290 BOUGUER's voyage to PERU, 



hollow fpheres, the interior air more or lefs dilating them muft neceffarily oblige the 

 water which forms the bubble to vary its thicknefs, and the fmall fphere changing 

 its bulk, the cloud muft afcend to a greater or lefs height, till it meets with an equili- 

 brium in the bed of the atmofphere in which it floats. To-day the clouds are of a 

 certain fpecific weight, and maintain their fituations at a precife height ; they are ob- 

 ferved throughout the whole mountain to attain but to a certain point ; to-morrow the 

 fmall bubbles will be bigger or lefs, the clouds become more or lefs light, and they 

 will be obferved to ftation themfelves ui a higher or lower region. It is at fun-rife 

 they are noticed to be more fufceptible of motion, when they afcend in an uniform 

 manner, and fometimes with great velocity. But to return to their tranfparency, as 

 the fmall bubbles which compofe them, prefent too large a number of fmall furfaces 

 to the light, they appear opake when viewed from below ; whereas were the fpeclator 

 ftationed above them, as we frequently were upon Pichincha and other mountains, 

 all the reflected and intermingled rays, after having undergone various refradions, form 

 the white, conformably to what we are acquainted with, regarding the property of 

 light. 



There is an extraordinary phenomenon vifible almoft every day upon thefe moun- 

 tains, and which muft neceflarily be as old as the world, yet there is much probability 

 we have been the firft to notice it. The firft time we remarked it, we were together upon a 

 mountain of a medial height called Pambamarca. A cloud in which we were enve- 

 loped, removing, opened to our view the fcene of a very brilliant riling fun, the cloud 

 palTed from the other fide ; it was not thirty paces diftant, being yet too fhort a one to 

 give it that whitenefs of which I have fpoken, when each of us faw his own ftiadow 

 projected above, and only faw his own, by reafon the cloud did not prefent an even 

 furface. Its proximity, allowed us to diftinguifli every part of the ftiadow j we faw the 

 arms, legs, and head ; but what aftoniftied us the moft was, that the head was deco- 

 rated with a glory or circlet compofed of three or four concentric coronets, of a very 

 lively colour, each with the fame variety as the firft rain-bow, the red being the out- 

 ward colour. The diftances between thefe circles were ^qual, the laft circle the 

 fainteft ; and after all at a great diftance we noticed a large white circle, which fur- 

 rounded the whole. This was a fort of apotheofis to each fpedator ; and I muft not 

 negleft to apprize you, each every day calmly enjoyed the exquifite pleafure of viewing 

 himfelf decorated with all thefe glories, and faw no trace of thofe of his neighbour's. 

 It is true it is precifely the fame thing with regard to the rain-bow, although it has not 

 always been attended to. Each fpeftator views a diftintt rain-bow, fmce the arch has 

 a different centre for every perfon ; but as the coronets which are feen upon the moun- 

 lains of Peru are very fmall, and feem to belong to the fhadow of the fpe6lator, each 

 has a right to appropriate what he difcovers to himfelf. The firft immediately encircles 

 the head of the fhadow, the others follow, and the fpedator, only witnefTmg what 

 concerns himfelf, merely conjedures that his neighbours find themfelves in a fimilar 

 fituation. 



I frequently noticed the diameters of thefe circles, nor did I fail to do fo the firft 

 time I beheld them ; for I haftily made a fort of radius with the firft rules at hand, 

 becaufe I was apprehenfive this admirable fight might prefent itfelf but feldom. I 

 have remarked the diameters from one moment to another to vary in dimenfion, but 

 whether leffer or greater, the interval or fpace between them always maintained its 

 equality. Befide the phenomenon is only pictured upon the clouds, and on fuch only 

 whofe particles are congealed, and not, like the rain-bow, on drops of rain. When a 

 clouci that (hades the fun withdraws, and the fun becomes nwre ardent, quickly the 



12 little 



