COMETS. 



combined with the identity of the paths while visible establishes 

 identity. 17. Many comets recorded few observed. 18. Classifica- 

 tion of the cometary orbits. II. ELLIPTIC COMETS REVOLVING WITHIN 

 THE ORBIT OF SATURN : 19. Encke's comet. 20. Table of the elements 

 of the orbit. 21. Indications of the effects of a resisting medium. 

 22. The luminiferous etter would produce such an effect. 23. Comets 

 would ultimately fall into the sun. 



I. COMETAHY OUBTTS. 



1. FOR the civil and political historian the past alone has 

 existence the present he rarely apprehends ; the future never. 

 To the historian of science it is permitted, however, to penetrate 

 the depths of past and future with equal clearness and certainty : 

 facts to come are to him as present, and not unfrequently more 

 assured than facts which are passed. Although this clear per- 

 ception of causes and consequences characterises the whole domain 

 of physical science, and clothes the natural philosopher with 

 powers denied to the political and moral inquirer, yet foreknow- 

 ledge is eminently the privilege of the astronomer. Nature has 

 raised the curtain of futurity, and displayed before him the suc- 

 cession of her decrees, so far as they affect the physical universe, 

 for countless ages to come ; and the revelations of which she has 

 made him the instrument, are supported and verified by a never- 

 ceasing train of predictions fulfilled. He " shows us the things 

 which will be hereafter," not obscurely shadowed out in figures 

 and in parables, as must necessarily be the case with other reve- 

 lations, but attended with the most minute precision of time, 

 place, and circumstance. He converts the hours as they roll into 

 an ever-present miracle, in attestation of those laws which his 

 Creator through him has unfolded ; the sun cannot rise the moon 

 cannot wane a star cannot twinkle in the firmament, without 

 bearing witness to the truth of his prophetic records. It has 

 pleased the " Lord and Governor" of the world, in his inscrutable 

 wisdom, to baffle our inquiries into the nature and proximate 

 cause of that wonderful faculty of intellect that image of his 

 own essence which he has conferred upon us ; nay, the springs 

 and wheelwork of animal and vegetable vitality are concealed 

 from our view by an impenetrable veil, and the pride 'of philo- 

 sophy is humbled by the spectacle of the physiologist bending in 

 fruitless ardour over the dissection of the human brain, and 

 peering in equally unproductive inquiry over the gambols of an 

 animalcule. But how nobly is the darkness which envelopes 

 metaphysical inquiries compensated by the flood of light which is 

 shed upon the physical creation ! There all is harmony, and 

 order, and majesty, and beauty. From the chaos of social and 

 political phenomena exhibited in human records- phenomena 

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