[Sidenote: * _See _Num. 9_. of the _Phil. Transact_. p. 159 the last
_paragraph_._]
As to the _Barometrical_ Observations (as for brevities sake I use to call
them) though you * guessed aright, that, when I saw those of the Learned
and Inquisitive Dr. _Beale_, I had not Mine by me, (for I left them, some
years since, in the hands of a _Virtuoso_, nor have I now the leasure to
look after those Papers;) yet since by the Communication, you have made
publick, 'tis probable, that divers Ingenious men will be invited to
attempt the like Observations, I shall (notwithstanding my present haste)
mention to you some particulars, which perhaps will not appear
unseasonable, that came into my mind upon the reading of what you have
presented the Curious.
[Sidenote: * _Some whereof have been since invited by the _Publisher_, to
give their concurrence herein_.]
When I did, as you may remember, some years agoe, publickly express and
desire that some Inquisitive men would {182} make _Baroscopical_
Observations in several parts of _England_ (if not in forrain Countries *
also;) and to assist them, to do so, presented some of my Friends with the
necessary Instruments: The declared reason of my desiring this
Correspondence was (among other things) that by comparing Notes, _the
Extent of the Atmospherical Changes, in point of Weight, might be the
better estimated_. But not having hitherto received some account, that I
hoped for, I shall now, without staying for them, intimate thus much to
you: That it will be very convenient, that the Observers take notice not
only of the _day_, but as near as they can, of the _Houre_ wherein the
height of the _Mercurial Cylinder_ is observ'd: For I have often found,
that within less than the compass of one day, or perhaps half a day, the
Altitude of it has so considerably vary'd, as to make it in many cases
difficult, to conclude any thing certainly from Observations, that agree
but in the day.
It will be requisite also, that the Observers give notice of the
_Scituation of the place_, where their _Barometers_ stand, not only,
because it will assist men to Judge, whether the Instruments were duely
perfected, but principally, because, that though the _Baroscope_ be good
(nay, because it is so) the Observations will much disagree, even when the
_Atmosphere_ is in the same state, as to Weight, if one of the Instruments
stand in a considerably higher part of the Countrey, than the other.
To confirm _both_ the foregoing admonitions, I must now inform you, that,
having in these parts two Lodgings, the one at _Oxford_, which you know
stands in a bottom by the _Thames_ side, and the other at a place four
miles thence, seated upon a moderate _Hill_, I found, by comparing two
_Baroscopes_, that I made, the one at _Oxford_, the other at _Stanton St.
Johns_, that, though the former be very good, and have been noted for such,
during some years, and the latter was very carefully fill'd; yet by reason,
that in the _Higher_ place, the incumbent part of the _Atmosphere_ must be
lighter, than in the _Lower_, there is almost {183} always between 2 and 3
Eights of an Inch difference betwixt them: And having sometimes order'd my
servants to take notice of the Disparity, and divers times carefully
observ'd it my self, when I pass'd to and fro between _Oxford_ and
_Stanton_, I generally found, that the _Oxford Barometer_ and the _other_,
did, as it were by common consent, rise and fall together so, as that in
the former the _Mercury_ was usually 3/8 higher, than in the latter.
Which Observations may teach us, that the Subterraneous steams, which
ascend into the Air, or the other Causes of the varying Weight of the
_Atmosphere_, do, many times, and at least in some places, uniformly enough
affect the Air to a greater height, than, till I had made this tryall, I
durst conclude.
But, as most of the _Barometricall_ observations are subject to exception,
so I found the formerly mentioned to be. For (to omit lesser variations)
riding one evening from _Oxford_ to _Stanton_, and having, before I took
horse, look't on the _Baroscope_ in the former of these 2. places, I was
somewhat surprised, to find at my comming to the latter, that in places no
farther distant, and notwithstanding the shortness of the time (which was
but an hour and a half, if so much) the _Barometer_ at _Stanton_ was short
of its usual distance from the _other_, near a quarter of an _Inch_,
though, the weather being fair and calm, there appear'd nothing of manifest
change in the Air, to which I could adscribe so great a Variation; and
though also, since that time, the _Mercury_ in the two Instruments hath,
for the most part, proceeded to rise and fall as before.
