Here is a new picture. This dust jacket is for book #10 (Tommy Foster’s Adventures). Dating it is relatively easy.

First note that the jacket is brown and uncoated. These jackets were done prior to 1915.
The back of the jacket has the title Boy Geologist on it. This title was added to the series in 1910.
The price of the books listed on the back of the jacket is $1.00. The $1.00 price was advertised until 1911.

Thus this book was published between 1910 and 1911.

Of note is that the internal ads do not list the Boy Geologist. This probably indicates a 1909 book with an early 1910 jacket. Thus overall an early 1910 book/jacket.

Dating the books of this series is discussed at http://henryaltemus.com/series/series125.htm .