in architecture, such stairs as go straight, and do not wind round, or have the steps made tapering; but the fore and back part of each stair and the ends respectively parallel to one another: So that if one flight do not carry you to your designed height, there is a broad half space; and then you fly again, with steps everywhere of the same breadth and length as before.

the performers in a celebrated exhibition among the Mexicans, which was made on certain great festivals, and is thus described by Clavigero in his History of that people. "They fought in the woods for an extremely lofty tree, which, after stripping it of its branches and bark, they brought to the city, and fixed in the centre of some large square. They cased the point of the tree in a wooden cylinder, which, on account of some resemblance in its shape, the Spaniards called a mortar. From this cylinder hung four strong ropes, which served to support a square frame. In the space between the cylinder and the frame, they fixed four other thick ropes, which they twisted as many times round the tree as there were revolutions to be made by the flyers. These ropes were drawn through four holes, made in the middle of the four planks of which the frame consisted. The four principal flyers, disguised like eagles, herons, and other birds, mounted the tree with great agility, by means of a rope which was laced about it from the ground up to the frame; from the frame they mounted one at a time successively upon the cylinder, and after having danced there a little, they tied themselves round with the ends of the ropes, which were drawn through the holes of the frame, and launching with a spring from it, began their flight with their wings expanded. The action of their bodies put the frame and the cylinder in motion; the frame by its revolutions gradually untwisted the cords by which the flyers swung; so that as the ropes lengthened, they made so much the greater circles in their flight. Whilst these four were flying, a fifth danced upon the cylinder, beating a little drum, or waving a flag, without the smallest apprehension of the danger he was in of being precipitated from such a height. The others who were upon the frame (10 or 12 persons generally mounted), as soon as they saw the flyers in their last revolution; precipitated themselves by the same ropes, in order to reach the ground at the same time amidst the acclamations of the populace. Those who precipitated themselves in this manner by the ropes, that they might make a still greater display of their agility, Flyers, frequently passed from one rope to another, at that part where, on account of the little distance between them, it was possible for them to do so. The most essential point of this performance consisted in proportioning so justly the height of the tree with the length of the ropes, that the flyers should reach the ground with 13 revolutions, to represent by such number their century of 52 years, composed in the manner we have already mentioned. This celebrated diversion is still in use in that kingdom; but no particular attention is paid to the number of the revolutions of the flyers; as the frame is commonly hexagonal or octagonal, and the flyers five or eight in number. In some places they put a rail round the frame, to prevent accidents, which were frequent after the conquest; as the Indians became much given to drinking, and used to mount the tree when intoxicated with wine or brandy, and were unable to keep their station on so great a height, which was usually 60 feet.