Science Weekly - wk#17

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Across
  1. 1. an alphabet with letters that are represented by long and short signals of sound or light
  2. 2. huge world-wide database
  3. 4. a service that delivered mail from Missouri to California by horseback
Down
  1. 1. sea-related
  2. 3. an invention using electricity to communicate over long distances
  3. 5. a universal distress signal (call for help)