Decemb 14th. 1675.


The notice you gave me of ye R. Societie's intending to see ye expt of glass rubb'd to cause various motions in bits of paper unde{illeg}|r|neath, put me upon recollecting my self a little further about it, & then remembring yt if one edge of ye brass hoop was laid downward ye glass was as neare again to ye table as it was when ye other {illeg}|e|dge was laid downward & yt ye papers plaid best when ye glass was nearest to ye table: I began to suspect yt I had set down {illeg}|a| greater distance of ye glas from ye table then I should have done, for in setting down yt experimt I trusted to ye Idea I had of ye bignes of ye hoop \in wch I might easily be mistaken having n{illeg}|o|t s{illeg}|e|en it of a long time/. And this suspicion was increased by trying ye experimt wth an object glass of a Telescope placed about ye 3d part of an inch from ye Table: for I cou{illeg}|l|d not see ye papers play any thing neare so well as I had seen them formerly. Whereupon I lookt for ye old hoop wth its' glas, & at length found ye hoop ye glass being gone, but by ye hoop I perceiv'd that when one edge was turnd down ye glas was almost ye third part of an inch from ye table & when ye other \edge/ was down wch made ye papers play so well ye glass was scarce ye 8th part of an inch from ye Table. This I thought fit to signify to you that if ye expt succeed not well at ye distance I set down it may be tryed at a less distance, & that you may alter my paper & write in it an eighth part of an inch instead of 12 or 13 of an inch. The bits of paper ought to be very little & of thin paper. <45v> Perhaps little bits of ye wing of a fly or other light substances m{illeg}|a|y do better then paper. Som{illeg}|e| of ye motions as that of hanging by a corner & twirling about, & that of leaping from one side of {illeg} part of ye glas to ye another \wthout touching ye table/ happen but seldom but it made me take ye more notice of them.

Pray present my humble service to Mr Boyle \wn you see him/ & thanks for ye favour of ye convers I had wth him at spring. My conceit of trapanning ye common Ether, as he was pleas{illeg}|d| to expres it, it makes me beg{illeg}|i|n to have ye better thoughts on yt he was pleasd to entertein it wth a smile. I am apt to think yt wn he has a set of expts to try in his air pump, it will he will make that one to see how ye compression {illeg} or relaxation of a muscle will shrink or swell, soften or harden, lengthen or shorten it.

As for Registring ye two discourses you may do it, only I desire you would suspend till my next letter, in wch I intend to set down something to be altered & something to be added in ye Hypothesis, being in ye mean while


Yor humble Servant

Is. Newton.


For Henry Oldenburg Esqꝫ at
his house about ye middle
of ye old Pal-mall
in Westminster



|Mr Newton to Mr Oldenburg concerning an Experiment of gl{illeg} glas rubbed to cause various motions in litle bits of paper underneath ye glas.|

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