1. Otto   Vaccination   Internal Combustion Engine   Electric Furnace   Galvanometer   Hint Half-n-half Clue   2. Evangelista Torricelli   Barometer   Internal Combustion Engine   Logarithmic Tables   Laboratory Gas Burner   Half-n-half Clue   3. H. W. Seeley   Electric Flat Iron   Submarine   Air Pump   Rabies Vaccine   Half-n-half Clue   4. Lewis E. Waterman   Electric Furnace   Vaccination   Refrigerator   Fountain Pen   Half-n-half Clue   5. David Bushnell   Submarine   Automobiles using gasoline   Bicycle   Logarithmic Tables   Half-n-half Clue   6. William Siemens   Laboratory Gas Burner   Electric Furnace   Submarine   Automobiles using gasoline   Half-n-half Clue   7. Alessandro Volta   Electric Motor (AC)   Electric Battery   Jet Engine   Vaccination   Half-n-half Clue