RIVER. 



after rain ; which is alfo to be underftood of all the other 

 rivers, none of which yield any thing confiderable, except 

 in rainy feafons. 6. In Peru, Sumatra, Cuba, Hifpamola, 

 and Guinea. Laftly, there are feveral brooks in the 

 countries about the Alps, efpecially Tyrol, out of the fedi- 

 ment of whofe waters gold has been drawn, though there 

 be no grains confpicuous in them. Add to this, that the 

 Rhine alfo, in many places, has afforded a golden mud. 



As to rivers that bring grains or particles of filver, iron, 

 copper, lead, &c. we find no mention of them in authors, 

 though, doubtlefs, there are great numbers of each ; and 

 many of the medicinal effects of mineral waters are, doubt- 

 lefs, owing to particles of thefe kinds. 



We muft not here omit a water in Germany, which is 

 ordinarily fuppofed to change iron into copper. The truth 

 is, there is no real converfion of the metal ; all that is done 

 is, that the cuprine and vitriolic particles in the water 

 corrode the iron ; and, detaching parts of them by means of 

 the motion of the water, coppery particles fucceed in their 

 room. 



From this variety in the mixture of river-water refult 

 various qualities, different fpecific gravities, different co- 

 lours, &c. 



Some rivers, at certain feafons of the year, fwell fo as to 

 overflow their banks, and drown the neighbouring lands. 

 Of thefe the moft eminent is the Nile, which rifes fo as to 

 cover all Egypt, except the hills. The inundation begins 

 about the feventeenth day of June, and increafes for the 

 fpace of forty days, and decreafes for as many ; during which 

 period, the cities of Egypt, which are all built on hills, 

 appear as fo many iflands. 



To thefe inundations Egypt owes all its fertility ; the 

 heavens there affording no rain, or at leaft none in any refpect 

 confiderable. Hence, as the inundation is great or fmall, 

 Egypt, for that year, is fruitful or barren. 



The ancient Greeks, &c. were much perplexed in affign- 

 ingthe caufe of this inundation. From the modern Englifli 

 and Portuguefe traders into Congo, Angola, Monomotapa, 

 &c. we learn, that the fource of the Nile is in a large lake 

 called Zaire, round which are the mountains of the moon, 

 which being about io° to the fouthof the equator, inftead 

 of being covered with fnow in their winter, have rain every 

 day, at leall two hours before, and two hours after noon. 

 So that their tops are always covered with clouds ; and the 

 rains are, at the proper feafon, almoft continual. Hence 

 torrents are conltantly defcending from the mountains into 

 the lake of Zaire ; whence they flow into the channel of the 

 Nile, and other rivers arifing from the fame lake ; and 

 hence the inundation of the Nile. See Nile and Nilo- 



METER. 



Mr. Bruce is the firfl perfon who, in his " Travels to Dif- 

 cover the Source of the Nile," has defcribed, from his own 

 obfervations, the fpot in which he apprehends that the Nile 

 fprings. 



Tracing one of the ftreams, that run into the lake Tzana, 

 to a fwamp in the I ith degree of N. lat. he there remarks the 

 head of the Nile, as our modern map-makers had actually 

 done before he vifited this dreary region. Whether his 

 guide deferved credit, and whether he could juftly infer 

 that this rivulet was the Nile from the refpect paid to 

 it by the barbarous natives, it is not necefiary particularly 

 to enquire. The moft important object in inveftigating 

 the fource of the Nile is to account for its extraordinary 

 inundations. 



In doing this, Mr. Bruce has felected from the various 

 opinions enumerated by Diodorus Siculus (1. i. c. 24.) that 

 of Democritus of Abdera, and Agatharcides of Cnidus, 



which agrees in the main with that of Herodotus (1. ii. c. 8. ) 

 and has well explained the manner in which the fun, con- 

 tinuing nearly ftationary for fome days in the tropic of 

 Capricorn, rarefies the air, and collects a quantity of vapours 

 from the Atlantic on the weft, and the Indian ocean on the 

 eaft ; and then, in its progrels north towards the tropic of 

 Cancer, draws thefe vapours after him. So that as he 

 advances, the rainy feafon begins upon his arrival at the zenith 

 of every place, and the rains continue and increafe after he 

 has paffed it in his progrels northward. 



In April many rivers join the Nile, and enable it to force 

 its way through the ftagnant lake Tzana, without mixing 

 with it. In the beginning of May many other ftreams pour 

 themfelves into the fame lake, and furnifh the Nile with an 

 additional fupply of water. In the beginning of June, the 

 fun having palled over Abyfiinia, the rivers are there full, 

 and the time of the greateft rains in this country is during the 

 fun's being almoft ftationary in the tropic of Cancer. Thefe 

 rains are collected by the four great rivers of Abyflinia, 

 of which the Nile is one, which derives alfo a very copious 

 fupply from the White river, that rifes in a country of 

 almoft perpetual rain. 



As the vapours meet with no mountains to interrupt their 

 progrefs in the flat country that lies between Gerri and 

 Syene, the tropical rains extend no farther north of the line 

 than 1 6°. 



When the fun declines towards the equator, he reverfes 

 the effects which he produced in his paffage northward ; 

 and after his arrival at the line in the autumnal equinox, his 

 influence ceafes on the fide of Abyffinia, and extends itfelf 

 to the fouthern hemifphere. Thus on the 25th of September, 

 three days after the equinox, the Nile is generally found at 

 Cairo to be at the higheft, and then begins to decreafe. 

 Mr. Bruce explains the inundations that take place fouth of 

 the equator. The ancients were not unacquainted with this 

 caufe of the inundations of the Nile. The tropical rains 

 falling to the extent of 1 6° on each fide of the line gave 

 rife to the Nile and to its tributary ftreams which flowed 

 northward, through the kingdom of Sennar, &c. as well 

 as to the Zebee, and many large rivers which flow fouthward 

 into Ethiopia, and according to the defcent of the countries 

 into the Indian or Atlantic ocean. Homer gives to the 

 Nile the epithet ^(sttstih qui arhtus defcendit, a river produced 

 and fed by rains. See Nile. 



The other rivers which have any notable ftated inundations, 

 are the Gambia, and the Niger, which overflow at the fame 

 time with the Nile, and Jlofe themfelves in fands or lakes. 

 (See Niger.) Leo Africanus fays, it begins on the 15th 

 day of June, increafes for forty days, and decreafes as long. 

 The Zaire, a river of Congo, is affected in the fame manner 

 with the Nile. ( See Zaire. ) The Rio de la Plata, in Brafil, 

 as Maffeus obferves, overflows at the fame time with the Nile. 

 (See Rio de la Plata.) Of the fame kind of rivers is the 

 Ganges (which fee) ; and the Indus, both which laft over- 

 flow in June, July, and Auguft ; at which times the 

 natives fave great quantities of the water in ponds to ferve 

 them the reft of the year ; feveral rivers flowing out of the 

 lake Chiamay into the bay of Bengal, which overflows in 



September, October, and November : thefe all bring a very 

 great fertility with them to the ground ; the river Macoa. 

 in Camboi'a ; the river Parana, or Paranguala, which fome 

 will have to be the fame with the Silver river ; feveral rivers 

 in Coromandel, a part of India, which overflow in the 

 rainy months, from the great quantity ot water iffuing from 

 the mountain Gads ; the Euphrates, which overflows Me- 

 fopotamia certain days in the year ; and, laftly, the river 

 Sus, in Nwnidia. 



The 



