  The abundance of holmium (Z = 67) in the Sun remains uncertain. The
photospheric abundance, based on lines of Ho II, has been reported as +0.26 +/-
0.16 (on the usual scale where log(H) = 12.00), while the meteoretic value is
+0.51 +/- 0.02. Cowan code calculations have been undertaken to improve the
partition function for this ion by including important contributions from
unobserved levels arising from the (4f^{11}6p + 4f^{10}(5d + 6s)^{2}) group.
Based on 6994 computed energy levels, the partition function for Ho II is 67.41
for a temperature of 6000 K. This is approximately 1.5 times larger than the
value derived from the 49 published levels. The new partition function alone
leads to an increase in the solar abundance of Ho to log(Ho) = +0.43. This is
within 0.08 dex of the meteoretic abundance. Support for this result has been
obtained through LTE spectrum synthesis calculations of a previously
unidentified weak line at 3416.38 A in the solar spectrum. Attributing the
feature to Ho II, the observations may be fitted with log(Ho) = +0.53. This
calculation assumes log(gf) = 0.25 and is uncertain by at least 0.1 dex.
