The existing volcanoes belong to four separate arcs or chains.
These semicircles and the circles A'A' are joined by tangents and short arcs struck from the centre of the figure.
If the two places are upon the same meridian or upon the equator the exact distance separating them is to be found by reference to a table giving the lengths of arcs of a meridian and of the equator.
The disk really consists of a series of successive arcs which increase in size until they burst.
The whole plan is drawn from three centres, the outer portion of the curves being arcs of a larger circle than the one used for the central portion; the complete circle of the orchestra is marked by a sill of white limestone, and greatly enhances the effect of the whole.
In these arrangements, which were similar if not identical, the furnace charge was crushed to a fine powder and passed through two or more electric arcs in succession.
In the South African war improvised detachable deflection scales of wood or iron placed over the fore-sight, called gun arcs, were used, but this device was clumsy, inaccurate and insufficient, as it only gave about 30° right or left deflection, and only a sight that admitted of all-round laying could really satisfy the requirements.
While the majority of his researches bear on one or other of the subjects just mentioned, others deal with such widely different topics as the birds of Greenland, ocean temperatures, the Gulf Stream, barometric measurement of heights, arcs of meridian, glacier transport of rocks, the volcanoes of the Hawaiian Islands, and various points of meteorology.
The lengths of arcs of the same circle being proportional to the angles subtended by them at the centre, we get the idea of circular measure.
Repeating the process with the arcs AC and CB, and continuing the repetition indefinitely, we divide up the required area and the remainder of the triangle ATB into corresponding elements, each element of the former being double the corresponding elements of the latter.
The main girders rest on the revolving platform, and the ends of the bridge are circular arcs fitting the fixed roadway.
Let measurements along the beam be represented according to any convenient scale, so that calling L 1 and 1 1 the lengths to be drawn on paper, we have L = aL i; now let r1, r 2, r 3 be a series of radii such that r 1 = R i /ab, r 2 = R 2 /ab, &c., where b is any convenient constant chosen of such magnitude as will allow arcs with the radii, r 1, &c., to be drawn with the means at the draughtsman's disposal.
72 with arcs of the length 1,, l2, l3, &c., and with the radii r1, r 2, &c. (note, for a length 2l 1 at each end the radius will be infinite, and the curve must end with a straight line tangent to the last arc), then let v be the measured deflection of this curve from the straight line, and V the actual deflection of the bridge; we have V = av/b, approximately.
They exhibit in an exaggerated form the irregularities of distribution visible in our zodiacal constellations, and present the further anomaly of being frequently reckoned as twenty-eight in number, while the ecliptical arcs they characterize are invariably twenty-seven.
Here the " signs " and the " constellations " of the lunar zodiac form two essentially distinct systems. The ecliptic is divided into twenty-seven equal parts, called bhogas or arcs, of Boo' each.
I „ Logarithms of the ratios of arcs to sines from 04 00000 to 0 4.05000, and log sines throughout the quadrant 4 „ Logarithms of the ratios of arcs to tangents from 0 4 00000 to 0 4.05000, and log tangents throughout the quadrant 4 The trigonometrical results are given for every hundred-thousandth of the quadrant (to" centesimal or 3" 24 sexagesimal).
From these results the mensuration of any figure bounded by circular arcs and straight lines can be determined, e.g.
The islands of these outer arcs consist chiefly of crystalline schists and limestones, overlaid by Jurassic, Cretaceous and Tertiary deposits.
A spherical angle is a particular dihedral angle; it is the angle between two intersecting arcs on a sphere, and is measured by the angle between the planes containing the arcs and the centre of the sphere.
These are known as the "arcs of Lowitz," having been first described in 1794 by Johann Tobias Lowitz (1757-1804).
Luminous arcs (T), tangential to the upper and lower parts of each halo, also occur, and in the case of the inner halo, the arcs may be prolonged to form a quasi-elliptic halo.1 The physical explanation of halos originated with Rene Descartes, who ascribed their formation to the presence of icecrystals in the atmosphere.
The "arcs of Lowitz" (L) are probably due to small oscillations of the vertical prisms.
The "tangential arcs" (T) were explained by Young as being caused by the thin plates with their axes horizontal, refraction taking place through alternate faces.
Similarly, the tangential arcs to the halo of 46° are due to refraction through faces inclined at 90°.
He was buried at Port Royal; in 1711, on the desecration of the cemetery, his, remains were transferred to the church of St Andre des Arcs in Paris.
Those heated by electric arcs, or " induction " ones, i.e.
