Lane and Evans have reported measurements on transverse-film bolometers and have analysed these to obtain values for the inductance of film. Their inductances are about 15% below those predicted by normal waveguide theory. It is shown in this paper that the discrepancy can be attributed to the presence of a capacitance associated with the glass strip on which the film is mounted. A further complication is the relative insensitiveness of the measured quantities to the film inductance. The results calculated using a modified circuit to allow for the capacitance give excellent agreement between the experimental and theoretical inductances, and it is concluded that there is no reason to doubt the validity of the usual inductance formula.