28 ANNUAL OF SCIENTIFIC DISCOVERT. 



near the openin<r, into which, when the core is removed, an eii^hth 

 of an inch sheet-iron disk is sprung. This method is emplojcd 

 on wheels designed specially lor passenger coaches, and prevents 

 the entrance of stones, wli^ch, rattling within a wheel of so large 

 diameter, become a source of much annoyance." 



WOODEN WHEELS. 



The directors of the New York and New Haven Railroad have 

 decided, as an experiment, to use wooden wheels on some of the 

 cars upon their road. Quite a number of these wheels have been 

 purchased, and will be substituted for the present iron ones on 

 some of the new cars. They are understood to cost nearly treble 

 the price of iron wheels, but are considered quite as cheap in the 

 end. They are made of elm or teak wood, and bound with steel 

 tires. Besides being less liable to break by the action of frost, 

 they make less noise. 



SLIDING OF CAR-WHEELS. 



An experiment has been made at Munich for the purpose of 

 determining if a railway -carriage wheel rolls regularly without 

 sliding, so that by recording tlie number of revolutions of a 

 wheel, the circumference of which is known, tlie distance accom- 

 plished could be accurately ascertained. The difference between 

 the measurement by mathematical instruments and that obtained 

 by noting the revolutions of the wheel was found to be no more 

 than one sixty-eight thousandth of the wiiole. 



A NEW ALARM-BELL FOR LOCOMOTIVES. 



A new alarm-bell w\as tested on the Detroit and Milwaukie 

 Railroad lately. The invention consists of an ordinary l)ell, 

 weighing about 100 pounds, i)laced on the platform of tlu^ loco.- 

 motive, immediately over the cow-catcher. A rod attached to 

 the eccentric shaft causes a clapper to strike the bell each turn of 

 the driving-wheel. The bell is suspended loosely, and revolves 

 from the force of the stroke it receives, so that all parts of the 

 surface are equally exposed to wear. The advantages of this 

 arrangement are a continuous sound, slow or rapid in proportion 

 to the speed of the engine, each 15 feet producing a stroke of the 

 bell. In case of an accident, the railroad company can always 

 prove that their bell was ringing according to law ; and owing to 

 the position in which this bell is placed, the sound can be 

 distinctly heard about 3 miles in daytime, and by night i 

 miles or more, the ground and the continuous rail, both excellent 

 conductors of sound, assisting in carrying the vibrations. The 

 Detroit and Milwaukie Railroad have 2-4 of these alarms already 

 in use, and intend to provide all their passenger-engines with 

 them. 



