  It is argued that the findings of a recent reanalysis by Compagno and Persico
[Phys. Rev. A 57, 1595 (1998)] of the Bohr--Rosenfeld procedure for the
measurement of a single space-time-averaged component of the electromagnetic
field are incorrect when the field measurement time is shorter than that
required for light to traverse the measurement's test body. To this end, the
time-averaged "self-force" on the test body, assumed for simplicity to be of a
spherical shape, is evaluated in terms of a one-dimensional quadrature for the
general trajectory allowed for the test body by Compagno and Persico, and in
closed form for the limiting steplike trajectory used by Bohr and Rosenfeld.
