Keith's astrolabes: initial settings of the applet
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Initial settings

If you run the program off-line, you can pre-set the details of your location, and these will then be used each time you run the program. The values you can enter are your latitude, hemisphere, longitude and timezone. The method you use will depend upon whether you run the program as an applet or an application.


If you run the program as an applet, you must alter either the index.html file, the mini.html file or the mini2.html file. These three files are similar, but the index.html file has links within the web site, as well as more information, which aren't usually needed off-line. All three files load and display the astrolabe applet, but the mini2.html file loads the applet with different initial values from those used by the other two files. If you load any of these three files into a text editor, you will find that there is a section which starts with the line:

<applet code=Open.class width=250 height=80>

Following it are eight lines: four information lines and four lines which set parameters.

<!-- value of latparam in degrees must be in range 2.0 to 88.0 -->
<param name=latparam value=21.0>
<!-- value of hemiparam must be n,N,north,North,s,S,south or South -->
<param name=hemiparam value="south">
<!-- value of longparam in degrees must be in range -180.0 to 180.0 -->
<param name=longparam value=56.0>
<!-- value of timezparam in hours must be in range -13.0 to 13.0 -->
<param name=timezparam value=4.0>

You can adjust any of the four settings which follow value=

With the settings shown in this example, the astrolabe which appears will be set for a latitude of 21.0° in the southern hemisphere, with a longitude of 56.0° and a time zone of 4.0 hours in advance of Greenwich Mean Time. These are the settings used in mini2.html. The other two files have settings for latitude 52.04°, north, longitude 0.0° and time zone of 0.0 hours. These are adequate for Keith's location, which isn't far from Greenwich in the UK. (It is even closer to the Museum for the History of Science, Oxford. Some of us were born lucky!)

The information line above each setting gives guidance on the possible entries. You should enter:
your latitude as the value of latparam,
your hemisphere as the value of the hemiparam,
your longitude as the value of the longparam,
and your timezone as the value of the timezparam.

Your latitude should be in the range of 2.0 to 88.0, without a positive or negative sign. It must include a decimal point and at least one number after the decimal point.

Your hemisphere can be either n, N, north or North if you live in the northern hemisphere, or s, S, south or South if you live in the southern hemisphere.

Your longitude should be in the range of -180.0 to 180.0. If you live on the Greenwich meridian, which has a longitude of 0.0 degrees, you would enter 0.0 of course, and in North or South America you would need the negative sign.

Your time zone should be in the range of -13.0 to 13.0, the negative sign being used if you live in North or South America, for instance.


If you run the program as an application on a PC, you will use a .bat file. If you download the .zip file, you will find it contains a file called Run.bat and a file called Runjv.bat. The former works if you have the Java Development Package. The latter works with Microsoft's Internet Explorer although the printing function doesn't work correctly on some systems, the screen flashing or the printout having all the characters but no lines, circles or arcs.

In fact, both the Run.bat file and the Runjv.bat file are identical apart from the first word on the last line. If you load the former file into a text editor, you will find that looks like this:

rem - after Open are four arguments
rem - latitude in degrees must be in range 2.0 to 88.0
rem - hemisphere must be n, N, north, North, s, S, south or South
rem - latitude in degrees must be in range of -180.0 to 180.0
rem - timezone in hours must be in range of -13.0 to 13.0
javaw Open 52.04 n 0.0 0.0

The opening lines explain how you can alter the four arguments in the last line. The arguments are the four entries after the word Open, separated with spaces.

Please don't expect my program to be robust. Don't try to crash it by changing the full stops to commas, by omitting the full stop and a following number, etc.. If the information in the rem lines isn't clear, you will probably find adequate information about the range of values in the section on applets, above.

You can contact me at

(Sorry, you can't click on this link.)

Copyright Keith Powell 1999-2002