Simplon
2 of the 7 encyclopedias on this shelf carry an entry for Simplon. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a mountain in the canton of Valais, Switzerland. The Simplon pass, 6,595 feet in altitude, leads from the upper valley of the Rhone southward to Italy. In 1800 Napoleon, desiring a military road from France into Italy, ordered the construction of a route passable for commerce. Work was begun at each end. Six years and an outlay of 18,000,000 francs were required. The Simplon road is forty-one miles in length. A roadway twenty to thirty feet wide is carried through numerous tunnels, along the face of mountains, and over 611 bridges. There are twenty widened resting places for travelers. A hotel at the summit is known as the Hospice of Simplon. The diligence, as the Swiss coach is called, requires ten hours to cross the Simplon. By taking steeper short cuts the wayfarer is able to make the passage on foot in less time. The scenery is grand. As a precaution against invasion in case of war, one of these tunnels at the Swiss end of the road has been provided with massive gates. A granite monument marks the boundary between Switzerland and Italy. A railroad tunnel, 12.4 miles in length, the greatest in the world, has lately been completed at a cost of $14,000,000. It is a double-track tunnel. In fact it consists of two parallel passages or tunnels separated by thirty-nine feet of rock. It connects French Switzerland with Milan. It shortens the railway distance between that city and London by eighty miles. The work was conducted from both ends. The workmen met February 24, 1905. In order to obviate smoke and offensive odors, it is proposed to employ electric locomotives in the tunnel.
Collier's New Encyclopedia (1921)
a mountain of the Alps, in the S. of Switzerland, separating the canton of Valais from the Piedmontese territory. The old road across it being impracticable for heavy carriages, a new one, called the Route of the Simplon, was formed by order of Napoleon I. at the joint expense of France and the kingdom of Italy. Though the ascent is everywhere gradual, the highest point of the road is nearly 6,600 feet above the level of the sea. The length is 38 miles, and the width between 25 and 30 feet. It is carried through several tunnels, over upward of 600 bridges, and has 20 station houses for travelers. The road of the Simplon, long regarded as one of the greatest teats accomplished by modern engineering, has become of less importance since the formation of a railroad. The Simplon tunnel, completed in February, 1905, is larger than either that of St. Gothard or Mt. Cenis. It is 122 miles long as against 8 miles for the Mt. Cenis and 9.3 miles for the St. Gothard.