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expense and risk. If I can be the means of communicating any thing valuable to the world, I do not always think of gaining, nor even of saving, by my business; but a piece of that kind, as it must excite the curiosity of all the learned, can hardly fail of bearing its own expense.

I must not pretend to dispute with you on any part of the animal economy. You are quite too strong for me. I shall just mention two or three little things, that I am not quite clear in.

If there is no contrivance in the frame of the auricles or ventricles of the heart, by which they dilate themselves, I cannot conceive how they are dilated. It is said, by the force of the venal blood rushing into them. But if that blood has no force which was not first given to it by the contraction of the heart, how can it (diminished as it must be by the resisting friction of the vessels it has passed through) be strong enough to overcome that contraction? Your doctrine of fermentation in the capillaries helps me a little; for if the returning blood be rarefied by the fermentation, its motion must be increased; but, as it seems to me that it must by its expansion resist the arterial blood behind it, as much as it accelerates the venal blood before it, I am still somewhat unsatisfied. I have heard or read somewhere, too, that the hearts of some animals continue to contract and dilate, or to beat, as it is commonly expressed, after they are separated from the other vessels, and taken out of the body. If this be true, their dilation is not caused by the force of the returning blood.

I should be glad to satisfy myself, too, whether the blood is always quicker in motion, when the pulse beats quicker. Perhaps more blood is driven forward by one strong, deep

stroke, than by two that are weak and light; as a man may breathe more air by one long common respiration, when in health, than by two quick, short ones in a fever. I applied the siphon I mentioned to you in a former letter to the pipe of a water-engine. E is the engine; a, its pipe; bbb, the

E

siphon; c and d, the two glass pipes communicating with the siphon. Upon working the engine, the water flowed through the siphon, and the glass tube c; but none was discharged through d. When I stopped with my finger the end of the siphon, the water issued at both glass tubes, with equal force, and on only half stopping the end of the siphon, it did the same. I imagine the sudden bending of the siphon gives such a resistance to the stream, as to occasion its issuing out of the glass tube c. But I intend to try a farther experiment, of which I shall give you an account.

I am now determined to publish an American Philosophical Miscellany, monthly or quarterly. I shall begin with next January, and proceed as I find encouragement and assistance. As I purpose to take the compiling wholly upon myself, the reputation of no gentleman or society will be affected by

what I insert of another's; and that perhaps will make them more free to communicate. Their names shall be published or concealed, as they think proper, and care taken to do exact justice to matters of invention, &c. I shall be glad of your advice in any particulars that occurred to you in thinking of this scheme; for, as you first proposed it to me, I doubt not but you have well considered it.1

I have not the original of Dr. Mitchell's tract on the Yellow Fever.2 Mine is a copy I had taken, with his leave, when here. Mr. Evans will make a copy of it for you.

I hope it will be confirmed by future experiment, that the yaws are to be cured by tar-water. The case you relate to Dr. Mitchell gives great hopes of it, and should be published, to induce people to make trials. For, though it should not always succeed, I suppose there is no danger of its doing any harm.

As to your pieces on Fluxions and the different species of matter, it is not owing to reservedness that I have not yet sent you my thoughts; but because I cannot please myself with them, having had no leisure yet to digest them. If I was clear, that you are anywhere mistaken, I would tell you so, and give my reasons with all freedom, as believing nothing I

1 It does not appear that this scheme was ever carried into execution. S. 2 Dr. John Mitchell, a physician and botanist, of unknown origin, settled early in the eighteenth century at Urbanna on the Rappahannock. Peter Collinson read before the Royal Society, his "Essay upon the Causes of the different Colours of People in different Climates." He left his "Essay upon the Yellow Fever," in manuscript. Benjamin Rush read it and derived from it new views of the nature of that malady when it appeared in Philadelphia in 1793. Rush desired it to be printed in The American Medical and Philosophical Register, and it appeared there in October, 1813 (Vol. IV. p. 181). Rush obtained the manuscript from Franklin who had it from Dr. Mitchell. See Miller's "Retrospect," Vol. I. p. 318. —Ed.

could do would be more obliging to you. I am persuaded you think, as I do, that he who removes a prejudice, or an error, from our minds, contributes to their beauty, as he would do to that of our faces, who should clear them of a wart

or a wen.

I have a friend gone to New York with a view of settling there, if he can meet with encouragement. It is Dr. John Bard,' whom I esteem an ingenious physician and surgeon, and a discreet, worthy, and honest man. If, upon conversation with him, you find this character just, I doubt not but you will afford him your advice and countenance, which will be of great service to him in a place where he is entirely a stranger, and very much oblige, Sir,

Your most humble servant,

B. FRANKLIN.

P. S. I shall forward your letter to Dr. Mitchell. Thank you for leaving it open for my perusal.

52.

PREFACE TO POOR RICHARD, 1746

Who is Poor Richard? People oft enquire,
Where lives? What is he? never yet the nigher.
Somewhat to ease your Curiositee,

Take these slight Sketches of my Dame and me.
Thanks to kind Readers and a careful Wife,

With plenty bless'd, I lead an easy Life;

My business Writing; less to drain the Mead,

1 Dr. John Bard (1716-1799), first president of The New York Medical Society. This introduction was the origin of a long and intimate friendship between Dr. Bard and Mr. Colden. - ED.

Or crown the barren Hill with useful Shade;
In the smooth Glebe to see the Plowshare worn,
And fill the Granary with needful Corn.

Press nectareous Cyder from my loaded Trees,
Print the sweet Butter, turn the Drying Cheese.
Some Books we read, tho' few there are that hit
The happy Point where Wisdom joins with Wit;
That set fair Virtue naked to our View,

And teach us what is decent, what is true.
The Friend sincere, and honest Man, with Joy
Treating or treated oft our Time employ.
Our Table next, Meals temperate; and our Door
Op'ning spontaneous to the bashful Poor.
Free from the bitter Rage of Party Zeal,
All those we love who seek the publick Weal.
Nor blindly follow Superstitious Love,
Which cheats deluded Mankind o'er and o'er,
Not over righteous, quite beyond the Rule,
Conscience perplext by every canting Tool.
Nor yet when Folly hides the dubious Line,
When Good and Bad the blended Colours join:
Rush indiscreetly down the dangerous Steep,
And plunge uncertain in the darksome Deep.
Cautious, if right; if wrong resolv'd to part
The Inmate Snake that folds about the Heart.
Observe the Mean, the Motive, and the End,
Mending ourselves, or striving still to mend.
Our Souls sincere, our Purpose fair and free,
Without Vain Glory or Hypocrisy :
Thankful if well; if ill, we kiss the Rod;
Resign with Hope, and put our Trust in God.

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