Balloons had not long been invented when the idea arose of a device by means of which an aeronaut who found himself in difficulties might be able to reach the ground in safety. In other words, the need was felt for something which should play towards the balloon the part which the lifeboat does to the ship. The original idea of a parachute was even older than that, since we are told of a man away back in the seventeenth century who amused the King of Siam by jumping from a height and steadying his descent by means of a couple of umbrellas. It was not, however, until the very end of the eighteenth century or the beginning of the nineteenth that descents were made from really considerable heights from balloons. The usual arrangement then was to have the parachute hanging at full length fastened below the basket, or tied to one side of the balloon in such a manner that it could be detached by cutting the cords that held it up. When the parachute was carried below the balloon basket the man was already in the cradle or seat of the parachute ready to be dropped, but when the seat was tied to the side of the car of the balloon the aeronaut, when he wished to make a descent, first got from the car into the seat, and, casting himself adrift from the car, swung out from under the centre of the balloon so that when he was hanging clear another man in the balloon cut the cords or pulled a slip-knot which set the parachute free. There were different ways of doing this and when a man was by himself he had to get into the sling of the parachute and, on finding himself clear of everything, he would give a tug to a cord which would release a catch holding up the parachute and allow it to drop to earth. The parachute, at the very first, was but a simple affair, being little more than a circular sheet of cotton or similar fabric, but it was very soon found necessary to make it _a bag_ or it would not properly hold the air. Cords were attached at regular intervals all around the edge of this bag, these cords being gathered together and attached to the edge of a basket which carried the man. Sometimes only a sling was used, or a simple light seat after the fashion of the "bosun's chair" upon which a sailor is sometimes hauled to the top of an unclimbable mast, or a steeplejack to the top of a chimney. Thus, when it was dropped, the weight of the man, pulling upon all the cords simultaneously, drew down the edge of the bag, which, catching the air in its fall, acted as a powerful brake and reduced the rate of falling to such an extent that if all went well the man alighted in safety if not comfort. As has already been remarked in another chapter, air, which seems to us sometimes to be so exceedingly light as to have practically no weight at all, really has weight and also the property which we call inertia, by virtue of which things at rest prefer to stay at rest.