  We present the first K'-band, long-baseline interferometric observations of
the northern Be stars gamma Cas, phi Per, zeta Tau, and kappa Dra. The
measurements were made with multiple telescope pairs of the CHARA Array
interferometer, and in every case the observations indicate that the
circumstellar disks of the targets are resolved. We fit the interferometric
visibilities with predictions from a simple disk model that assumes an
isothermal gas in Keplerian rotation. We derive fits of the four model
parameters (disk base density, radial density exponent, disk normal
inclination, and position angle) for each of the targets. The resulting
densities are in broad agreement with prior studies of the IR excess flux and
the resulting orientations generally agree with those from interferometric
H-alpha and continuum polarimetric observations. We find that the angular size
of the K' disk emission is smaller than that determined for the H-alpha
emission, and we argue that the difference is the result of a larger H-alpha
opacity and the relatively larger neutral hydrogen fraction with increasing
disk radius. All the targets are known binaries with faint companions, and we
find that companions appear to influence the interferometric visibilities in
the cases of phi Per and kappa Dra. We also present contemporaneous
observations of the H-alpha, H-gamma, and Br-gamma emission lines. Synthetic
model profiles of these lines that are based on the same disk inclination and
radial density exponent as derived from the CHARA Array observations match the
observed emission line strength if the disk base density is reduced by
approximately 1.7 dex.
