Transcriber’s note:
Inconsistent hyphenation (matter transmitter/matter-transmitter, scintillation counter/scintillation-counter, spacesuit/space-suit) has been retained.
Corrections to spelling are flagged thus; holding the mouse over the word will show a note of the original printing. Deliberate mis-spellings (borogroves, momraths; plus all the lithping) have been retained. Minor changes to punctuation were made without comment.