A Cryptic Book Label Identified

A reader sent me this image and asked if I knew whose book label it is, suggesting that the letters in the central monogram might be read as "Daume". I didn't recognise it, but by Googling the unambiguous part, "EX LIB HEN RY", I was quickly able to find the answer.

In the digitized Archives de la Société des collectionneurs d'ex-libris ..., XI, nos. 9-10 (Sept-Oct, 1904), p. 142 is this:

"Duhamel (Henri [sic]), bibliophile à Gières, près Grenoble. ― Inscription en deux lignes: Ex ― lib. Hen ― ry ... "

Once one knows his name, one can discern in the monogram the constituent letters, and it also becomes easy to find more information about him. He has his own English Wikipedia page, almost as detailed as the French one. Here we learn that in addition to being a book collector, he was an author, mountaineer, and skiing pioneer; and we find a photo:

Wikipedia includes a link to another site with an image of the book-label:

and details of the dispersal of his library:

"il possédait une belle bibliothèque. Elle a été dispersée en 2 ventes à Lyon:

Catalogue de la bibliothèque de M. Henry Duhamel de Gières (Isère), 1ère partie: vente les 22-26 novembre 1921,
2e partie: vente du 15-20 mai 1922, 6 rue de l'Hôpital, Lyon. La 2e partie contenait: incunables - livres des XVIe et XVIIe siècles - Histoire - Géographie - Voyages - Littérature - Ouvrages sur les Alpes - Le Dauphiné et la Savoie - Atlas - Cartes - Plan"

 I have not yet consulted a copy of the catalogue, but hope to do so in due course.