Sometimes these spectres are surrounded by colored concentric arcs.
It was a mile in diameter, built in concentric circles, with the mosque and palace of the caliph in the centre, and had four gates toward the four points of the compass.
The old fortress consisted of the town enceinte, the castle (situated on high ground and fortified by several concentric envelopes), and the entrenched camp, a hollow enclosed by continuous lines, the salients of which were the castle, Fort La Justice and Fort La Miotte.
The Greeks supposed it to be the capital of Media, confusing the Manda, of whom Astyages was king, with the Mada or Medes of Media Atropatene, and ascribed its foundation to Deioces (the Daiukku of the cuneiform inscriptions), who is said to have surrounded his palace in it with seven concentric walls of different colours.
Mensuration of the Platonic Solids.-The mensuration of the regular polyhedra is readily investigated by the methods of elementary geometry, the property that these solids may be inscribed in and circumscribed to concentric spheres being especially useful.
A compact variety of a pale liver-brown colour and forming concentric layers with a reniform surface is known in Germany as Schalen- blende or Leberblende.
The last elaboration of the insulated slip water-bottle by Ekman, Nansen and Pettersson has produced an instrument of great perfection, in which the insulation is effected by layers of water between a series of concentric ebonite cylinders, all of which are closed both above and below when the apparatus encloses a sample, and each of which in turn must be warmed considerably before there is any rise of temperature in the chamber within.
He was himself a great builder, and many of the perfected castles of that concentric style, which later ages have called the Edwardian type, were of his own planning.
And still in the distracted distance we beheld the tumults of the outer concentric circles, and saw successive pods of whales, eight or ten in each, swiftly going round and round, like multiplied spans of horses in a ring; and so closely shoulder to shoulder, that a Titanic circus-rider might easily have over-arched the middle ones, and so have gone round on their backs.
The laboratory form in common use consists of a bellows worked by either hand or foot, and a special type of gas burner formed of two concentric tubes, one conveying the blast, the other the gas; the supply of air and gas being regulated by stopcocks.