This event has given rise in my mind to several serious and important reflections. I consider that if I had not been awakened so early in the morning I should have slept six hours longer by the light of the sun, and in exchange have lived six hours the following night by candle-light; and the latter being a much more expensive light than the former, my love of economy induced me to muster up what little arithmetic I was master of, and to make some calculations, which I shall give you, after observing that utility is, in my opinion, the test of value in matters of invention, and that a discovery which can be applied to no use, or is not good for something, is good for nothing. I took for the basis of my calculation the supposition that there are 100,000 families in Paris, and that these families consume in the night half a pound of _bougies_, or candles, per hour. I think this is a moderate allowance, taking one family with another; for though I believe some consume less, I know that many consume a great deal more. Then estimating seven hours per day, as the medium quantity between the time of the sun’s rising and ours, he rising during the six following months from six to eight hours before noon, and there being seven hours of course per night in which we burn candles, the account will stand thus:— In the six months between the 20th of March and the 20th of September there are— Nights 183 Hours of each night in which we burn candles 7 —— Multiplication gives for the total number of hours 1281 These 1281 hours multiplied by 100,000, the number of inhabitants, give 128,100,000 One hundred twenty-eight millions and one hundred thousand hours, spent at Paris by candle-light, which, at half a pound of wax 64,050,000 and tallow per hour, gives the weight of Sixty-four millions and fifty thousand of pounds, which, estimating the whole at the medium price of thirty sols the pound, makes the sum of ninety-six millions and seventy-five thousand 96,075,000 _livres tournois_ An immense sum! that the city of Paris might save every year, by the economy of using sunshine instead of candles. If it should be said that people are apt to be obstinately attached to old customs, and that it will be difficult to induce them to rise before noon, consequently my discovery can be of little use; I answer, _Nil desperandum_. I believe all who have common sense, as soon as they have learned from this paper that it is daylight when the sun rises, will contrive to rise with him; and to compel the rest, I would propose the following regulations:— First. Let a tax be laid of a louis per window on every window that is provided with shutters to keep out the light of the sun.