The Observatory was particularly fun, as we brought our GPS in an attempt at finding the Prime Meridian.  We actually ended up in a field about 50 yards east of the line.  But after speaking with one of the museum people, Jon’s suspicions were confirmed that it had something to do with the Coordinate System set in the GPS.  We could not determine the right one to use, but found out that there are two different meridians!  All of the British Maps, which use the British Ordinance Survey Coordinate System, use a 2^nd meridian which is about 10 yards west of the Prime Meridian.  So, we reset the GPS to use the BOS CS, and Voila, it actually read 0 degrees longitude right on the other meridian.

The Observatory was much smaller than expected, but it was interesting to note that its instruments were the most advanced for its time.  One device, for reading the angle of stars above the horizon could only read the northern stars.  Halley was in charge at that time, and he could not afford a second one facing south.  His successor was finally able to add that.