Observations of the folding rate of the tail rays are shown to be indicative of a small magnetic field, Bi, in type-1 comet tails, of the order of the interplanetary magnetic field or less. Equilibrium pressure balance across the tail yields Bi ≲ 10 γ (at 1 AU) throughout the tail cross-section. Observations of helical waves also result in the same Bi values. Arguments in favour of substantial amplification of the solar-wind magnetic field in the cometary tails are shown to be unconvincing.