668 Scientific Memoranda, 



surface; and on the supposition that the undulatory theory of 

 light was the true view of its phenomena, he remarked that the 

 present effect pointed out how the direct vibrations of the lu- 

 minous body might be supposed to become converted into lateral 

 vibrations, and so produce that particular condition of the lu- 

 minous ether which Young and Freswell have shown would 

 account for all the phenomena of palarised hght. 



Birmingham and London Railway. — This great undertaking 

 will be a monument of the enterprise of the age. Not so much 

 on account of the distance between the two cities, which is one 

 hundred and twelve miles and a half, but on account of the 

 skill with which the line has been established. The engineers 

 appear to have availed themselves fully of the experience which 

 previous undertakings have produced in every branch of railway 

 motion. There are to be two lines of tracks, one leading to 

 London, the other to Birmingham, and the general line has been 

 so planned as to avoid encroachments upon private property, 

 that were of an unwelcome nature. The tunnels amount to 

 ten in number, one of which will be a mile and a quarter long, 

 others will be less than a quarter of a mile. In consequence of 

 this judicious plan of forcing an approximation to the most prac- 

 ticable system of slopes, the inclination never exceeds one in 

 330, or 16 feet in a mile of 5280 feet. Upon such a level it is 

 probable that steam locomotion may be permanent and econo- 

 mical. The rise of one foot in 96 feet, or 55 feet in a mile of 

 5280 feet, on the Whiston and Sutton inclined planes, has been 

 very trying, and has put the Liverpool Company to great ex- 

 pense. It is now said that this last company proposes to aban- 

 don steam locomotive power, and to substitute stationary or 

 animal power, or both. It is very clear that the system which 

 requires the least repair, although involving additional capital, 

 is the true one to pursue. Things must be made that they may 

 last, and not that they may eternally be tinkered. Of the 

 twenty-four locomotives belonging to the Liverpool and Man- 

 chester Company, seldom more than six are in operation, the 

 rest are mending. It is stated, too, that the annual repairs on 

 each of their locomotives amounts to £1500 sterling. These are 

 important lessons for all railways to be constructed in the United 



