size of subplots with par() / layout()

Hi

If I do this:

par(mfrow=c(2,2))
persp(matrix(1:4,6,6),box=F,phi=33,theta=33)
persp(matrix(1:4,6,6),box=F,phi=33,theta=33)
persp(matrix(1:4,6,6),box=F,phi=33,theta=33)
persp(matrix(1:4,6,6),box=F,phi=33,theta=33)


(
or indeed

layout(matrix(1:4,2,2))
persp  . . . .
)


then the mesh plots look too small to me.  How do I make them larger?



--
Robin Hankin
Uncertainty Analyst
National Oceanography Centre, Southampton
European Way, Southampton SO14 3ZH, UK
  tel  023-8059-7743