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in order to shew, that we cannot by the Naked eye make any astronomicall or other observation to a
greater exactnesse than that of a minute, by Reason that what euer obiect appears vnder a lesse angule is
not Distinguishable by the naked Eye. And therefore alledged that whatsoeuer curiosity was used to make
the Diuisions of an instrument more nice was of noe vse, unlesse the Eye were assigned by other helps
from optick Glasses. [Lucas Hodgsons minerall present.
[In margin]61.   Ian. 22. Mr Hooke proposed the making of a new kind of astronomicall instrument of his Own Inuen
tion for taking heights angules & Distances of Celestiall bodys, by one observator more exactly than
euer was yet done, vizt to a second. He added that in this was the exactnesse of /the/ an instrument as to Di-
uisions, sights & Perpendicularity, might vpon occasion be duely ordered by the astronomicall observer
Soe as not to Rely vpon the credit or skill of the Instrument maker. He being asked what the making
of such a quadrant would amount to, and answering that he thought it could be made vnder 10 pounds
It was ordered that he should Cause one to be made of that price -- The Expt of the Last Day shewing
that with Common sights we are not capable to Distinguish a minute was Repeated againe & it made
out what it was designed for. [Lister abt. fungus subterraneous. a milk white coleliquor.
[In margin]62   Feb: 5. 1674. mr Hooke produced a new kind of Reflecting telescope of his own contriuance dif
fering from Mr Newtons in this that the Obseruer Lookd Directly at the obiect erected, this was performd
by a way propounded by Mersennus, and is repeated in Mr Gregorys opticks, but it is belieued was
neuer actually done before. [grew fig of oake & Elm. Arbury about stormy winds. [Lysters stiptick tryd.
[In margin]64.   Feb: 12. mr Hooke made seuerall tryalls with a Loadstone, to find whether the interposition of any body
would hinder the power of its effluuians. And having by weight soe poysd a ballance fitted for this purpose
that the Iron was made to hange there at a certaine Distance from the Loadstone, soe as to Leaue some -
room for Diuers body to be Interposed. It was found that though a Siluer Crown, a peice of Glasse of about
the same thicknesse & 4 XXs peices of Gold called guinyes were seueraly vpon seuerally interposed
between the Iron and the magnet, yet the iron did not at all alter its distance which at first it had by the poise
It was ordered that the curator should be desired to try by himself a good number of experiments vpon this head and
put the narrative of the successe of them all, in writing and present them to the society, that soe they might
call for such of them as they should think good to be shewed before them.
[In margin]66.   Feb: 19. There were some more expts made with the magnet vizt. a small barr of steel about an inch in length
and about 1/4 of an inch in Diameter, was soe suspended that the Lower end was distant from the pole of a
very good Loadstone, and counterpoised by 6 grains. and by seuerall tryalls it was found that a plate
of glasse 6 inches broad and 1/2 an inch thick. a thin boord of wood about the same bulk, a plate of
Sparr about the Same bredth and thicknesse, a cutt of Butter on a trencher, a pewter plate a sett
of Brasse weights, a burning deal boord, a red hott tile, a Bright Burning cole, the same also -
blowed each of them interposed between the steel & Loadstone suspended as aforesaid, made noe
variation of the attractive virtue of the stone, nor did an onion slit in two & layd vpon the same
stone, nor the interposing of wood Lead glasse wood siluer gold all at once make any manner of
change. the attraction remaining Constant. Further by the interposing of a knife the vertue of
the Loadstone was much diminished, but by interposing a little barr of Iron half an inch in -
Length endways, it increased about a quarter of the stength. -- The bringing of Iron anyways neer
the stone weakned the attraction - [grew more microsc figures of Holly a fig tree. Slusius letter. --
Mr. Hooke produced a quadrat of 4 inches diameter with telescopicall sights to be made vse of by 2 obseruers
and Distinguishing to minutes. The same was put in mind of his other quadrants whereby parallaxes Re-
fractions &c may be obserud to seconds by one Obseruer.
[In margin]67.   Feb: 26. Mr. Hooke shewd an Expt. of the inclination of the lines of Direction to the Axis of the Terrella, which
he performed by placing a terella in an herisphericall hole cut in a round table, and ordering the terella
soe that the axis lay in the Levell with the surface of it vpon the surface of this table was placed a large
Skin of Parchment stretcht on a hoop like a drum head, in the middle of which was cutt a circular hole
Iust big enough to Receiue the terrella. vpon this parchment were sifted fine filings of iron, which by the gentle
vibration of the extended Parchment, soon ranged themselves into magneticall orbes, which were thought
to be all of an ouall figure, and of Oualls of one kind but of Different bignesse, and all of them to touch -
one axis in the center of the Loadstone. But these being only ghesses and not certainly verifyd, it was
thought fit in order to the cleerer & more certaine Discouery thereof, there should be other ways
attempted to make it out. which Mr Hooke propounded, and ingaged to haue at Least some of them -
ready against the next Day --- The same obserued further to the Company, that a Loadstone being
moued to & fro vnder the parchment on which the said filings Lay scattered. those filings did all rise
vp like soe many bristles, making an appearance as if the Loadstone had been seen through the Parchment
He also applying a Loadstone to a small peice of tin, the stone seemed to hold it, both after it was
rubbd & without Rubbing. He suggested also the making Experimts. with a capped & vncapped Load-
stone, interposing a single paper between it and a peice of iron. He was desired also to shew some
of these expts. next Day. --
[In margin]68   March. 5. the Presidt & vicepresidts being absent noe sitting. But mr Hooke repeated the magneticall expt. which was made
Last meeting, which seemd to confirme that phenomenon of the Magnetick orbes ranging themselues into Ellipticall
figures. some expts. also with Loadstone capt & vncapt were made. The south end of an vncapt Magnet with a single
paper betwixt it and a small Bar of Steel Suspended held the said barr with 4 graines drachms & 15 grains. The same
south end capd with out paper a single without paper held the said Barr with 7 ounces & a drachm. The same south
end cappd. with a single paper interposd held that Barr with one ouce & 5 drachms. -
[In margin]69.   Mar. 12. Mr. Hooke indeavoured to shew a new way of making a loadstone Let it self north and South
which was by suspending it from a string fastned to the 2 Eares of a cap, like the cap of a magneticall w
nedle which was conuertible vpon the sharp point of a needle. But the contrivance not proving tender
enough, he was desired to fitt it better for the next Day. the same Intimated a theory for finding out
the Loadstones variation all over the world, and promised to make an apparatus for it against next day.
and particularly a Rete for the magneticall Meridians. The Expt. about the inclination of the magneticall direction
to the axis of the terrella being again made & those Lines considerd there were severall of the company doubting whether

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