Notes on using Java applets in browsers

updated: March, 2014

Test your browser's Java version by clicking here

Security changes in Java version 1.7.0
If you have installed this version of Java or the Java plug-in, you will only be able to run applets from sites that have created "signed versions" of the applets. Many, but not all of our applets have been converted and/or repackaged.

Regardless, you will still get a "Security Advisory" pop-up that will require you to agree to run the applets. While you may change the security level in the Java Control Panel, this is not advised.

If you upgrade to Firefox to version 3.6 or later...
You must install the Java 1.6.0_10 plug-in or later applets simply will not work! We have also found that you might need to clear out the Java cache ("Temporary Internet Files") using the Java Console.

Upgrade to Java 1.5 or 1.6 (version 1.6.x is preferred) -- BUT, beware the cache size!
For security and performance reasons, it might be a good time to upgrade to Java 1.6....however, it is very important to go into the Java Control Panel, and set the cache size to something reasonable! (In Java 1.5, the default is "unlimited", in Java 1.6 it is a GB!).

There are also issues coming to light regarding the amount of memory available for the Java Plug-in to use...which can even cause the plugin not to start. Please refer to this page for information on changing the values.

Important information regarding Java version 1.4.1 (May, 2003)
Try not to use Java version 1.4.l - it has significant problems with layouts of widgets and screen refreshing. If that version is installed in your browser, I recommend strongly that you revert back to version 1.3.1 or install 1.4.2...or jump to 1.5.
Information about Microsoft's support for Java - April, 2004
You might be interested in reading this page, and consider using the Sun JVM, as noted at the bottom. If you cannot use the Sun JVM and still have problems, you might consider trying to turn off the Microsoft VM's "JIT" -- Click here for details.

While we make every effort to keep our applets compatible with the various versions of Java available in common browsers, you might at times experience some difficulties. Here are some of our tips and notes that we hope will be helpful. If, after reading and trying out this information, you still have difficulties, please write to Tom Whittaker (tomw at Thanks!

General Instructions for enabling Java

What to do if you have a problem

The first thing to do is to find the "Java Console" and open it. This may be located in the "View" menu, the "Tools" menu, or the "Web Development" menu, depending on your browser. If you are using the Java Plug-in, then you can also launch the Java Console by clicking (sometimes right-clicking) on the Java icon when you try to run the applet.

If you have error messages in the Java Console, these will be very helpful to the software support people, and you should consider sending the text in the Java Console to them.

General Information on the Java Runtime

Try to use the Sun Java Plug-in whenever possible. If you experience an "out-of-memory" error, or receive messages about "multiple instances of Java running", please refer to this page and adjust the "heap space" memory