The letter's a manifest forgery, as I'll prove by confronting Feisul with it.

But there's a little oversight that should convince you it's a forgery.

Have you a magnifying glass, doc ?" Ticknor produced one in a minute, and Grim held the letter under the lamp.

On the rather wide margin, carefully rubbed out, but not so carefully that the indentation did not show, was the French word magnifique that had been written with a rather heavy hand and one of those hard pencils supplied to colonial governments by exporters from stocks that can't be sold at home.
"That proves nothing," Mabel insisted.

"All educated Arabs talk French.
Somebody on Feisul's staff was asked for an opinion on the letter before it went.