Page:The American Cyclopædia (1879) Volume VIII.djvu/42

 34 GLOBE opposite each other for receiving the brass meridian, which when adjusted is free to slide around in its own plane, so that the poles may be upright, horizontal, or at any angle to the horizontal circle. Around this circle, which represents the rational horizon or imaginary plane passing through the centre of the earth, are drawn several concentric circles ; the inner- most represents the horizon, and the slots for the brass circle are on the N. and S. points ; the degrees on the northern two quadrants are reckoned from E. and W. toward the N., and those on the southern toward the S. Outside of this is the circle representing the calendar, with the names of the months and divisions corresponding to the days. The next circle contains the signs and degrees of the ecliptic, so arranged that against each day of the year is found the point of the ecliptic in which the sun is situated. In some globes the horizontal circle is made to revolve. It is attached to arms which extend below the brass meridian and unite, supporting the adjusting clamp which supports the brass meridian. A taper pin extends down three inches from the lowest part of the arms, and fits into a socket in the iron base, thus securing by the revolutions of the meridian and horizon in their own planes the effect of a universal joint, so that any part of the globe can be brought under observa- tion without changing the position of the base. To the N. pole of the globe is attached a small circle of brass, called the hour circle, the pole passing through its centre, and holding it so that the two move round together, but yet per- mitting the hour circle to be moved round by the hand upon the axis. The circle is divided into 24 equal parts, corresponding to the hours of the day, and any one of these can be placed upon any meridian by turning the circle. The quadrant of altitude is a brass slip equal in length to a quarter of the circumference, and divided into 90. It is fastened to the brass meridian, and is used for measuring degrees in any direction on the globe. A mariner's com- pass is sometimes attached to the frame of the globe for the purpose of placing the meridian in a N. and S. line. The various circles con- nected with the terrestrial globe are equally appropriate to the celestial ; and as the latter are ordinarily constructed, the observer is sup- posed to be looking down upon the heavens presenting a convex surface, upon which the tan and constellations are mapped in their proper relative positions. To render the na- ture of the imaginary circles to which the points upon both globes are referred more clear for the student, the armillary sphere was contrived, which consists of the several circles in the f..rm of -rn.luated brass rings placed in their appropriate positions, and containing in the centre a small globe representing the earth. These circles are the horizon, meridian, equator. . equinoctial colure, and the solstitial colure. The sphere formed by them is sup- ported in a frame in the same manner as the GLOBIGERINA globes. Celestial and terrestrial globes are sometimes combined, the latter being enclosed in a glass sphere marked with the constella- tions. Globes are sometimes made also of India rubber or thin paper, and so contrived that they may be inflated with air. Some ter- restrial globes contain, in addition to the usual geographical delineations, geological strata, at- mospheric currents, isothermal lines, hydro- graphic information, and trade routes ; and in some the land is represented in relief. Slate globes for school use are made with only the lines of latitude and longitude drawn on them ; and wooden globes, painted black and similar- ly marked, are constructed, on which maps are drawn with chalk. GLOBE FISH. See SEA PORCUPINE. GLOBIGERINA) a microscopic protozoan ani- mal, of the foraminiferous order of the class of rhizopods. The body is composed of simple sarcode or protoplasmic matter, enclosed in a shell pierced by numerous mi- nute openings, through which a film of the animal substance is exuded, capable of thro wing out small thread-like processes, or pseudopodia. The animals in- crease by budding, each sarcode mass being enveloped in its cal- careous shell, but connected irregularly with all the rest of the colony ; there is no definite shape, the mass being compared by Huxley to that of a badly grown raspberry. Recent deep-sea dredgings (in the Gulf stream at a depth of 3,100 ft., near the Faroe islands at a depth of 3,900 ft., off Cape Farewell, Green- land, at 7,560 ft., and between the Azores and Newfoundland at 10,000 ft., and in the north Atlantic at still greater depths in the track of the Atlantic cable) have brought up the sheila of living globigerinffi from the calcareous ooza of the ocean bottom. In the compound proto- plasmic animal to which the name of 'bathybiw has been given, are found globigerinso, with coccoliths and coccospheres ; the ancient chalk deposits are made up almost entirely, in many specimens, of remains of the three last named animals, the same as those now living on the bottom of the ocean ; the great central plain of the North Atlantic, 1,000 m. wide and many hundreds in length, nearly level, is covered with a chalky mud containing innumerable glo- bigerinee with their attendant coccoliths and coccospheres, and the deeper the sea the larger are these animals. They doubtless constitute the food of the star fishes, which also have been dredged from these great depths. There is no reason to think that the habits and the habitats of the ancient chalk animals were different from those of the living globigerinae ; hence we may conclude that the chalk formation, constituting a large part of southern Great Britain and cen- tral and southern Europe, often 1,000 ft. thick, is the dried and elevated mud of an ancient deep sea. From the fact that this present deep-sea fauna is apparently identical with that