278 PHILOSOPHICAL TRANSACTIONS. . [aNNO I698. 



contract, till at length the two arches fhg, and fg became coincident ; when 

 for a great space, the secondary iris lost its colours, and appeared like a white 

 arch at the top. I observed also, that at the points f and g, the intersection 

 of the interior red of the secondary iris, and the exterior red of the arch, was 

 much more intensely red than the outward limb of the primary iris ; and that 

 during the whole appearance, the upper part of the third iris was not at all 

 visible, beyond the intersections, f, g. This uncommon sight entertained me 

 for about 20 minutes, when the clouds blowing away, the whole vanished. I 

 was at first amazed with the sight, but afterwards recollecting that the sun 

 shone along the river Dee, which from thence empties itself w. n. w. where the 

 sun then was, I concluded this secondary arch afhgc was produced by the beams 

 of the sun reflected from that water, which at the time was very calm ; and it 

 had been much more bright had it been at that time about high, as it was low 

 water, when all the sands were bare. I was soon confirmed that my supposition 

 was right, and that it answered all the appearance without any scruple, and that 

 the arch afhgc, was no other than that part of the circle of the Iris, that would 

 have been under the earth, bent upwards by reflection. 



Accounl of Boohs. — 1. Voyages and Discoveries in South America : The First 

 up the River of Amazo7is to Quito in Peru, and back again to Brazil, per- 

 formed at the Command of the King of Spain, by Christopher U Acugna. 

 The Second, up the River of Plata, and thence by Land to the Mines of Potosi, 

 by M. ylcarete. The Third, from Cayenne into Guiana, in search of the Lake 

 of Parima, by M. Grillet, and Bechamel. Done into English from the 

 Originals, being the only Accounts of those Parts hitherto extant, with Maps. 

 Land. W 240, p. I96. 



Father D' Acugna begins vv'ith a short account of some remarkable attempts 

 that had been made unsuccessfully at several times by the Spaniards, to discover 

 the river Amazons ; and then proceeds to the perfect discovery of it, by Don 

 Pedro de Texeira, who in the year 1637, set out from Para in Brazil, with 70 

 Portugueze, and 1200 Indians, in 47 canoes, and passing up the river with 

 much difficulty, got to Quito in Peru. 



By the account which Father D' Acugna gives of this river, it takes its rise 

 8 leagues from Quito, within 20 minutes of the equinoctial line, runs from east to 

 west, coasting along the south side of the equinoctial line, and is not distant 

 from it above 5 degrees, in the greatest of its windings ; the narrowest part of 

 it is a quarter of a league broad, in some places it is one, in others 2, 3, and 

 4 leagues wide ; and after a course of above 1200 leagues, discharges itself into 



