On stationery with the letterhead of the Hotel Bristol, Paris.
The book to which Broadley is referring is probably his Chats on Autographs, published in 1910. The Library has a copy of the book inscribed to J. Pierpont Morgan by the author.
Presenting to him a copy of his book on autograph collecting; mentioning that it has received an enthusiastic reception in the United States and earned the particular praise of "our mutual friend Mr. Adrian H. Joline"; concluding "I ask you as a great collector to accept it from a very humble fellow -- worker in that great field which is to make history for posterity."