This is generally regarded as the first "proper" Tintin book, and I had of course read it ages ago. I now realise that it shares a lot of the flaws of the generally disregarded first three, Tintin in the Land of the Soviets, Tintin in the Congo and Tintin in AmericaEvil Under the Sun a few years later. Another is the self-reference – an Arab chieftain greets Tintin by showing him a copy of Tintin in the Congo which he has acquired (more recent editions paste in instead the cover of Destination Moon, which actually comes later in the sequence). Basically not really as good as I had remembered, alas.