1.75" and only the second we know of. Reverse has W&H backpaper used only 1898-1900. Reads "Fatima, The Midway Dancer At Hagenback's." Hagenback's was a famous menagerie and traveling circus which appeared at the 1898 Omaha Expo as well as the 1904 St. Louis Expo. Given the backpaper design and use of the word "Midway," it's likely this button was a Trans-Mississippi Expo promotional giveaway. Our Collectible Pin-Back Button book example in Auction #191 exceeded $600. This is the only other example known to us and is Exc. displaying Mint.