The book is available at Internet Archive, Hathi Trust, and Google Books.
Isolde
THE FLYING DUTCHMAN - Wikipedia
I. The Spellbound Seaman
II. In the House of Daland
III. Senta's Sacrifice
TANNHAUSER - Wikipedia
I. In the Venusberg
II. The Contest of Song
III. The Pope's Staff
LOHENGRIN - Wikipedia
I. The Coming of the Knight
II. Before the Minster
III. The Three Questions
IV. How the Knight Went Away
TRISTAN AND ISOLDE - Wikipedia
I. From Ireland to Cornwall
II. In Isolde's Garden
III. Kareol
THE MASTERSINGERS OF NUREMBERG - Wikipedia
I. Trial by the Masters
II. Hans Sachs, the Cobbler
III. The Cobbler's Workshop
IV. The Singing of the Mastersong
I made an animated gif of all the illustrations; click here for the full-sized view:
