Benjamin Franklin
(1706 - 1790)

To Lord Kames

My dear Lord, London, Jany. 3. 1760

I ought long before this time to have acknowledg'd the Receipt of your Favour of Nov. 2. Your Lordship was pleas'd kindly to desire to have all my Publications. I had daily Expectations of procuring some of them from a Friend to whom I formerly sent them when I was in America, and postpon'd Writing till I should obtain them; but at length he tells me he cannot find them. Very mortifying, this, to an Author, that his Works should so soon be lost! So I can now only send you my Observations on the Peopling of Countries, which happens to have been reprinted here; The Description of the Pennsylvanian Fireplace, a Machine of my contriving; and some little Sketches that have been printed in the Grand Magazine; which I should hardly own, did not I flatter myself that your friendly Partiality would make them seem at least tolerable.

How unfortunate I was, that I did not press you and Lady Kames more strongly, to favour us with your Company farther! How much more agreable would our Journey have been, if we could have enjoy'd you as far as York! Mr. Blake, who we hop'd would have handed us along from Friend to Friend, was not at home, and so we knew nobody and convers'd with nobody on all that long Road, till we came thither. The being a Means of contributing in the least Degree to the restoring that good Lady's Health, would have contributed greatly to our Pleasures, and we could have beguil'd the Way by Discoursing 1000 Things that now we may never have an Opportunity of considering together; for Conversation warms the Mind, enlivens the Imagination, and is continually starting fresh Game that is immediately pursu'd and taken and which would never have occur'd in the duller Intercourse of Epistolary Correspondence. So that whenever I reflect on the great Pleasure and Advantage I receiv'd from the free Communication of Sentiments in the Conversation your Lordship honour'd me with at Kaims, and in the little agreable Rides to the Tweedside, I shall forever regret that unlucky premature Parting.

No one can rejoice more sincerely than I do on the Reduction of Canada; and this, not merely as I am a Colonist, but as I am a Briton. I have long been of Opinion, that the Foundations of the future Grandeur and Stability of the British Empire, lie in America; and tho', like other Foundations, they are low and little seen, they are nevertheless, broad and Strong enough to support the greatest Political Structure Human Wisdom ever yet erected. I am therefore by no means for restoring Canada. If we keep it, all the Country from St. Laurence to Missisipi, will in another Century be fill'd with British People; Britain itself will become vastly more populous by the immense Increase of its Commerce; the Atlantic Sea will be cover'd with your Trading Ships; and your naval Power thence continually increasing, will extend your Influence round the whole Globe, and awe the World! If the French remain in Canada, they will continually harass our Colonies by the Indians, impede if not prevent their Growth; your Progress to Greatness will at best be slow, and give room for many Accidents that may for ever prevent it. But I refrain, for I see you begin to think my Notions extravagant, and look upon them as the Ravings of a mad Prophet.

Your Lordship's kind Offer of Penn's Picture is extreamly obliging. But were it certainly his Picture, it would be too valuable a Curiosity for me to think of accepting it. I should only desire the Favour of Leave to take a Copy of it. I could wish to know the History of the Picture before it came into your Hands, and the Grounds for supposing it his. I have at present some Doubts about it; first, because the primitive Quakers us'd to declare against Pictures as a vain Expence; a Man's suffering his Portrait to be taken was condemn'd as Pride; and I think to this day it is very little practis'd among them. Then it is on a Board, and I imagine the Practice of painting Portraits on Boards did not come down so low as Penn's Time; but of this I am not certain. My other Reason is an Anecdote I have heard, viz. That when old Lord Cobham was adorning his Gardens at Stowe with the Busts of famous Men, he made Enquiry of the Family for a Picture of Wm. Penn, in order to get a Bust form'd from it, but could find none. That Sylvanus Bevan, an old Quaker Apothecary, remarkable for the Notice he takes of Countenances, and a Knack he has of cutting in Ivory strong Likenesses of Persons he has once seen, hearing of Lord Cobham's Desire, set himself to recollect Penn's Face, with which he had been well acquainted; and cut a little Bust of him in Ivory which he sent to Lord Cobham, without any Letter of Notice that it was Penn's. But my Lord who had personally known Penn, on seeing it, immediately cry'd out, Whence came this? It is William Penn himself! And from this little Bust, they say, the large one in the Gardens was formed. I doubt, too, whether the Whisker was not quite out of Use at the time when Penn must have been of the Age appearing in the Face of that Picture. And yet notwithstanding these Reasons, I am not without some Hope that it may be his; because I know some eminent Quakers have had their Pictures privately drawn, and deposited with trusty Friends; and I know also that there is extant at Philadelphia a very good Picture of Mrs. Penn, his last Wife. After all, I own I have a strong Desire to be satisfy'd concerning this Picture; and as Bevan is yet living here, and some other old Quakers that remember William Penn, who died but in 1718, I could wish to have it sent me carefully pack'd in a Box by the Waggon (for I would not trust it by Sea) that I may obtain their Opinion, The Charges I shall very chearfully pay; and if it proves to be Penn's Picture, I shall be greatly oblig'd to your Lordship for Leave to take a Copy of it, and will carefully return the Original.

