I spotted this auction a couple of weeks ago and promised myself that if I won the lottery I would buy the two panels from the "Le Soir" version of
Les 7 Boules Des Cristal. Not only one of the best books of the series (in my opinion), but the ball lightning sequence is one of my favourites - and also, these panels weren't published in the book giving them an added curiosity value; Hergé redrew a larger panel for the entrance of the ball lightning leaving these out of the final book.
I recently got a copy of the book
Les Mystères des 7 Boules de cristal, which is a re-publication of the "Le Soir" version of the story as it appeared in daily strips (more about that in
this thread). Note, in the panel numbered 163 of the catalogue Haddock originally shouts "La foudre!", which is French for "Lightning!". The lettering has been whited out, or by the looks of it completely cut out, perhaps with the intention of having it in the final book? I also love the solo Haddock panel (number 164 in the catalogue) of him jumping clear of the ball. This was adapted and incorporated into the larger panel that Hergé redrew for the book, allowing him another chance to have Haddock lose yet another monocle.
Needless to say, I haven't won the lottery, so good luck to whoever can afford to have a punt on them...