Safari, Apple's browser, has several features I like including the way it handles RSS feeds. It is possible to read the information offline. A new link in the browser allows a user to use RSS bookmarks in Mail. Feeds are listed in the sidebar and items are displayed like mail messages.

The calendar application, iCal, has some interface changes. Switching between panels (day, week, month) is at the top of the window; and a clearer calendar is displayed in the sidebar. Editing an entry in the main window is effected by double clicking; or using the Edit menu (or command + e). This reveals a new panel in which changes are made, then a "Done" button must be pressed. A red icon at the side with a line across the page indicates the current time. The line appears only in the current Week or Day displays.

Two of the most important changes to Leopard concern how links and external data may be used: Screen Sharing and Time Machine.

I sometimes receive phone calls early morning, or late at night. The main theme begins with, "Help". Trying to diagnose a user's problems using voice and ineffectual arm-waving is not easy: "What's the Finder" or "I don't see any file" are possible replies. It takes patience.

Being able to work on someone else's computer remotely would be a major help to such a process. Screen Sharing is intended for this. It can work either via the Finder or through the iChat program. Excellent descriptions may be found at the MacFixit site and at Ars Technica.

While Apple has had the Remote Desktop application for some years, this is intended for in-house use at a school. Using the Finder, it has also been possible to connect to a remote computer and access files, but not to run software or make changes.

Screen Sharing is usable not only on a local area network (LAN) but also over the internet, but will have problems if there is a router or if more than one computer is attached to that network. In such situations, iChat, which works using AIM, Jabber, Google Talk or .Mac accounts, would be the solution.

Although I have not yet been able to test this remotely, I have linked the computers in my home network and, like some ghost in the machine, could work on the eMac upstairs from my MacBookPro downstairs.

A few months ago, I bought an external hard disk as I needed a better backup system than CDs or DVDs. I also knew that Leopard had Time Machine which would require a hard disk.

A few hours after the update, when I was happy that my new installation was apparently stable. I inserted the hard disk connector into the Firewire port and opened the Time Machine preference panel.

The system recognises that a disk is available, but by default, Time Machine is Off and has to be turned on for the specific disk to be used. The first backup takes a long time. If there is more than one partition on the external disk, the transfer may be slowed if Spotlight indexes the others. Spotlight preferences can be used to drag the partition icon to the "Privacy" panel. Indexing will stop.

A full description of how it works is available from Apple Insider.

Whenever the disk is connected, the entire system will be backed up every hour, every day and every week. That does not mean a total backup as the FSEvents file records any changes and Time Machine only uses that. While my first backup carried over more than 50G of data, I noticed that one backup midweek was some 350MB.

Over the course of the first seven days, with the disk in my office, backups occurred when the hard disk was connected, but at home Time Machine was dormant and showed, Next Backup: When Disk is Connected. When the disk is connected I am able easily to scroll back to the data state that existed earlier and to access the file, as if it were current.

I did find that Time Machine will not run unless the power supply is connected: a safety feature so that backup is not a victim of a low battery. A complete system can be restored using "Restore from Time Machine" on the DVD Installer. Several computers can be backed up on the same disk.