The Slide Rule

Early forms for doing calculations.

The Abacus

The Chinese Abacus

The School Abacus

The Mechanical Calculator

Then came:“The Slide Rule” Prior to 1980, Webster's Dictionary

defined the word “COMPUTER” as a person who computes, typically with a slide rule!

““History of the Slide History of the Slide Rule”Rule”

16301630 - Invention of the slide rule by William - Invention of the slide rule by William Oughtred Oughtred

18901890 - William Cox of the U.S. patented the slide - William Cox of the U.S. patented the slide rule.rule.

1950 thru 19701950 thru 1970 - The precision of the slide rule - The precision of the slide rule causes it to be used extensively by scientists and causes it to be used extensively by scientists and engineers.engineers.

19761976 - The final slide rule made by K&E donated to - The final slide rule made by K&E donated to the the

Smithsonian Institute, Washington, DC, USA.Smithsonian Institute, Washington, DC, USA.

During the 1960’s, the slide rule was used by every During the 1960’s, the slide rule was used by every scientist and engineer. scientist and engineer.

Knowing the principles of a slide rule Knowing the principles of a slide rule help understand the nature of a help understand the nature of a

logarithm.logarithm.

What is a logarithm?What is a logarithm?

A logarithm is the A logarithm is the exponentexponent or or powerpower to which a stated to which a stated number, called the base, is raised to yield a specific number.number, called the base, is raised to yield a specific number.

The logarithm of 100 to the base The logarithm of 100 to the base 10 is 2 10 is 2

This is written: log 10 100 This is written: log 10 100 = 2 = 2

So the logarithm is _____ ? So the logarithm is _____ ?

Apollo 11 Apollo 11 - - NASA's Lunar Lander space NASA's Lunar Lander space vehicle, with the crew Neil Armstrong, Buzz vehicle, with the crew Neil Armstrong, Buzz

Aldrin and Michael Collins carried the slide rule, Aldrin and Michael Collins carried the slide rule, for the first time in history, into space and onto for the first time in history, into space and onto

the Moon! the Moon!

July, 1969.July, 1969.

The Pickett 600-T (white) was taken by The Pickett 600-T (white) was taken by

the Apollo the Apollo 1111 NASA astronauts to moon! NASA astronauts to moon!

The First Pocket Calculator

The HP-35 “Slide Rule Calculator”

First introduced in mid-1970's

Sold for $295.00 or

$3000 in today's money!

Parts of the Slide Rule

Using the Slide Rule

Multiplication (uses C and D scales)Example: calculate 2.3 × 3.4

Using the Slide Rule

Simple Division (use C & D scales) Calculate 4.5 / 7.8

1. Move the cursor to 4.5 on the D scale. 2. Slide 7.8 on the C scale to the cursor.

Calculate the following:

1.9 x 5 = ?

Calculate the following:

3.1 x 5 = ?