228 Notices respecting New Books. 



ram, in fighting, butts with his hard forehead; but in order to 

 increase his momentum he moves backward, and then coining 

 forward with great velocity dashes his head against his antago- 

 nist. Making these animals fight, is a favourite amusement at 

 the Court of the King of Persia. One of the Barber of Bagdad's 

 brothers is said, in the Arabian Tales, to have been a favourite 

 with the nobility for his skill in teaching these animals to fight. 

 It is not improbable that the sight of rams assaulting each other, 

 first suggested the idea of the warlike machine called the batter- 

 ing ram, which was used for breaking down the walls of a town." 

 p. 39. 



Centre of Gravity. — " In old buildings where the whole fabric 

 is closely bound together, it may occur that a part may overhang 

 the base, and yet that part not fall: but if the centre of gravity 

 of the whole building were brought without the base, ruin would 

 instantly ensue. The two towers of Bologna, in Italy, close be- 

 side one another, hang several feet beyond the perpendicular, and 

 seem to beholders as if ready to fall; but as the whole building 

 firmly adheres together, and as the centre of gravity is still above 

 the base, they are perfectly secure. They must have been long 

 in this state, as they are mentioned in the poems of Dante who 

 died in 1586. The tower of Pisa is 182 feet high, and is swagged 

 thirteen feet and a half from the perpendicular; it is built of fine 

 marble, and is most firm and secure. No records can tell how 

 long it has been in this state." p. 56. 



The Pendulum. — " The same principle which occasions the 

 motion of a pendulum, viz. that a body in its descent acquires 

 force sufficient to raise it to the same height, has given rise to an 

 amusement which is pretty common in Russia when the rivers 

 are frozen over. The ice is piled up so as to form a declivity 

 sloping with a smooth surface to the level of the river, and there 

 commences another pile which rises to nearly the same height,but 

 not quite. It again slopes down to the river, and again another 

 commences, and so on. A person gets into a vessel like a but- 

 cher's tray, and gliding along the first pile of ice acquires a velo- 

 city which carries him up to the top of the second, down which 

 he goes and ascendsthe third, and so on. In summer they em- 

 ploy wood instead of ice. Near Paris, in the summer of 1816 

 this Russian amusement was introduced, and gave great satisfac- 

 tion to the Parisians, and it still continues in favour." p. 102. 



Hydrostatics. — " The rapidity with which water flows from 

 a hole in the side of a cask is in the same proportion as above 

 stated (as the square root of the depth). Get a bucket or cask 

 and make a hole in the lower part of it, and mark at the side, by 

 means of any scale or measure, the height of one inch, of four 

 inches, of nine inches, of sixteen inches, and of twenty-five 



inches. 



