60 FirzceraLp— Quantity of Energy Transferred to Ether by a Variable Current. 
and as « generally equals unity in electro-magnetic measure, the energy radiated 
= Warttety) IN" tx 105%, 
where WV is the number of vibrations per second, so that even if it were as many as 
ten million per second (10), the energy radiated would still be only 75 (7a?) ergs 
per second. 
If we knew what the radiating power of a gas were, and assumed that its mole- 
cules gave their energy to the ether according to the same laws as varying electric 
currents do, we might estimate the magnetic moment of what correspond to electric 
currents in a molecule. 
The energy in the neighbourhood of the radiating point that I rejected as vary- 
ing with the distance from it, and consequently as unconnected with the radiation, 
is what would be got if we neglected the effects of induction of the displacement 
currents ; 7.e. it is the energy of the forced displacement currents produced directly 
by the variation of the primary current, and which start the radiating displacement 
currents. This part of the whole energy in the medium is but a small part of that 
at any point except within a few wave lengths of the origin. 
