From Benjamin Franklin to Cadwallader Colden, 28 November 1745
To Cadwallader Colden
ALS: New-York Historical Society
Philada. Nov. 28. 1745
Sir
I shall be very willing and ready, when you think proper to publish your Piece on Gravitation, &c., to print it at my own Expence and Risque.2 If I can be a Means of Communicating anything 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 Expence.
I must not pretend to dispute with you on any Part of the animal Œconomy:3 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 it by the Contraction of the Heart, how can it (diminish’d as it must be by the Resisting Friction of the Vessels it has pass’d thro’) be strong enough to overcome that Contraction? Your Doctrine of Fermentation in the Capillaries helps me a little; for if the returning Blood be rarified by the Fermentation, its Motion must be encreas’d: 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 ’tis commonly express’d, after they are separated from the other Vessels and taken out of the Body. If this be true, their Dilatation is not caus’d 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 apply’d the Syphon I mention’d to you in a former Letter, to the Pipe of a Water Engine. E is the Engine; a its Pipe bbb 
the Syphon; c and d the two glass Pipes communicating with the Syphon. Upon working the Engine, the Water flow’d thro’ the Syphon, and the Glass Tube c; but none was discharg’d thro’ d. When I stop’d with my Finger the End of the Syphon, the Water issu’d at both Glass Tubes with equal Force; and on only half Stopping the End of the Syphon it did the same. I imagine the sudden Bending of the Syphon 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 determin’d 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 my self, the Reputation of no Gentleman or Society will be affected by what I insert of anothers; and that perhaps will make them more free to communicate. Their Names shall be publish’d or conceal’d as they think proper; and Care taken to do exact Justice in Matters of Invention, &c. I shall be glad of your Advice in any Particulars that occur’d to you in Thinking of this Scheme; for as you first propos’d it to me, I doubt not but you have well consider’d it.
I have not the Original of Dr. Mitchel’s Tract on the Yellow Fever. Mine is a Copy I had taken with his Leave when here. Mr. Evans4 will make a Copy of it for you.
I hope it will be confirmed by future Experiments that the Yaws are to be cured by Tar Water. The Case you relate to Dr. Mitchel gives great Hopes of it, and should be publish’d to induce People to make Trials: for tho’ it should not always succeed, I suppose there is no Danger of its doing any Harm.5
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 my self 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 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. Jno. Bard, whom I esteem an ingenious Physician and Surgeon, and a discreet, worthy and honest Man.6 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
I shall forward your Letter to Dr. Mitchel.7 Thank you for Leaving it open for my Perusal.
2. Colden did not accept BF’s offer. The essay was printed the next year (though dated 1745 on the title page) by James Parker in New York, under the title An Explication of the First Causes of Action in Matter, and, of the Cause of Gravitation.
3. The ideas to which BF responds here are expressed in Colden’s “Inquiry into the Principles of Vital Motion,” especially secs. 15–18, and his treatise on “The Animal Oeconomy,” surviving in several MS versions in N.-Y. Hist. Soc. Colden may have sent BF a revised or abridged version of either of these.
4. Lewis Evans (c.1700–1756), surveyor, draftsman, geographer; born in Wales, he was settled in Pennsylvania before 1736, and seems to have been employed by BF as a clerk. He accompanied John Bartram and Conrad Weiser to Onondaga, 1743; lectured on natural philosophy in Newark, N. J., New York (at the house of Rev. Ebenezer Pemberton), and Philadelphia, 1751. As a draftsman he prepared the diagrams for BF’s Account of the New Invented Pennsylvanian Fireplaces, 1744 (see above, II, 432, 445), and compiled A General Map of the Middle British Colonies in America, 1755. Deborah Franklin was godmother of his daughter Amelia. DAB; Lawrence H. Gipson, Lewis Evans (Phila., 1939), pp. 1–14.
5. Mitchell had asked Colden on Sept. 10, 1745, what he knew about yaws; Colden, replying on Nov. 7, enclosed an account of a cure by tar water, which he had received from Rev. Samuel Johnson of Stratford, Conn. Colden Paps., VIII, 322, 334–5. Bishop George Berkeley’s Siris: A Chain of Philosophical Reflexions and Inquiries Concerning the Virtue of Tar water (Dublin and London, 1744) was then making a great impression. Johnson borrowed BF’s copy and Colden published an abstract with his own “reflexions” on the value of tar water in the treatment of diseases frequent in America. Colden Paps., III, 98, 102, 108, 121, 149, 206.
6. John Bard (1716–1799), physician; educated under Alexander Annand in Philadelphia; apprenticed to Dr. John Kearsley; practiced in Philadelphia. BF encouraged him to move to New York, as to a place of greater opportunity, two physicians having recently died there. He became health officer of New York, wrote several scientific papers, and was first president of the Medical Society of the State of New York, 1788. DAB. BF’s Ledger D, p. 5, contains an account with Bard, 1739–45, for advertisements, paper, and books.
7. Probably Colden’s letter of Nov. 7, cited in note 5 above.