Widespread counterfeiting of the first issue of fractional currency (Postage Currency) led Spencer Morton Clark to state that in order to protect the public, a new issue was needed.  The second issue (sometimes referred to as the first issue of Fractional Currency) was released on October 10, 1863 and ended on February 23, 1867.  The total of all four denominations was 161,341,194 notes with a face value of $23,164,483.65. It was estimated that 27,567,597 notes were still extant in 1884. 

About a year ago, I concluded my blog series on Large Size Replacement Nationals.  Since then, I've given a presentation and printed an 8-page handout for Memphis 2013.  The presentation (it can be downloaded here: https://www.spmc.org/member-presentations) was well received and was the best attended seminar at the convention.  An article is forthcoming in Bank Note Reporter.