From a letter to The Journal of Paris. Less than a month after this letter was dated, the peace treaty between Great Britain and the U.S. was formally ratified, and Franklin requested that he be able to leave his posting in France, where he had been known to stay up all night playing chess. A signer of the Declaration of Independence and the Constitution, he invented, among other things, the lightning rod, bifocal glasses, and the glass harmonica. The observation of daylight-savings time in the U.S. was federally mandated in 1918.
To the authors of The Journal of Paris
You often entertain us with accounts of new discoveries. Permit me to communicate to the public, through your paper, one that has lately been made by myself, and which I conceive may be of great utility.
I was the other evening in a grand company where the new lamp of Messrs. Quinquet and Lange was introduced and much admired for its splendor; but a general inquiry was made whether the oil it consumed was not in proportion to the light it afforded, in which case there would be no saving in the use of it. No one present could satisfy us in that point, which all agreed ought to be known, it being a very desirable thing to lessen, if possible, the expense of lighting our apartments, when every other article of family expense was so much augmented.
I was pleased to see this general concern for economy, for I love economy exceedingly.
I went home, and to bed, three or four hours after midnight, with my head full of the subject. An accidental sudden noise waked me about six in the morning, when I was surprised to find my room filled with light—and I imagined at first that a number of those lamps had been brought into it. But, rubbing my eyes, I perceived the light came in at the windows. I got up and looked out to see what might be the occasion of it, when I saw the sun just rising above the horizon, whence he poured his rays plentifully into my chamber, my domestic having negligently omitted the preceding evening to close the shutters.
I looked at my watch, which goes very well, and found that it was but six o’clock, and still thinking it something extraordinary that the sun should rise so early, I looked into the almanac, where I found it to be the hour given for his rising on that day. I looked forward, too, and found he was to rise still earlier every day till toward the end of June; and that at no time in the year he retarded his rising so long as till eight o’clock. Your readers, who with me have never seen any signs of sunshine before noon, and seldom regard the astronomical part of the almanac, will be as much astonished as I was, when they hear of his rising so early—and especially when I assure them, that he gives light as soon as he rises. I am convinced of this. I am certain of my fact. One cannot be more certain of any fact. I saw it with my own eyes. And, having repeated this observation the three following mornings, I found always precisely the same result.
This event has given rise in my mind to several serious and important reflections. I considered 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 candlelight; 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 March 20 and September 20, there are
Hours of each night in which we burn candles..........7
Multiplication gives for the total number of hours........1,281
These 1,281 hours multiplied by 100,000, the number of inhabitants, gives.........128,100,000
128 million and 100,000 hours, spent at Paris by candlelight, which, at half a pound of wax and tallow per hour, gives the weight of..........64,050,000
64 million and 50,000 pounds, which, estimating the whole at the medium price of thirty sols per pound, makes the sum of 96 million and 75,000 livres toumois.........96,075,000
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 one louis per window, on every window that is provided with shutters to keep out the light of the sun.
Second. Let the same salutary operation of police be made use of to prevent our burning candles that inclined us last winter to be more economical in burning wood; that is, let guards be placed in the shops of the wax and tallow chandlers, and no family be permitted to be supplied with more than one pound of candles per week.
Third. Let guards also be posted to stop all the coaches, etc., that would pass the streets after sunset, except those of physicians, surgeons, and midwives.
Fourth. Every morning, as soon as the sun rises, let all the bells in every church be set ringing; and if that is not sufficient, let cannons be fired in every street to wake the sluggards effectually, and make them open their eyes to see their true interest.
All the difficulty will be in the first two or three days, after which the reformation will be as natural and easy as the present irregularity; for, Ce n’est que le premier pas qui coûte. [It is only the first step that is demanding.] Oblige a man to rise at four in the morning, and it is more than probable he will go willingly to bed at eight in the evening, and having had eight hours sleep, he will rise more willingly at four the morning following. But this sum of 96 million and 75,000 livres is not the whole of what may be saved by my economical project. You may observe, that I have calculated upon only one half of the year, and much may be saved in the other, though the days are shorter.
For the great benefit of this discovery, thus freely communicated and bestowed by me on the public, I demand neither place, pension, exclusive privilege, nor any other reward whatever. I expect only to have the honor of it.