Seems like they've been around moisture at one point in their lives, but in good condition for being over 100 years old. Some of the pages are a little wrinkly but no water spots. Some discoloration and cover wear

The Hound of Baskerville has some math problems written on the inside cover

Adventures of Gerard - 1903

The Green Flag - 1900

Sir Nigel - 1906

The Hound of Baskervilles - 1902

Let me know if you have any detailed questions about condition