My Son joins with me in the most respectful Compliments to you, to Lady Kaims, and your promising and amiable Son and Daughter. He had the Pleasure of conversing more particularly with the latter than I did, and told me, when we were by our selves, that he was greatly surprized to find so much sensible Observation and solid Understanding in so young a Person; and suppos'd you must have us'd with your Children some uncommonly good Method of Education, to produce such Fruits so early. Our Conversation till we came to York was chiefly a Recollection and Recapitulation of what we had seen and heard, the Pleasure we had enjoy'd and the Kindnesses we had receiv'd in Scotland, and how far that Country had exceeded our Expectations. On the whole, I must say, I think the Time we spent there, was Six Weeks of the densest Happiness I have met with in any Part of my Life. And the agreable and instructive Society we found there in such Plenty, has left so pleasing an Impression on my Memory, that did not strong Connections draw me elsewhere, I believe Scotland would be the Country I should chuse to spend the Remainder of my Days in.

I have the Honour to be, with the sincerest Esteem and Affection, My Lord, Your Lordship's most obedient and most humble Servant

PS. My Son puts me in mind that a Book published here last Winter, contains a number of Pieces wrote by me as a Member of the Assembly, in our late Controversies with the Proprietary Governors; so I shall leave one of them at Millar's to be sent to you, it being too bulky to be sent per Post.

To Jane Mecom

Dear Sister, London, Jan. 9. 1760 I received a Letter or two from you, in which I perceive you have misunderstood and taken unkindly something I said to you in a former jocular one of mine concerning CHARITY. I forget what it was exactly, but I am sure I neither express nor meant any personal Censure on you or any body. If anything, it was a general Reflection on our Sect; we zealous Presbyterians being too apt to think ourselves alone in the right, and that besides all the Heathens, Mahometans and Papists, whom we give to Satan in a Lump, other Sects of Christian Protestants that do not agree with us, will hardly escape Perdition. And I might recommend it to you to be more charitable in that respect than many others are; not aiming at any Reproof, as you term it; for if I were dispos'd to reprove you, it should be for your only Fault, that of supposing and spying Affronts, and catching at them where they are not. But as you seem sensible of this yourself, I need not mention it; and as it is a Fault that carries with it its own sufficient Punishment, by the Uneasiness and Fretting it produces, I shall not add Weight to it. Besides, I am sure your own good Sense, join'd to your natural good Humour will in time get the better of it.

I am glad that Cousin Benny could advance you the Legacy, since it suited you best to receive it immediately. Your Resolution to forbear buying the Cloak you wanted, was a prudent one; but when I read it, I concluded you should not however be without one, and so desired a Friend to buy one for you. The Cloth ones, it seems, are quite out of Fashion here, and so will probably soon be out with you; I have therefore got you a very decent one of another kind, which I shall send you by the next convenient Opportunity.

It is remarkable that so many Breaches should be made by Death in our Family in so short a Space. Out of Seventeen Children that our Father had, thirteen liv'd to grow up and settle in the World. I remember these thirteen (some of us then very young) all at one Table, when an Entertainment was made in our House on Occasion of the Return of our Brother Josiah, who had been absent in the East-Indies, and unheard of for nine Years. Of these thirteen, there now remains but three. As our Number diminishes, let our Affection to each other rather increase: for besides its being our Duty, tis our Interest, since the more affectionate Relations are to one another, the more they are respected by the rest of the World.

My Love to Brother Mecom and your Children. I shall hardly have time to write to Benny by this Conveyance. Acquaint him that I received his Letter of Sept. 10, and am glad to hear he is in so prosperous a Way, as not to regret his leaving Antigua. I am, my dear Sister, Your ever affectionate Brother

March 26. The above was wrote at the time it is dated; but on reading it over, I apprehended that something I had said in it about Presbyterians, and Affronts, might possibly give more Offence; and so I threw it by, concluding not to send it. However, Mr. Bailey calling on me, and having no other Letter ready nor time at present to write one, I venture to send it, and beg you will excuse what you find amiss in it. I send also by Mr. Bailey the Cloak mention'd in it, and also a Piece of Linnen, which I beg you to accept of from Your loving Brother

I received your Letter, and Benny's and Peter's by Mr. Baily, which I shall answer per next Opportunity.

To Lord Kames

My dear Lord, London, May 3. 1760.

Your obliging Favour of January 24th. found me greatly indispos'd with an obstinate Cold and Cough accompany'd with Feverish Complaints and Headachs, that lasted long and harass'd me greatly, not being subdu'd at length but by the whole Round of Cupping, Bleeding, Blistering, &c. When I had any Intervals of Ease and Clearness, I endeavour'd to comply with your Request, in writing something on the present Situation of our Affairs in America, in order to give more correct Notions of the British Interest with regard to the Colonies, than those I found many sensible Men possess'd of. Inclos'd you have the Production, such as it is. I wish it may in any Degree be of Service to the Publick. I shall at least hope this from it for my own Part, that you will consider it as a Letter from me to you, and accept its Length as some Excuse for its being so long acoming.

