<fe ^Philosophical trans AeTioNS. [anno i666. 



That S. Campani having also observed at Rome, with glasses of 50 palmes, or 

 about 35 feet, likewise of his own contrivance, had seen in the same planet the 

 same phaenomena ; as M the first face March 3 in the evening, and N the 2d 

 face March 1 8 in the evening 



That sometimes he saw during the same night, the two faces of Mars, one 

 in the evening, the other in the morning. 



That the motion of these spots in the inferior part of the apparent hemisphere 

 of Mars is made from east to west, as that of all the other celestial bodies, and 

 is performed by parallels, that decline much from the equator, and little from 

 the ecliptic. 



That the spots return the next day to the same situation, 40 minutes later 

 than the day before; so that in every 36 or 37 days, about the same hour they 

 come again to the same place. 



He states that some other astronomers have also made at Rome several ob- 

 servations of these spots of Mars, from March -i-|- to March -f-g-, with glasses 

 wrought by Eustachio Divini, of 25 and 45 palmes : which spots he makes but 

 little different from his own of the first face ; as will by and by appear, by the 

 direction to the schemes. 



But he adds that those other Roman astronomers who have observed with 

 Divini's glasses, will have the conversion of Mars to be performed, not in 24h. 

 40 m, as he maintains it is, but in about 13h. 



And to evince that they are mistaken in these observations of theirs, he 

 alleges, that they assure that the spots which they have seen in this planet 

 by an Eustachian telescope, the ^ of March, were small, very distant from 

 one another, remote from the middle of the disk, and the oriental spot was less 

 than the occidental, as- is represented by the fig. O, like that of the first face of 

 Mars ; whereas, on the contrary, Cassini pretends to evidence by his observations, 

 made at the same time at Bononia, that the same day and hour those spots were 

 very large, near one another, in the midst of the disk, the oriental larger 

 than the occidental, as appears by fig. P, which is that of the second face of 

 Mars. 



Besides, he declares that those astronomers were too hasty in determining, 

 after five or six observations only, in how much time Mars finished his revolu- 

 tion ; and denies it to be performed in 13 hours : adding, that though he him- 

 self had observed for a much longer time than they, yet he durst not for a great 

 while define whether Mars made but one turn in 24 hours 40 minutes, or two ; 

 and that all that he could for a long time afiirm, was only this, that after 24 h. 

 40 m. this planet appeared in the same manner he did before. 



But since those first observations, he affirms to have found cause to deter- 



