On two types of pulsars

The arguments favouring the subdivision of pulsars into two classes are considered: 1) short-period pulsars desrpibed by the Smith's model and 2) long-period pulsars for which the hollow-cone model is valid. These arguments are: the difference in the period dependence of the pulse width and of the total change of the position angle of linear polarization through the integrated profile; only type 1 pulsars having an interpulse; the difference in the rms deviations in the times of arrival of pulses and in the shapes of the directivity pattern of the radio emission; the difference of the slowing-down mechanisms. The data for the recently discovered PSR 1937+21 (P=1.56 ms) are shown to be in a good agreement with the above conception, this pulsar being a typical representative of the first group of pulsars