XXXII INTRODUCTION. 



XII. 



If this nebulous matter gives us its reflected light only from certain portions of it i. e. only 

 from portions in position for admitting such reflection to our eye, as seems to he shown in I 

 may not the light from the tails of comets* (query: portions of very elliptic rings, the plane of 

 the rings then coinciding with our eye?) he given and withdrawn in the same manner; so that, 

 instead of such appendages suddenly shot out, and as suddenly withdrawn or dissipated, and at 

 times, contrary to all laws of dynamics, preceding the body from which it emanates, we have, 

 more philosophically, a substance always permanent, but giving its light to our eye only in 

 certain portions of its orbit? 



In conclusion, I wish here to express my acknowledgments for indulgences and kindnesses 

 often received from the officers of the United States frigates "Mississippi" and "Macedonian," 

 while in the prosecution of my work; especially from Captain S. S. Lee, of the former, and 

 from the late Commodore Abbot, of the latter ship. I owe, still more, my most hearty thanks 

 to Commodore Perry, who never failed to encourage others in useful efforts, while himself lead- 

 ing successfully in an honorable and glorious enterprise. 



GEORGE JONES. 



BROOKLYN, NEW YORK, May 26, 1856. 



"The tail of the great comet of 1680, immediately after its perihelion passage, was found by Newton to have been no 

 less than 20,000,000 of leagues in length, and to have occupied only two days in its emission from the comet's body ; a 

 decisive proof, this, of its being darted forth by some active force, the origin of which, to judge from the diameter of the 

 tail, must be sought in the sun itself." Sir J. Herschdl's Outlines of Astronomy. 



