112 



A HISTORY OF 



at last, stood over the Adriatic sea. In its 

 course it crossed over all Italy ; and, by com- 

 putation, it could not have been less than 

 thirty-eight miles above the surface of the 

 earth. In the whole line of its course, wher- 

 ever it approached, the inhabitants below 

 could distinctly hear it, with a hissing noise, 

 resembling that of a fire-work. Having pass- 

 ed away to sea, towards Corsica, it was heard, 

 at last, to go off with a most violent explosion, 

 much louder than that of a cannon : and, im- 

 mediately after, another noise was heard, like 

 the rattling of a great cart upon a stony pave- 

 ment ; which was, probably, nothing more 

 than the echo of the former sound. Its mag- 

 nitude, when at Bononia, appeared twice as 

 long as the moon, one way, and as broad the 

 other; so that, considering its height, it could 

 not have been less than a mile long, and half 

 a mile broad. From the height at which this 

 was seen, and there being no volcano on that 

 quarter of the world from whence it came, it 

 is more than probable that this terrible globe 

 was kindled on some part of the contrary side 

 of the globe, in those regions of vapours which 

 we have been just describing; and thus, rising 

 above the air, and passing in a course oppo- 

 site to that of the earth's motion, in this man- 

 ner it acquired its amazing rapidity. 



To these meteors, common enough south- 

 ward, we will add one more of a very uncom- 

 mon kind, which was seen byUlloa, at Quito, 

 in Peru; the beauty of which will, in some 

 measure, serve to relieve us, after the descrip- 

 tion of those hideous ones preceding. " At 

 day break," says he, " the whole mountain 

 of Pambamarca, where we then resided, was 

 encompassed with very thick clouds ; which 

 the rising of the sun dispersed so far, as to 

 leave only some vapours, too fine to be seen. 

 On the side opposite to the rising sun, and 

 about ten fathoms distant from the place 

 where we were standing, we saw, as in a 

 looking-glass, each his own image ; the head 

 being as it were, the centre of three circular 

 rainbows, one without the other, and just 

 near enough to each other as that the colours 

 of the internal verged upon those more ex- 

 ternal ; while round all was a circle of white, 

 but with a greater space between. In this 

 manner these circles were erected, like a mir- 

 ror, before us ; and as we moved, they moved, 

 in disposition and order. But what is most 



remarkable, though we were six in number, 

 every one saw the phenomenon with regard 

 to himself, and not that relating to others. 

 The diameter of the arches gradually altered, 

 as the sun rose above the horizon ; and the 

 whole, after continuing a long time, insensibly 

 faded away. In the beginning, the diameter 

 of the inward iris, taken from its last colour, 

 was about five degrees and a half; and that 

 of the white arch, which surrounded the rest, 

 was not less than sixty-seven degrees. At the 

 beginning of the phenomenon, the arches 

 seemed of an oval, or elliptical figure, like the 

 disk of the sun ; and afterwards became per- 

 fectly circular. Each of these was of a red 

 colour, bordered with an orange ; and the 

 last bordered by a bright yellow, which altered 

 into a straw colour, and this turned to a green ; 

 but, in all, the external colour remained red." 

 Such is the description of one of the most 

 beautiful illusions that has ever been seen in 

 nature. This alone seems to have combined 

 all the splendours of optics in one view. To 

 understand the manner, therefore, how this 

 phsenomenon was produced, would require a 

 perfect knowledge of optics ; which it is not 

 our present province to enter upon. It will 

 be sufficient, therefore, only to observe, that 

 all these appearances arise from the density 

 of the cloud, together with its uncommon and 

 peculiar situation, with respect to the specta- 

 tor and the sun. It may be observed, that 

 but one of these three rainbows was real, the 

 rest being only reflections thereof. It may 

 also be observed, that whenever the spectator 

 stands between the sun and a cloud of fulling 

 rain, a rainbow is seen, which is nothing more 

 than the reflection of the different coloured 

 rays of light from the bosom of the cloud. If, 

 for instance, we take a glass globe, filled wit 

 water, and hang it up before us opposite th 

 sun, in many situations it will appear trans- 

 parent ; but if it is raised higher, or sidewnys, 

 to an angle of forty-five degrees, it will ot lirst 

 appear red ; altered a very little higher, yellow ; 

 then green, then blue, then violet colour: in 

 short, it will assume surrossively all the colours 

 of the rainbow ; but, if raisi d higher still, it 

 will become transparent again. A falling 

 shower may be considered as an infinite Dum- 

 ber of these little transparent globes, assuming 

 different colours, by being placed at their 

 proper heights. The rest of the shower will 



