of Edison, persuaded Frank J. Sprague to work for Edison. One of Sprague's significant contributions to the Edison Laboratory was the introduction of mathematical methods. – Vacuum Apparatus (1881) – Governor for Electric Engines – Utilizing Electricity as a Motive Power – Depositing Cell for Plating the Connections of Electric Lamps, & c. – Apparatus for Treating Carbons for Electric Lamps – Webermeter – Vacuum-Pump – Dynamo-Electric Machine – Electric Light – Electric Lamp – Carbon for Electric Lamps – Electro-Magnetic Motor – System of Electric Lighting – Electric Lamp – Manufacture of Electric Lamps – Electric Meter – Electric Lamp – Electrical Governor – Incandescent Electric Lamp – Electric Lamp and the Manufacture Thereof – Magneto or Dynamo Electric Machine – System of Electric Lighting – Underground Conductors – Electric Chandelier – Electric Lamp and Socket or Holder – Regulator for Dynamo-Electric Machines – Regulator for Magneto or Dynamo Electric Machines – Webermeter – Webermeter – Electrical Drop-Light – Telephone – Telephone – Magnetic Ore-Separator – Electro-Magnetic Railway – Dynamo or Magneto Electric Machine – Regulator for Dynamo or Magneto Electric Machines – Electric Lamp – Regulator for Dynamo or Magneto Electric Machines – Electric Chandelier – Electric-Arc Light – Manufacture of Carbons for Electric Lamps – Dynamo-Electric Machine – Straightening Carbons of Electric Incandescent Lamps – Electrical Distribution System – Magneto or Dynamo Electric Machine – Mold for Carbonizing Incandescents – Process of Making Incandescents – Dynamo Magneto Electric Machine – Vacuum Apparatus – Dynamo or Magneto Electric Machine – Commutator for Dynamo or Magneto Electric Machines – Magneto or Dynamo Electric Machine – Electric Lamp – Electric Distribution and Translation System – Magneto-Electric Machine – System of Conductors for the Distribution of Electricity – Dynamo or Magneto Electric Machine – Dynamo or Magneto Electric Machine – Dynamo or Magneto Electric Machine – Dynamo or Magneto Electric Machine – Manufacture of Incandescing Electric Lamps – Incandescent Electric Lamp – Incandescent Electric Lamp – Incandescent Electric Lamp – Incandescent Electric Lamp – Incandescing Electric Lamp – Incandescent Electric Lamp – Incandescent Electric Lamp – Regulator for Dynamo-Electric Machines – Regulator for Dynamo-Electric Machines – Regulator for Dynamo-Electric Machines – Regulator for Dynamo-Electric Machines – Regulator for Dynamo-Electric Machines – Regulator for Dynamo-Electric Machines – Regulator for Dynamo-Electric Machines – Regulator for Dynamo-Electric Machines – Regulator for Dynamo-Electric Machines – Regulator for Dynamo-Electric Machines – Regulator for Dynamo-Electric Machines –