The Action of Light on Selenium in Philosophical Transactions of the Royal Society, Volume 167, [Received 1876], 1877, pp. 313-349. [EXTRACT: INVENTION OF THE SOLAR CELL. 1st DEMONSTRATION THAT ELECTRICITY COULD BE PRODUCED FROM LIGHT WITHOUT MOVING PARTS AND LED TO THE MODERN SOLAR CELL]

London: Royal Society, 1877. 1877. PRISTINE EXTRACT, 1st edition of the INVENTION OF THE SOLAR CELL. This printing is the true first and preceeds the Proceedings of the Royal Society printing which we offer separately]. ADAMS' & DAYS DEMONSTRATION THAT ELECTRICITY COULD BE PRODUCED FROM LIGHT WITHOUT MOVING PARTS AND LED TO THE MODERN SOLAR CELL" (Wikipedia). William Grylls Adams and Richard Evans Day write of their discovery of a completely new phenomenon - "that light had caused a flow of electricity through a solid material. Adams and Day called current produced by light "photoelectric." Today, we call it "photovoltaic." (Perlin). Community Environmental Council, From Selenium to Silicon and Beyond). Note that this paper was also published in The Philosophical Transactions just prior to this publication.

The field of solar photovoltaics began in 1872 when British engineer Willoughby Smith published a paper on the photo-sensitivity of selenium. The dream of harnessing the near limitless energy of the sun attracted a great deal of scientific attention.

Many scientists began to experiment with selenium, but it wasn't until three years later (and presented in this paper) that Adams and Day discovered and proved that ‘illuminating a junction between selenium and platinum has a photovoltaic effect', or, more simply said, selenium produces electricity when exposed to light (Wikipedia). Together, Adams and Day "subjected selenium to many experiments, including one in which they passed a battery-generated current through it.

"After the selenium was detached from the battery, Adams and Day discovered to their surprise that the current running inside the selenium had reversed itself. To find out why the selenium had changed the direction of the electrical flow, they repeated the experiment with on e variation. After removing the selenium from the battery, they let a flame shine onto the selenium. The flame forced the current to flow in the direction opposite to that in the previous experiment. ‘Here there seemed to be a case of light actually producing an electromotive force within the selenium, which in this case was opposed to and could overbalance the electromotive force' of the battery, the amazed scientists observed.

"This unexpected result led Adams and Day to alter their course of investigation and to immediately examine ‘whether it would be possible to start a current in the selenium merely by the action of light.' The next morning, they lit a candle an inch away from the same piece of selenium. " (Perlin, The Story of Solar Electricity, 16). The needle to their measuring device reacted immediately. Screening the selenium from light caused the needle to drop to zero. These rapid responses ruled out the possibility that the heat of the candle flame had produced the current (a phenomenon known as thermal electricity), because when heat was applied or withdrawn in thermoelectric experiments, the needle would always rise or fall slowly.

"‘Hence,' the investigators concluded, ‘it was clear that a current could be started in the selenium by the action of the light alone.' They therefor felt confident that they had discovered something completely new: that light caused ‘a flow of electricity' in a solid material. Adams and Day called current produced by light ‘photoelectric'" (Perlin, 17). CONDITION & DETAILS: London: The Royal Society. 8.5 by 5.5 inches (213 x 138mm). Bright and clean throughout. Near fine condition in every way.