Yet the Brazilian engineers had attempted a daring engineering work in the first instance. The configuration of Brazil is somewhat peculiar. A few miles from the coast, and running roughly parallel with the water-line, is a rugged range of mountains dividing the low-lying stretch of shore from the fertile highlands in the interior. The mountain ridge is not regular, but is badly broken up, forming, as it were, a succession of walls placed one behind the other. In order to gain the interior, and owing to the abrupt nature of the ascent, the line has to climb sharply, at the same time winding in and out among the clumps of mountains in a bewildering manner. In fact, the differences in level are so sudden that the track could be lifted only by means of resort to the rack rail, and other devices such as are adopted in Switzerland to ascend the steep mountain slopes. For instance, after leaving the coast, the first ridge is met within 30 miles, and in the course of 5 miles the line has to rise some 3000 feet. This involved the use of grades varying from 15 to 18 per cent.--from 1 in 6⅔ to 1 in 5-5/9--and when first laid down the line was worked upon the Riggenbach system. It is worth while to recall that it was on the low-level part of this section to Petropolis that the iron horse made its first appearance in South America. The short length of line, representing about 13 or 14 miles, between Maua and Raiz da Serra was the first stretch of railway to be laid and used on the continent south of the Equator. [Illustration: A STEEP BANK SHOWING THE CENTRAL RACK RAIL] [Illustration: TRAIN ON THE RACK SECTION OF THE PETROPOLIS DIVISION, SHOWING THE CURIOUS TYPE OF LOCOMOTIVE ADOPTED HOW THE LEOPOLDINA RAILWAY OVERCOMES HEAVY GRADES] On another part of the system--the line running inland from Nictheroy, on the eastern side of the bay of Rio de Janeiro--the Brazilian engineers were compelled to overcome one of the most searching problems in railway engineering in the world. After traversing forty miles of the level country, the mountain ridge barred their way. They realised that it could be surmounted only by some exceptional system, and the local authorities seized a unique opportunity. The Mont Cenis tunnel, connecting Italy and France, had been bored successfully, and this new steel highway through the heart of the range displaced the construction railway operating on the Fell system which had been laid over the crest of the Cenis range. The Brazilian engineers thereupon approached the Swiss authorities for the purchase of this abandoned stretch of mountain line, and their offer was accepted. Thereupon the Mont Cenis “Fell” railway was torn up, transported to South America, and pressed into service to help the Brazilian engineers over the obstacle that confronted them. [Illustration: REBUILDING A BRIDGE ON THE LEOPOLDINA RAILWAY The masonry structure had to be built beside the original iron structure so as not to disturb traffic.]