45
Cambr.Cambridge
DecembDecember 14th. 1675.
SrSir
The notice you gave me of yethe R.Royal Societie's intending
to see yethe exptexperiment of glass rubb'drubbed to cause various motions
in bits of paper underneath, put me upon recollecting
my self a little further about it, & then remembring
ytthat if one edge of yethe brass hoop was laid downward yethe glass
was as neare again to yethe table as it was when yethe other
edge was laid downward & ytthat yethe papers plaid best when
yethe glass was nearest to yethe table: I began to suspect
ytthat I had set down a greater distance of yethe glas from
yethe table then I should have done, for in setting down ytthat
experimtexperiment I trusted to yethe Idea I had of yethe bignes of yethe hoop in wchwhich I might easily be mistaken having not seen it of a long time. And this suspicion was increased by trying yethe experimtexperiment
wthwith an object glass of a Telescope placed about yethe 3d
part of an inch from yethe Table: for I could not see
yethe papers play any thing neare so well as I had seen
them formerly. Whereupon I lookt for yethe old hoop wthwith
its' glas, & at length found yethe hoop yethe glass being gone,
but by yethe hoop I perceiv'dperceived that when one edge was turnd
down yethe glas was almost yethe third part of an inch from
yethe table & when yethe other edge was down wchwhich made yethe
papers play so well yethe glass was scarce yethe 8th part
of an inch from yethe Table. This I thought fit to sig
nify to you that if yethe exptexperiment succeed not well at yethe dis
tance 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 or of an inch. The bits of paper ought to be very little & of thin paper. Perhaps Perhaps little bits of yethe wing of a fly or other light substances may do better then paper. Some of yethe motions as that of hanging by a corner & twirling about, & that of leaping from one side of part of yethe glas to yethe another wthwithout touching yethe table happen but seldom but it made me take yethe more notice of them.
Pray present my humble service to Mr Boyle wnwhen you see him & thanks for yethe favour of yethe convers I had wthwith him at spring. My conceit of trapanning yethe common Ether, as he was pleasd to expres it, it makes me begin to have yethe better thoughts on ytthat he was pleasd to entertein it wthwith a smile. I am apt to think ytthat wnwhen he has a set of exptsexperiments to try in his air pump, it will he will make that one to see how yethe compression or relaxation of a muscle will shrink or swell, soften or harden, lengthen or shorten it.
As for Registring yethe two discourses you may do it, only I desire you would suspend till my next letter, in wchwhich I intend to set down something to be altered & something to be added in yethe Hypothesis, being in yethe mean while
SrSir
YorYour humble Servant
Is. Newton.