If you follow the link I posted you will see the text as it appears in the book titled "A Course of Instruction in Ordnance and Gunnery."
I also have a copy of the Scribner book from 1872. It contains the same text with regards to selecting and felling timber, with several references to "ordnance". Rudy is correct that this refers to the carriages that artillery was mounted to.
I find it curious that the same text occurs in both books without a reference to the other. My best guess is that the Scribner book plaigerized the "Ordnance" book-- that would explain the strange preoccupation of the Scribner book with timber for "ordnance" purposes.
The Scribner book is primarily a book of tables listing cubic volumes for different log diameters and lengths and board foot tables for different scantlings. It appears the entire 3 page section on selecting, felling, and seasoning timber has been lifted straight out of the ordnance book.
Here is another link to the ordnance book. ordnance book