Comment on ‘‘Anomalous peak in the thermopower of ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ single crystals: A possible fluctuation effect’’

In an experiment of Howson et al. the temperature dependence of the thermopower of a ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ single crystal was measured with an oscillating heat source. A sharp peak in the temperature dependence of the thermopower in the vicinity of the critical temperature was observed. In contrast, Ri et al., who used a dc technique, could not observe such a peak. We show that the observation of the peak may be an artifact of the ac measuring technique used by Howson et al.