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THE POPULAR SCIENCE MONTHLY. 



the great river, of which the inhabitants of 

 the adjacent country stand in extreme terror. 

 It was not his privilege to witness an exhi- 

 bition of the phenomenon, althougli he much 

 wished to do so, while the people with whom 

 he was staying desired that he or any one 

 else should not, but he observed some of its 

 effects and had the scene described to him. 

 The most impressive manifestations of the 

 force of the wave are near the mouth of the 

 Araguary River. An eye-witness of one of 

 the appearances of the pororoca, at that 

 place, one of a party of soldiers, related that 

 " shortly after the tide had stopped running 

 out they saw something coming toward them 

 from the ocean in a long white line, which 

 grew bigger and whiter as it approached. 

 Then there was a sound hke the rumbling 

 of distant thunder, which grew louder and 

 louder as the white line came nearer, until 

 it seemed as if the whole ocean had risen 

 up, and was coming charging and thundering 

 down on them, boiling over the edge of this 

 pile of water like an endless cataract, from 

 four to seven metres high, that spread across 

 the whole eastern horizon. This was the poro- 

 roca ! When they saw it coming, the crew 

 became utterly demoralized, and fell to cry- 

 ing and praying in the bottom of the boat, 

 expecting that it would certainly be dashed 

 to pieces, and they themselves be drowned. 

 The pilot, however, had the presence of mind 

 to heave anchor before the wall of waters 

 struck them ; and, when it did strike, they 

 were first pitched violently forward, and then 

 lifted, and left rolling and tossing like a cork 

 on the foaming sea it left behind, the boat 

 nearly filled with water. But their trouble 

 was not yet ended ; for, before they had emp- 

 tied the boat, two other such seas came 

 down on them at short intervals, tossing them 

 in the same manner, and finally leaving them 

 within a stoue's-throw of the river-bank, 

 when another such wave would have dashed 

 them on the shore. They had been anchored 

 near the middle of the stream before the 

 waves struck them, and the stream at this 

 place is several miles wide." The signs of 

 the devastation wrought upon the land by 

 this gigantic wave are very impressive. Great 

 trees, dense tropical forests, " uprooted, torn, 

 and swept away like chaff" — for the most 

 powerful roots of the largest trees can not 

 withstand its rush ; the destruction of the 



banks for some distance inland ; and the 

 formation of new land in places, are among 

 the signs of its ravages. The pororoca is 

 an accompaniment of the spring tides, and 

 is due to the resistance offered to the tidal 

 waves by the sand-bars and narrow channels 

 which they have to meet. Its effects are 

 most marked in the northern channels of the 

 mouth of the Amazon, while little is known 

 of it in the southern channels. 



Drift-Copper in Iowa.— Mr. A. R. Ful- 

 ton, president, read a paper, before a recent 

 meeting of the Des Moines Academy of Sci- 

 ence, on the pieces of native copper that 

 occasionally occur in the drift of Iowa. He 

 named several specimens that had been 

 found in different parts of the State, vary- 

 ing from ten ounces to thirty pounds in 

 weight, all identical in appearance with the 

 native copper of the Lake Superior district. 

 They had doubtless been brought down from 

 there by glacial action, and this made it 

 probable that the glacial current had some 

 time during the Ice age flowed in a south- 

 west direction. So, pieces of lead-ore have 

 been found in parts of the State southwest 

 of the lead-region around Dubuque, point- 

 ing to the same supposition. 



Sowing Fertilizers.— Professor Storer, 

 of the Bussey Institution, has made some 

 experiments to determine the quantity of 

 given fertilizers which a man would natu- 

 rally throw from his hand in sowing an 

 aci'e field. Having measured off a half-acre, 

 he employed a careful laborer, accustomed 

 to such work, to scatter the fertilizers over 

 the soil, directing him to sow them as if he 

 were sowing grain thickly. Doubling the 

 amount actually sowed on the half -acre to 

 adapt the proportion to the standard of a 

 whole acre, the quantities sown were, to the 

 acre: of nitrate of soda, 214 pounds; of 

 muriate of potash, 173 pounds; of super- 

 phosphate of lime, 173 pounds; of blood, 

 bone, and meat-dust fertilizer, 124 pounds. 

 All of the substances were quite finely pow- 

 dered up, except the nitrate of soda. The 

 blood, bone, and meat-dust fertilizer weighed 

 50 pounds to the bushel; the superphos- 

 phate of soda, 68 pounds ; the muriate of 

 soda, 69 pounds ; and the nitrate of soda, 88 

 pounds. The experiment was repeated with 



