We present deep, large-scale [S Il] lambda lambda 6716,6731 images of
Herbig-Haro (HH) flows and jets in HH 34, RNO 43, HH 38/43, and the HH
24 region. In all of these regions new emission knots and filaments a
re seen to connect previously known HH objects. We find three bipolar
outflows which have total projected lengths of more than 1.5 pc, and t
wo more objects in which a blueshifted lobe of more than 0.6 pc is obs
erved together with a shorter redshifted lobe. The large extent of the
se outflows consequently implies dynamical ages of about 10(4) years o
n average. With such a life time HH jets are perfectly able to transfe
r enough momentum to the surrounding medium to drive CO outflows. Most
of the jets studied here do nut show very large gaps of emission betw
een the source and the flow end, indicating that long phases of total
inactivity of the source (i.e., with durations greater than or similar
to 30% of the dynamical age) usually do not occur. We argue that the
rather strong changes in how direction over a relatively short part of
the total outflow length observed in some of the outflows is difficul
t to explain by precession of the jet beam. (C) 1997 American Astronom
ical Society.