World-life; or, Comparative geology . in equilibrium. The peripherywould experience no tendency tomove toward the centre. The cen-tral portions would experience littleor no tendency to remain both parts attract each ,1 rpi • 1 xu JFiG- 29. Nebula, Becom- other. The periphery, with progres- ^^^ annular. sive shrinkage, might move toward the centre until accelerated velocity should nullify theattraction of the central portion. The latter portionwould move, by its own gravity, toward the periphery,until a state of condensation should be reached, such asto correspond with the existi
World-life; or, Comparative geology . in equilibrium. The peripherywould experience no tendency tomove toward the centre. The cen-tral portions would experience littleor no tendency to remain both parts attract each ,1 rpi • 1 xu JFiG- 29. Nebula, Becom- other. The periphery, with progres- ^^^ annular. sive shrinkage, might move toward the centre until accelerated velocity should nullify theattraction of the central portion. The latter portionwould move, by its own gravity, toward the periphery,until a state of condensation should be reached, such asto correspond with the existing temperature. Thus, Iimagine, a simple annular nebula might originate, such aswe are acquainted with in the Lyre (Figure 11), in H1,909. and H 2,621. Thus, nebular aggregation and secular refrigerationmay reasonably be regarded as the general causes of thevaried forms, conditions and evolutions of nebulne. Letus now attempt to trace the development some stepsfarther. *Schellen: Spectral Analysis, 555 and 542, Figures 192 and 118 KEBULAR LIFE. 4. JSfon-annulating Nehulm and Stratified Rings.—The progressive changes of nebulji? seem to be toward thestellar condition. Not improbably, many nebulae, espe-cially small ones, shrink into single stars, as Sir WilliamHerschel supposed. Some of the planetary nebulae maypossibly contract indefinitely without breaking into separatenebulous fragments. In either event, they appear toundergo a sort of annulation. It seems more probable, however, that most nebulasbreak up normally into a large number of partial have indicated a process of curdling as a possible step inthe stellation of a non-rotating nebula. Each separatemass may be regarded as embracing in some instances,material for a sun and planetary system. This idea, how-ever, supposes that a rotation comes into existence in eachmass. How this could be generated while the physicalconditions are such as to favor the segregation of themasses, and thus prevent that preci
Size: 1651px × 1512px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, bookpublisherchica, bookyear1883
