Introduction to the Slide Rule
11
William Oughtred and others developed the slide rule in the 17th century based on the emerging work on logarithms by John Napier. Before the advent of the pocket calculator, it was the most commonly used calculation tool in science and engineering. The use of slide rules continued to grow through the 1950s and 1960s even as digital computing devices were being gradually introduced; but around 1974 the electronic scientific calculator made it largely obsolete Introduction to the Slide Rule
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Introduction to the Slide Rule. - PowerPoint PPT Presentation
Transcript of Introduction to the Slide Rule
William Oughtred and others developed the slide rule in the 17th century based on the emerging work on logarithms by John Napier. Before the advent of the pocket calculator, it was the most commonly used calculation tool in science and engineering. The use of slide rules continued to grow through the 1950s and 1960s even as digital computing devices were being gradually introduced; but around 1974 the electronic scientific calculator made it largely obsolete
Introduction to the Slide Rule
0 1 2 3 4 5 6 7 8
Addition Using a Ruler
0 1 2 3 4 5 6 7 8
What addition sum does this show?
2 + 3 = 5 2 + 4 = 62 + 5 = 7 …
Alternatively this could be seen as a subtraction:5 – 2 = 36 – 2 = 47 – 2 = 5…
0 1 2 3 4 5 6 7 8
Addition Using a Ruler
0 1 2 3 4 5 6 7 8
What addition sum does this show?
4 + 3 = 7 4 + 4 = 84 + 5 = 9 …
Alternatively this could be seen as a subtraction:5 – 4 = 16 – 4 = 27 – 4 = 3…
Logarithmic Scales
1 2 4 8 16 32 64 128 25620 21 22 23 24 25 26 27 28
0 1 2 3 4 5 6 7 8
We are going to replace the numbers 0, 1, ,2, 3 … with Powers of 2
1 2 4 8 16 32 64 128 25620 21 22 23 24 25 26 27 28
0 1 2 3 4 5 6 7 8
1 2 4 8 16 32 64 128 25620 21 22 23 24 25 26 27 28
0 1 2 3 4 5 6 7 8
Logarithmic Scales
1 2 4 8 16 32 64 128 25620 21 22 23 24 25 26 27 28
1 2 4 8 16 32 64 128 256
This leaves us with the logarithmic scale shown below.When we move one unit along instead of adding 1 we are doubling
This has the effect of extending the scale from the original 0 to 8 to 1 to 256If we had picked Powers of 3 it would have been an even larger range …
1 2 4 8 16 32 64 128 25620 21 22 23 24 25 26 27 28
0 1 2 3 4 5 6 7 8
Logarithmic Scales on a Slide Rule0 1 2 3 4 5 6 7 820 21 22 23 24 25 26 27 28
1 2 4 8 16 32 64 128 256
We are now going to put the two logarithmic scale together and see why this is useful
We are now going to put the two logarithmic scale together and see why this is useful
1 2 4 8 16 32 64 128 25620 21 22 23 24 25 26 27 28
0 1 2 3 4 5 6 7 8
Logarithmic Scales on a Slide Rule
0 1 2 3 4 5 6 7 820 21 22 23 24 25 26 27 28
1 2 4 8 16 32 64 128 256
Previously we used this to show that 2 + 3 = 5Or 5 – 2 = 3
1 2 4 8 16 32 64 128 25620 21 22 23 24 25 26 27 28
0 1 2 3 4 5 6 7 8
Logarithmic Scales on a Slide Rule
0 1 2 3 4 5 6 7 820 21 22 23 24 25 26 27 28
1 2 4 8 16 32 64 128 256
Looking at the logarithmic scale we see that 4 x 8 = 32Or 32 / 4 = 8
1 2 4 8 16 32 64 128 25620 21 22 23 24 25 26 27 28
Logarithmic Scales on a Slide Rule
20 21 22 23 24 25 26 27 28
1 2 4 8 16 32 64 128 256
If we look at the powers we can see that 2 + 3 = 5It becomes a multiplication because 22 x 23 = 25
We are adding the powers and therefore we are multiplying the numbers
1 2 4 8 16 32 64 128 25620 21 22 23 24 25 26 27 28
Logarithmic Scales on a Slide Rule
20 21 22 23 24 25 26 27 28
1 2 4 8 16 32 64 128 256
If we look at the powers we can see that 3 + 4 = 7It becomes a multiplication because 23 x 24 = 27
Or a division because 27 ÷ 23 = 24
This is a simplified slide rule with just the two scales: Click here
This is complete slide rule (Use the A&B scales which go up to 100 or C&D scales which go up to 10): Click hereIf you Flip the middle scale (see top right of the Slide Rule) you can see some convenient conversion scales.
D to A is squaringD to K is cubing
