Scientific Lectures. 175 



twenty-five years, the celebrated trial of locomotives was had at 

 Liverpool, in 1829. Stephenson won the prize at this trial with the 

 Rocket (which is now kept on exhibition at the Kensington Museum), 

 an engine which weighed but four and one-quarter tons, ran fourteen 

 miles an hour, and hauled a gross load of seventeen tons. To exhibit 

 the progressive changes in the locomotive, the maximum speed 

 attained at different periods will be given. In 1834 it was twenty 

 miles an hour ; in 1839 it was thirty-five miles ; in 1847 it was sixty 

 miles ; and since that time a speed of 100 miles an hour has been 

 attained. The first locomotive in the United States was driven by 

 horse-power, in 1829, and attained a speed of ten miles an hour, and 

 was designed by Mr. Detmold of JSTew York, who tlie next year built 

 a steam locomotive for the Charleston, S. C, railway. In 1829, 

 Horatio Allen, of New York, brought over two locomotives from 

 England for the Carbondale railway. In 1830, Peter Cooper placed 

 a small one on the Baltimore railway ; and in 1831, John B. Jervis 

 placed two upon the Albany railway, one of which vras built in England 

 and one at the West Point fo.undery. There are now some 15,000 

 locomotives on our American railways; and on one line in England 

 there are about 3,000. The usual Aveight of the locomotive is now 

 thirty tons ; but tliere are a great many in use of forty, and a few of 

 fifty tons, M. Petiet has placed twenty-five locomotives of sixty-nine 

 tons weight upon the Northern railway of France, to run the express 

 passenger trains between Paris and Dover. These are mounted on 

 twelve drivers and carry their own wood and water. It was once 

 considered that curves of less than half a mile radius, or grades of 

 more than fifty feet per mile were inadmissible. I^ow curves of 500 

 feet radius and grades of 100 feet per mile are common. The tem- 

 porary railway over Mount Cenis has long grades of 440 feet per 

 mile, over which all of its traflic is conducted by locomotives grasping 

 a central rail. Some years ago there was also a temporary track on 

 the Baltimore railway of 528 feet per mile, up which the locomotives 

 daily hauled twice their own weight. Forty years ago Mr. Allen 

 had to mount the foot-board of the first locomotive and run it 

 himself. Not a mechanic in the employ of the railway company 

 dared to let loose this monster. Now, 15,000 of them are daily 

 whirling over 40,000 miles of railway in this country alone, and 

 nearly twice as many in the rest of the world. To-day locomotives 

 are passing over the summits of the Rocky mountains and of 

 the Sierra Nevada — more than 8.000 feet above the level of the 



