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Gunter's scale

Ruler with logarithmic scales made by Gunter. Gunter mounted this lines, together with other lines giving the logarithms of trigonometric functions, upon a ruler or scale, commonly called "Gunter's scale" (10)

1621

The Calculator Ruler, an improved and possibly simplified model of the calculator disc was invented.

This ruler stayed the most important calculating tool for engineers and others until well into the 1970's, when electronic calculators became available at affordable prices in the form of the Hewlett Packard HP35 scientific calculator.

1622

(1620)

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Oughtred circles of proportion (pub. in 1632)

William Oughtred (1575-1660) invents, on the basis of Napiers' theory, the logarithmic calculating disk. (1644^(8a) 1622^{(11a), 1632(7)}

But Oughtred did not think his invention is worth publishing. Others improved on his design. But it will take until 1850 for this tool to be improved by a French officer Amedee Mannhein in the form of a slide ruler, to become generally accepted by others than scientists and mathematicians. Until then it was regarded as a "toy" for the latter.

However his invention is disputed by one of his students: Richard Delamain (1600-1644) and later fellow. It is presumed that Oughtred was there first but Delemain was the first to publish. It is undisputed that Oughtred invented the rectilinear sliderule in 1633.(9)

1623

1624⁽¹⁾

Wilhelm Schickard

Dr. Franz Hammer of Stuttgart, while he researched Johann Kepler's papers, discovered some letters from Prof. Wilhelm Schickard (1592-1635), a professor at the University from Tübingen (Germany). The letters described the working of a calculating mechanism.

Kepler(14)

In a letter dated September 1623, Schickard wrote: "The same thing which you have done by hand calculation, I have just recently tried to do in a mechanical way."

^(11b)

"I have constructed a machine which automatically reckons together the given numbers in a moment, adding, subtracting, multiplying and dividing."

The next letter contained sketches of the machine, and a third told the sad story of the machine being destroyed by fire. No records exist of the events that led Schickard to build a calculator, although he was familiar with Napier's logarithms and his bones.

^(11b)

It's hard to tell how successful his machine would have been because he didn't rebuild it. But he would have had to overcome the problems that the inventors of this visionary period encountered, such as lack of precision and over-rotation of the wheels.

It is was construction that shifted a 1 to the left when the sum of a certain column became greater than 9. This was the first known description of an adding machine.
It also was the first counting mechanism that added and subtracted with automatic carry of tens and with 6 digits. It is called a "Calculating Clock" (ref. Niel Brandt 1994), see picture below.
The mechanism was said to be designed for the astronomer Kepler who wanted to perform calculations on the paths of stars and other celestial bodies. It was Dr. Bruno Baron von Freytag Löringhoffater, with the help of sketches and copperplates, who managed to build a reconstruction.
Since no original copies of Schickard's machine have been found the credit for the first adding machine with automatic carry is often given to Blaise Pascal.²³

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Finding a way to transport or 'carry' the tens turned out to be a very important development, which we now consider obvious.
But we should not forget that in this time everything, including calculation, was done by hand or heart. A relatively small business easily employed a few dozen of calculators. The few people with knowledge of counting and calculation were held in high esteem. The technology of using gears was only known to a few engineers. And in this light, a mechanism that counts the tens automatically was an invention of extraordinary proportions.

1624

In this year Henry Briggs published his first logarithmic table with base 10

1637

Descartes formulated the theorem of optical breaking and the principles of modern analytical geometry.

Descartes is a skeptic, a classical philosophical trend which gained a following in the seventieth century. He drove skepticism to the extreme in his

Discours de La Methode.

In which we wrote his famous conclusion: I think therefore I am

This statement contributed tremendous to the phylosophical thinking in the 'Age of Enlightenment' and shaped the deterministic approach of the world like the western civilization uses now.

1642

Blaise Pascal (1623-1662) from France developed a mechanism to calculate with 8 figures and carrying of 10's , 100's, and 1000's etc. (nine-s complement)

The machine is called the 'Pascaline' but the machine never performed flawlessly and didn't sell.
While several models were completed, Pascal's machine  was more likely to be found in the living rooms of their owners as a conversation piece rather than in the work room.

Pascal tried many different methods and some 50 models were discarded. He truly believed that his machines would save men hours of labor. However, they did not work well. Accurate gear cutting was difficult in that time. The mechanisms were always out of alignment and only Pascal and one of his workmen could fix them.^(11b)

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want to know

1646

One of the first references to the word COMPUTER is given by Sir Thomas Brown. He spoke of : "The calendars of Compotystes.⁽²⁾"

1660

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The technological advances in watchmaking caused many watchmakers to design calculators based on Pascal's original designs. This one is a fine example by J. Sauter, displayed at the Science Museum in London, UK.

1666⁽³⁾

Sir Samuel Moorland, master of mechanics to King Charles II of England, designed a more or less mechanized sector: "the trigonometrically calculating machine".
A sector was the forerunner of the slide rule like it was used between 1950-1980 and looked like a pair of compasses, with numbers engraved at specific distances on the legs. The width (span) of the legs in combination of the engraved numbers could be used to multiply in some way. Moorland put a few gears on the sector that mechanized the contraption. He also improved on the Pascaline

^(11b)

1668

Sir Samuel Morland constructed the money adder(13); a non-decimal adding machine suitable for use with English money. It uses auxiliary dials instead of a carry meachanism and this required the user to re-enter the numbers manually.(18) This is the first calculator in the UK.

1670

Blaise Pascal's Pensées published posthumously. This work became very important and of great influence on the way of thinking of the western world.

Last Updated on 22-jun-04

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Footnotes & References