I am now reading, with great Pleasure and Improvement, your excellent Work, the Principles of Equity. It will be of the greatest Advantage to the Judges in our Colonies, not only in those which have Courts of Chancery, but also in those which having no such Courts are obliged to mix Equity with the Common Law. It will be of the more Service to the Colony Judges, as few of them have been bred to the Law. I have sent a Book to a particular Friend, one of the Judges of the Supreme Court in Pensilvania.

I will shortly send you a Copy of the Chapter you are pleas'd to mention in so obliging a Manner; and shall be extreamly oblig'd in receiving a Copy of the Collection of Maxims for the Conduct of Life, which you are preparing for the Use of your Children. I purpose, likewise, a little Work for the Benefit of Youth, to be call'd The Art of Virtue. From the Title I think you will hardly conjecture what the Nature of such a Book may be. I must therefore explain it a little. Many People lead bad lives that would gladly lead good ones, but know not how to make the Change. They have frequently resolv'd and endeavour'd it; but in vain, because their Endeavours have not been properly conducted. To exhort People to be good, to be just, to be temperate, &c. without shewing them how they shall become so, seems like the ineffectual Charity mention'd by the Apostle, which consisted in saying to the Hungry, the Cold, and the Naked, be ye fed, be ye warmed, be ye clothed, without shewing them how they should get Food, Fire or Clothing. Most People have naturally some Virtues, but none have naturally all the Virtues. To acquire those that are wanting, and secure what we acquire as well as those we have naturally, is the Subject of an Art. It is as properly an Art, as Painting, Navigation, or Architecture. If a Man would become a Painter, Navigator, or Architect, it is not enough that he is advised to be one, that he is convinc'd by the Arguments of his Adviser that it would be for his Advantage to be one, and that he resolves to be one, but he must also be taught the Principles of the Art, be shewn all the Methods of Working, and how to acquire the Habits of using properly all the Instruments; and thus regularly and gradually he arrives by Practice at some Perfection in the Art. If he does not proceed thus, he is apt to meet with Difficulties that discourage him, and make him drop the Pursuit. My Art of Virtue has also its Instruments, and teaches the Manner of Using them. Christians are directed to have Faith in Christ, as the effectual Means of obtaining the Change they desire. It may, when sufficiently strong, be effectual with many. A full Opinion that a Teacher is infinitely wise, good, and powerful, and that he will certainly reward and punish the Obedient and Disobedient, must give great Weight to his Precepts, and make them much more attended to by his Disciples. But all Men cannot have Faith in Christ; and many have it in so weak a Degree, that it does not produce the Effect. Our Art of Virtue may therefore be of great Service to those who have not Faith, and come in Aid of the weak Faith of others. Such as are naturally well-disposed, and have been carefully educated, so that good Habits have been early established, and bad ones prevented, have less Need of this Art; but all may be more or less benefited by it. It is, in short, to be adapted for universal Use. I imagine what I have now been writing will seem to savour of great Presumption; I must therefore speedily finish my little Piece, and communicate the Manuscript to you, that you may judge whether it is possible to make good such Pretensions. I shall at the same time hope for the Benefit of your Corrections.

My respectful Compliments to Lady Kaims and your amiable Children, in which my Son joins. With the sincerest Esteem and Attachment, I am, My Lord, Your Lordship's most obedient and most humble Servant

P.S. While I remain in London I shall continue in Craven Street, Strand: if you favour me with your Correspondence when I return to America, please to direct for me in Philadelphia, and your Letters will readily find me tho' sent to any other Part of North America.

To Peter Franklin

SIR, London, May 7, 1760.

It has, indeed, as you observe, been the opinion of some very great naturalists, that the sea is salt only from the dissolution of mineral or rock salt, which its waters happened to meet with. But this opinion takes it for granted that all water was originally fresh, of which we can have no proof. I own I am inclined to a different opinion, and rather think all the water on this globe was originally salt, and that the fresh water we find in springs and rivers, is the produce of distillation. The sun raises the vapours from the sea, which form clouds, and fall in rain upon the land, and springs and rivers are formed of that rain. -- As to the rock-salt found in mines, I conceive, that instead of communicating its saltness to the sea, it is itself drawn from the sea, and that of course the sea is now fresher than it was originally. This is only another effect of nature's distillery, and might be performed various ways.

It is evident from the quantities of sea-shells, and the bones and teeth of fishes found in high lands, that the sea has formerly covered them. Then, either the sea has been higher than it now is, and has fallen away from those high lands; or they have been lower than they are, and were lifted up out of the water to their present height, by some internal mighty force, such as we still feel some remains of, when whole continents are moved by earthquakes. In either case it may be supposed that large hollows, or valleys among hills, might be left filled with sea-water, which evaporating, and the fluid part drying away in a course of years, would leave the salt covering the bottom; and that salt coming afterwards to be covered with earth, from the neighbouring hills, could only be found by digging through that earth. Or, as we know from their effects, that there are deep fiery caverns under the earth, and even under the sea, if at any time the sea leaks into any of them, the fluid parts of the water must evaporate from that heat, and pass off through some vulcano, while the salt remains, and by degrees, and continual accretion, becomes a great mass. Thus the cavern may at length be filled, and the volcano connected with it cease burning, as many it is said have done; and future miners penetrating such cavern, find what we call a salt mine. -- This is a fancy I had on visiting the salt-mines at Northwich, with my son. I send you a piece of the rock-salt which he brought up with him out of the mine.

I am, Sir, &c.

To Mary Stevenson

Dear Polly, Cravenstreet, June 11. 1760

'Tis a very sensible Question you ask, how the Air can affect the Barometer, when its Opening appears covered with Wood? If indeed it was so closely covered as to admit of no Communication of the outward Air to the Surface of the Mercury, the Change of Weight in the Air could not possibly affect it. But the least Crevice is sufficient for the Purpose; a Pinhole will do the Business. And if you could look behind the Frame to which your Barometer is fixed, you would certainly find some small Opening.

There are indeed some Barometers in which the Body of Mercury at the lower End is contain'd in a close Leather Bag, and so the Air cannot come into immediate Contact with the Mercury: Yet the same Effect is produc'd. For the Leather being flexible, when the Bag is press'd by any additional Weight of Air, it contracts, and the Mercury is forc'd up into the Tube; when the Air becomes lighter, and its Pressure less, the Weight of the Mercury prevails, and it descends again into the Bag.

Your Observation on what you have lately read concerning Insects, is very just and solid. Superficial Minds are apt to despise those who make that Part of Creation their Study, as mere Triflers; but certainly the World has been much oblig'd to them. Under the Care and Management of Man, the Labours of the little Silkworm afford Employment and Subsistence to Thousands of Families, and become an immense Article of Commerce. The Bee, too, yields us its delicious Honey, and its Wax useful to a multitude of Purposes. Another Insect, it is said, produces the Cochineal, from whence we have our rich Scarlet Dye. The Usefulness of the Cantharides, or Spanish Flies, in Medicine, is known to all, and Thousands owe their Lives to that Knowledge. By human Industry and Observation, other Properties of other Insects may possibly be hereafter discovered, and of equal Utility. A thorough Acquaintance with the Nature of these little Creatures, may also enable Mankind to prevent the Increase of such as are noxious or secure us against the Mischiefs they occasion. These Things doubtless your Books make mention of: I can only add a particular late Instance which I had from a Swedish Gentleman of good Credit. In the green Timber intended for Ship-building at the King's Yards in that Country, a kind of Worms were found, which every Year became more numerous and more pernicious, so that the Ships were greatly damag'd before they came into Use. The King sent Linnaeus, the great Naturalist, from Stockholm, to enquire into the Affair, and see if the Mischief was capable of any Remedy. He found on Examination, that the Worm was produc'd from a small Egg deposited in the little Roughnesses on the Surface of the Wood, by a particular kind of Fly or Beetle; from whence the Worm, as soon as it was hatch'd, began to eat into the Substance of the Wood, and after some time came out again a Fly of the Parent kind, and so the Species increas'd. The Season in which this Fly laid its Eggs, Linnaeus knew to be about a Fortnight (I think) in the Month of May, and at no other time of the Year. He therefore advis'd, that some Days before that Season, all the green Timber should be thrown into the Water, and kept under Water till the Season was over. Which being done by the King's Order, the Flies missing their usual Nests, could not increase; and the Species was either destroy'd or went elsewhere; and the Wood was effectually preserved, for after the first Year, it became too dry and hard for their purpose.

There is, however, a prudent Moderation to be used in Studies of this kind. The Knowledge of Nature may be ornamental, and it may be useful, but if to attain an Eminence in that, we neglect the Knowledge and Practice of essential Duties, we deserve Reprehension. For there is no Rank in Natural Knowledge of equal Dignity and Importance with that of being a good Parent, a good Child, a good Husband, or Wife, a good Neighbour or Friend, a good Subject or Citizen, that is, in short, a good Christian. Nicholas Gimcrack, therefore, who neglected the Care of his Family, to pursue Butterflies, was a just Object of Ridicule, and we must give him up as fair Game to the Satyrist.

Adieu, my dear Friend, and believe me ever Yours affectionately

You good Mother is well, and gives her Love and Blessing to you. My Compliments to your Aunts, Miss Pitt, &c.;

To Mary Stevenson

My dear Friend, London, Sept. 13. 1760

I have your agreable Letter from Bristol, which I take this first Leisure Hour to answer, having for some time been much engag'd in Business.

Your first Question, What is the Reason the Water at this Place, tho' cold at the Spring, becomes warm by Pumping? it will be most prudent in me to forbear attempting to answer, till, by a more circumstantial Account, you assure me of the Fact. I own I should expect that Operation to warm, not so much the Water pump'd as the Person pumping. The Rubbing of dry Solids together, has been long observ'd to produce Heat; but the like Effect has never yet, that I have heard, been produc'd by the mere Agitation of Fluids, or Friction of Fluids with Solids. Water in a Bottle shook for Hours by a Mill Hopper, it is said, discover'd no sensible Addition of Heat. The Production of Animal Heat by Exercise, is therefore to be accounted for in another manner, which I may hereafter endeavour to make you acquainted with.

