  Jupiter Family comets (JFCs) are short period comets which have recently
entered the inner solar system, having previously orbited in the Kuiper Belt
since the formation of the planets. We used two nights on the 3.6m New
Technology Telescope (NTT) at the European Southern Observatory, to obtain VRI
photometry of three JFCs; 7P/Pons-Winnecke, 14P/Wolf and 92P/Sanguin. These
were observed to be stellar in appearance. We find mean effective radii of 2.24
\pm 0.02 km for 7P, 3.16 \pm 0.01 km for 14P and 2.08 \pm 0.01 km for 92P,
assuming a geometric albedo of 0.04. From light-curves for each comet we find
rotation periods of 7.53 \pm 0.10 and 6.22 \pm 0.05 hours for 14P and 92P
respectively. 7P exhibits brightness variations which imply a rotation period
of 6.8 \le P_rot \le 9.5 hours. Assuming the nuclei to be ellipsoidal the
measured brightness variations imply minimum axial ratios a/b of 1.3 \pm 0.1
for 7P and 1.7 \pm 0.1 for both 14P and 92P. This in turn implies minimum
densities of 0.23 \pm 0.08 g cm^{-3} for 7P, 0.32 \pm 0.02 g cm^{-3} for 14P
and 0.49 \pm 0.06 g cm^{-3} for 92P. Finally, we measure colour indices of
(V-R) = 0.40 \pm 0.05 and (R-I) = 0.41 \pm 0.06 for 7P/Pons-Winnecke, (V-R) =
0.57 \pm 0.07 and (R-I) = 0.51 \pm 0.06 for 14P/Wolf, and (V-R) = 0.54 \pm 0.04
and (R-I) = 0.54 \pm 0.04 for 92P/Sanguin.
