148 TENUITY AND VELOCITY OF ELECTRICITY. 



entirely lost ; for they constructed a powerful mag- 

 neto-electric machine, for ringing the alarm bells 

 for the Fire Department in the city of Boston. 

 This machine was operated by the water-power of 

 the Cochituate Aqueduct. The electro-motive 

 power was transmitted through telegraph wires, 

 detaching weights, which, in descending, rang the 

 bells for a fire-alarm. In this way originated the 

 admirable system of Telegraphic Fire-Alarms. 



TENUITY AND VELOCITY OF THE ELECTRIC ETHER. 



Momentum is the combined force of velocity 

 and mass. If therefore, as in the electric ether, 

 there is great tenuity, there must be a compen- 

 sating increase of velocity to produce a like result. 

 A swiftly projected cannon-ball is the equivalent 

 of a ponderous mass with a slow motion. Light 

 particles of sand driven swiftly against flint glass 

 rapidly cut away its surface. The hand, by turning 

 an electric machine, may thereby charge a battery, 

 whose force will disintegrate steel wire, and send 

 the light of an electric spark to the distance of the 

 moon in a second and one third of time. The 

 voice transmitted through the telephone outstrips 

 in speed " the winged couriers of the air." Ar- 

 'chimedes proposed theoretically wondrous things 

 with his lever, could he but find a fulcrum. 1 



1 This speed of transmission by electro-magnetic action appears to 

 have been anticipated by Galen as the medium of communicating 

 thoughts; and most remarkably by Lucretius, in his treatise " De Natura 

 Rerum," published before the Christian era. Addisnn gives an inter- 



