2o8 THE POPULAR SCIENCE MONTHLY. 



THE "POROROCA," OR BORE, OF THE AMAZON. 



By JOHN C. BEANNEE, 



STATE GEOLOGIST OF AEKAUSAS. 



I ONCE had an opportunity, while traveling upon the Amazon, 

 to observe some of the effects of a remarkable phenomenon 

 which occurs at the northern mouth of that river in connection 

 with the spring tides. It is known to the Indians and Brazilians 

 as the pororoca* and is, I believe, generally supposed to be 

 caused in the same manner as the " bore " of the Hoogly branch 

 of the Ganges, of the Brahmapootra, and of the Indus, f I regret 

 very much that, like Condamine, who passed through this region 

 in 1740, I could not observe this phenomenon in actual operation; 

 but the gentleman whose guest I was at the time, and upon whose 

 boat I was a passenger, was fairly horrified at my suggesting 

 such a thing, while his boatmen united in a fervent " God forbid 

 that we should ever see the pororoca ! " and ever afterward 

 doubted my sanity. I give some of the results of my observa- 

 tions, however, as collateral evidence, and in order that those who 

 in the future visit this particular part of the Amazon Valley, con- 

 cerning which so little is known, may be able to see and establish 

 as far as possible the rate of destruction and building up here 

 being carried on. 



I was upon a trip from Macapa a small town on the northern 

 bank of the Amazon, and about one hundred miles from its 

 mouth down the river to the ocean, and thence up the Rio Ara- 

 guary as far as the last might be navigable. The one inhabited 

 place on the Araguary is a very small military colony, called the 

 Colonia Militar Pedro Segundo. At Macapa I became acquainted 

 with the then director of this colony, Lieutenant Pedro Alexan- 

 drino Tavares, and was invited by him to visit the Araguary. 



The trip from Macapa was by a small sail-boat down the Ama- 

 zon to the ocean, and thence up the Araguary. Our departure 

 was so timed that we should reach that part of the region dis- 

 turbed by the pororoca exactly at the time of the month when 

 there would be the least probability of its being met with that 

 is, at the time of the neap tides. The voyage down the river was 

 in the face of the wind, and it was only five days after leaving 



* Pronounced paw-raw-raw' ea. This word, which is of Tupv or native Brazilian origin, 

 is the one invariably used by the Brazilians. Father Jcao Tavares says it is probably a 

 frequentative form derived from the Tupy word opoe, which means "to break with a noise.'' 



f Similar phenomena, though on a much smaller scale, occur on the Garonne in France, 

 on the Wye, Severn, and Trent in England, and on the following streams in Brazil : Eio 

 Guama, Capim, and Mojii in the province of Para, en the Eio Purus in the province of the 

 Amazonas, and on the Mearirn in the province of Maranhao. 



