biosphere vs hearth

biosphere

noun
  • The totality of living organisms and their environment. 

  • The part of the Earth and its atmosphere capable of supporting life. 

hearth

noun
  • A hearthstone, either as standalone or as the floor of an enclosed fireplace or oven. 

  • The place in a home where a fire is or was traditionally kept for home heating and for cooking, usually constituted by at least a hearthstone and often enclosed to varying degrees by any combination of reredos, fireplace, oven, smoke hood, or chimney. 

  • The lowest part of a metallurgical furnace. 

  • A brazier, chafing dish, or firebox. 

  • Home or family life. 

  • A fireplace: an open recess in a wall at the base of a chimney where a fire may be built. 

  • A household or group in some forms of the modern pagan faith Heathenry. 

How often have the words biosphere and hearth occurred in a corpus of books? (source: Google Ngram Viewer )