Prior to its construction, a school bus could only pass over it empty, necessitating the children to alight, walk, and rejoin their transportation of the far side.
But as in Ireland so Cromwell's policy in Scotland was unpopular and was only upheld by the maintenance of a large army, necessitating heavy taxation and implying the loss of the national independence.
Or conductive telegraphy not necessitating a continuous cable.
This system has the advantage of the greatest convenience in operation, no lifts being required, since the distance from the street surface to the station platform is about 12 to 15 ft.; it has the disadvantages, however, of necessitating the tearing up of the street surface during construction, and the readjustment of sewer, water, gas and electric mains and other subsurface structures, and of having the gradients partially dependent on the surface topography.
Sand bars keep filling up the mouths of these channels, necessitating frequent dredging and extension of the breakwaters, work undertaken by the Federal government, which also maintains a most comprehensive and completeystem of aids to navigation, including lighthouses and lightships, fog alarms, gas and other buoys, life-saving, storm signal and weather report stations.