  We present the first detection of a gravitational depletion signal at
near-infrared wavelengths, based on deep panoramic images of the cluster Abell
2219 (z=0.22) taken with the Cambridge Infrared Survey Instrument (CIRSI) at
the prime focus of the 4.2m William Herschel Telescope. Infrared studies of
gravitational depletion offer a number of advantages over similar techniques
applied at optical wavelengths, and can provide reliable total masses for
intermediate redshift clusters. Using the maximum likelihood technique
developed by Schneider, King & Erben (1999), we detect the gravitational
depletion at the 3 sigma confidence level. By modeling the mass distribution as
a singular isothermal sphere and ignoring uncertainty in the unlensed number
counts, we find an Einstein radius of 13.7 +3.9/-4.2 arcsec (66% confidence
limit). This corresponds to a projected velocity dispersion of approximately
800 km/s, in agreement with constraints from strongly-lensed features. For a
Navarro, Frenk and White mass model, the radial dependence observed indicates a
best-fitting halo scale length of 125/h kpc}. We investigate the uncertainties
arising from the observed fluctuations in the unlensed number counts, and show
that clustering is the dominant source of error. We extend the maximum
likelihood method to include the effect of incompleteness, and discuss the
prospects of further systematic studies of lensing in the near-infrared band.
