difficult to advise in particular cases at a distance, where one cannot have all the circumstances under view. If two rooms and chimneys are "perfectly similar" in situation, dimension, and all other circumstances, it seems not possible, that, "in summer, when no fire had been in either of them for some months, and in a calm day, a current of air should at the same time go up the chimney of the one, and down the chimney of the other." But such difference may and often does take place, from circumstances in which they are dissimilar, and which dissimilarity is not very obvious to those who have little studied the subject. As to your particular case, which you describe to be, that, "after a whole day's fire, which must greatly heat the vent, yet, when the fire becomes low, so as not to emit any smoke, neighbour smoke immediately begins to descend and fill the room;" this, if not owing to particular winds, may be occasioned by a stronger fire in another room, communicating with yours by a door, the outer air being excluded by the outward door's being shut, whereby the stronger fire finds it easier to be supplied with air down through the vent, in which the weak fire is, and thence through the communicating door, than through the crevices. If this is the circumstance, you will find that a supply of air is only wanting, that may be sufficient for both vents. If this is not the circumstance, send me, if you please, a complete description of your room, its situation, and connexion, and possibly I may form a better judgment. Though I imagine your Professor of Natural Philosophy, Mr. Russel, or Mr. George Clark, may give you as good advice on the subject as I can. But I shall take the liberty of sending you, by the first convenient opportunity, a collection of my philosophical papers lately published, in which you will find some

thing more relating to the motions of air in chimneys.*

To commence a conversation with you on your new project, I have thrown some of my present sentiments into the concise form of aphorisms, to be examined between us, if you please, and rejected or corrected and confirmed, as we shall find most proper. I send them enclosed.t

With thanks for your good wishes, and with unalterable esteem, I remain, my dear friend, affectionately yours, B. FRANKLIN.

TO JOHN BARTRAM.

A Box for the King. Recommends to Mr. Bartram to write a Natural History of the Colonies.

MY DEAR OLD FRIEND,

London, 9 January, 1769.

I received your kind letter of November 5th, and the box directed to the King is since come to hand. I have written a line to our late dear friend's son,‡

*The fourth edition of the author's Philosophical Papers, in a quarto volume of more than five hundred pages, was published in London, with the date of 1769 on the titlepage. Another letter to Lord Kames on smoky chimneys is contained in Vol. VI. p. 280.

These were probably "Positions to be examined concerning National Wealth." See Vol. II. p. 373.

In his reply to the above letter, Lord Kames said, "The letter you mention, about American affairs, never came to hand. I have an essay on the subject of your Queries, and you shall hear from me soon about our agreeing or differing. I have a great fund of political knowledge reduced into writing, far from being ripe, but fit for your perusal. If you will come to my aid, I know not but that we shall make a very good thing of it. If not, it may be lost to the world, and what a loss will that be!"- Edinburgh, January 21st, 1769.

This "dear friend" was Peter Collinson, who had recently died, and who had long corresponded with John Bartram.

(who must be best acquainted with the usual manner of transacting your affairs here,) to know whether he will take charge of the delivery of it; if not, to request he would inform me how or to whom it is to be sent for the King. I expect his answer in a day or two, and I shall, when I see him, inquire how your pension is hereafter to be applied for and received, though I suppose he has written to you before this time.*

I hope your health continues, as mine does hitherto; but I wish you would now decline your long and dangerous peregrinations in search of new plants, and remain safe and quiet at home, employing your leisure hours in a work that is much wanted, and which no one besides is so capable of performing; I mean the writing a Natural History of our country. I imagine it would prove profitable to you, and I am sure it would do you honor. My respects and best wishes attend Mrs. Bartram and your family. With sincere esteem I am, as ever, your affectionate friend,

B. FRANKLIN.

P. S. January 28th. The box is delivered, according to Mr. Michael Collinson's directions, at Lord Bute's.

* Mr. Bartram, though self-taught and with few advantages, possessed uncommon talents, and, by observation and study, unassisted by books and the instructions of others, made great attainments in botany and natural history. His passionate fondness for this kind of knowledge led him to undertake long and hazardous rambles in the wild and unsettled parts of the country, from Canada to Florida, searching for new plants, collecting rare specimens, and examining nature in all its varieties. Several communications from him were inserted in the Philosophical Transactions; and he also published accounts of his travels and observations. His merit attracted the attention of the King, and he was appointed American botanist to his Britannic Majesty, which station probably entitled him to a pension. No biographer has done any adequate justice to his character or his acquisitions.

VOL. VII.

55

KK

I have sent over some seed of naked oats and some of Swiss barley, six rows to one ear. choose to try some of it, call on Mrs. Franklin.

If you would

TO LORD KAMES.

Use of Oxen and Horses in Agriculture. - A Meas

ure of Value.

Chosen President of the American

Philosophical Society.

London, 21 February, 1769.

MY DEAR FRIEND, I received your excellent paper on the preferable use of oxen in agriculture, and have put it in the way of being communicated to the public here. I have observed in America, that the farmers are more thriving in those parts of the country where horned cattle are used, than in those where the labor is done by horses. The latter are said to require twice the quantity of land to maintain them; and after all are not good to eat, at least we do not think them so. Here is a waste of land that might afford subsistence for so many of the human species. Perhaps it was for this reason, that the Hebrew lawgiver, having promised that the children of Israel should be as numerous as the sands of the sea, not only took care to secure the health of individuals by regulating their diet, that they might be fitter for producing children, but also forbade their using horses, as those animals would lessen the quantity of subsistence for men. Thus we find, when they took any horses from their enemies, they destroyed them; and in the commandments, where the labor of the ox and ass is mentioned, and forbidden on the Sabbath, there is no mention of the horse, probably because they were to have none. And, by the great

armies suddenly raised in that small territory they inhabited, it appears to have been very full of people.*

Food is always necessary to all, and much the greatest part of the labor of mankind is employed in raising provisions for the mouth. Is not this kind of labor, then, the fittest to be the standard by which to measure the values of all other labor, and consequently of all other things whose value depends on the labor of making or procuring them? May not even gold and silver be thus valued? If the labor of the farmer, in producing a bushel of wheat, be equal to the labor of the miner in producing an ounce of silver, will not the bushel of wheat just measure the value of the ounce of silver. The miner must eat; the farmer indeed can live without the ounce of silver, and so perhaps will have some advantage in settling the price. But these discussions I leave to you, as being more able to manage them; only, I will send you a little scrap I wrote some time since on the laws prohibiting foreign commodities.

I congratulate you on your election as president of your Edinburgh Society. I think I formerly took notice to you in conversation, that I thought there had been some similarity in our fortunes, and the circumstances of our lives. This is a fresh instance, for, by letters just received, I find that I was about the same

* There is not in the Jewish law any express prohibition against the use of horses; it is only enjoined, that the Kings should not multiply the breed, or carry on trade with Egypt for the purchase of horses. Deuteronomy, xvii. 16. Solomon was the first of the Kings of Judah who disregarded this ordinance. He had forty thousand stalls of horses, which he brought out of Egypt. 1 Kings, iv. 26; and ibid. x. 28. From this time downwards horses were in constant use in the Jewish armies. It is true that the country, from its rocky surface and unfertile soil, was extremely unfit for the maintenance of those animals. -A. F. TYTLER.