Rockgod writes to tell us about Google Earth's latest expansion. From the article: "Google skipped right past the third dimension and landed directly in the fourth (time) by offering historical maps on Google Earth. Now you can travel back in time — for example, I am looking at the globe of 1790. Don't expect detailed high resolution photography from days gone by, but it's still interesting to see old maps overlaid on the satellite imagery of today." I suppose a link to Earth4 would have been good.