Keith's astrolabes: printing the parts of the astrolabes displayed with my Java applet
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Printing paper astrolabes

I wrote the astrolabe program because I wanted to explore the features of astrolabes more easily than was possible by reading words and looking at photographs and drawings. By viewing my active astrolabe displays on the screen I partly achieved this objective. By printing out the components and assembling a 'paper' astrolabe, I found that understanding the workings of an astrolabe became so much clearer. For the same reason, I hope you will also want to print out paper astrolabes.

Calling them paper astrolabes isn't quite accurate. Although you will print out some of the components on paper, to make a working astrolabe you will need to print out other components on transparent film. Such film is readily availabe in shops selling computer supplies. It is intended for printing transparencies to be used with overhead projectors. Ensure you purchase film which is suitable for your printer - you need different kinds of film for inkjet and laser printers, and a different film is sold for photocopies.

As a compromise, you can print out on paper an active display (showing a plate over which is a rete) after selecting suitable variables. For instance, you could print a traditional astrolabe and an equinoctial astrolabe both with the rete set for midnight on the 15th of the present month. Similarly, the Universal Astrolabe is most often used with the rete rotated to suit your latitude, and you may want to print a second version with the rete rotated to 23.4 degrees. (There is a display intended specifically for the latter.) Currently, I don't provide displays which will allow the spherical astrolabe to be printed with the rete superimposed over the body.

I have written the program using the Java programming language at issue 1.0.2, which allows most people using the internet to view the applet using a Java-compatible browser, regardless of their computer platform. Unfortunately, printing cannot be arranged from the menu of a Java applet. If you want to print out a component of an astrolabe from the applet, it is necessary to make a copy of the window displaying the applet and then to load this into a suitable application for printing. On a PC, after setting the astrolabe window to a suitable size, this can be achieved by using Alt/PrtSc to copy the window to the clipboard, loading WordPad, using Ctrl/V to paste the clipboard into the WordPad window, setting the printing orientation to landscape, and, finally, printing.

If you can display Java applications (not applets) at Java 1.1 or above, you will find that after downloading the zipped version of the program, you can Run the program as an application. As an application, the window has an additional Menu item with the heading of 'Printing' which provides you with options to print the astrolabe window (including the button panel) or just the astrolabe area. This provides slightly higher quality than you obtain when printing a pixel by pixel image of the screen, but the graduations of the scales will highlight a Java limitation. With Java, all dimensions used by the program have to be given in pixels, and the nearest pixel is often not really adequate to define the start and finishing point of a line or arc. The result is that short lines are frequently drawn at an oblique angle to their ideal position, and equally spaced circles are drawn with unequal spacing.

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Copyright Keith Powell 1999-2002