ASTRONOMY AND METEOROLOGY. 387 



twice the magnifying power, and did not perceive it. This observation was 

 made in the buy of Rio Janeiro, at St. Domingos, when M. Liais was care- 

 fully determining the decrease in the luminosity of the sun from its centi-e 

 to its circumference, and from its equator to its poles. The first of these 

 observations was made between llh. 4m. and llh. 20m., and, from the inter- 

 ruption of clouds, the second was made between 12h. 42m. and Ih. 17m., on, 

 the very part of the sun where M. Lescarbault saw the planet enter, and at 

 a time when it must have been during a period of twelve minutes on the sun's 

 disk, and 1/.4 from its margin. "This quantity," says M. Liais, "is too 

 great to be accounted for by the difference of the parallaxes of Orgeres and 

 St. Domingos; and, consequently, when I jnade my last comparison, I ought 

 to have seen upon the sun the black spot in question if it had been seen at 

 Orgeres." It is certainly not easy to conceive how M. Liais could have 

 missed seeing the black spot when he was using a fine telescope, and mak- 

 ing such a nice observation on the light of the sun's disk at the very place 

 where the planet should have been; and had he continued his observations 

 even for a few minutes longer, we should have admitted the force of his 

 argument; but twelve minutes is so short a time, that it is just possible that 

 the planet may not have entered upon the sun during the time that he 

 observed it. Still, however, he is entitled to assert, as he does, " that he is 

 in a condition to deny, in the most positive manner, the passage of a planet 

 over the sun at the time indicated." 



M. Liais proceeds to support his astronomical fact by a moral argument, 

 which, we think, has not much force. He says, what is true, that Lescar- 

 bault contradicts himself in having first asserted that he saw the planet 

 enter upon the sun's disk, and having afterwards admitted to LeVerrier that 

 it had been on the disk some seconds before he saw it, and that he had 

 merely inferred the time of its entry from the rate of its motion afterwards. 

 " If this one assertion, then," says M. Liais, " be fabricated, the whole 

 may be so;" a conclusion which we cannot accept. These arguments M. 

 Liais considers to be strengthened by the assertion, which, as we have seen, 

 perplexed LeVerrier himself, that if M. Lescarbault had actually seen a 

 planet on the sun, he could not have kept it secret for nine months. 



2. The assertion of our author, in opposition to that of LeVerrier, that the 

 planet, if one existed, ought to be seeii in the vicinity of the sun, is not so 

 easily answered. 



In support of this opinion, he enters into an elaborate calculation of the 

 brightness of the planet Vulcan compared with that of Mercury. He 

 asserts that, from its proximity to the sun, it must be seven and one-third 

 times brighter than Mercury. But Mercury has been seen by himself and 

 others within 7 or 8 of the sun, and, therefore, assuming the diameter of 

 Vulcan to be 1" 5 (for which he assigns good reasons from Lescarbault's 

 observations), the total light which it sends to the earth will be nearly 

 double that of Mercury ; and, consequently, Vulcan, or LeVerrier's Ring of 

 Planets, ought to have been frequently seen by astronomers in the vicinity 

 of the sun, when they were searching for planets and comets in that 

 locality. 



3. The assertion that the planet of Lescarbault has not been seen during 

 eclipses of the sun, is of course true. 



As the planet Mercury has been frequently observed during solar eclipses, 

 we might reasonably expect to have seen Vulcan; but during the many 

 observations which were made in the vicinity of the sun during the time 



