by wingspan33 » Wed May 22, 2019 8:15 pm
Thanks Chopper Girl! This is an interesting topic. As for how it works, . . . I would think it uses a closed "system" between the two "markers". Down stream from one marker is open to the atmosphere as is the tube from the other marker up stream from it's position. Higher atmospheric pressure pushes the "sink" marker up and "lift" marker down. Visa-versa as atmospheric goes down (i.e., you're gaining altitude).