Follow this link to read the entire 4 page letter.
In The Collected Works of Abraham Lincoln, Volume 4 by Abraham Lincoln (link below) Lincoln
The following link will take you to a page from The Washington Times (May 27, 1905) that has an article and photo featuring John M. Carson, Sr. (about age 67)
John Miller Carson Sr. did go on to work for the goverment and presidents such as McKinley and Theodore Roosevelt. He twice served as President of the Gridiron Club, nicknamed the "Father of the Gridiron Club" and credited with naming the club.
From "Society in Washington: ITS NOTED MEN, ACCOMPLISHED WOMEN, ESTABLISHED CUSTOMS, and NOTABLE EVENTS," BY RANDOLPH KEIM, AUG 3 1887, Washington, D. C.
p. 212 SOCIETY IN WASHINGTON.
"John M. Carson, of the Philadelphia Ledger, began his career as a local reporter on Forney's Pennsylvanian, entered the Twenty-seventh Pennsylvania volunteers in 1861 as lieutenant, and rose to captain. After the war he resumed journalism, in 1873, coming to Washington as editor of the National Republican, A year later he became assistant, and soon after chief of the New York Times bureau, which he resigned in 1884, retaining his connection with the Ledger." He was also a news coorespondent for the Philadelphia Public Ledger. He became the chief of the Washington Post bureau and then delved into politics being elected as the Chief of the Bureau of Manufacturings of the American Department of Commerce and Labor in 1905 under President T. Roosevelt. He earned $4,000 for this job.
JM Carson, Sr. passed in 1912, his wife in 1932. John Miller Carson Sr. and his wife Anna Lavinia Miller Carson are buried in Arlington National Cemetery."