. Elements of astronomy: accompanied with numerous illustrations, a colored representation of the solar, stellar, and nebular spectra, and celestial charts of the northern and the southern hemisphere. ipse is the distance of eitherfocus from the centre, dividedby half the major axis. Hencethe greater the aforesaid dis-tance, the greater the eccentricity, and the more the ellipsedeviates from a circle. In Fig. 11, if D F, the distanceof one of the foci from the centre, is to G- F, half themajor axis, as 2 to 3, the eccentricity of the ellipse willbe |, or .66+. 36. A Solid is a magnitude that h
. Elements of astronomy: accompanied with numerous illustrations, a colored representation of the solar, stellar, and nebular spectra, and celestial charts of the northern and the southern hemisphere. ipse is the distance of eitherfocus from the centre, dividedby half the major axis. Hencethe greater the aforesaid dis-tance, the greater the eccentricity, and the more the ellipsedeviates from a circle. In Fig. 11, if D F, the distanceof one of the foci from the centre, is to G- F, half themajor axis, as 2 to 3, the eccentricity of the ellipse willbe |, or .66+. 36. A Solid is a magnitude that has length, breadth,and thickness. 37. A Sphere is a solid bounded by a curved surfaceevery point of which is equally distant from a point within, called the centre. AHemisphere is half a sphere. A Diameter of a sphere is astraight line passing through itscentre, and terminating at eachend in its surface. The Axis of a revolvingsphere is the diameter roundwhich it turns. The Poles arethe extremities of the axis. Inthe sphere represented in , the straight line connecting A and B is a diameter;and also the axis, if the sphere revolves round thisdiameter; in which case A and B are the What is a Diameter ? What is the Major Axis ? The Minor Axis ? What ismeant by the Eccentricity of an ellipse ? 36. What is a Solid ? 37. What is aSphere ? What is a Hemisphere ? What is a Diameter of a sphere ? What isthe Axis of a revolving sphere ? What are the Poles ? 38. What is a Great MATHEMATICAL DEFINITIONS. 23 38. Circles on the surface of a sphere are distinguishedas Great and Small. A Great Circle is one whose planedivides the sphere into two equal parts; as A SB G andG IT, in Fig. 12. A Small Circle is one whose plane Fig. 13. divides the sphere into two unequal parts, Oas CD and Circumference of a sphere is oneof its great circles. The Equator of asphere is that great circle which is equal-ly distant from the two poles, as G H inFig. 12. 39. A Spheroid is a solid whi
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectastronomy, bookyear18
