Venta de Estola, a solitary house in the midst of a wood near a fine spring. I took several altitudes of the sun there: the chronometer gave 6" 46′ 56′′ of longitude.

The village of Tepecuacuilco.-Latitude found by the method of Douwes, uncertain to the extent of nearly 3', 18′ 20° 0".

Village of Tehuilotepec.-Longitude, 6h 47′ 12′′. Double altitudes of the sun gave me 18°35'0"; but this latitude, determined under unfavourable circumstances, is uncertain from six to seven minutes. The position of this place is interesting, on account of the proximity of the great mines of Tasco.

Pont d'Istla, in the great plains of S. Gabriel. I found it 18° 37′ 41′′ of latitude, and 6h 46′ 19′′ of longitude.

Village of Sun Augustin de las Cuesas.-Longitude, 6" 45′ 46′′. Latitude, 19° 18' 37". This village terminates on the west the great valley of Mexico.

It will be useful, for a minute acquaintance with the country, to add the distances which the natives, particularly the muleteers, who travel as it were in caravans to the great fair of Acapulco, reckon from one village to another. The true distance from the capital to the port being known, and supposing a third more for windings in a road both strait and of easy access, we shall find the value of the leagues in use in these countries. This datum is interesting for geographers, who in re

mote regions must avail themselves of simple itineraries. It is evident that the people shorten the leagues as the road becomes more difficult. However, under equal circumstances we may have some confidence in the judgments formed by the muleteers of comparative distances; they may not know whether their beasts of burden go two or three thousand metres* in the space of an hour, but they learn from long habit if one distance be the third or fourth or the double of another.

The Mexican muleteers estimate the road from Acapulco to Mexico at 110 leagues. They reckon from Acapulco to the Passo d'Aguacatillo, four leagues; el Limon, three leagues; los dos Aroyos, five; Alto de Camaron, four; la Guarita de los dos Caminos, three; la Moxonera, one-half; Quaxiniquilapa, two and a half; Acaguisotla, four; Masatlan, four; Chilpansingo, four; Sampango, three; Sapilote, four; Venta Vieja, four; Mescala, four; Estola, five; Palula, one and a half; la tranca del Conexo, one and a half; Cuagolotal, one; Tuspa, or Pueblo nuevo, four; los Amates, three; Tepetlalapa, five; Puente de Istla, four; Alpuyeco, six; Xuchitepeque, two; Cuernavaca, two; S. Maria, three-fourths; Guchilaque, two and a half; Sacapisca, two; la Cruz del Marques, two; el Guarda, two; Axusco, two; San Augustin de las Cuevas, three; Mexico, four. In

* 6561 or 9842 feet English. Trans.

this itinerary the numbers indicate how many leagues one place is distant from the one which immediately precedes it. Other itineraries, which are distributed to travellers who come by the South sea, estimate the total distance at 104 or 106 leagues. Now, according to my observations it is in a straight line 151,766 toises. Adding a quarter for windings, we shall have 189,708 toises, or 1725 toises* for the league of the country.

JOURNEY FROM MEXICO TO VERA CRUZ.

I determined on this road thirteen points, either by purely astronomical means, or by geodesical operations, particularly by azimuths and angles of altitudes.

M. Oltmanns deduced from my observations the position of the Venta de Chalco, on the eastern bank of the great valley of Tenochtitlan, 19° 16′ 8′′"; that of la Puebla de los Angeles (near the cathedral) 19° 0′ 15" of latitude, and 6 41′ 31′′-100° 22′ 45′′ of longitude; of the Venta de Sotto, 19° 26' 30"; of the village of Perote, near the fortress of the same name, 19° 33′ 37′′ of latitude, and 6° 38′ 15′′ of longitude; of the village de las Vigas, 19° 37' 10"; and finally, the position of the city of Xalapa, 19° 30′ 8′′ of latitude, and 6h 97′ 0′′-99° 15′ 0′′ of longitude. Don Jose Joacquin Ferrer, who, long before me, deter

* 11040 feet. Trans.

mined several points in the environs of Vera Cruz and Xalappa, found for the last city 19° 31′ 10′′ of latitude, and 99° 15' 5" of longitude. Both of us observed near the convent of St. Francis. In this fertile and cultivated region, four mountains, three of which are perpetually covered with snow, deserve the greatest attention. A knowledge of their exact position serves to connect several interesting points. The two volcanoes distinguished by the names of Puebla or Mexico (Popocatepetl and Iztaccihuatl) have been connected with the capital and the pyramid of Cholula. I found the latitude of Popocatepetl 18° 59′ 47, and 6" 43′ 33′′-100° 53′ 15′′ of longitude; the latitude of Sierra Nevada, or Iztaccihuatl, 19° 10′ 0′′, and 6o 43′ 40′′= 100° 55′ 0′′ of longitude. M. Costanzo deduced from a series of geodesical operations, 19° 11′ 43′′ for the latitude of Iztaccihuatl, and 19° 1′ 54′′ for that of Popocatepetl. The operations of this engineer having been made by means of a compass, and the magnetic declension depending on a great number of small local causes, we ought to be astonished at the accuracy of the results which have been obtained. These two colossal mountains, as well as the Pic d'Orizaba, being visible from the level of the pyramid of Cholula, I endeavoured very carefully to determine the position of this ancient monument. I found the latitude of the chapel which crowns the extremity of the pyramid, 19° 2′ 6′′, and 6 42′ 14′′-100° 33′ 30′′ of longitude.

M. Ferrer deduced the position of the Cofre de Perote from the geodesical operations between l'Encero and Xalappa, and found 19° 29′ 14′′. I was able, in spite of the rigour of the season, to carry instruments on the seventh of February, 1804, to the top of this mountain, which is 384 metres* higher than the Peak of Teneriffe. I observed there the meridian altitude of the sun, which gave for l'Alto de los Caxones (43" en arc farther north than the summit o Peña del Cofre) 19° 29′ 40′′ of latitude. The longitude was found by M. Oltmanns, who employed the angles taken by me between the Cofre and the Pic d'Orizava, 6h 37′ 55", which differs but 26′′ in time from that fixed by M. Ferrer.

The exact knowledge of the position of the Pic d'Orizaba is of great importance for navigators on landing at Vera Cruz. The chart of the gulf of Mexico, published in 1799 by the Deposito Hydrografico at Madrid, places this mountain a degree too far to the east, at 100° 29′ 45′′ of longitude. Angles of altitudes and azimuths taken by me, gave M. Oltmanns 19° 2′ 17" of latitude, and 99° 35′ 15′′-6 38' 21" of longitude. But long before me the Spanish mariners knew the true position of the Pic d'Orizaba. It would appear that the error of the map of the Seno Mexicano, which passed into the French map, should

* 1260 feet. Trans.

+ Carte des côtes du golfe du Mexique, d'apres les observations des Espagnols, An. 9.