FREE BOOKS

Author's List




PREV.   NEXT  
|<   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51  
52   53   54   55   56   57   58   59   60   61   62   63   64   65   66   67   68   69   70   71   72   73   74   75   76   >>   >|  
se seasonal terms do not strictly apply to Venus, in the sense in which we employ them on the earth, for with us spring is characterized rather by the change in the quantity of heat and other atmospheric conditions that it witnesses than by a certain fixed and invariable temperature. To some minds it may appear very undesirable, from the point of view of animate existences, that there should be no alternation of seasons on the surface of a planet, but, instead, fixed conditions of climate; yet it is not clear that such a state of affairs might not be preferable to that with which we are familiar. Even on the earth, we find that tropical regions, where the seasonal changes are comparatively moderate, present many attractions and advantages in contrast with the violent and often destructive vicissitudes of the temperate zones, and nature has shown us, within the pale of our own planet, that she is capable of bringing forth harvests of fruit and grain without the stimulus of alternate frost and sunshine. Even under the reign of perpetual summer the fields and trees find time and opportunity to rest and restore their productive forces. The circularity of Venus's orbit, and the consequently insignificant change in the sun's distance and heating effect, are other elements to be considered in estimating the singular constancy in the operation of natural agencies upon that interesting planet, which, twin of the earth though it be in stature, is evidently not its twin in temperament. And next as to the all-important question of atmosphere. In what precedes, the presence of an atmosphere has been assumed, and, fortunately, there is very convincing evidence, both visual and spectroscopic, that Venus is well and abundantly supplied with air, by which it is not meant that Venus's air is precisely like the mixture of oxygen and nitrogen, with a few other gases, which we breathe and call by that name. In fact, there are excellent reasons for thinking that the atmosphere of Venus differs from the earth's quite as much as some of her other characteristics differ from those of our planet. But, however it may vary from ours in constitution, the atmosphere of Venus contains water vapor, and is exceedingly abundant. Listen to Professor Young: "Its [Venus's] atmosphere is probably from one and a half to two times as extensive and as dense as our own, and the spectroscope shows evidence of the presence of water vapor in it." And P
PREV.   NEXT  
|<   27   28   29   30   31   32   33   34   35   36   37   38   39   40   41   42   43   44   45   46   47   48   49   50   51  
52   53   54   55   56   57   58   59   60   61   62   63   64   65   66   67   68   69   70   71   72   73   74   75   76   >>   >|  



Top keywords:
atmosphere
 

planet

 

evidence

 
presence
 

change

 
conditions
 

seasonal

 

effect

 

elements

 

precedes


fortunately

 
insignificant
 

visual

 

spectroscopic

 

distance

 

considered

 

heating

 

convincing

 

assumed

 
estimating

evidently

 

stature

 
interesting
 

agencies

 

temperament

 

constancy

 

important

 
question
 

operation

 
natural

singular

 

reasons

 

exceedingly

 

abundant

 
Listen
 

Professor

 

constitution

 
spectroscope
 

extensive

 

differ


nitrogen

 
breathe
 

oxygen

 

mixture

 

supplied

 

precisely

 

characteristics

 

differs

 

thinking

 

excellent