And these being the only Observations, I have yet met with, wherein
_Baroscopes_, at some _Distance of Place_, and _Difference of Height_, have
been compar'd (though I cannot now send you the Reflexions, I have else
where made upon them;) as the opportunity I had to make them my self,
rendred them not unpleasant to me, so perhaps the Novelty will keep them
from being unwelcome to you. And I confess, I have had some flying
suspicions, that the odd _Phaenomena_ of the _Baroscope_, which have
hitherto more pos'd, than instructed us, may in time, if a {184} competent
number of Correspondents do diligently prosecute the Inquiries (especially
with _Baroscopes_, accommodated with Mr. _Hooks_ ingenious additions) make
men some _Luciferous_ discoveries, that possibly we do not yet dream off.
[Sidenote: * _This hath been inquired into, and is found, that several
Accurate and Curious persons (as the Most Noble _President of the Royal
Society_, the Lord Viscount _Brounker_, _Doctor Beale_, _Mr. Hook_ _&c._)
have observed the same._]
I know not, whether it will be worth while to add, that since I was oblig'd
to leave _London_, I have been put upon so many lesser removes, that I have
not been able to make _Baroscopical_ Observations with such a constancy, as
I have wished, but, as far as I remember, the _Quick-silver_ has been for
the most part, so high, as to invite me to take notice of it; and to desire
you to do me the favour to inquire among your correspondents whether they
have observ'd the same thing. * For, if they have, this lasting (though not
uninterrupted) Altitude of the _Quick-silver_, happening, when the Seasons
of the year have been extraordinary dry (so much as to become a grievance,
and to dry up, as one of the late _Gazettes_ informs us, some springs near
_Waymouth_, that used to run constantly) it may be worth inquiry, whether
these obstinate Droughts, may not be cleaving of the ground too deep, and
making it also in some places more porous and as it were, spungy, give a
more copious Vent, than is usual, to subterraneal steams, which adscending
into the Air, increase the gravity of it. The inducements I have to propose
this inquiry, I must not now stay to mention. But perhaps, if the
Observation holds, it may prove not useless in reference to some Diseases.
[Sidenote: * _See Number 9. _Phil. Transact._ p. 157. 5. 8 & 9. where the
Word, _Generally_, signifies no more, than _for the most part_._]
Perhaps it will be needless to put you in mind of directing those
_Virtuosi_, that may desire your Instructions about _Baroscopes_, to set
down in their Diarys not only the day of the month, and the hour of the
day, when the _Mercuries_ height is taken, but (in a distinct _Columne_)
the weather, especially the Winds, both as to the Quarters, whence they
blow (though that be not always so easy nor necessary,) and as to the
Violence or Remisness, wherewith they blow. For, though it be more
difficult, {185} than one would think, to settle any general rule about the
rising and falling of the _Quick-silver_; yet in these parts one of those,
that seem to hold oftnest, is, * that when high winds blow, the _Mercury_
is the lower; and yet that it self does sometimes fail: For, this very day
(_March_ 3.) though on that hill, where I am, the somewhat Westerly Winds
have been blustering enough, yet ever since morning the _Quick-silver_ has
been rising, and is now risen near 3/8 of an _Inch_.
I had thoughts to add something about another kind of _Baroscope_ (but
inferiour to that in use) whereof I have given some intimation in one of
the _Praeliminaries_ to the _History of Cold_. But you have already too much
of a letter, and my occasions, &c.
[Sidenote: * _Dr. _Beale_ concurs with this Observation, when he saith, in
a late _Letter_ of _March 19_. to his Correspondent in _London_;_ By change
of Weather and Wind, the _Mercury_ is sunk more than an Inch, since I wrote
to you on _Munday_ last. _March_ 12. This last night, by Rain and South
wind, 'tis sunk _half an Inch_.]
