Our long-term program of aperture synthesis imaging at the WHT entered a new stage in July 1994 after the successful comissioning of a new optics, image rotator and detector package (Rogers et al. 1994). Data from the 5 observing runs in 1993--1994 have been used to address a number of topics.
Tuthill et al. (1994) have used monochromatic angular
diameter measurements of RLeonis, coupled with a dynamic atmospheric
model and a new parallax distance, to derive a precise estimate for the
star's photospheric radius. Their value of 
far
exceeds the range of theoretical predictions for fundamental-mode
pulsation (
), and thus requires that
RLeo pulsates in the first or a higher overtone mode. More recently,
their analysis has been extended to a sample of 10 nearby Miras for
which effective temperatures, angular and linear sizes and pulsation
modes have been determined (Haniff, Scholz & Tuthill in press).
The measurements imply photospheric radii in excess of 
for the complete sample, so unless the favoured mass scale for
Miras is increased by at least a factor of two, or the current
understanding of their Period-Luminosity relation is incorrect, the
data rule out fundamental mode pulsation in Mira variables with periods
in the range 280 -- 430 days.
Imaging of M Supergiants has concentrated on 4 sources: 
Ori,
Her, 
Sco and 
Cep. Evidence for asymmetries
on the stellar surface have now been detected for all four targets
(Tuthill, PhD thesis, 1994), suggesting a possibly ubiquitous mechanism.
Most likely are the large convective zones first proposed by Schwarzschild,
whose sizes and timescales are closest to those observed. New observations
of 
Cep (Tuthill, PhD thesis, 1994)
have revealed an asymmetric component of the brightness distribution
even more extreme than the prototype 
Ori. If interpreted in the
context of a large convective zone, then 
of the stellar
flux must arise from this unresolved feature on the stellar disk, a
conclusion that may be difficult to explain theoretically.