In these Papers the Excellent Cassini affirms;
1. That with a Telescope of 24. Palmes, or of about 16 Foot, wrought after S. Campani's way, he began to observe February 6. 1666 (st.n.) in the morning, and saw two dark Spots in the first Face of Mars.
2. That with the same Glass he observ'd Febr. 14/24. in the Evening, in the other Face of this Planet, two other Spots, like those of the first, but bigger.
3. That afterwards continuing the Observations, he found the Spots of these two Faces to turn by little and little from East to West, and to return at last to the same situation, wherein he had seen them first.
4. That S. Campani, having also observ'd at Rome with Glasses of 50. Palmes or about 35 Foot, likewise of his own contrivance, had seen in the same Planet the same Phenomena.
5. That sometimes he hath seen, during the same night, the two Faces of Mars, one, in the Evening, the other in the Morning.
6. 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 peform'd by Parallels, that decline much from the Equator, and little from the Ecliptick.
7. That the Spots return the next day to the same situation, 40. minuts later, than the day before; so that in every 36. or 37. daies, about the same hour, they come again to the same place.
8. He promises shortly to give us the particular Tables of this Motion and of its Inequalities, together with the Ephemerides themselves.