Cette erreur est trop ordinaire
Et c'est la seule que l'on fit
En allant au cercle polaire.

M. A. Maury in his "History of the Academy of Sciences," remarks,—

"At the same time, the importance of the instruments and methods employed by the astronomers sent to the North, afforded a support to the defenders of the theory of the flattening of the globes, which was hardly theirs by right, and in the following century the Swedish astronomer, Svanburg, rectified their involuntary exaggerations, in a fine work published by him in the French language."

Meantime the mission despatched by the Academy to Peru proceeded with analogous operations. It consisted of La Condamine, Bouguer, and Godin, three Academicians, Joseph de Jussieu, Governor of the Medical College, who undertook the botanical branch, Seniergues, a surgeon, Godin des Odonais, a clock-maker, and a draughtsman. They started from La Rochelle, on the 16th of May, 1735.

Upon reaching St. Domingo, they took several astronomical observations, and continued by way of Porto Bello, and Carthagena. Crossing the Isthmus of Panama, they disembarked at Manta in Peru, upon the 9th of March, 1736.

Arrived there, Bouguer and Condamine parted from their companions, studied the rapidity of the pendulum, and finally reached Quito by different routes. Condamine pursued his way along the coast, as far as Rio de las Esmeraldas, and drew the map of the entire country, which he traversed with such infinite toil. Bouguer went southwards towards Guayaquil, passing through marshy forests, and reaching Caracol at the foot of the Cordillera range of the Andes, which he was a week in crossing. This route had been previously taken by Alvarado, when seventy of his followers perished; amongst them, the three Spaniards who had attempted to penetrate to the interior. Bouguer reached Quito on the 10th of June. At that time this city contained between thirty and forty thousand inhabitants, and boasted of an episcopal president of the Assembly, and numbers of religious communities, besides two colleges.

Living there was cheap, with the exception of foreign merchandises, which realized exorbitant prices, so much so indeed, that a glass goblet fetched from eighteen to twenty francs.

The adventurers scaled the Pichincha, a mountain near Quito, the eruptions from which had more than once been fatal to the inhabitants, but they were not slow in discovering that they could not succeed in carrying their implements to the summit of the mountains, and that they must be satisfied with placing the signals upon the hills.

"An extraordinary phenomena may be witnessed almost every day upon the summit of these mountains," said Bouguer in the account he read before the Academy of Sciences, "which is probably as old as the world itself, but what it appeared was never witnessed by any one before us. We first remarked it when we were altogether upon a mountain called Pamba Marca. A cloud in which we had been enveloped, and which dispersed, allowed us a view of the rising sun, which was very brilliant. The cloud passed on, it was scarcely removed thirty paces when each of us distinguished his own shadow reflected above him, and saw only his own, because the cloud presented a broken surface.

"The short distance allowed us fully to recognize each part of the shadow; we distinguished the arms, the legs, the head, but we were most amazed at finding that the latter was surrounded by a glory, or aureole formed of two or three small concentric crowns of a very bright colour, containing the same variety of hues as the rainbow, red being the outer one. The spaces between the circles were equal, the last circle the weakest, and in the far distance, we perceived one large white one, which surrounded the whole. It produced the effect of a transfiguration upon the spectator."

The instruments employed by these scholars were not as accurate as more modern ones, and varied with changes of temperature, in consequence of which, they were forced to proceed most carefully, and with most minute accuracy, lest small errors accumulating should end by leading to greater ones. Thus, in their trigonometrical surveys Bouguer and his associates never calculated the third angle by the observation of the two first, but always observed all three.

Having calculated the number of fathoms contained in the extent of country surveyed, the next point was to discover what part this was of the earth's circumference, which could only be ascertained by means of astronomical observations.

After numerous obstacles, which it is impossible to give in detail, after curious discoveries, as for example the attraction exercised on the pendulum by mountains, the French inquirers arrived at conclusions which fully confirmed the result of the expedition to Lapland. They did not all return to France at the same time.

Jussieu continued his search after facts in natural history, and La Condamine decided to return by way of the Amazon River, making an important voyage, to which we shall have occasion to refer later.