514 INDEX. 



Paoe. 



Dufay's theory of electricity 302 



Dumas' theory of animal power 222 



Ear, artificial, an instrument for testing intensity of sound 379 



Echo, aerial, probably reflection from the ocean surface 505, 510 



Echo from the ocean observed at Block Island 435, 436, 454, 502 



Echo, limit of distance required to distinguish 296 



Education, address on 325 



Education a forced condition, requiring exertion 326 



Education to follow the order of development of the faculties 335 



Edwards, Mr. Charles, co-operation of, in observations on sound.. 487 



Electrical discharge by simultaneous opposite waves 241 



Electrical discharge, divellent effects of 142 



Electrical discharge, experiments on 240 



Electrical fish, shocks from, probably secondary 160 



Electrical induction from feeble battery 98 



Electrical research, the lateral discharge 101 



Electrical spark, most phosphorogenic at its extremities 205 



Electricity and Magnetism, contributions to 80, 92, 108, 149,200 



Electricity, currents and sparks of, from magnetism 93 



Electricity, free or redundant 101 



Electricity, generation of, from steam 189 



Electricity in the thunder-cloud, Becquerel's theory of 190 



Electricity less dissipated when slowly thrown on wire 102 



Electricity of different intensities, battery for producing 80 



Electricity, ordinary and galvanic, induction of 108 



Electricity, ordinary, induction currents from 105, 106 



Electricity, the lateral discharge of 101, 105 



Electric lights and calcium lights useless as fog-beacons 417 



Electro-dynamic induction, conditions of 108, 111 



Electro-magnetic apparatus, on some modifications of 3 



Electro-magnetic apparatus, principle of Schweigger's galvanic 



" multiplier" applied to 37 



Electro-magnetic engine 54 



Electro-magnet of " intensity " adapted to a telegraph 42 



Electro-magnet made for Yale College 50 



Elevation, effect of, on range of audibility 458, 463, 472 



Elliot, Major George H., commissioned to inspect European light- 

 houses 368 



Emmet, Professor, improvement on magneto-electric machines 91 



Ericsson hot-air engine used with fog-trumpet 384 



Ettinghausen, Professor, of Vienna, investigations on armature 



currents in magneto-electric machine 144 



Evans, the introducer of the high-pressure locomotive 318 



Faculties, the successive development of, the key to education 335 



Earaday on effect at commencement and ending of current 132 



