The elevations due to the atmospheric pressure, as indicated by the barometer, are extracted from tables calculated, after the complete formula of La Place, by M. F. Delcros, contained in a volume of meteorological tables prepared by Arnold Guyot, and published by the Smithsonian Institution.

Those due the indications of the boiling-point apparatus are taken from a table in the same volume, calculated by Regnault, from his "Tables of forces of vapor," published in the Annales de Physique et de Chimie, t. xiv, p. 206.

The height of the barometer at the level of the sea is assumed at 30.00, and the temperature of the air at 65° Fah.

I have added a column of heights, measured with the barometer by Don Mariano Rivero, at places where they compare with mine.

At the pass of Antarangra we took our observations on the summit of a hill about two hundred feet above the road at its highest point.

Morococha is situated near the line of perpetual snow, on the eastern slope of the western chain of the Andes.

Tingo Maria is the place of embarcation on the Huallaga. The distance from Callao to this point, by our route, is 337 miles. The distance hence to the Atlantic is 3,662. If we add to these sums the 90 miles of travel from Tarma to Fort San Ramon and back, with the 626 from the mouth of the Ucayali to Sarayacu and back, we shall have the whole distance travelled over—4,715 miles.

TABLE OF APPROXIMATE HEIGHTS AND DISTANCES FROMCALLAO TO THE ATLANTIC.
Names of places.Dist-
ance.		Barometer.Boiling Point.Thermo-
meter.		Height, in feet.Height by Rivero-baro-
meter.
Callao . . . 30.000 212 65 . . . . . .
Lima 6 29.528 . . . 75 476 .505
Pacayar 12 28.580 . . . 61 10,346. . .
Yanacoto 10 27.568 . . . 57 2,337. . .
Coca Chacra 16 25.574 . . . 58 4,452. . .
Moyoc 15 23.027 . . . 50 7,306 . . .
Do. 15 23.027 198.25 50 7,380. . .
San Mateo 13 20.843 . . . 59 10,200 10.232
Do. . . . 20.843 193.25 59 10,128. . .
Acchahuarcu 9 . . . 188.3 33 12,898. . .
Lower edge of snow on western slope 3 17.836 . . . 49 14,300. . .
Pass of Antarangra 3 16.730 . . . 43 16,044 15.758
Do. . . . 16.730 182.5 43 16,199. . .
Morococha 4 17.700 . . . 46 14,409. . .
Pachachaca 9 . . . 188.5 40 12,786. . .
Oroya 12 19.542 . . . 36 11,654 12.270
Do. . . . 19.542 190.2 36 11,825. . .
Tarma 18 21.144 . . . 55 9,738 10.092
Do. . . . 21.144 193.9 55 9,770. . .
Palca 11 21.972 . . . 43 8,512. . .
Matichacra 12 23.292 . . . 61 7,091. . .
Huacapishtana 4 24.482 . . . 60 5,687. . .
Challuapuquio 12 26.804 . . . 68 3,192. . .
Fort San Ramon 6 27.406 . . . 76 2,605 . . .
Do. . . . 27.406 206.5 . . . 2,953. . .
From Tarma to Palcamayo 15 . . . 192.5 37 10,539. . .
Junin 18 . . . 188.2 32 12,947 13.330
Ninacacca 18 . . . 187.8 40 13,171. . .
Cerro Pasco 17 . . . 188.7 45 13,802 14.279
Chiquirin 12 . . . 190.7 54 11,512. . .
San Rafael 18 . . . 196.1 62 8,551 8.791
Huanuco 35 . . . 200.9 65 5,946 6.284
Chullqui 8 . . . 201.5 67 5,626. . .
Acomayo 6 . . . 198 74 7,518. . .
Cashi 12 . . . 199.8 58 6,540. . .
Atajo 10 . . . 204.7 71 3,910. . .
Chihuangala 8 . . . 205.6 74 3,421. . .
La Cueva 20 . . . 206.5 76 2,944. . .
Tingo Maria 10 . . . 207.8 75 2,260. . .
Tocache 174 . . . 209.1 77 1,579. . .
Sion 58 . . . 209.7 80 1,269
Lupuna 58 . . . 210 84 1,109. . .
Chasuta 87 . . . 210.5 82 846. . .
Sta. Cruz 220 . . . 211.2 85 490. . .
Nauta 353 . . . 211.3 74 434. . .
Pebas 197 . . . 211.1 . . . 537. . .
Egas 707 . . . 208.2 88 2,052. . .
River Bank 131 . . . 208.4 84 1,947. . .
Do. 60 . . . 208.5 82 1,890. . .
Do. 168 . . . 208.6 76 1,834. . .
Do. 50 . . . 208.8 78 1,740. . .
Barra 14 . . . 209.3 81 1,475. . .
Mouth of Madeira 104 . . . 209.8 80 1,212. . .
Villa Nova 209 . . . 210.3 76 959. . .
Santarem 220 . . . 210.5 78 846. . .
Para 759 . . . 211.5 80 331. . .
Do. . . . 29.708 . . . 81 320. . .
Sea 93 . . . . . . . . . . . . . . .
From mouth of Ucayali to Sarayacu 313 . . . 210.3 82 868. . .

