An expansion type cloud chamber controlled by an internal counter has been used to study the discharge formed in the latter when operated in the Geiger and transitional regions. Both ethyl and iso-amyl alcohols have been used at their saturation vapour pressures as the combined condensant and quenching agent, together with argon or helium at various total pressures below one atmosphere. Significant differences in the behaviour of the counter are observed for the two alcohols, which can be attributed to the difference in the proportion of quenching agents in the two cases. The photographic evidence shown supports the accepted theory of Geiger counter operation.