Trin.Trinity Coll.College Cambr.Cambridge May 18 1669

FrFrancis:

Since in your letter you give mee so much liberty of spending my Judgment about wtwhat may bee to yoryour advantage in travelling, I shall doe it more freely then perhaps would otherwise have beene decent. First therefore I will lay down some generall rules most of wchwhich I beleve you have considered already; but if any of them bee new to you they may excuse yethe rest, if none at all yet tis my punisment more in writing them then yorsyours in reading ymthem.

When you come into any fresh company, 1, observe their humours; 2 suit your own carriage thereto, by wchwhich insinuation you will make their converse more free & open: 3 let your discours bee more in Quærys & doubtings ynthan peremptory assertions or disputings, it being yethe designe of Travellers to learne not teach; besides it will persuade yoryour acquaintance ytthat you have the greater esteem of them & soe make ymthem more ready to communicate wtwhat they know to you; whereas nothing sooner occasions disrespect & quarrells ynthen peremptorinesse. You will find little or noe advantage in seeming wiser or much more ignorant ynthan yoryour company. 4, seldome discommend any thing though never so bad, or doe it but moderatly, least you bee unexpectedly forced to an unhansom retraction. Tis safer to commend any thing more then it deserves ynthen to discommend a thing so much as it deserves: a bad For commendantionscommendations meet not soe often wthwith oppositions or at least are not usually so ill resented by men if that think otherwise as discommendations. And you will insinuate into mens favour by nothing sooner then seeming to approve & commend wtwhat they like; but beware of doing it by a comparison. 5 If you bee affronted, tis better in a forrain Country to passe it by in silence or wthwith a jest though wthwith some dishonour then to endeavour revenge; For in the first case yoryour credit's ne're the wors when you return into England or come into other company ytthat have not heard of the quarrell, but in the second case you may beare yethe marks of yethe quarrell while you live, if you out live it att all. But if you find yoryour self unavoydably engaged tis best, I think, if you can command your passion & language, to keep them pretty eavenly at yethe some certain moderate pitch, not much heightning them to exasperate yethe adversary or provoke his freinds nor letting them grow overmuch dejected to make him insult. In a word if you can keep reason above passion, ytthat & watchfulnesse will bee yoryour best defendants. To wchwhich purpose you may consider ytthat though such excuses as this [He provok't mee so much I could not forbeare] may passe amongst freinds yet amongst strangers they are insignificant & only argue a Travellers weaknesse.

To these I may ad some generall heads for inquirys or observations such as at present I can think on. As 1 to observe yethe policys wealth & State affaires of nations so far as a solitary Traveller may conveniently doe. 2 Their impositions upon all sorts of People Trades or commoditys ytthat are remarpkeable. 3 Their Laws & Customes how far they differ from ours. 4 Their Trades & Arts wherin they excell or come short of us in England. 5 Such fortifications as you shall meet wthwith, their fashion strength & advantages for defence; & other such military affaires as are considerable. 6 The power & respect belonging to their degrees of nobility or Magistracy. 7 Wh you c It will not bee time mispent to make a Catalogue of the names & excellencys of those men that are most wise learned or esteemed in any nation. 8 Observe yethe Mechanisme & man̄nner of guiding ships. 9 Observe the products of nature in severall places especially in mines wthwith yethe circumstances of mining & of extracting metalls or mineralls out of their oare and refining them and if you meet wthwith any transmutations out of one species into another (as out of Iron into Copper, out of any metall into quicksilver, out of one salt into another or into an insipid body &c) those above all others will bee worth yoryour noting being yethe most luciferous & many times lucriferous experiments too in Philosophy. 10 The prizes of diet & other things. 11 & And the staple commoditys of Places.

These Generalls (such as at present I could think of) if they will serve for nothing else yet they may assist you in drawing up a Modell to regulate yoryour Travels by

As for particulars these ytthat follow are all ytthat I can now think of, viz: Whither at Schemnitium in Hungary (where there are Mines of Gold, copper, Iron, vitrioll, Antimony, &c) they change Iron into Copper by dissolving it in a Vitriolate water wchwhich they find in cavitys of rocks in the mines & then melting the slymy solution in a strong fire wchwhich in yethe cooling proves copper. The like is said to bee done in other places wchwhich I cannot now remember. Perhaps too it may bee done in Italy; For about 20 or 30 years algone there was a certain Vitriol came from thence (called Roman Vitrioll, but of a nobler vertue ynthan ytthat wchwhich is now called by ytthat name) wchwhich Vitrioll is not now to bee gotten becaus perhaps they make a greater gain by some such trick as turning Iron into Copper wthwith it then by selling it. 2 Whither in Hungary, Sclavonia, Bohemia neare yethe town Eila, or at yethe Mountains of Bohemia neare Silesia there be rivers whose waters are impregnated wthwith gold; perhaps yethe Gold being dissolved by som corrosive waters like Aqua Regis & yethe solution carried along wthwith yethe streame that runs through yethe mines. And whither yethe practise of laying mercury in the rivers till it be tinged wthwith gold & then straining yethe mercury through leather ytthat yethe gold may stay behind, bee a secret yet or openly practised. 3 There is newly contrived in Holland a mill to grind glasses plane wthwith all & I think polishing them too, perhaps it will bee worth yethe while to see it. 4 There is in Holland one — Bory, who some yeares since was imprisoned by the Pope to have extorted from him some secrets (as I am told) of great worth both as to medicine & profit, but hee escaped into Holland where they have granted him a guard. I think he usually goes clothed in green pray enquire wtwhat you can of him, & whither his ingenuity bee any profit to the Dutch. 5 You may inform your selfe whither yethe Dutch have any tricks to keep their ships from being all worm eaten in their voyages to yethe Indys. Whither Pendulum clocks doe any service in finding out yethe longitude &c. I am very weary & shall not stayd to part wthwith a long complement only I wish you a Good Iourney & God bee wthwith you

Is Newton.