Vacuum in the manifold drops as engine demand increases. If you use ported vacuum you always have a vacuum signal. If you want to make adjustments it can be done using the advance pot on the distributor when you use ported vacuum.
The decreasing or waning phases are when the moon shrinks from the full moon down to the new moon (darkness). As the moon wanes during the 3rd and 4th quarters, this is a good time to prune plants, as the water table is diminishing and so less sap will flow out of the cut ends.
After full moon, the moon will rise later each night until it is a new phase again. On day 21 of the moonâs orbit, it rises around midnight local standard time. This is the third quarter phase of the moon. Itâs called third quarter because it has traveled three quarters of the way in its orbit around the earth.