How to read the scales with graduation length of 20 inches: W 1 W 1 ' W 2 W 2 '

These scales are provided along the edges and adjacent edges of the slide, on the back of the slide rule, and run from 1 to 3.3 at the bottom and from 3 to 10 at the top. Their use results in doubled accuracy. They are sub.divided differently, however, from the scales on the 10 inch graduations.

Graduation range from 1 to 2.

This section is first of all divided into ten sub.divisions, marked 1·1, 1·2, 1·3, 1·4... 1.9. Each of these, in turn, is divided into ten further sub.divisions, but the latter are not numbered, owing to lack of space. Finally, a small stroke is also provided to show the exact centre between these graduation marks. Readings can be taken as follows: 1.1.2.5, 1.3.1.5, 1.4.4.5, 1.5.2.5, 1.7.1.5... 1.9.7.5.

Graduation range from 2 to 5.

Hero again, this section is first of all divided into tenths, but they are not numbered, except for the graduation marks corresponding to the values 2, 2.5, 3, 3·5. 4, 4.5 and 5. The user must recognise the remaining tenths for himself, i.e. the values 2·1, 2·2, 2.3 ... to 4·7. 4.8, 4·9. Further tenths are entered In between these tenths but without "marked centres". We thus hove the following values, starting with 2 and without using the decimal point: 2.0.0, 2.0.1, 2.0.2. 2.0.3, 2.0.4, 2.0.5, 2.0.6, etc., up to 4.9.7, 4.9.8, 4.9.9, 5.0.0.

Graduation range from 5 to 10.

In this range, the tenths first of all appear, as before, but in between these it is only the fifths that are provided. Starting with 5, we thus have the following graduation marks: 5.0.0, 5.0.2, 5.0.4, 5.0.6, 5.0.8, 5.1.0, 5.1.2, etc. up to 9.9.6, 9.9.8, 1.0.0. The reading range of these scales exceeds by far these possibilities. Further intermediate values, however, must be estimated.