The text on slide 54 at 45:45 is sadly covered by the "STOP SHARING" button. It reads: "(b) Engine - inverted "V" chemically cooled with improved carburettor to obviate cutting out on sudden dives." (As noted in the audio, "chemically cooled" means using pure Glycol, which was at the time the only way to stop boiling at high engine powers before the idea of high-pressure cooling with 70% water 30% glycol, started slowing coming in, during the late 30`s. Note that Glycol boils at very high temperatures but has substantially inferior heat capacity and heat transfer to water, hence pressurised 70/30 is a lot better than unpressurised (or indeed pressurised) glycol).