This Prudence of not attempting to give Reasons before one is sure of Facts, I learnt from one of your Sex, who, as Selden tells us, being in company with some Gentlemen that were viewing and considering something which they call'd a Chinese Shoe, and disputing earnestly about the manner of wearing it, and how it could possibly be put on; put in her Word, and said modestly, Gentlemen, are you sure it is a Shoe? Should not that be settled first?

But I shall now endeavour to explain what I said to you about the Tide in Rivers, and to that End shall make a Figure, which tho' not very like a River, may serve to convey my Meaning. Suppose a Canal 140 Miles long communicating at one End with the Sea, and fill'd therefore with Sea Water. I chuse a Canal at first, rather than a River, to throw out of Consideration the Effects produc'd by the Streams of Fresh Water from the Land, the Inequality in Breadth, and the (Diagram omitted) Crookedness of Courses. Let A, C, be the Head of the Canal, C D the Bottom of it; D F the open Mouth of it next the Sea. Let the strait prick'd Line B G represent Low Water Mark the whole Length of the Canal, A F High Water Mark: Now if a Person standing at E, and observing at the time of High water there that the Canal is quite full at that Place up to the Line E, should conclude that the Canal is equally full to the same Height from End to End, and therefore there was as much more Water come into the Canal since it was down at the Low Water Mark, as could be included in the oblong Space A. B. G. F. he would be greatly mistaken. For the Tide is a Wave, and the Top of the Wave, which makes High Water, as well as every other lower Part, is progressive; and it is High Water successively, but not at the same time, in all the several Points between G, F. and A, B. -- and in such a Length as I have mention'd it is Low Water at F G and also at A B, at or near the same time with its being High Water at E; so that the Surface of the Water in the Canal, during that Situation, is properly represented by the Curve prick'd Line B E G. And on the other hand, when it is Low Water at E H, it is High Water both at F G and at A B at or near the same time; and the Surface would then be describ'd by the inverted Curve Line A H F.

In this View of the Case, you will easily see, that there must be very little more Water in the Canal at what we call High Water than there is at Low Water, those Terms not relating to the whole Canal at the same time, but successively to its Parts. And if you suppose the Canal six times as long, the Case would not vary as to the Quantity of Water at different times of the Tide; there would only be six Waves in the Canal at the same time, instead of one, and the Hollows in the Water would be equal to the Hills.

That this is not mere Theory, but comformable to Fact, we know by our long Rivers in America. The Delaware, on which Philadelphia stands, is in this particular similar to the Canal I have supposed of one Wave: For when it is High Water at the Capes or Mouth of the River, it is also High Water at Philadelphia, which stands about 140 Miles from the Sea; and there is at the same time a Low Water in the Middle between the two High Waters; where, when it comes to be High Water, it is at the same time Low Water at the Capes and at Philadelphia. And the longer Rivers have, some a Wave and Half, some two, three, or four Waves, according to their Length. In the shorter Rivers of this Island, one may see the same thing in Part: for Instance; it is High Water at Gravesend an Hour before it is High Water at London Bridge; and 20 Miles below Gravesend an Hour before it is High Water at Gravesend. Therefore at the Time of High Water at Gravesend the Top of the Wave is there, and the Water is then not so high by some feet where the Top of the Wave was an Hour before, or where it will be an Hour after, as it is just then at Gravesend.

Now we are not to suppose, that because the Swell or Top of the Wave runs at the Rate of 20 Miles an Hour, that therefore the Current or Water itself of which the Wave is compos'd, runs at that rate. Far from it. To conceive this Motion of a Wave, make a small Experiment or two. Fasten one End of a Cord in a Window near the Top of a House, and let the other End come down to the Ground; take this End in your Hand, and you may, by a sudden Motion occasion a Wave in the Cord that will run quite up to the Window; but tho' the Wave is progressive from your Hand to the Window, the Parts of the Rope do not proceed with the Wave, but remain where they were, except only that kind of Motion that produces the Wave. So if you throw a Stone into a Pond of Water when the Surface is still and smooth, you will see a circular Wave proceed from the Stone as its Center, quite to the Sides of the Pond; but the Water does not proceed with the Wave, it only rises and falls to form it in the different Parts of its Course; and the Waves that follow the first, all make use of the same Water with their Predecessors.

But a Wave in Water is not indeed in all Circumstances exactly like that in a Cord; for Water being a Fluid, and gravitating to the Earth, it naturally runs from a higher Place to a lower; therefore the Parts of the Wave in Water do actually run a little both ways from its Top towards its lower Sides, which the Parts of the Wave in the Cord cannot do. Thus when it is high and standing Water at Gravesend, the Water 20 Miles below has been running Ebb, or towards the Sea for an Hour, or ever since it was High Water there; but the Water at London Bridge will run Flood, or from the Sea yet another Hour, till it is High Water or the Top of the Wave arrives at that Bridge, and then it will have run Ebb an Hour at Gravesend, &c. &c.;Now this Motion of the Water, occasion'd only by its Gravity, or Tendency to run from a higher Place to a lower, is by no means so swift as the Motion of the Wave. It scarce exceeds perhaps two Miles in an Hour. If it went as the Wave does 20 Miles an Hour, no Ships could ride at Anchor in such a Stream, nor Boats row against it.

