VOL. I.J PHILOSOPHICAL TRANSACTIONS. 73 



distant from that of the sun, and whose circumference about its middle D was 

 joined to that of the least circle, intersecting the greatest circle at its two ex- 

 tremities H N. In this circle were discerned also the colours of a rainbow, but 

 they were not so strong as those of the second. 



At the part where the circumference of this third circle closed with that of 

 the second, there was a great brightness of rainbow-colours mixed together : 

 And at the two extremities, where this second circle intersected the first, ap- 

 peared two parhelias or mock-suns H N ; which shone very bright, but not so 

 bright or so well defined as the true sun. The false sun H towards the south, 

 was larger, and far more luminous than that towards the east. 



Besides those two parhelias which were on the two sides of the true sun, in 

 the intersection of the first and third circle, there was also upon the first great 

 circle, a third mock sun C, situated to the north, which was less and less bright 

 than the two others. So that at the same time there were seen four suns in the 

 heavens. There was also a very dark space I, between D and R. 



This appearance is considered as one of the most remarkable that can be seen, 

 by reason of the eccentricity of the circle H D N, and because the parhelia were 

 not in the intersectioiTof the circle D E B O with the great circle S C H IS, but 

 in that of the semicircle H D N. Which are different from the position of 

 those five suns seen at Rome on March 29, 1629, between two and three 

 o'clock A. M, two of them appearing in the intersection of a circle passing 

 through the sun's disk, with another that was concentric with the sun, as in 



%• 7. 



As for the two uncommon rainbows, they appeared at Chartres the 10th of 

 August 1665, about half an hour past six in the evening ; crossing each other 

 nearly at right angles, as seen in fig. 8. 



That opposite to the sun, in the usual manner, was more deeply coloured 

 than that which crossed it ; though the colours of the first Iris were not indeed 

 so strong as they are seen at other times. 



The greatest height of the stronger rainbow was about 45 degrees ; the 

 feebler rainbow lost one of its legs by growing fainter, about 20 degrees above 

 the stronger ; and the leg below appeared continued to the horizon. 



The fainter seemed to be a portion of a great circle ; and the stronger but a 

 portion of a small circle, as usual. 



The sun at their appearance was about six degrees high above the horizon: 

 and the river of Chartres, which runs nearly from south to north, was between 

 the observer and the rainbow ; and he stood level with this river, at the dis- 

 tance of 150 paces from it. 



VOL. I. K 



