« ПретходнаНастави »
that they do not quite believe me. One indeed, who is a learned natural philosopher, has assured me, that I must certainly be mistaken as to the circumstance of the light coming into my room ; for it being well known, as he says, that there could be no light abroad at that hour, it follows that 'none could enter from without; and that of consequence, my windows being accidentally left open, instead of letting in the light, had only served to let out the darkness : and he used many ingenious arguments to shew me how I might, by that means, have been deceived. I own that he puzzled me a little, but he did not satisfy me ; and the subsequent observations I made, as above mentioned, confirmed me in my first opinion.
“ 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 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 bougie, 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 twentieth of March and the twentieth of September there are Nights
183 Hours of each night in which we burn candles
Multiplication gives for the total number of hours
1,281 These 1,281 hours, multiplied by
100,000, the number of inhabi-
123,100,000 One hundred and twenty-eight millions
and one hundred thousand hours
64,050,000 Sixty-four millions and fifty thousand
of pounds, which, estimating the
96,075,000 "An immense sum! that the city of Paris might sáve 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 learnt from this paper, that it is day-light 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.
“ 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
week. “ Third. Let guards also be posted to stop all the coaches, &c., 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 a ringing; and if that is not sufficient, let cannon be fired in every street, to wake the sluggards effectually, and make
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. Oblige a man to rise at four in the morning, and it is more than probable he shall go willingly to bed at eight in the evening ; and, having had eight hours' sleep, he will rise more willingly at four the following morning. But this sum of ninety-six millions and seventy-five thousand livres, is not the whole of what may be saved by my economical project. You may observe, that I have calculated
only one half of the year, and much may be saved in the other, though the days are shorter. Besides, the immense stock of wax and tallow left unconsumed during the summer, will probably make candles much cheaper for the ensuing winter, and continue cheaper as long as the proposed reformation shall be supported.
“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 honour of it. And yet I know there are little, envious minds who will, as usual, deny me this, and say that my invention was known to the ancients, and perhaps they may bring passages out of the old books in proof of it. I will not dispute with these people that the ancients knew not the sun would rise at certain hours; they possibly had, as we have, almanacks that predicted it: but it does not follow from thence, that they knew he gave beyht as soon as he rose. This is what I claim as my discovery. If the ancients knew it, it must have been long since forgotten, for it certainly was unknown to the moderns, at least to the Parisians; which to prove, I need use but one plain simple argument. They are as well instructed, judicious, and prudent a people as exist anywhere in the world, all professing, like myself, to be lovers of economy; and, from the many heavy taxes required from them by the necessities of the state, have surely reason to be economical. I say it is impossible that so sensible a people, under such circumstances, should have lived so long by the smoky, unwholesome, and enormously expensive light of candles, if they had really known that they might have had as much pure light of the sun for nothing.
66 I am, &c.
" AN ABONNE."
Dr Franklin is certainly from this time to be con• sidered rather as a statesman than a professed philosopher; but he continued to extend his researches into electricity, and particularly examined, in 1759, the tourmalin, a stone which has the singular property of being electrified positively on one side, and negatively on the other, by heat alone, without friction. Professor Simpson of Glasgow, too, reported to Dr Franklin some experiments (made by Dr Cullen) on the cold produced by the evaporation of air; the latter endeavoured to improve upon them, and found by the evaporation of ether in the exhausted receiver of an
air-pump, so great a degree of cold was produced in a warm summer's day, that water was congealed by it. Among other things, he applied this discovery to the solution of the following phenomena, which had hitherto been unexplained:-" That the temperature of the human body, when in health, never exceeds 96° of Fahrenheit's thermometer, though the atmosphere which surrounds it may be heated in a much greater degree;" which, on this principle, he attributed to increased perspiration, and conseqent evaporation.
In 1760 he mentions, in a letter to Mr Small, some observations tending to shew, that in North America the north-east storms regularly begin in the south-west, and instances one particularly, which, extending a considerable distance, commenced at Philadelphia, and four hours afterwards was felt at Boston. This he accounts for by supposing, that the heat about the gulf of Mexico occasioned considerable rarefaction of the air, and that the air farther north, rushing in, was succeeded by cooler and denser air still farther north, until it occasioned a perpetual current in this direction.
It was during this visit to London also that, being delighted with the tones produced by: wet fingers pressed along the brim of different sized glasses, he endeavoured to make an instrument which should include three complete and regular octaves: he describes it at length, in a letter to the celebrated father Beccaria*,
Dr Franklin, as a politician, considered himself at this time a bona fide member of the great British commonwealth, and entered warmly into the state of the general politics of this country. Conceiving that, by prosecuting the war with France upon the European continent, we were expending our resources upon objects of no permanent British interest, he warmly recommended, in all companies, an attack upon French North America. The subsequent disputes between the mother-country and her colonies * Vide Appendix. No. 2.