"A third and last paper in this department of physics [the infrared and light spectrum]... was published in volume ninety of the Philosophical Transactions and gave the results of two hundred and nineteen quantitative experiments. ...Herschel made a careful determination of the quantitative distribution of light and of heat in the prismatic spectrum, and discovered the surprising fact that not only where the light was at a maximum the heat was very inconsiderable, but that where there was a maximum exhibition of heat, there was not a trace of light. ...Herschel ...finally concluded that light and radiant heat were of essentially different natures... for a long time the question was looked upon as closed, and not until thirty-five years later was there any dissent. Then the Italian physicist, Melloni, with instrumental means a thousand times more delicate than that of Herschel, and with a far larger store of cognate phenomena, collected during the generation which had elapsed... discovered the true law."