  Two motions in the galactic plane have been detected and characterized, based
on the determination of a common systematic component in Hipparcos catalogue
proper motions. The procedure is based only on positions, proper motions and
parallaxes, plus a special algorithm which is able to reveal systematic trends.
Our results come from two stellar samples. Sample 1 has 4566 stars and defines
a motion of apex (l,b)=(177.8,3.7)+/-(1.5,1.0) and space velocity V=27+/-1
km/s. Sample 2 has 4083 stars and defines a motion of apex
(l,b)=(5.4,-0.6)+/-(1.9,1.1) and space velocity V=32+/-2 km/s. Both groups are
distributed all over the sky and cover a large variety of spectral types, which
means that they do not belong to a specific stellar population. Herschel's
method is used to define the initial samples of stars and later to compute the
common space velocity. The intermediate process is based on the use of a
special algorithm to determine systematic components in the proper motions. As
an important contribution, this paper sets out a new way to study the
kinematics of the solar neighborhood, in the search for streams, associations,
clusters and any other space motion shared by a large number of stars, without
being restricted by the availability of radial velocities.