_So far that Letter._ Since which time, another from the same Noble
Observer intimates, That, as for that cause of the height of the
_Quick-silver_ in Droughts, which by him is suspected to be the elevation
of steams from the _Crust_ or Superficial parts of the Earth, which by
little and little may add to the Weight of the _Atmosphere_, being not, as
in other seasons, carried down from time to time by the falling Rain, it
agrees not ill with what he has had since occasion to observe. For, whereas
about _March_ 12^{th}, at _Oxford_, The _Quick-silver_ was higher, than,
for ought he knew, had been yet observ'd in _England_, viz. above 5/16
above 30. _Inches_, upon the first considerable showers, that have
interrupted our long Drought, as he affirms, he foretold divers hours
before that the _Quick-silver_ would be very low, (a blustering Wind
concurring with the Rain) so he found it at _Stanton_ to fall 3/8 beneath
29. _Inches_.*
{186}
* * * * *
_General Heads for a _Natural History of a Countrey_, Great or Small,
imparted likewise by Mr. _Boyle_._
It having been already intimated (_Num. 8 of Phil. Transact._ p. 140. 141.)
that divers _Philosophers_ aime, among other things, at the Composing of a
good Natural History, to superstruct, in time, a _Solid_ and _Useful_
Philosophy upon; and it being of no slight importance, to be furnisht with
pertinent Heads, for the direction of Inquirers; that lately named
_Benefactour to Experimental Philosophy_, has been pleased to communicate,
for the ends abovesaid, the following _Articles_, which (as himself did
signifie) belong to one of his _Essays_ of the unpublisht part of the
_Usefulness of Nat. and Experimen. Philosophy_.
But first he premises, that what follows, is design'd only to point at the
more _General_ heads of Inquiry, which the proposer ignores not to be
Divers of them very comprehensive, in so much, that about some of the
_Subordinate_ subjects, perhaps too, not the most fertile, he has drawn up
_Articles_ of inquisition about particulars, that take up near as much
room, as what is here to be deliver'd of this matter.
The _Heads_ themselves follow;
The things, to be observ'd in such a History, may be variously (and almost
at pleasure) divided: As, into _Supraterraneous, Terrestrial_, and
_Subterraneous_; and otherwise: but we will at present distinguish them
into those things, that respect the _Heavens_, or concern the _Air_, the
_Water_, or the _Earth_.
1. To the _First_ sort of Particulars, belong the Longitude and Latitude of
the Place (that being of moment in reference to the observations about the
Air &c.) and consequently the length of the longest and shortest days and
nights, the Climate, parallels &c. what fixt starrs are and what not seen
there: What Constellations 'tis said to be subject to? Whereunto may be
added other Astrological matters, if they be thought worth mentioning.
{187}
2. About the _Air_ may be observ'd, its Temperature, as to the first four
Qualities (commonly so call'd) and the Measures of them: its Weight,
Clearness, Refractive power: its Sublety or Grossness: its abounding with,
or wanting an _Esurine_ Salt: its variations according to the seasons of
the year, and the times of the day; What duration the several kinds of
Weather usually have: What _Meteors_ it is most or least wont to breed; and
in what order they are generated; and how long they usually last:
Especially, what Winds it is subject to; whether any of them be stated and
ordinary, &c. What diseases are Epidemical, that are supposed to flow from
the Air: What other diseases, wherein _that_ hath a share, the Countrey is
subject to; the Plague and Contagious sicknesses: What is the usual
salubrity or insalubrity of the Air; and with what Constitutions it agrees
better or worse, than others.
3. About the _Water_, may be observ'd, the Sea, its Depth, degree of
Saltness, Tydes, Currents, &c. _Next_, Rivers, their Bigness, Length,
Course, Inundations, Goodness, Levity (or their Contraries) of Waters, &c.
_Then_, Lakes, Ponds, Springs, and especially Mineral waters, their Kinds,
Qualities, Vertues, and how examined. To the _Waters_ belong also _Fishes_,
what kinds of them (whether Salt or Fresh-water fish) are to be found in
the Country; their Store, Bigness, Goodness, Seasons, Haunts, Peculiarities
of any kind, and the wayes of taking them, especially those that are not
purely _Mechanical_.