consuming. Especially if it is necessary to work with multidigit numbers.

## Byurgi method

The first logarithmic tables were made by the Swiss mathematician Yost Byurgi in 1590. The essence of its method was as follows. To increase, for example, 10,000 by 1,000, it is enough to count number of zero in a multiplicand and a multiplier, to put them (4 + 3) and to write down the work of 10,000,000 (7 zero). Factors are the whole degrees of number 10. At multiplication the indicators of degrees develop. Also division is also for short carried out. It is replaced with subtraction of indicators of degrees. Thus, it is possible to divide and multiply not all numbers. But they will become more if as the basis to take the number close to 1. For example, 1.000001. And the mathematician Yost Byurgi arrived four hundred years ago. The truth the work "Tables of arithmetic and geometrical progressions, together with thorough manual …" he published only in 1620. Yost Byurgi in Liechtenstein was born on February 28, 1552. From 1579 to 1604 Hesse-Kassel of William IV served as the court astronomer at the landgrave. Later at the emperor Rudolf II in Prague. One year prior to the death, in 1631, it returned to Kassel. Byurgi is known and as the inventor of the first pendulum clock.

## Napier's tables

In 1614 John Napier's tables appeared. This scientist took the number close to unit for the basis too. But it was less than unit. The Scottish baron John Napier (1550-1617) studied in the homeland. Liked to travel. Visited Germany, France and Spain. In 21 years returned to the family estate near Edinburgh and lived to death there. Studied divinity and mathematics. Studied the last according to Euclid, Archimedes and Copernicus's compositions.

## Decimal logarithms

Napier and Englishman Briggu possess the idea of drawing up the table of decimal logarithms. They began work on recalculation of earlier made Napier's tables together. After Napier Brigg's death continued it. He published work in 1624. Therefore decimal logarithms are called still briggovy. Drawing up logarithmic tables demanded from scientists of long-term laborious work. But many times over the labor productivity of thousands of calculators who used the tables made by them increased.