Abstract
The present paper shows how the result obtained by experimental measurement of the degree of ventilation of a cigarette clamped on both sides can correctively be adjusted by calculation to the accurate and actually existing degree of ventilation of the ''free'' cigarette clamped on the side of the cigarette tip only. This correction is necessary if the degree of ventilation is determined by means of the apparatus presented by Lipp and van Nooy (1) which, owing to the bilateral clamping of the cigarette, restricts the ventilation stream to a part (50 mm) of the paper wrapping. The corrective values listed in Table 3 of the paper take the place of the values indicated by Lipp and van Nooy in the mentioned article.