Fig. (6) A simple respiratory monitor can be made by taping a piece of cotton wool to the upper lip such that it is placed under one of the nostrils and thus moves with each breath. From the film entitled Intravenous anaesthesia: No. 6 (1944) Pt. 1 of 2, available online at https://www.youtube.com/watch?v=2nz2VnV9Nu0 (Image is taken from time position 10:40).