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He also proposed an Obseruatio to be made of the texture of Muscles by a microscope which he promised he would make
for the next Day. and then shew it to the Company. -- expts. of motio to be presented by D Crone & mr Hooke.
April. 15. 1669. The curator again produced the Expt. of the Watch moued by a magnet which according to its
seuerall Distances from the flight fitted to the Watch made it Goe faster or Slower: - Sr. Rob. Moray suggested
seuerall doubts to be in this Expt. first whether the Loadstone hath the same attraction in all postures. 2. whe
ther some kind of Earth or Rock may not alter the power of attraction. Alledging that in Scotland there was
a whole ridge of Rocky mountaines of a magneticall virtue &c. 3ly. whether there would not be found
a Difference in the attraction, according to a neerer or farther Distance of the Loadstone from the Land
The President suggested that it might be tryed, whether a watch thus moued by a magnet would goe aequally
with a stronger or weaker Spring to try which his Lop. Proposed that the watch & Loadstone being fixt, the
Spring of the watch should be wound vp more or Lesse high, to see whether the motion Caused by the magnet
would be always aequall. -- It was orderd that a peice of clockwork with a Spring should be prouided for the
next Day, to be tryd with a Loadstone. -- Vz. Tanned moorskin.
Ap. 22. nought. Apr. 29. The curator produced his magneticall watch improued by hauing soe contriued the magne
ticall Ballance (which is insteed of a Pendulum as to make it vibrate as Little arches as shall be desird thereby to make
the Vibrations always aequall and the magnet to haue a stronger influence vpon the said Ballance. It was again
ordered that a hand shewing minutes & seconds should be added to it, thereby to compare it with a Pendulum for
an assurance of its aequall going. The curator mentiond that he had yet another way for measuring time Exactly
wherein a Suddain turning motion should not cause a stop or Disorder as it did in this way. There were
also made 2 microscopicall obseruations. 1. of the texture of fatt. which apppeared to be like froth full of cells. the
other of a kind of mould vpon Bookbinders Paste, which was found to haue a fine mosse growing on it: that had
on the tops of its stems a head Like seed. -- mr neiles theory of motio-
May. 6. The curator produced a new kind of Pendulum of his own inventio hauing a great weight appendant to it, &
moued with a very Small force: vizt by such a contriuance, that a pendulum of about 14 foot Long soe as a single
vibration of it is made in 2 seconds with an excursion of half an inch or Lesse hauing a weight of 3 pounds hanging
and moued by the Sole force of a pocket watch with 4 wheels, shall goe 14 months & cause very equall vibrations -
He shewd two seuerall contriuances for it, one was with a pin vpon the ballance of a pocket watch, making a bifurcated
needle to vibrate on one end, and on the other end the pendulum. Another was with a threed fastned on one end to
the ballance of the watch and on the other end to the pendulum & soe mouing it to & fro.    Dr. Wren suggested
a 3d way. vizt by taking a Cylindricall staff of twenty Eight foot Long, and making it moue in its middle on a
Pin and hanging an aequall weights on each end of it to be moued with a pocket watch. The Curator was orderd
to cause one to be made for the Society closing the pendulum in a glasse tube, with a bolt head beneath. --
The same produced his instrument for obseruing Second minutes by the Sun, by a small telescope fastned
on a boord, and Casting the picture of the Sun without a Penumbra, through it vpon an arch of wood -
couered with white paper fastned to the opposite end of the boord, an instrument of Excellent vse to Obserue
Eclipses. He was orderd to cause the arch to be diuided against next Day.
May. 13. the new charter Read. May. 20. the Curator produced again his his magneticall watch soe improued
as he sayd that it should moue in all positions, with any kind of Motion without stopping or being Disturbed
he communicated the way of this Improuement to the President, being not yet free to Declare it in publique till
he hath brought it to perfection. It was again orderd that a minute hand should be fitted to it to see the aequality
of its Vibrations.
May. 27. the Curator produced again his magneticall watch with a minute hand vpon it, being tryed it was found ^ /not/ to
goe very iust. the cause of which fault was conceiued might be in the pinion that carryed the Hand, orderd that care
be taken to amend this fault. ---- Mr. Oldenburg produced & read a Letter written to him from Paris by Mor. Huygens
Dated may 29. 1669 (St. N) and conteining his opinion concerning Mr. Hooks new way of mouing great pendulums with
the force of a small pocket watch. as also his offer of Communicating to the Society a new way of his own contrivance
to print things written and Geometricall figures with Little cost and great speed of which he sent along with this
Letter a specimen. [query this Letter in the Letter book]
Iune. 3. there was produced the module of an Engine contriued by Dr Wren for the Grinding hyperbolicall glasses
Mr Hooke mentiond that he had a way of grinding Ellipticall glasses which he would shortly bring in
Iune. 10. Dr. Christopher Wren explained his module for grinding hyperbolicall glasses. vizt vpon what Goemetricall principle
It depends, and how that is to be applyed to practise. The President affirmed that he had considerd the principle being formerly
imparted to him and found it mathematically true; and as to its application to vse the sucesse of that did depend upon
Experiment. the contriuance was that in this engine there was a complication of three Different motions whereby three bodys
doe soe work vpon one another as to produce an hyperbolicall figure; any irregularity made by the encountring
one another being rectifyed immedeatly. The authour intimated that great care must be had in setting the engine
that being somewhat Nice, for as much as the 3 axes must all intersect in a point and one at Right angles with the
other two. He was thanked for communicating this Inuention of his; and the Paper conteining the Demonstration
was orderd to be Registred [lib 4 fol 71] and an Engine to be made the Care of Mr Hooke to try the principle in Matter.
Mr. Hooke produced the module of an other Engine contriued by himself soe as to work a glasse into any Ellipticall
or Hyperbolicall figure assigned by two motions one vpon the centers the other vpon a flatt. Some obiections
were made against it. But it was ordered that an Engine hereof should likewise be made for tryall.
[two papers read. one against Dr Wr. & Mor Zul: rules of motion. 2d about motio of Sap. Vz] Cassinj abt. Ephem of Satellits.
Iune. 17. Dr. Wallis's confutatio of Hobs &c -- The Curator Excused himself for hauing prepared noe Expts. for this Day. he was
orderd to take care that against next Day either his own new instrument for working Ellipticall glasses or that of Dr. Wren for
grinding hyperbolicall ones might be ready, as also that a couple of the Long pendulums to be moued by the force of a poket
watch be prepared to see how Long they will goe euen together. -- Mr. Hooke mentiond that he hoped he should
now be able to rectify the engine formerly contriued by him for the well grinding of Great sphericall glasses soe as
to free it from those Defects, that were hitherto Discouerd therein. The Company incouraged him to put this in Execution
The President put the Curator in minde of making a true meridian for obseruing the present variation of the Needle
as also to make at Length the Obseruation concerning the magnitude of the Earth.
Iune 24. no meet. Iuly. 1. A Letter of Mor Huygens from Paris Iune 26. 1669. ----- and a reflection made on Mr Hookes Pen
dulum applyed to a Poquet Watch. [qr. in the Letter booke] Mr. Hooke taking notice of the Reflection made on his Long Pendu
-lum moued by a poket Watch. vizt that the Smallnesse of the vibrations renders the Pendulum more sensible of the
impression which the Watch makes vpon it. sayd. that the weight appendent to the string was soe great that the impression
could haue noe power vpon it. [venetian Embassador Expt. magnetick watch Exp] of Mr Hooke going Slower or faster according
to farther or Neerer Distances of the Loadstone & soe moving Regular in any posture. 2. 3. 4. Burning Coles in a box displaced by the

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