  We investigate the dependence of the He/H8 emission ratio on kinetic
temperature and total Balmer brightness. The line pair He\,{\sc i}\,3888\,\AA{}
and H$_8$\,3889 has been observed simultaneously with the Ca II 8498 line in a
number of quiescent prominences. The He/H8 emission ratio R is found to cover
defined parts of a general anti-relation with the total H8 emission, depending
on the kinetic temperature, T_kin, of the individual prominence: High H8
brightness is related to small R and T_kin values, and preferably occurs in
prominences with a less significant fine-structure.
