FREE BOOKS

Author's List




PREV.   NEXT  
|<   9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26   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   >>   >|  
the earliest ages there was no doubt a rational view entertained of the movements of the planets in space. From the Chaldeans to the Arabs, a belief prevailed, that space was filled with a pure ethereal fluid, whose existence probably did not rest on any more solid foundation than analogy or tradition. One hundred years after Copernicus had given to the world the true arrangements of our planetary system, Descartes advanced his theory of vortices in the ethereal medium, in which the planets were borne in orbits around the sun, and the satellites around their primaries. This idea retained its ground with various additions, until the Geometry of Newton reconciled the laws of Kepler with the existence of a power pertaining to matter, varying inversely as the squares of the distances, to which power he showed the weight of terrestrial bodies was owing, and also the revolution of the moon about the earth. Since Newton's day, those deviations from the strict wording of Kepler's laws, have been referred to the same law, and the avowed object of the author of the "Mechanique Celeste," was to bring all the great phenomena of nature within the grasp of analysis, by referring them to one single principle, and one simple law. And in his Introduction to the Theory of the Moon, he remarks: "Hence it incontestibly follows, that the law of gravitation is the sole cause of the lunar inequalities." BESSEL'S OPINION. However beautiful the conception, it must be admitted that in its _a priori_ aspect, it was not in accordance with human experience and analogy to anticipate a successful issue. In nature law re-acts upon law, and change induces change, through an almost endless chain of consequences; and it might be asked, why a simple law of matter should thus be exempt from the common lot? Why, in a word, there should be no intrinsic difference in matter, by which the gravitation of similar or dissimilar substances should be affected? But experiment has detected no such differences; a globe of lead and a globe of wood, of equal weight, attract contiguous bodies with equal force. It is evident, therefore, that if there be such differences, human means are not yet refined enough to detect them. Was the issue successful then? Generally speaking, we may say yes. But where there is a discrepancy between theory and observation, however small that may be, it shows there is still something wanting; and a high authority (Professor Bessel) says
PREV.   NEXT  
|<   9   10   11   12   13   14   15   16   17   18   19   20   21   22   23   24   25   26   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   >>   >|  



Top keywords:

matter

 
analogy
 
weight
 

differences

 
successful
 
bodies
 
planets
 

gravitation

 

Kepler

 

simple


existence
 

theory

 

change

 

Newton

 
nature
 
ethereal
 

endless

 

consequences

 

induces

 
aspect

inequalities
 

BESSEL

 

OPINION

 

incontestibly

 
However
 

beautiful

 

experience

 
anticipate
 

accordance

 
priori

conception
 

admitted

 

similar

 

discrepancy

 

speaking

 
Generally
 

refined

 

detect

 

observation

 
wanting

Bessel

 

authority

 

Professor

 

dissimilar

 
difference
 

substances

 

remarks

 
affected
 

intrinsic

 

exempt