<1r>

Sir

I meet with no other amendments which need be made beside these which follow.

pag. 368 lin. ult. pro 1665 lege 1666.

pag. 392 lin. ult. pro $-2\stackrel{.}{x}oo\stackrel{.}{y}\stackrel{.}{y}$ $+\stackrel{.}{x}oo\stackrel{.}{y}\stackrel{.}{y}+x{o}^{3}\stackrel{.}{y}\stackrel{.}{y}$ lege $-2\stackrel{.}{x}oo\stackrel{.}{y}y-\stackrel{.}{x}oo\stackrel{.}{y}\stackrel{.}{y}-x{o}^{3}\stackrel{.}{y}\stackrel{.}{y}$

pag. 393 l. 2. pro $+xo\stackrel{.}{y}\stackrel{.}{y}+\stackrel{.}{x}o\stackrel{.}{y}\stackrel{.}{y}$ lege $-xo\stackrel{.}{y}\stackrel{.}{y}-\stackrel{.}{x}o\stackrel{.}{y}\stackrel{.}{y}$.

The plague was in Cambridge in both the years 1665 & 1666 but it was in 1666 that I was absent from Cambridge & therefore I have set down an amendment of the year. I wrote to you lately that I found the method of converging series in the winter between the years 1665 & 1666. For that was the earliest mention of it I could find then amongst my papers. But meeting since with the notes which in the year 1664 upon my first reading of Vieta's works Schooten's Miscelanies & your Arithmetica Infinitorum I took out of those books & finding among these notes my deduction of the series for the circle out of yours in your Arithmetica Infinitorum : I collect that it was in the year 1664 that I deduced these series out of yours Then is also among these notes Mercators series for squaring the Hyperbola found by the same method with some others. But I cannot find that I understood the invention of these series by division & extraction of roots or made any further progress in this business before the writer which was between the years 1665 & 1666. But in that winter & that spring following by the use of Division & extraction of roots I brought that method to be general, & then the plague made me leave Cambridge. But I do not think it requisite that you should make a particular mention of these things. I believe you have said enough in the beginning of your 91th Chapter.

In your third Chapter you have given us a collation of the Arabic cyphers with ours both old & modern. The other day looking into Taverniere's travells into India lib. 1 pag 23 I met with the cyphers now used all over India. They are these.
$\begin{array}{ccccccccccccc}q& ɀ& \epsilon & ४& \mathit{y}& ʒ& \mathit{9}& ﺡ& ७& q.& q..& q...& q....\\ 1& 2& 3& 4& 5& 6& 7& 8& 9& 10& 100& 1000& 10000\end{array}$
Our old figures 2, 4 5 & 8 (thus marked ɀ ४ $\mathit{y}$ ﺡ) seem to be borrowed from these.