Although we have in general availed ourselves of the map of Arrowsmith for the eastern part of the United States, some slight changes have however been made from the researches of M. Ebeling, and information obtained by M. de Volney in his journey to the west of the Alleghanys.

The north west coast of North America, from Cape Saint Lucas to Cape Saint Sebastian, was traced agreeably to the learned researches of M. Oltmanns, in his work on the Geography of the New Continent *. We have attended to the bearings of Vancouver and Alexander Malaspina. The longitude of the Island of Guadaloupe appears somewhat doubtful. An Ukase which issued in 1799, under the reign of the Emperor Paul the 1st, declares that all the coast situated to the north of the parallel of 55° belongs to the Russian government. In this Ukase, the north west coast is constantly called the north east coast of America, an extraordinary denomination, which was believed to be justifiable from this circumstance," that from Kamtschatka, we must sail to the east to find America." Storch's Russland, B. I. S. 145, 163, 265 and 297.

* Oltmanns Untersuchungen über die Geographie des Neuen Continents (Paris, F. Schoell) Th. II. S. 407. Recueil d'Observations Astronomiques, Vol. II. p. 592-619.

Although the results adopted by M. Oltmanns in the great Table of positions placed at the head of our Recueil d'Observations Astronomiques, do not sensibly differ from those which I have given above, Vol. I. p. cxxxiv-cxlv., it will be of utility however to specify here, the rectified longitudes of eight points of the

In the map of the points of separation*, the isthmus of Panama, was in great part traced from the astronomical and trigonometrical operations of M. M. Fidalgo, Noguera, and Tiscar, See the beautiful map published by the board of longitude of Madrid, in 1805, under the title of Carta esferica del mar de las Antillas y de las costas de Tierra Firme desde la isla de la

Introduction, p. cv.

Trinidad hasta el golfo de Honduras. According to the investigations of the expedition of Fidalgo, the Bay of Mandinga, extends towards the south, to the 9° 9′ of north latitude, and the Town of Panama is 7' to the east of the Town of Portobello. Don Jorge Juan concluded from his bearings in the river Chagre, that Panama was situated 31 to the west of Portobello*. According to the more recent map of the deposito, the isthmus is only 15 to the south of the Bay of Mandinga, or 14,258 toises in breadth; while by the map of La Cruz, this breadth is 55' or 52,277 toises. Notwithstanding the great confidence which the bearings of the coast by M. Fidalgo undoubtedly merit, we must not forget, that his operations embrace only absolutely the northern coasts, which have not been hitherto connected with the southern coast by a chain of triangles, or by the transference of time. It is however by these means only, or by a great corresponding number of observations of satellites and occultations of stars, that we can be enabled to resolve the important problem of the difference of longitude between Panama and Portobello. I call this an important problem, because the longitude of Panama has an influence on the mouth of the Rio Chepo, and consequently on the po.

* Voyage dans l'Amerique meridionale, T. i. p. 99.

sition of that part of the gulf of Panama which corresponds to the meridian of the point of San Blas, and the fort of Saint Raphael de Madinga. By glancing at the configuration of the northern and southern coasts we easily perceive that although the mean direction is nearly from east to west, the breadth of the isthmus does not depend on the latitudes alone.

What is the height of the mountains at the point where the Isthmus is narrowest? What is the breadth of the Isthmus at the point where the chain of mountains is least elevated? These are the two great questions which an enlightened government should endeavour to resolve by employing an experienced observer whom it would be sufficient to furnish with a sextant, two time-keepers, and a barometer. No measure of elevation, and no level has ever yet been executed in the Isthmus of Panama; and neither the archives of Simancas, nor those of the council of the Indies contain any paper of importance calculated to throw the least light on the possibility of cutting canals between the two seas. It is unfair, therefore to accuse the ministry of Madrid of a wish to conceal matters of which they have never had any more knowledge than the geographers of London and Paris.

In the small map of Choco* which exhibits the canal dug by the priest of Novita, in a district called Bocachica, I have marked as uncertain, the direction of the coast which. extends from the point of San Francisco Solano to the gulf of San Miguel. It is desirable that we should know more accurately the position of Cupica where the Spanish pilot, M. Gogueneche, made his settlement.

In the map of false positions we have distinguished the result drawn by M. Cassini from the observations of longitude contained in the voyage of the Abbe Chappe, which are to be found in the Connoissance des Temps for 1784, from the result adopted by the members of the academy of sciences who were entrusted with publishing the map of Alzate in 1772. We read on this map the following note:

"The voyage of M. Chappe to California "was the means of correcting the position of "different places, which it may be interesting "to specify here,

Longitude from the
Island of Fer.

North latitude.

"Nueva Vera Cruz† 285° 35′ 15" 19° 9' 30"

↑ Undoubtedly a typographical error, 285o for 282o,