Transcriber's Notes.
Spelling irregularities where there was no obviously preferred version were left as is. Variants include: "embedded" and "imbedded;" "a hypothesis" and "an hypothesis;" "inexhausted" and "unexhausted;" "volcanos" and "volcanoes."
Changed "intelligencies" to "intelligences" on page xvi: "may be rational intelligences."
Changed "familar" to "familiar" on page 43: "had been familiar."
Changed "Chalmer's" to "Chalmers'" on page 67: "Chalmers' reasonings."
Inserted missing period after "live in the sea" on page 78.
Changed "disapear" to "disappear" on page 82: "at last they disappear."
Changed "natturally" to "naturally" on page 84: "we may naturally ask."
Changed "planets" to "plants" on page 91: "plants and animals."