http://www.hsp.org/library/guides/cwmss.html

In the category of "things found while looking up other things" is this reference from the Guide to Civil War Manuscript & Newspaper Collections at the Historical Society of Pennsylvania:

Snowden, James Ross. Diary (1864-65). Co. 'I,' 23rd PA Infantry & Co. 'I,' 61st PA Infantry & Co.'I,' 61st PA Infantry. Collection no. 616; call no. Am .1565.

The reference is on this web page:

Pete Smith's Snowden entry in "American Numismatic Biographies" notes that "Snowden was appointed Director of the Mint by President Pierce serving June 1853 to April 1861... He resigned to accept an appointment with the Supreme Court of Pennsylvania and served there until 1873."

So ... does this diary belong to a different James Ross Snowden?