Modern Bygrave Slide Rule Emulator

Settings User Notes

Please wait whilst the scales are being constructed.

USER CONFIGURABLE ITEMS

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Please note that there will be a delay after any change whilst the scales are being reconstructed.

NUMBER OF ROWS Default 45.
The number of rows (which must be an odd number).
LENGTH OF ROW Default 1200.
The length of each row in pixels. Ideally about 90% of your screen pixel width.
MAXIMUM VALUE Default 89°.
89° will draw a more compact display than the Bygrave Mk II, which has a maximum value of 89° 40'.
1. The Bygrave Mk IIA slide rule has a helical cotangent scale on the inner cylinder that has 45 turns and an effective length of about 7.6 metres or 300 inches. A typical modern laptop has a screen resolution of about 180 pixels per inch. So, the default NUMBER OF ROWS of 45 and the default LENGTH OF ROW of 1200 pixels will give a total scale length of 54000 pixels and a total length of around 300 inches.

2. You may choose to use (say) 90% of your screen width for LENGTH OF ROW and take advantage of fewer rows.

3. You can gain greater definition by increasing the NUMBER OF ROWS and LENGTH OF ROW. If you do so, it will probably overflow the screen window and you will then need to use the window side or bottom scroll bars. You can also zoom the screen (Ctrl + Wheel) to achieve a similar effect.

Flat Bygrave Slide Rule Emulator - USER NOTES

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INTRODUCTION
1. This slide rule emulation is designed to be used on a desktop or laptop computer with a genuine mouse.
It is not intended to work when using fingers or stylus on touch screens. Testing has only been done on Windows 10 systems with various browsers.

2. Upon initial load, and whenever the settings are changed, there is a noticeable delay whilst the scales are redrawn.

ON-SCREEN CONTROLS
1. The (black) cotangent scale cannot be moved.

2. The (red) cosine scale is moved by dragging with the left mouse button depressed.
When mouse released in approximately the desired position, the scale will 'snap' to the nearest horizontal line. The scale can then be accurately positioned by clicking the left or right mouse button. (Alternative - 'l' or 'r' keys).

3. The red cosine scale can be frozen by PRESSING the MIDDLE mouse button/wheel. (Alternative 'f' or 'v' keys).
This simultaneously displays a vernier (see 7 below) and the border turns BLUE.
A second press unfreezes the cosine scale and restores the red border.
Such freezing of the cosine scale can be useful to ensure an established setting is not accidentally moved whilst scrolling to find the solution value.

4. Unlike a true Bygrave, the scale is sub-divided into many rows rather than being helical.
If you find that you need to be at the 'other end' of a row, move the mouse over the red edge border which will turn green. Now left clicking it will 'Snap' the entire scale to EXACTLY the opposite end position. At the same time, snapping will move the cosine scale up or down by exactly one row. Alternatively, you can 'Snap' by pressing the 's' key.
Snapping will still work (outside the vernier area) whilst the cosine scale is frozen.

5. When setting the cosine scale against the background cotangent scale, always adjust 'RED over BLACK'.

6A. To SCROLL the entire window, use the mouse wheel. (Except when the mouse is within the vernier area.)
6B. To ZOOM the entire window, use the 'Ctrl' key + mouse wheel.
Zooming can be very useful to set/read accurate values

7. To show the vernier, press the mouse middle button or 'f' or 'v' key. (Second press hides vernier.)
To move the vernier, drag with the mouse as with the cosine scale.
To fine adjust the vernier horizontally, use left/right click or 'l'/'r' keys as above.
To fine adjust the vernier vertically, use the mouse wheel or 'u'/'d' keys.
You may like to use the vernier's left or right edge lines as a cursor. None of the splayed lines are vertical.
Use the vernier in places where the graduations are widely spaced. Set the outer lines exactly on the outer marks and use the four inner lines to help estimate tenth's of the appropriate unit.
The vernier's exact position is remembered for next use. (Hold the mouse steadily or use f/v key!)

8. The window vertical and horizontal scroll bars are also useful if you have intentionally overzoomed to gain better resolution.

SETTINGS PAGE
Separate help information is given on that page.

VERSION. Beta Test 2020 March 5th 2150 UTC + 13
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