Midway between a rock lighthouse and a shore station, both as to structure and as to the experiences of life in it, is that mongrel breed amongst edifices, the Pile Lighthouse. There are many sands at the mouths of tidal rivers where the water is not deep enough, nor are the channels sufficiently wide to make a light-vessel suitable, and which yet need marking, and marking, too, at a spot where not only the ordinary foundations of masonry, but even the pile foundations used for many purposes, would be at fault. Here it is that two very ingenious plans have been of service. The one is to fit the lower extremity of piles with broad-flanged screws, something like the screw of a steam-vessel, and then setting them upright in the sand, screw them down with capstans worked from the decks of dumb lighters. These bottom piles once secured, the spider legs are bolted on to them, and the spider bodies on the top; a ladder draws up, and a boat swings ready to be lowered. The other mode of meeting the difficulty of mud or loose silt and sand, is by hollow cylinders, which, placed upright on the sand, have the air exhausted from the inside of them, and on the principle that nature abhors a vacuum (at all events in cylinders), the weight of the atmosphere on the sand outside forces it up into the exhausted receiver, and the pile sinks at a rate which, until one gets accustomed to it, is rather surprising. Here, as in the screw pile, the foundation once established, the superstructure, whether of straight shafts or spider legs, is only a matter of detail. These, then, be the variations of lighthouse structure: rock lighthouses, solitary giants rising from the ocean deeps; pile lighthouses, stuck about the shallow estuaries on long red legs, like so many flamingoes fishing; safer, but with less of dignity and more of ague;--and lastly, the real _bonâ fide_ shore lighthouse, with its broad sweep of down, its neat cottages, and trim inclosures. If my Lord Grenville had had any thought of occupying the residence that he calculated to eliminate from the king’s good-humour, we take it there is very little doubt on which class in the foregoing category he would have fixed his choice.