A pair of electric arcs play between these electrodes and the molten steel, passing through the layer of slag, G, and generating much heat.
The ends of arcs frequently extend to the horizon, but often one or both ends stop short of this.
Several arcs may be visible at the same time.
These may be nearly straight and regular in outline, as if broken portions of arcs; frequently they are ribbon-like serpentine forms showing numerous sinuosities.
Arcs, bands and, generally speaking, the more regular and persistent forms, show their greatest frequencies earlier in the night than rays or patches.
Was the hour of most frequent occurrence for arcs and bands, whereas patches had their maximum frequency at I I P.M.
In temperate latitudes auroral arcs are seldom near the zenith, and there is reason to believe them at very great heights.
At Cape Thorsden (7) in 1882-1883 the mean azimuth derived from 371 arcs was 24° 12' W., or 11°27' to the W.
Of S.), the mean derived from the 113 arcs observed between midnight and 6 A.M.
At Jan Mayen (8) in 1882-1883 the mean azimuth of the summit of the arcs was 28.8° W.
At Jan Mayen (8) in 1882-1883, out of 177 arcs whose position was accurately determined, 44 were seen in the north, their summits averaging 38.5° above the northern horizon; 88 were seen in the south, their average altitude above the southern horizon being 33.5° while 45 were in the zenith.
The following data for the apparent angular width of arcs were obtained at Cape Thorsden, the arcs being grouped according to the height of the lower edge above the horizon.
Contained thirty arcs whose altitudes did not exceed 11 ° 45' Group II.
Thirty arcs whose altitudes lay between 12° and 35°; and Group III.
Thirty arcs whose altitudes lay between 36° and 80 The altitude.
At the same time, arcs near the horizon often appeared wider than others near the zenith.
Furthermore, Gyllenskold says that when arcs mounted, as they not infrequently did, from the horizon, their apparent width might go on increasing right up to the zenith, or it might increase until an altitude of about 45° was reached and then diminish, appearing much reduced when the zenith was reached.
Of course the phenomenon might be due to actual change in the arc, but it is at least consistent with the view that arcs are of two kinds, one form constituting a layer of no great vertical depth but considerable real horizontal width, the other form having little horizontal width but considerable vertical depth, and resembling to some extent an auroral curtain.
According to numerous observations made at Cape Thorsden, the apparent angular velocity of arcs increases on the average with their altitude.
Dividing the whole number of arcs, 156, whose angular velocities were measured into three numerically equal groups, according to their altitude, the following were the results in minutes of arc per second of time (or degrees per minute of time): - Each group contained auroras which appeared stationary.
In 1882-1883 the direction of motion of arcs was from north to south in 62% of the cases at Jan Mayen, and in 58% of the cases at Cape Thorsden.
Outside this are three arcs of large cells showing characters typical of the endodermis in a vascular plan.t; these are interrupted by strands ofnarrow, elongated, thick-walled cells, which send branches into the little brown scales borne by the rhizome.
Sometimes the original cambial ring is broken into several arcs, each of which is completed into an independent circle, so that several independent secondary vascular cylinders are formed.
Sometimes the activity of the successive cambiums simply results in the formation of concentric rings or arcs of secondary xylem and phloem.
The rough surface of the bark of many trees is due to the successive phellogens not arising in regular concentric zones, but forming in arcs which join with the earlier-formed arcs, and thus causing the bark to come off in flakes or thick chunks.
From its intersection with A'A' arcs are struck cutting B in two points.
This last determination was effected through four arcs as follows: I.
North of this lies a broad belt in which the Mesozoic deposits and even the lower divisions of the Tertiary system are thrown into folds which extend in a series of arcs from west to east and now form the principal mountain ranges of central Asia.
There are considerable tracts which are but little disturbed, but these tracts are enclosed within the arcs formed by the folds, and the zone taken as a whole is distinctly one of crumpling.
Elements received symbols composed of circles, arcs of circles, and lines, while certain class symbols, such as1W for metals, - - foracids, for alkalies, for salts, U for calces, &c., were used.
He also gave approximate rectifications of circular arcs after the manner of Huygens; and, what is very notable, he made an ingenious and, according to J.
Combining the results from arcs and bands, Carlheim-Gyllenskäld gives the " anomaly " of the auroral meridian at Jan Mayen as 5.7° E.
But clearly, whilst the arcs and bands, and to a lesser extent the patches, showed a marked preference for the magnetic meridian, the rays showed no such preference.