METEOROLOGICAL JOURNAL.
Place.Approx. height.Date.Time.Thermo-
meter.		Remarks.
A.W.W. B.
Feet.1851. ° ° °
Palcamayo10,500 July 1 6 p.m. 56 . . . . . . Calm; sky white and beautifully clear.
Do.10,500 2 6 a.m.37 . . . 34 Remarkably clear.
Road 11,000 2 8½ a.m.45 53* . . . *Temperature of a spring issuing from the rock.
Junin 13,000 2 6½ p.m.45 . . . . . . Light westerly breeze; light cirrus clouds.
Do. 13,000 3 7 a.m.32 . . . 28 Clear and calm; stratus clouds covering the Andes.
Road 13,000 3 12½ 46 . . . . . . Snow squall, small round flakes; wind variable from northward and westward to northward and eastward; western Cordillera in the sunshine, the eastern covered with storm.
Ninaccaca 13,200 3 6 p.m.40 . . . 36 Beautiful night; light air from the westward.
Do. 13,200 4 6 a.m.39 . . . . . . Calm; ground covered with hoar frost.
Cerro de Pasco 13,800 9 Noon 45 . . . . . . Hail and snow; wind from northward and eastward.
Do. 13,800 10 10 a.m.46 . . . 40
Do. 13,800 10 5 p.m.42 . . . 38 Clear and calm.
Do. 13,800 10 10 p.m.37 . . . 34
Do. 13,800 11 8 a.m.40 . . . 36 Light airs from northward and westward; cloudy.
Do. 13,800 11 10 p.m.39 . . . 36 Cloudy.
Do. 13,800 12 8 a.m.39 . . . 36 Light cirrus clouds.
Do. 13,800 12 Noon 44 . . . 37
Do. 13,800 12 6 p.m.40 . . . 35 Wind northward and eastward; heavy stratus clouds; light snow.
Do. 13,800 12 10 p.m.37 . . . 34
Chiquirin 11,500 13 8 a.m.39 . . . 36 Calm; light cirrus clouds.
San Rafael 8,400 14 6 p.m.62
Do. 8,400 15 7 a.m.56
Huanuco 6,000 17 4 p.m.71 . . . . . . Clear; strong breeze from north, which always sets in, at this season, about noon, and ceases about dark.
Do. 6,000 18 9 a.m.65 . . . 57½
Do. 6,000 18 9 p.m.69
Do. 6,000 19 9 a.m.64 . . . 56 Clear; calm.
Do. 6,000 19 9 p.m.68½
Do. 6,000 20 9 a.m.63 . . . 55
Do. 6,000 21 9 a.m.65 . . . 58½ Cloudy, with appearance of rain; light breeze from the northward.
Chullqui 5,600 22 7 p.m.67 . . . . . . Light breeze from northward and eastward; half cloudy.
Road 5,500 2310 a.m. 72 62*. . . *Mountain stream; cirrus clouds.
Acomayo 7,500 2311 a.m. 74
Near top of Cerro de Carpis 8,000 232½ p.m.67 51*. . . *A spring in the woods.
Casha 6,500 237 p.m. 58 . . . . . . Calm; cloudy to the south; night quite cool.
Do 6,500 246 a.m. 52 . . . . . . Clear and calm.
Atajo 4,000 245 p.m. 71 . . . 67 Cirro-cumulus clouds; calm.
Do . . . 257 a.m.61
Chihuan-
gala 		3,500 255 p.m. 74.5
Do 3,500 26. . . . . . . . . . . . Heavy rain.
Do 3,500 272 p.m. 78 . . . 72 Cumulus clouds; calm.
Do 3,500 288 a.m. 64 . . . . . . Calm; cirro-cumulus, rained all the latter part of the night.
Do 3,500 298 a.m. 67 . . . 67 Calm; cloudy.
Do 3,500 291 p.m. 78 . . . . . . Breeze northerly; heavy clouds and thunder to the northward.
Do 3,500 298 p.m. 69 . . . . . . Calm; cloudy.
Do 3,500 309 a.m. 69 . . . . . . Calm; clear.
Do 3,500 303 p.m. . . . . . . . . . Heavy shower of rain, with thunder; most of the rain clouds came from the north.
Chinchay-
vitoc 		. . . 318 a.m.70. . . . . . Half cloudy.
Do. . . 3111 a.m.7167*. . . *Mountain stream.
La Cueva 3,000 315 p.m. 76 68*. . . *Huallaga river.
On the road . . . Aug. 17 a.m.74. . . . . . Cloudy; close and hot in the woods.
Tingo Maria 2,200 29 a.m. 75 . . . . . . River at Tingo Maria 100 yards broad, 2¾ fathoms deep; smooth and unbroken.
Do 2,200 27 p.m. 72 . . . 71 Cloudy; light breeze from the northward.
Do 2,200 38 a.m. 72 . . . . . . Calm; cloudy; had been showery during the night.
Do 2,200 34 p.m. 82 . . . 76