  In a previous paper, we had shown that because of varying angles of incidence
there is a varying degree of convolution down a trace and across a gather,
necessitating deconvolution operators varying with time and offset. This idea
is examined further in $t$-$x$ as well as $\tau$-$p$ domain. We suggest better
ways to deconvolve data in $\tau$-$p$ domain, taking into account varying
degree of convolution in this domain. We derive formulae for periods of surface
multiples in $\tau$-$p$ domain, e.g., water column peg-legs and reverberations,
which have a fixed period depending only on the value of $p$ -- and suggest a
way to check/revise the picked velocity using the formulae, provided the
multiples are well separated from the primary. Periodicity of two way surface
multiples is also studied.
