The tram, having disonnected from its toast-rack trailer, moves from one line to the other at Ramsey so that it can return south to Douglas. The trailer was moved releasing its brake and letting gravity carry it past the points so that it can be reconnected to the (now) rear of the tram.
This aqueduct-like structure doesn’t in fact carry water to (or from) the Laxey water-wheel, but rather supports the arm which the wheel drives, which in turn was used to operate the pumps to clear the nearby mines of water.
Here the mechanical piston-arm attached to Lady Isabella (the Laxey water-wheel) is more plainly visible. When the mines were operating, the wheel’s motion was used to drive the pumps to clear the mines of water.