In 1747-8 Benjamin Franklin made numerous investigations into the characteristics of the Leyden jar. He devised a method of charging jars in series, also called charging in cascade. The inner coated surface of the first jar is connected by a hook to the conductor of an electrostatic generator, and its outer coated surface is connected to the inside coating of the next jar and so on for a whole series. The inner coating of the first jar and the outer coating of the third are the terminals of the capacitor.