Ridpath's history of the world; being an account of the ethnic origin, primitive estate, early migrations, social conditions and present promise of the principal families of men .. . al axes position of the two axes, always at rightangles to each other, constantly point to different parts of the sur-rounding heavens, each of them con-tracting and expanding within fixedlimits which are determinative of thecharacter and stability of our orbit. It is assumed that the reader is famil-iar with such terms as aphelion andperihelion, that he has a Assumption ofclear concept of our planet-
Ridpath's history of the world; being an account of the ethnic origin, primitive estate, early migrations, social conditions and present promise of the principal families of men .. . al axes position of the two axes, always at rightangles to each other, constantly point to different parts of the sur-rounding heavens, each of them con-tracting and expanding within fixedlimits which are determinative of thecharacter and stability of our orbit. It is assumed that the reader is famil-iar with such terms as aphelion andperihelion, that he has a Assumption ofclear concept of our planet- ^^oSicSary orbit, of the plane of phenomena,the ecliptic, of the equator of the earthand the heavens, of the inclination ofthe earths axis to the plane in which ourglobe makes its journey around the sun, 62 GREAT RACES OE MANKIND. and of the circumstance of a summerand winter solstice, a vernal and autum-nal equinox, and of the precession of theequinoxes. It is also assumed that heapprehends the nature of the solar illu-mination of an ever-changing hemisphereof the earths surface, of the altered andaltering position of the sun as viewedfrom any given point on our planet, and. THE MOON—AN EXPIRED PLANET. of the attendant phenomena of the sea-sons. Presumably he is able to appre-hend that these phenomena go back fortheir causes to the inclination of the axisof the earth to the plane of its orbit, andto the eccentricity of that orbit; that is,its deviation from the circle. It may not be known, however, thatthe phase of our orbital career throughwhich we are now passing is that of con- traction, or approach to the circle. Themajor axis of the earths orbit is diminish-ing, and the minor axis in-creasing in measurement, of the planetary rni , • •, r ,i oscillation. I he eccentricity of theorbit is slowly but surely diminishingtoward zero. This signifies that thedifference between the perihelion, ornearest approach of the earth to the sun,and its aphelion, orgreatest distance,
Size: 1520px × 1644px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksub, booksubjectworldhistory
