[Max_Almond]

In 'Earth Not a Globe' Rowbotham states:

"In the account of the trigonometrical operations in France, by M. M. Biot and Arago, it is stated that the light of a powerful lamp, with good reflectors, was placed on a rocky summit, in Spain, called Desierto las Palmas, and was distinctly seen from Camprey, on the Island of Iviza. The elevation of the two points was nearly the same, and the distance between them nearly 100 miles. If the earth is a globe, the light on the rock in Spain would have been more than 6600 feet, or nearly one mile and a quarter, below the line of sight."

http://www.sacred-texts.com/earth/za/za19.htm

I have some questions about that:

1. What was the altitude of the two summits?

2. Why does Rowbotham say the lamp "should have been 6600 feet below the line of sight"?

Even if the peaks were only 500 feet high, that means less than 3000 feet would have been below the line of sight.

Did Rowbotham make a mistake?

[Max_Almond]

In fact, even if the peaks were only 35 feet high - and I think we can safely assume they were a good deal higher than that - then "the light on the rock in Spain" would only have been around 5000 feet below the line of sight.

So I guess there's not a chance in a trillion that Rowbotham wasn't wrong on this, right?