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or whether it Doth proceed in a parallell meridian or in a parallell or in
any other great circle or any other irregular curue and whether the concaue
or conuex side of that curue be towards vs more time & obseruations must make
cleer. but It seems most probable by comparing seuerall Delineations obserued
by Capn. Iames & others that the progress of this magneticall north pole is from
west to East beyond the north pole. RH proposed also the making of an easy
and nice instrument thereby to obserue exactly the variation of the Variation
of the needle in many Differing parts of the world. he was orderd to get it made
march. 26. 1674. RH. repeated and agmented his former Discourse
of magneticall variations as also his purpose of preparing an easy and ac
curate way to be sent all ouer the world for making exact magn: obserua
tions. he was desired to begin these obseruations and to fix a meridian in
Gresham colledge, which he promised to Doe by the north starr -
/Aprill 2. 1674./
RH shewd many curious experiments about the various ways that
the magneticall effluuia doe bend themselues by making vse of seue
rall steel barrs variously applyd to the magnet vpon the draw of
parchment. and the curues seemd quite contrary to those of a magnet
of the like shappe. he promisd to prosecute these expts
He mentiond also that whereas a Loadstone would attract red hot Iron
steel would not at all respect it -
/Ap: 23./
RH shewd the texture of the pith of a bulrush in a microscope consisting
of pipes interwouen one wthin another in the manner of a hurdle
or resembling loos needle work - he made also an expt. to find whe
ther a bar of steel touch would moue more strongly toward the stone
then before it was toucht, by suspended by accarate ballences the toucht
& vntoucht were both the same. - RH produced a quadrant wth telesco
picall sights. wherein appeard the preeminence of such sights aboue
comon dioptras.    Heuelius intimating as if the french had made an
obseruation that the sun had no parrellax RH Desird to know by what
Instruments they obserud it if by telescopicall sights he supposd they might
Discouer itdicouer it to haue a parallax but if wth other sights
It was to noe purpose since the eye cannot Distinguish a smaller angle
than a minute whereas the parallax is much Lesse
Ap. 30. RH curator could not get his quadrant Ready. he tryd whether an
Iron ring will by magneticall vertue be suspended about a globous
magnet as the Ring of about symbol . but it could not be found. RH
propounded to examine whether all parts of the terrella haue an attracti[on]
towards the center of it. 2 whether if there be any such attraction, it be
in all places of the terrella of equall strength 3 to examine wt thes[e]
curue lines are by wch. the approaches are made to the said stone
RH suggested that the best deeping needle may be made in water because
^ /water/ takes off the grauity as also that a pipe of iron /should/ may be made
of equall grauity wth. the water. wasmuth Helicall Astronomicall hy
pothesis RH affirmd it the same wth. the Ld Bacons in his opuscula
Iune 4. 74. RH affirmed his quadrant to be soe contriued as to doe what
could be required from any astronomicall Instrument

Ref: CELL/RS/HF_s03  © Centre for Editing Lives and Letters