The paper considers whether observers in the XVII century provide historical records on the observation of the plasma tails of comets, which would allow to reveal the physical parameters of the solar wind. The angle ϵ between the tail axis and the prolonged radius vector of the comet may indirectly define the type of the comet tail: plasmous or dusty. We consider the calculations of F.A. Bredikhin concerning 10 comets, 4 of which were Great, appeared in the period of the Maunder minimum (1645–1715). For these comets, he found the values of the angles ϵ. On average, these angles exceed 10○ , which is typical of dust tails. Also note that visual observations of the cometary ion stream are very difficult due to the spectral composition of their radiation. This confirms our conclusion that the comet tails in the seventeenth century are of little use for discussion about the physical parameters of the solar wind in the past.