There have been many theories respecting the methods that may have been practised by the Indians in executing their carvings upon stone, but no knowledge has been obtained which throws sufficient light upon the subject.[92] No attention has however been directed to the artisan qualities of the workmen who shaped and fitted the lintels, which however prove that the workers in wood were as skilful as the masons. The lintels were made of wood harder than mahogany. I examined many of them with the utmost care, and could not detect the slightest mark or dent. It is doubtful whether a good carpenters plane could have given them a smoother surface. The zapote trees out of which they were formed, must have been fashioned into broad baulks of timber, and afterwards squared and divided into the required lengths. The face of the timber was levelled and smoothed, and the corners or angles were sharply defined. All this work had to be done, as far as is known, with stone implements. [Illustration: QUADRANGLE, CASA DE LAS MONJAS.] Upon taking a final glance at these ruins it seems reasonable to form the conclusion that Uxmal was built exclusively for the purposes of religion. The pyramids and their teocallis or temples were devoted as shrines for the gods, and monasteries were attached to them. The human sacrifices and the ceremonies that were customary in time of war took place in the open courts attached to the high altars of the chief idols. • • • • • Upon the last day of my stay at Uxmal, the morning was fine and the sky was clear. In the forenoon I observed that there were dense volumes of light-coloured smoke covering the fields towards the east. As the day advanced the air became hot and oppressive, and the sky was obscured. Upon inquiring the cause of this smoke I was told that the Indians were burning their weeds and stalks in accordance with their custom at that time of the year. In the afternoon, whilst I was engaged in sketching the south-east angle of the Casa del Gobernador, heavy drops of rain began suddenly to fall. As it was the dry season, this change of weather was unexpected. The rain drops soon ceased, but after an interval there were some slight showers which continued for about two hours. At the farmhouse I was told that such weather was unusual, and that the rain must have been caused by the smoke and heat rising from the fires. If this opinion was correct the change may have been caused by the heated air rising into a cooler region above, and thus producing an atmospherical disturbance.