The original sheet music of “Jingle Bells” is online at the Library of Congress website, here: http://memory.loc.gov/cgi-bin/ampage?collId=mussm&fileName=sm2/sm1857/620000/620520/mussm620520.db&recNum=1&itemLink=S?ammem/mussm:@OR(@field(AUTHOR+@od1(Pierpont,+J++))+@field(OTHER+@od1(Pierpont,+J++)))&linkText=0
I notice that the original tune has the same verse melody as still used, but the chorus is closer to that of “Jolly Old Saint Nicholas.” Just thought this was interesting.
The Hayden Quartet are said to have recorded a cylinder record in 1902 of “Jingle Bells” with the modern tune for the chorus.