`The people of Mali are, like us, suffering from water shortages. Fringing the Sahara, perhaps they have a better excuse'

"If you want to go to Timbuktu by boat, you will have to pay more for it." The treasures of the Thomas Cook Overseas Timetable, whose latest edition is published this weekend, are buried in reams of schedules - which makes them all the more rewarding when you find them.

PI Tremlett, the book's editor - and doyen of rail travellers all over the globe - sometimes lets his feelings show through the humdrum chronology of timetables. A note about railways in eastern Bolivia remarks that: "We have received confirmation that the details we show for the main lines are correct," followed by a mild dose of parenthetical exasperation: "(not, of course, that any of the services actually operate as scheduled)".

The autumn timetable ventures into political activism, with the request: "Please take the time to write to the US Embassy." America's railway system is facing a slow death because of budget cuts, and the editor suggests interested travellers should express their views to the US government.

What about reaching the desert city of Timbuktu in Mali by water? There is indeed a boat along the Niger once a fortnight, taking three days for the 550-mile journey from Koulikoro. The one-way fare has increased to about pounds 170; but, as Mr Tremlett points out: "If the water level stays as low as it has been, the vessels will not be able to sail in any case." So the people of Mali are, like us, suffering from water shortages. Fringing the Sahara, perhaps they have a better excuse.

"That old canard about the Great Wall of China being visible from the Moon is a prime example of how people today just don't think," writes Len Clarke of Uxbridge. I asked for confirmation that the wall is indeed visible, but Mr Clarke says I am unlikely to get it.

"The Moon is about 25 million wall-widths away. So if you can see the Great Wall of China from it, your visual acuity is such that you could also manage to see a human hair at a distance of five miles. Even if you were in low-Earth orbit of 100 miles, you'd be pushed to see the wall." That would be like seeing a hair at a distance of 10 feet, he explains. "QED, as they say."

The last postcard story of the summer comes from Robert Benzies of Coupar Angus in Scotland. "My story cannot exceed the pounds 7.80 you paid to post a card in Taiwan, but it could if one were daft enough."

Mr Benzies was on a side-trip to Israel from his holiday in Cyprus: "Coaching between Haifa, Tel Aviv, Jerusalem and Bethlehem, our proud and intelligent guide passed on his love of the Bible and his country's heritage. He was too bright to look for tips, but he knew we had no time to buy stamps if we were to get to the diamond-cutting factory before we sailed for Cyprus."

So the guide said his son would be happy to post cards for the tourists, if they could offer the money for the stamps. "Few seemed to give less than $10 [pounds 6], and the son has probably got a place at university."

Ian MacDonald of Stourbridge asked how to fill a six-hour wait at Charles de Gaulle airport in Paris, during a long connection for a flight to Toulouse.

George Matthews of Dorset has a simple solution: "Why doesn't he get into an RER train for Gare Montparnasse and take the TGV train to Toulouse? The journey time is about five hours. That's probably why there are so few planes."