In common Speech, indeed, this Current of the Water both Ways from the Top of the Wave is call'd the Tide; thus we say, the Tide runs strong, the Tide runs at the rate of 1, 2, or 3 Miles an hour, &c. and when we are at a Part of the River behind the Top of the Wave, and find the Water lower than High-water Mark, and running towards the Sea, we say, the Tide runs Ebb; and when we are before the Top of the Wave, and find the Water higher than Low-water Mark, and running from the Sea, we say, the Tide runs Flood: But these Expressions are only locally proper; for a Tide strictly speaking is one whole Wave, including all its Parts higher and lower, and these Waves succeed one another about twice in twenty four Hours.

This Motion of the Water, occasion'd by its Gravity, will explain to you why the Water near the Mouths of Rivers may be salter at Highwater than at Low. Some of the Salt Water, as the Tide Wave enters the River, runs from its Top and fore Side, and mixes with the fresh, and also pushes it back up the River.

Supposing that the Water commonly runs during the Flood at the Rate of two Miles in an Hour, and that the Flood runs 5 Hours, you see that it can bring at most into our Canal only a Quantity of Water equal to the Space included in the Breadth of the Canal, ten Miles of its Length, and the Depth between Low and Highwater Mark. Which is but a fourteenth Part of what would be necessary to fill all the Space between Low and Highwater Mark, for 140 Miles, the whole Length of the Canal.

And indeed such a Quantity of Water as would fill that whole Space, to run in and out every Tide, must create so outrageous a Current, as would do infinite Damage to the Shores, Shipping, &c. and make the Navigation of a River almost impracticable.

I have made this Letter longer than I intended, and therefore reserve for another what I have farther to say on the Subject of Tides and Rivers. I shall now only add, that I have not been exact in the Numbers, because I would avoid perplexing you with minute Calculations, my Design at present being chiefly to give you distinct and clear Ideas of the first Principles.

After writing 6 Folio Pages of Philosophy to a young Girl, is it necessary to finish such a Letter with a Compliment? Is not such a Letter of itself a Compliment? Does it not say, she has a Mind thirsty after Knowledge, and capable of receiving it; and that the most agreable Things one can write to her are those that tend to the Improvement of her Understanding? It does indeed say all this, but then it is still no Compliment; it is no more than plain honest Truth, which is not the Character of a Compliment. So if I would finish my Letter in the Mode, I should yet add something that means nothing, and is merely civil and polite. But being naturally awkward at every Circumstance of Ceremony, I shall not attempt it. I had rather conclude abruptly with what pleases me more than any Compliment can please you, that I am allow'd to subscribe my self Your affectionate Friend

To David Hume

Dear Sir, Coventry, Sept. 27. 1760

I have too long postpon'd answering your obliging Letter, a Fault I will not attempt to excuse, but rather rely on your Goodness to forgive it if I am more punctual for the future.

I am oblig'd to you for the favourable Sentiments you express of the Pieces sent you; tho' the Volume relating to our Pensilvania Affairs, was not written by me, nor any Part of it, except the Remarks on the Proprietor's Estimate of his Estate, and some of the inserted Messages and Reports of the Assembly which I wrote when at home, as a Member of Committees appointed by the House for that Service; the rest was by another Hand. But tho' I am satisfy'd by what you say, that the Duke of Bedford was hearty in the Scheme of the Expedition, I am not so clear that others in the Administration were equally in earnest in that matter. It is certain that after the Duke of Newcastle's first Orders to raise Troops in the Colonies, and Promise to send over Commissions to the Officers, with Arms, Clothing, &c. for the Men, we never had another Syllable from him for 18 Months; during all which time the Army lay idle at Albany for want of Orders and Necessaries; and it began to be thought at least that if an Expedition had ever been intended, the first Design and the Orders given, must, thro' the Multiplicity of Business here at home, have been quite forgotten.

I am not a little pleas'd to hear of your Change of Sentiments in some particulars relating to America; because I think it of Importance to our general Welfare that the People of this Nation should have right Notions of us, and I know no one that has it more in his Power to rectify their Notions, than Mr. Hume. I have lately read with great Pleasure, as I do every thing of yours, the excellent Essay on the Jealousy of Commerce: I think it cannot but have a good Effect in promoting a certain Interest too little thought of by selfish Man, and scarce ever mention'd, so that we hardly have a Name for it; I mean the Interest of Humanity, or common Good of Mankind: But I hope particularly from that Essay, an Abatement of the Jealousy that reigns here of the Commerce of the Colonies, at least so far as such Abatement may be reasonable.

