A airship like a Zeppelin or similar.
As the Zuzu Magore drew near the coastline, the hum grew deeper and lower as the ship slowed its speed to scarcely more than that of a seabird. The Zuzu Magore was confident of its ability to sustain its mass in the sky, for it was as much a part of the sky as the clouds. Or so it seemed to the onlookers, to whom that stately low-humming approach conveyed an impression of immense reservoirs of effortless power.
But on the bridge of the skyship, there was concern, and concern was approaching the point of panic.
The dials on the bridge showed the hideous truth all too clearly. The ship was losing contact with the device which provided its power supply. [EoH Ch1]