In order that no other settlements should encroach upon his centre of government, New Castle, the northern boundary was determined by drawing an arc of a circle, 12 m.
Dyson has measured some eight hundred lines in the lower chromosphere and identified them with emission spectra of the following elements: hydrogen, helium, carbon with the cyanogen band, sodium, magnesium, aluminium, silicon, calcium, scandium, titanium, vanadium, chromium, manganese, iron, zinc, strontium, yttrium, zirconium, barium, lanthanum, cerium, neodymium, ytterbium, lead, europium, besides a few doubtful identifications; it is a curious fact that the agreement is with the spark spectra of these elements, where the photosphere shows exclusively or more definitely the arc lines, which are generally attributed to a lower temperature.
The vertical distortion of the curve must not be so great that there is a very sensible difference between the length of the arc and its chord.
For the illumination of large stations by night electric arc lamps are frequently employed, but some authorities favour high-pressure incandescent gas-lighting.
The military posts were drawn up in echelon along the frontier of the desert, especially along the southern slopes of the Aures, as far as Ad Majores (Besseriani), and on the Tripolitan frontier as far as Cydamus (Ghadames), forming an immense arc extending from Cyrenaica to Mauretania.
The arc furnaces now widely used in the manufacture of calcium carbide on a large scale are chiefly developments of the Siemens furnace.
Cassini, obtained employment, first in surveying the coast from Nantes to Bayonne, then, in 1 739, in remeasuring the French arc of the meridian.
Upon the outer side of the arc the central zone of crystalline rocks is flanked by Mesozoic and Tertiary belts; towards the west, indeed, the individuality of these belts is lost, to a large extent, but the rocks remain.
Hence, in accordance with the rule for compounding vector quantities, the resultant vibration at B, due to any finite part of the primary wave, is represented in amplitude and phase by the chord joining the extremities of the corresponding arc (U2-0.1).
The voyage of Lord Anson to the Pacific in 1740-1744 was of a predatory character, and he lost more than half his men from scurvy; while it is not pleasant to reflect that at the very time when the French and Spaniards were measuring an arc of the meridian at Quito, the British under Anson were pillaging along the coast of the Pacific and burning the town of Payta.