1. Stethoscope   Dr. Wallace H. Carothers   Dr. William Stokes, Rene Laennec   Sir Isaac Pitman   John J. Loud   Hint Half-n-half Clue   2. Electric Battery   Alessandro Volta   James Harrison, Alexander Catlin   Roger Bacon   Dr. Wallace H. Carothers   Half-n-half Clue   3. Printing Press   Johann Gutenberg   Otto   G. Ferdinand Von Zeppelin   Nikola Tesla   Half-n-half Clue   4. Internal Combustion Engine   Robert Wilhelm Von Bunsen   Edward Jenner   Dr. Alan M. Turing   Otto   Half-n-half Clue   5. Jet Engine   Andre-Marie Ampere   Dr. Wallace H. Carothers   Z. Janssen   Sir Frank Whittle   Half-n-half Clue   6. Laboratory Gas Burner   Otto   David Bushnell   Robert Wilhelm Von Bunsen   Dr. Wallace H. Carothers   Half-n-half Clue   7. Carburettor   Otto von Guericke   John Napier   Edward Jenner   Gottlieb Daimler   Half-n-half Clue