  We report the Chandra detection of resolved X-ray emission of luminosity 3.5
\times 10^{40} ergs s^{-1} (0.4--4.5 keV) and power-law energy spectral index
alpha = 1.5 \pm 0.7 from a roughly 10 arcsec length of the north-west radio jet
in NGC 315. The X-ray emission is brightest at the base of the radio-bright
region about 3 arcsec from the nucleus, and is consistent with a synchrotron
origin. At a projected distance of 10 arcsec from the core, the jet is in
approximate pressure balance with an external medium which is also detected
through its X-ray emission and which has kT \approx 0.6 \pm 0.1 keV, consistent
with earlier ROSAT results. The high spatial resolution and sensitivity of
Chandra separates nuclear unresolved emission from the extended thermal
emission of the galaxy atmosphere with higher precision than possible with
previous telescopes. We measure an X-ray luminosity of 5.3 \times 10^{41} ergs
s^{-1} (0.4--4.5 keV) and a power-law energy index of alpha = 0.4 \pm 0.4 for
the nuclear component.

Astrophysics