Toward an Empirical Theory of Pulsar Emission. IX. On the Peculiar
  Properties and Geometric Regularity of Lyne & Manchester's "Partial Cone"
  Pulsars
  Lyne & Manchester (1988) identified a group of some 50 pulsars they called
"partial cones" which they found difficult to classify and interpret. They were
notable for their asymmetric average profiles and asymmetric polarization
position-angle (PPA) traverses, wherein the steepest gradient (SG) point fell
toward one edge of the total intensity profile. Over the last two decades, this
population of pulsars has raised cautions regarding the core/cone model of the
radio pulsar-emission beam which implies a high degree of order, symmetry and
geometric regularity. In this paper we reinvestigate this population "partial
cone" pulsars on the basis of new single pulse polarimetric observations of 39
of them, observed with the Giant Meterwave Radio Telescope in India and the
Arecibo Observatory in Puerto Rico. These highly sensitive observations help us
to establish that most of these "partial cones" exhibit a core/cone structure
just as did the "normal" pulsars studied in the earlier papers of this series.
In short, we find that many of these "partial cones" are partial in the sense
that the emission above different areas of their polar caps can be (highly)
asymmetric. However, when studied closely we find that their emission
geometries are overall identical to core/double cone structure encountered
earlier-that is, with specific conal dimensions scaling as the polar cap size.
