Progress was made during the next few years, and in 1829 two inventors had constructed a steam carriage which could travel at the rate of fifteen miles an hour. A little later we learn that there was a regular service of steam coaches running between Gloucester and Cheltenham. After that, however, many years elapsed before horseless carriages came into general use, one reason being that such conveyances were heavily taxed and subjected to many rules. It was not until 1896 that these were altered, and then immediately there was a change and cars driven by steam, electricity, and petrol came into use. CHAPTER XII THE TRAVEL OF TO-MORROW The travel of to-morrow! It is a fascinating subject, for, as we look backward through the last century and see the marvellous progress that has been made, it is impossible to believe that now we have come to a standstill. How then shall we travel in the future? Will it be in some new form of railway train or motor-car, with increased speed and added comfort? Or shall we leave solid earth behind us altogether and make our journeys in great airships and aeroplanes? We will begin with the more commonplace methods, and consider the possibilities of improvements and innovations in railway travel. Lately a great deal has been said and written about the mono-rail, and it seems quite likely that alterations will take place in this direction, for a single-line railway is comparatively cheap to construct, and has many other advantages, among them that of greatly increased speed. It is estimated that this could easily reach two miles a minute. In Africa we saw a very primitive form of mono-railway, and there is another in Algeria, where the trucks or baskets filled with agricultural produce hang on either side of a single line and are drawn along by mules. A real mono-railway with engines, railway carriages, and trucks is already in existence in Ireland, where it runs between Listowel and Ballybunion. The line is raised some feet from the ground, and is about 10 miles in length. The engine is a very curious-looking machine, with a boiler on each side and two funnels. This is arranged so that the weight is evenly balanced. There are also methods by which the trains on a mono-railway may be steadied by means of a wonderful contrivance called a gyroscope. Closely allied to the single-line railway is the hanging railway, which was first invented to carry loads of merchandise or minerals across rivers or over rough forest lands where an ordinary line would be difficult and expensive to construct. There is one of these hanging railways in Rhodesia, where a strong wire crosses from bank to bank of a river, and carries a chair-shaped seat which can hold two passengers. This is dragged backwards and forwards by means of a second wire. [Illustration: MONO-RAIL CAR, WITH GYROSCOPE.] Sometimes, instead of wire, rope is used, and these rope railways can be seen in use at many of the mines in South Africa.