BC

'B.C.' Before Computers

28^th April to 7^th July, 2007

A selection, from our collection, of weird and wonderful machines designed to help hard pressed secretaries and accountants of yore.

BEFORE COMPUTERS

Computers enable almost anyone do many tasks to a high standard which in the past a number of skilled people using special equipment used to do.

They have replaced many skills such as calculating and good handwriting which most people were taught, and have given many the opportunity to learn special skills such as document design and photograph manipulation.

Computers should save a lot of paper, but almost certainly produce far more than any office worker used to produce.

CALCULATORS

Before electronic calculators were invented in the 1960s, calculations were done in the head, on paper, with slide rules or on mechanical machines (sometimes powered by electricity to drive the mechanism).

Many people were very proficient at adding up complex numbers such as pounds, shillings and pence (£-s-d) in their heads. It was very difficult to devise a calculator to add up £-s-d so Britain changed to decimal currency in 1971.

£ s d

5 16 3

2 5 8

3 14 6

11 16 5

CALCULATING MACHINES

The first mechanical calculating machine was invented in 1887 in America.

These were made to do the calculations by rotating the mechanism with a handle. This action was replaced by electrical motors but they were still essentially mechanical.

Numbers are entered by sliding the leavers down to the correct number, then rotating the handle clockwise. The number appears on the right hand section of the carriage.

The arrow on the bar at the top indicates the position of a decimal point.

To add, change the leavers to the number required and rotate the handle clockwise. The answer will appear below.

To subtract, turn the handle anti-clockwise.

To multiply, rotate the handle as many times as required (e.g. to multiply 6 x 3 enter the number 6 and rotate the handle 3 times; to multiply 6 by 33, enter the number six, rotate the handle 3 times then move the carriage to the right by one step (equivalent to multiplying the number by 10) and rotate the handle once.

Division is more complex and involves subtracting one number from another until the answer is less than one, then moving the carriage back one place and repeating the process until the right-hand section of the carriage is zero. The answer appears in the left-hand side.