INDEX. 
557 
time, on dune sands in France, 506 ; 
the pitch, hardihood of, 273 ; unbrella, 
the, most elegant of trees, 309, 313 ; 
the white, rapidity of its growth, 274. 
Pinus cembra of Switzerland, 309. 
Pisciculture, its valuable results, 118. 
Plants, cultivated, uncertain identity of 
ancient and modern, 19 ; do. of wild and 
domestic species, 73; changes of habit 
by domestication, 19; geographical in¬ 
fluence of, 58 ; foreign, grown in United 
States, 61; American, grown in Europe, 
63 ; modes of introduction, 64; accident¬ 
al do., 66; power of accommodation of, 
65 ; how affected by transfer, 68 ; tena¬ 
city of life in wild species, 69 ; extirpa¬ 
tion of, 70 ; domestic origin of, 72 ; spe¬ 
cies employed for protection of sand 
dunes, 600. 
Pliny, the elder, theorv of springs, 198, 
216. 
Po, river, ancient state of its basin, 255 ; 
modem changes, 256 ; its floods, tribu¬ 
taries, and deposits, 256-261, 405; 
embankments of, 385, 404; sediment 
of, 410; age and consequences of its 
embankments, 411; mean delivery of, 
412 ; salti of, 415. 
Poland, sand plains of, 514. 
Poplar, the Lombardy, 68 ; characterized, 
313. 
Potato, native country of, 73. 
Prairies, conjectural origin of, 134. 
Provence, physical structure of, 237; an¬ 
cient state of, 238; destructive action 
of torrents on, 236 ; Alps of, 245. 
Prussia, sand dunes of, 485 ; drifting of, 
498 ; measures for reclaiming of, 505. 
Q UADRUPEDS, number in United 
States, 79 ; extirpation of, 84. 
Quebec, high tides of, 271; lumber trade 
of, 272. 
AILWAYS, scientific uses of, 53. 
Rain water, its absorption and infil¬ 
tration, 438, 439 ; economizing its pre¬ 
cipitation, 449. 
Ravenna, cathedral of, 60; pine woods 
of, 150. 
Red Sea, richness of, in organic life, 320; 
diversion of the Nile to, its effects, 530. 
Reindeei*, the, 83. 
Reservoirs, geographic and climatic effects 
of, 258. 
Reventlov’s organization of dune economy 
in Denmark, 504 ; a benefactor to his 
race, 515. 
Rhine, river, proposed diversion of, 533. 
Rice, cultivation of, 381. 
Rivers, transporting power of, 252; in 
Vermont, 253; their origin, 262 ; in¬ 
jury to their banks by lumbermen, 277 ; 
conditions of their rise and fall, 278 ; 
mutual action of rivers and valleys, 
408 ; effect of obstructions in, 409; 
subterranean course of, 409 ; confluen¬ 
ces of, effect on the current below, 424; 
sediment of, its extent, 547. 
River beds, natural change of, 401 ; arti¬ 
ficial do. in Egypt, 402; Italy and 
Switzerland, 403. 
River deposits, 408; of the Nile, 410; 
the Po, 411; the Tuscan rivers, 414. 
River embankments, 384 ; their use, 404; 
disadvantages, 405; transverse do., su¬ 
periority of, 406 ; effects of, 409. 
River mouths, obstructions of, 430; by 
sand banks, 431; accelerated by man’s 
influence, 432 ; effect of tidal move¬ 
ments, 432. 
Robin, the American, voracity of, 88. 
Rock generally permeable by water, 265. 
Roman empire, natural advantages of its 
territory, 1; increased by intelligent 
labor, 2 ; physical decay of, 3 ; present 
desolation, 4 ; caused by its despotism 
and oppression, 5. 
Rozet’s plan for diminishing inundations, 
406. 
Rude ti'ibes, continuity of arts among, 17; 
comme/ue of, 18 ; relations to organic 
life, 39; and to nature, 41. 
Russia, diminution of forests in, 298 ; ef¬ 
fects of, on rivers and lakes, 299 ; sand 
drifts of the steppes of, 514 ; attempts 
to reclaim them, 515. 
S ACRAMENTO City, California, effect 
of river dike at, 405. 
Sand, its composition and origin, 452; 
action of rivers, 453 ; ancient deposits 
of, 454, 456; amount of, carried to the 
Mediterranean, 455; of Egypt, 458, 
461 ; movement of, by the wind, 459; 
drifts of, from the sea, 461; dangers of 
accumulation of, 463 ; two forms of 
deposit, 463 ; drifting of dune, 495, 
Sand banks, aquatic, 468 ; movement of, 
469; connect themselves with the 
coast, 490. 
Sand dunes, how formed, 464 ; utiliza¬ 
tion of, 465 ; inland, of the South 
American desert, 482 ; their peculiari¬ 
ties, 483 ; age, character, and perma¬ 
nence of, 484 ; naturally wooded, 486; 
