At sunrise Dr. Coller returned to San Domingo, leaving me alone at Palenque to carry out the investigation of the mounds and temples, a work which he thought would be laborious and oppressive. My guides were however well acquainted with the ruins, and I consequently knew that I should be spared all unnecessary exertion. But until I began the exploration I had no idea of the difficulties that had to be encountered. The men were employed in cutting a path through the brushwood and it was impracticable to do more than follow a certain line of direction and obtain ideas of distances by counting the number of paces or by noting intervals of time. I soon ascertained that with the means at my disposal it was hopeless to expect to do more than obtain a general knowledge of the extent and form of the chief structures, and the positions of the mounds. It was a serious disappointment to find that it was impossible to make a thorough examination without the aid of a large number of Indians to cut down the trees and clear the ground. This would have been a work involving much time and expenditure and was entirely beyond my power. The forest was sombre, for the light that penetrated through the trees, was insufficient. It was however possible to obtain a fair knowledge of the extent of the space covered by the mounds, and their distances from the monastery. The ground plan of the inclosure could also be approximately understood. The first and, with respect to its altar, the most important building that I saw, was that known by the name of the Temple of the Cross. Before ascending the sides of the mound upon which it stands, I examined the formation of an ancient causeway which covered, for some distance, the stream near its base. I traced it for about one hundred and fifty yards. A small portion was sufficiently preserved to enable the system of construction to be ascertained. It appears to have been intended for the purpose of confining the rivulet that ran beneath it, and thus to secure a dry roadway, or crossing, during the rainy season. It was stated by the Indians, that there still existed, in the forest, the remains of a stone bridge. As far as I could understand their description, it appeared that in shape it was not unlike the ancient Chinese bridges, and rose to the centre by steep gradients.