I thank you for your friendly Admonition relating to some unusual Words in the Pamphlet. It will be of Service to me. The pejorate, and the colonize, since they are not in common use here, I give up as bad; for certainly in Writings intended for Persuasion and for general Information, one cannot be too clear, and every Expression in the least obscure is a Fault. The unshakeable too, tho' clear, I give up as rather low. The introducing new Words where we are already possess'd of old ones sufficiently expressive, I confess must be generally wrong, as it tends to change the Language; yet at the same time I cannot but wish the Usage of our Tongue permitted making new Words when we want them, by Composition of old ones whose Meanings are already well understood. The German allows of it, and it is a common Practice with their Writers. Many of our present English Words were originally so made; and many of the Latin Words. In point of Clearness such compound Words would have the Advantage of any we can borrow from the ancient or from foreign Languages. For instance, the Word inaccessible, tho' long in use among us, is not yet, I dare say, so universally understood by our People as the Word uncomeatable would immediately be, which we are not allow'd to write. But I hope with you, that we shall always in America make the best English of this Island our Standard, and I believe it will be so. I assure you, it often gives me Pleasure to reflect how greatly the Audience (if I may so term it) of a good English Writer will in another Century or two be encreas'd, by the Increase of English People in our Colonies.

My Son presents his Respects with mine to you and Dr. Monro. We receiv'd your printed circular Letter to the Members of the Society, and purpose some time next Winter to send each of us a little Philosophical Essay. With the greatest Esteem I am, Dear Sir, Your most obedient and most humble Servant

To Mary Stevenson

My dear Friend It is, as you observed in our late Conversation, a very general Opinion, that all Rivers run into the Sea, or deposite their Waters there. 'Tis a kind of Audacity to call such general Opinions in question, and may subject one to Censure: But we must hazard something in what we think the Cause of Truth: And if we propose our Objections modestly, we shall, tho' mistaken, deserve a Censure less severe, than when we are both mistaken and insolent.

That some Rivers run into the Sea is beyond a doubt: Such, for Instance, are the Amazones, and I think the Oranoko and the Missisipi. The Proof is, that their Waters are fresh quite to the Sea, and out to some Distance from the Land. Our Question is, whether the fresh Waters of those Rivers whose Beds are filled with Salt Water to a considerable Distance up from the Sea (as the Thames, the Delaware, and the Rivers that communicate with Chesapeak Bay in Virginia) do ever arrive at the Sea? and as I suspect they do not, I am now to acquaint you with my Reasons; or, if they are not allow'd to be Reasons, my Conceptions, at least of this Matter.

The common Supply of Rivers is from Springs, which draw their Origin from Rain that has soak'd into the Earth. The Union of a Number of Springs forms a River. The Waters as they run, expos'd to the Sun, Air and Wind, are continually evaporating. Hence in Travelling one may often see where a River runs, by a long blueish Mist over it, tho' we are at such a Distance as not to see the River itself. The Quantity of this Evaporation is greater or less in proportion to the Surface exposed by the same Quantity of Water to those Causes of Evaporation. While the River runs in a narrow confined Channel in the upper hilly Country, only a small Surface is exposed; a greater as the River widens. Now if a River ends in a Lake, as some do, whereby its Waters are spread so wide as that the Evaporation is equal to the Sum of all its Springs, that Lake will never overflow: And if instead of ending in a Lake, it was drawn into greater Length as a River, so as to expose a Surface equal, in the whole to that Lake, the Evaporation would be equal, and such River would end as a Canal; when the Ignorant might suppose, as they actually do in such cases, that the River loses itself by running under ground, whereas in truth it has run up into the Air.

Now many Rivers that are open to the Sea, widen much before they arrive at it, not merely by the additional Waters they receive, but by having their Course stopt by the opposing Flood Tide; by being turned back twice in twenty-four Hours, and by finding broader Beds in the low flat Countries to dilate themselves in; hence the Evaporation of the fresh Water is proportionably increas'd, so that in some Rivers it may equal the Springs of Supply. In such cases, the Salt Water comes up the River, and meets the fresh in that part where, if there were a Wall or Bank of Earth across from Side to Side, the River would form a Lake, fuller indeed at some times than at others according to the Seasons, but whose Evaporation would, one time with another, be equal to its Supply.

When the Communication between the two kinds of Water is open, this supposed Wall of Separation may be conceived as a moveable one, which is not only pushed some Miles higher up the River by every Flood Tide from the Sea, and carried down again as far by every Tide of Ebb, but which has even this Space of Vibration removed nearer to the Sea in wet Seasons, when the Springs and Brooks in the upper Country are augmented by the falling Rains so as to swell the River, and farther from the Sea in dry Seasons.

Within a few Miles above and below this moveable Line of Separation, the different Waters mix a little, partly by their Motion to and fro, and partly from the greater specific Gravity of the Salt Water, which inclines it to run under the Fresh, while the fresh Water being lighter runs over the Salt.

