Letter from Thomas Horne to Newton, with notes by Newton on Middle Eastern cities
Sr
I have lately tryed to looke into Cartes 3d booke of ye nature of æquations, thinking to understand what goes before by ye helpe of his rules delivered there: & I begin to hope I may by my owne strength, & j judge it is better to find one conclusion out than have 20 shewed me, wch made me defer moving questions to you so long, & partly because j cannot move my many doubts in proper termes. But I know you are to good & wise to deride me. Some things \Rules/ I think j understand in yt discourse of æquation {sic}, but I stick at ye first hypothesis pag 69th. for first though I may suppose yt x is æquall to 2 or x − 2 æquall to nothing \&c: –/; yet methinks this does not reach ye ye universall nature of æquations, though some may be imagined so to be made & then all things follow according \to/ ye subsequent rules. let x − 2 be 0 ye & x − 3 = 0 \x − 4 = 0/ ye first magnitude yt rises is xx − ex + 6 & ye cube (if j may so call it) x3 − 9xx + 2bx − 29. But set you thus x 2 x 3 x 4 then ye first æquation on each hand is xx = 6 ye 2d æquation x3 = 29 Now heare all ye midle species are lost, such as −9xx + 26x. In ye next place why must I alter ye value of x & make it some times æquall to 2 & some times to 3 methinks this is more like a square x − 2 = 0 x − 2 = 0 & xx − 4x + 4 0. &c:
In pag. 74. I cannot understand ye note H.
pag. 78.{illeg} I cannot find out ye order of dividing ye noted æquation by yy − aa − cc. neither am j able to find ye meaning of those words in ye bottome of ye page. Id quod monstrat radiem quæsitā esse aa + cc quemadmodū per multiplicationem probari potest
pag. {illeg} \79/ ye rule of making 2 æquations + x4*.pxx.qx.r &c. I have practised \upon/ some of his æquations but have not ye reason of it nor {Basins} demonstration. p. 137. Nor ye rule p. 81 of making 2 æqua\tions/ out of one.
I remember Cartes says if one try methodically to examine his rules, one shall find ye demonstration of ym, be pleased to shew me ye methodicall examination in yt aponation pag. 78 or some other.
pray sir if you can spare time to ease a doubter, deliver a note to Mr Michell or Mr Yard of Kings & they will send it to yor
humble & thankfull pupill
T. Horne
Hadly Suffolk. Aug. 22d.
<1v>For his worthy freind Mr Is: Newton
Math: Prof.
Cambridge.