This gentleman had an idea that he could fly by the aid of this ingenious machinery.  You will see that his wings are arranged so that they are moved by his legs, and also by cords attached to his arms.  The umbrella over his head is not intended to ward off the rain or the sun, but is to act as a sort of parachute, to keep him from falling while he is making his strokes.  The basket, which hangs down low enough to be out of the way of his feet, is filled with provisions, which he expects to need in the course of his journey.

That journey lasted exactly as long as it took him to fall from the top of a high rock to the ground below.

But we are not going to trust ourselves to any such harem-scarem contrivance as this.  We are going up in a regular balloon.

We all know how balloons are made, and this one of ours is like most others.  It is a great globular bag, made of strips of silk sewn together, and varnished with a certain composition which renders the balloon air-tight.  The car in which we will travel is made of wicker-work, for that is both light and strong, and it is suspended from a net-work of strong cord which covers the whole balloon.  It would not do, you know, to attach a cord to any particular part of the silk, for that would tear it.  In the top of the balloon is a valve, and a cord from it comes down into the car.  This valve is to be pulled open when we wish to come down towards the earth.  The gas then escapes, and of course the balloon descends.  In the car are bags of sand, and these are to be emptied out when we think we are too heavy for the balloon, and are either coming down too fast or are not as high as we wish to go.  Relieved of the weight of a bag, the balloon rises.

Sand is used because it can be emptied out and will not injure anybody in its descent.  It would be rather dangerous, if ballooning were a common thing, for the aeronauts to throw out stones and old iron, such as are used for the ballast of a ship.  If you ever feel a shower of sand coming down upon you through the air, look up, and you will probably see a balloon—­that is, if you do not get some of the sand in your eyes.

The gas with which our balloon is to be filled is hydrogen gas; but I think we will not use the pure hydrogen, for it is troublesome and expensive to produce.  We will get permission of the city gas authorities to take gas from one of their pipes.

That will carry us up very well indeed.  When the balloon is nearly full—­we never fill it entirely, for the gas expands when it rises into lighter air, and the balloon would explode if we did not leave room for this expansion—­it is almost as round as a ball, and swells out proudly, struggling and pulling at the ropes which confine it to the ground.

[Illustration]

Now we have but to attach the car, get in, and cut loose.  But we are going to be very careful on this trip, and so we will attach a parachute to the balloon.  I hope we may not use it, but it may save us in case of an accident.  This is the manner in which the parachute will hang from the bottom of the car.