Cast your Eye on the Map of North America, and observe the Bay of Chesapeak in Virginia, mentioned above; you will see, communicating with it by their Mouths, the great Rivers Sasquehanah, Potowmack, Rappahanock, York and James, besides a Number of smaller Streams each as big as the Thames. It has been propos'd by philosophical Writers, that to compute how much Water any River discharges into the Sea, in a given time, we should measure its Depth and Swiftness at any Part above the Tide, as, for the Thames, at Kingston or Windsor. But can one imagine, that if all the Water of those vast Rivers went to the Sea, it would not first have pushed the Salt Water out of that narrow-mouthed Bay, and filled it with fresh? The Sasquehanah alone would seem to be sufficient for this, if it were not for the Loss by Evaporation. And yet that Bay is salt quite up to Annapolis.

As to our other Subject, the different Degrees of Heat imbibed from the Sun's Rays by Cloths of different Colours, since I cannot find the Notes of my Experiment to send you, I must give it as well as I can from Memory.

But first let me mention an Experiment you may easily make your self. Walk but a quarter of an Hour in your Garden when the Sun shines, with a Part of your Dress white, and a Part black; then apply your Hand to them alternately, and you will find a very great Difference in their Warmth. The Black will be quite hot to the Touch, the White still cool.

Another. Try to fire Paper with a burning Glass. If it is White, you will not easily burn it; but if you bring the Focus to a black Spot or upon Letters written or printed, the Paper will immediately be on fire under the Letters.

Thus Fullers and Dyers find black Cloths, of equal Thickness with white ones, and hung out equally wet, dry in the Sun much sooner than the white, being more readily heated by the Sun's Rays. It is the same before a Fire; the Heat of which sooner penetrates black Stockings than white ones, and so is apt sooner to burn a Man's Shins. Also Beer much sooner warms in a black Mug set before the Fire, than in a white one, or in a bright Silver Tankard.

My Experiment was this. I took a number of little Square Pieces of Broad Cloth from a Taylor's Pattern Card, of various Colours. There were Black, deep Blue, lighter Blue, Green, Purple, Red, Yellow, White, and other Colours or Shades of Colours. I laid them all out upon the Snow in a bright Sunshiny Morning. In a few Hours (I cannot now be exact as to the Time) the Black being warm'd most by the Sun was sunk so low as to be below the Stroke of the Sun's Rays; the dark Blue almost as low, the lighter Blue not quite so much as the dark, the other Colours less as they were lighter; and the quite White remain'd on the Surface of the Snow, not having entred it at all. What signifies Philosophy that does not apply to some Use? May we not learn from hence, that black Cloaths are not so fit to wear in a hot Sunny Climate or Season as white ones; because in such Cloaths the Body is more heated by the Sun when we walk abroad and are at the same time heated by the Exercise, which double Heat is apt to bring on putrid dangerous Fevers? That Soldiers and Seamen who must march and labour in the Sun, should in the East or West Indies have an Uniform of white? That Summer Hats for Men or Women, should be white, as repelling that Heat which gives the Headachs to many, and to some the fatal Stroke that the French call the Coup de Soleil? That the Ladies Summer Hats, however should be lined with Black, as not reverberating on their Faces those Rays which are reflected upwards from the Earth or Water? That the putting a white Cap of Paper or Linnen within the Crown of a black Hat, as some do, will not keep out the Heat, tho' it would if plac'd without? That Fruit Walls being black'd may receive so much Heat from the Sun in the Daytime, as to continue warm in some degree thro' the Night, and thereby preserve the Fruit from Frosts, or forward its Growth? -- with sundry other particulars of less or greater Importance, that will occur from time to time to attentive Minds? I am, Yours affectionately,

November? 1760

To John Baskerville

Dear Sir, Craven-Street, London.

Let me give you a pleasant Instance of the Prejudice some have entertained against your Work. Soon after I returned, discoursing with a Gentleman concerning the Artists of Birmingham, he said you would be a Means of blinding all the Readers in the Nation, for the Strokes of your Letters being too thin and narrow, hurt the Eye, and he could never read a Line of them without Pain. I thought, said I, you were going to complain of the Gloss on the Paper, some object to: No, no, says he, I have heard that mentioned, but it is not that; 'tis in the Form and Cut of the Letters themselves; they have not that natural and easy Proportion between the Height and Thickness of the Stroke, which makes the common Printing so much more comfortable to the Eye. -- You see this Gentleman was a Connoisseur. In vain I endeavoured to support your Character against the Charge; he knew what he felt, he could see the Reason of it, and several other Gentlemen among his Friends had made the same Observation, &c. -- Yesterday he called to visit me, when, mischievously bent to try his Judgment, I stept into my Closet, tore off the Top of Mr. Caslon's Specimen, and produced it to him as yours brought with me from Birmingham, saying, I had been examining it since he spoke to me, and could not for my Life perceive the Disproportion he mentioned, desiring him to point it out to me. He readily undertook it, and went over the several Founts, shewing me every-where what he thought Instances of that Disproportion; and declared, that he could not then read the Specimen without feeling very strongly the Pain he had mentioned to me. I spared him that Time the Confusion of being told, that these were the Types he had been reading all his Life with so much Ease to his Eyes; the Types his adored Newton is printed with, on which he has pored not a little; nay, the very Types his own Book is printed with, for he is himself an Author; and yet never discovered this painful Disproportion in them, till he thought they were yours. I am, &c.;

1760?