The History of Mechanical Calculator Development
Timeline created by jessbugcman

Nov 18th, 1387
The 1st calculating machine ABACUS
It was 1st developed in the 13th century by the Chinese. It is still used today in a "modern version". 
'Napier's Bones'
"John Napier, the inventor of logarithms, also invented this aid to calculation known as 'Napier's Bones'.The 'bones' consist of a set of rectangular rods, each marked with a counting number at the top, and the multiples of that number down their lengths. When aligned against the row of multiples as shown, any multiple of the top number can be read off from right to left by adding the digits in each parallelogram in the appropriate row. Multiplication is thus reduced to addition." 
The Slide Rule
This was a joint effort by two Englishmen Edmund Gunter and the reverend William Oughtred. This slide rule consisted of two logarithmic scales that could be manipulated together for calculation. SLIDE RULE 
The Pascaline
The Pascaline was possibly the first mechanical adding device actually used for a practical purpose. It was built by Blaine Pascal to help his father, Etienne Pascal, a tax collector, with the tedious activity of adding and subtracting large sequences of numbers. 
Leibniz Stepped Drum
The famous German polymath, mathematician and philosopher, Gottfried Wilhelm Von Leibniz invented a machine able to perform the four basic arithmetical operations. It uses a special type of gear named Leibniz Wheel which is a cylinder with nine barshaped teeth of incrementing length parallel to the cylinder’s axis. 
Calculators of th 18th Century.
There weren't many advancements made during the 18th century in regards to calulator development and portability. There were a few main ones: Stanhope's Machine 1775; POLENI'S MACHINE  Italy  1709 1727</a> 
Arithmometer
Charles Xavier Thomas was a French inventor and entrepreneur best known for designing, patenting and manufacturing the first commercially successful mechanical calculator called the Arithmometer. 
Scheutz Difference Engine
The world's first printing calculator, the Scheutz Difference Engine was introduced around 1853. It was built by George Scheutz and his son Edvard, based on the work of their friend Charles Babbage who later became known as the "father of computing". 
Pin Wheel Calculator
Start of period of development of commercially successful mechanical calculators. Frank Baldwin in the USA invents the pinwheel calculator. 
Bollee's Direct Muliplication Machine
Bollee was the first person to develop a machine capable of direct multiplication, The idea had originally been though of by a Spaniard, living in New York, called Ramon Verea,.
Bollee’s machine was one of the earliest of its type and was a direct multiplier with a builtin multiplication table 
Comptomer
Dorr E. Felt invents the Comptometer, the first succesfull keydriven adding and calculating machine. In 1886 he joined with Robert Tarrant to form the Felt & Tarrant Manufacturing Company which went on to make thousands of Comptometers . 
Millionaire Calculator
Millionaire calculator introduced. It allowed direct multiplication by any digit  "one turn of the crank for each figure in the multiplier". 
10 key adding machine
The Dalton addinglisting machine was the first of its type to use only ten keys  first 10key addlister. 
Curta I
A stepped gear type calculator capable of the four functions, and more using special techniques. One of the few major innovations in mechanical calculators in the mid 20th century. HAND HELD 
The Friden SRW
The Friden SRW was an imposing calculator weighing 42lbs. T MOST NOTABLE FOR BEING ABLE TO DO SQUARE ROOT function.. 
Madas 20BZS
Mechanical, electrically driven, steppedgear calculator.
4 functions  addition, subtraction, multiplication, division.
The accumulator is at the top and can show a result to 20 places of decimals. The numbers entered can be to 10 places of decimals. 
Period: to
1900 1975 Mechanical Calculators
Steady development of mechanical calculators  size reduction, electric motor drive, added features(eg. automatic multiplication & division).