Abstract: A sequential 20-port automatic smoking machine performing calibrated volume smoking of cigarettes is disclosed. The machine sequentially smokes 20 cigarettes for the collection and laboratory analysis of particulate matter and gas content of the cigarette smoke. Sequential smoking is accomplished by having each station take a 2-second puff every 3 seconds, yielding a 60-second cycle of time between puffs at each station. Control is electronic, utilizing solid-stage counters. Smoking syringes are individually operated by hydraulic cylinders in an even/odd arrangement of master drive cylinders both served by a common fluid reservoir. The master cylinders are disposed on opposite sides of the single crank system such that two halves are driven 180.degree. out of phase. Gas lines connecting individual cigarette ports to the analyzers are purged with room air between each puff delivered to the respective analyzers.