  The recurrent nova T CrB was one of the first well observed nova eruptions in
1866, and 80 years later it erupted again in 1946. Just after the 1866
eruption, Sir John Herschel reported to the Monthly Notices that he had seen
the same star in his naked-eye charting of the sky on 1842 June 9, implying
that there was a prior eruption 24 years earlier. Unfortunately, the chart in
the Monthly Notices was ambiguous and misleading, so it has long been unclear
whether T CrB did indeed have an eruption in 1842. To resolve this, I have
searched the various archives with Herschel material, and have found his
original correspondence. In one letter from 1866 to William Huggins, Herschel
enclosed his own copy of his original observations, and with this all the
ambiguities are resolved. It turns out that Herschel's indicated star was at
the same position as a steady background star (BD+25{\deg}3020, V=7.06, G8V)
and not that of T CrB, and Herschel regularly was seeing stars as faint as
V=7.5 mag because he was using an opera glass. With this, there is no evidence
for a T CrB eruption in 1842.
