Recall its actual activities.  Two hundred and fifty-eight vibrations of air per second produce on the ear the sensation we call do, or C of the soprano scale; five hundred and sixteen give the upper C, or an octave above.  So the sound runs up in air till, above, say, thirty-five thousand vibrations per second, there is plenty of sound inaudible to our ears.  But not inaudible to finer ears.  To them the morning stars sing together in mighty chorus: 

  “Forever singing as they shine,
  ‘The hand that made us is divine.’”

Electricity has as great a variety of vibrations as sound.  Since some kinds of electricity do not readily pass through space devoid of air, though light and heat do, it seems likely that some of the lower intensities and slower vibrations of electricity are not in ether but in air.  Certainly some of the higher intensities are in ether.  Between two hundred and four hundred millions of millions of vibrations of ether per second are the different sorts of heat.  Between four hundred and eight hundred vibrations are the different colors of light.  Beyond eight hundred vibrations there is plenty of light, invisible to our eyes, known as chemical rays and probably the Roentgen rays.  Beyond these are there vibrations for thought-transference?  Who knoweth?

These familiar facts are called up to show the almost infinite capacities and intensities of the ether.  Matter is more forceful, as it is less dense.  Rock is solid, and has little force except obstinate resistance.  Steam is rarer and more forceful.  Gases suddenly born of dynamite touched by fire in the rock under a mountain have the tremendous pressure of eighty thousand pounds to the square inch.  Ether is so rare that its density, compared with water, is represented by a decimal fraction with twenty-seven ciphers before it.

When the worlds navigate this sea, do they plow through it as a ship through the waves, forcing them aside, or as a sieve letting the water through it?  Doubtless the sieve is the better symbol.  Certainly the vibrations flow through solid glass and most solid diamond.  To be sure, they are a little hampered by the solid substance.  The speed of light is reduced from one hundred and eighty thousand miles a second in space to one hundred and twenty thousand in glass.  If ether can so readily go through such solids, no wonder that a spirit body could appear to the disciples, “the doors being shut.”

Marvelous discoveries in the capacities of ether have been made lately.  In 1842 Joseph Henry found that electric waves in the top of his house provoked action in a wire circuit in the cellar, through two floors and ceilings, without wire connections.  More than twenty years ago Professor Loomis, of the United States coast survey, telegraphed twenty miles between mountains by electric impulses sent from kites.  Last year Mr. Preece, the cable being broken, sent,