Frogs and pressure

To celebrate the arrival of frog spawn in the garden pond and sightings of the resident frog, here are pictures of our frog toy. The way that the tongue uncurls as air pressure increases reminded me of a diagram of an aneroid barometer that I had to copy down and learn in Physics at school. It looked like the one in the picture on this website https://www.thoughtco.com/definition-of-barometer-604816 The idea was that a needle was attached to the tube. The tube uncoiled as the pressure went up so the needle went round the meter. However, it seems that this is not actually the case. See https://www.explainthatstuff.com/barometers.html for how one actually works. There is a partial-vacuum chamber that resembles the coiled tube idea but the spiral shape with the needle is probably a spring. I'd like to find that old text book and see if I had just misunderstood what it was saying.