An Explication of the Sixth PLATE.
This Plate is in Reality but one compound Instrument or Apparatus, for
trying the Electricity of Glass, and its Luminousness, when put into
Motion, and rubb'd upon to heat it. Wherein B C is a Wheel, with its
String A B C. D E is a Sphere of Glass, whose Air has been drawn out by
the Air-Pump: This is turned round by the former Wheel-string at A. F is a
Stopcock, whereby the Air is exhausted, and may be readmitted at
Discretion.
In _Fig. 1._ K L M is an Arch with Threads of Cruel or Yarn upon it, as
they hang about the Glass D E, (here represented by a smaller Circle
within the Arch) before it is turned round or heated by rubbing.
_Fig. 2._ G H I is the same with the former; only the Threads are here
represented as they hang at the Beginning of the turning round of the
Globe, before it be heated by Friction; being plainly bent one way, by a
Wind arising from that Convolution.
_Fig. 3._ N P O is the same; only with the Threads pointing towards the
Sphere, or its Center, when the Arch is in an upright Posture, and some of
the Threads hang partly downwards, and this upon the Spheres being heated
sufficiently.
_Fig. 4._ Q S R is the same, with its Threads pointing the same way,
though in a downward Posture, when some of the Threads thereby are forc'd
to stand erect.
_Fig. 5._ T U is a Circular Arch, in an horizontal Position, when the
Threads point towards the same Center, in the same horizontal Plain.
_Fig. 6._ Is another Sphere, communicating with the Air, and to be apply'd
to the same Wheel in the Room of D E, where-into is inserted an Axis with
a Circle affixed to it; at the Edges of which Circle the Threads are
placed. These upon the Friction and Heat of the Glass extend themselves
outward, and point from the Center to the Circumference, contrary to the
former. In both Cases the Threads, when under the Influence of the
Electricity, will be moved by the Finger, even without Contact, nay by the
Finger and Breath, even through the Glass it self; so subtle are these
_Effluvia_. The Light is made when the Air is exhausted, and diminishes as
you readmit it. It spreads and branches it self inwardly like Lightning,
when about half that Air is readmitted. The Colour of that Light is always
Purple. It spreads at some Distance, and makes the Edges of a Cravat look
a little like the milky Way, by the great Number of Sparkles it emits:
Which may also be felt by the Flesh, with a crackling Noise that
accompanies them. If you also sufficiently rub and heat a large Tube of
Glass, either solid or hollow, it becomes strongly Electrical, even
through Glass it self; tho' not so much through Muslin. Other Heat than
that by Friction signifies nothing. It will attract and repel Leaf Gold,
and the like small and light Bodies, after a strange manner, by turns;
when once they have been fully repell'd they cannot be made to touch them,
till they have been reflected from some other Body. If they lye between
two Pieces of Wood, laid pretty near, the Electricity fails of its Effect.
With other Circumstances very surprizing and unaccountable.
_FINIS._
Transcription note:
The original punctuation and ortography of the book have been faithfully
preserved; words which are spelled variantly, or inconsistently
capitalized (e.g., _Axel_ vs. _Axle_, _crowded_ vs. _crouded_, _blue, red_
vs. _Blue, Red_, etc.) have been left as such.
Likewise, the (mis)spelling of names like Galilæo, Azout, Hugen, Guerick,
has been retained.
The following typographical mistakes have been corrected, taking into
account recurrences across the text:
* Page III, 25th day:
* The Ebullition of Liquors in _Vacuo_ → The Ebullition of Liquors
_in Vacuo_
* Mechanicks, Explication of the 2nd Plate:
* Figure. 1. Is the deceitful Balance; which yet is _in Equilibrio_
→ Figure 1. Is the deceitful Balance; which yet is _in Æquilibrio_
* _Fig. 3_ → Fig. 3.
* [Fig. 10]: perpendiculary → perpendicularly
* [between Fig. 9 and 10]: N. _B._ → _N. B._
* [Fig. 10]: and in this Leaver → and in this Lever
* Mechanicks, Expl. 5th Plate, Fig. 3:
* us it is less restrained. → as it is less restrained.
* Opticks, Expl. 1st Plate, Fig. 3:
* Looking-glass → Looking-Glass
* Opticks, Expl. 2nd Plate:
* _Fig. 8._ Shows → _Fig. 8._ Shews
* [Fig. 10]: on the like Acccount. → on the like Account.
* Hydrostaticks, Expl. 1st Plate:
* [Fig. 5]: specifick Gravity of Water → Specifick Gravity of Water
* Hydrostaticks, Table of Specifick Gravities:
* Spirit of Nirre → Spirit of Nitre
* Pneumaticks, Expl. 2nd Plate:
* [Fig. 1]: 'tis by this Thteefold → 'tis by this Threefold
* [Fig. 2]: small Part of ccmmon Air → small Part of common Air
* Pneumaticks, Expl. 5th Plate:
* [Fig. 6]: as between the Hemispheres → as between the
Hemispheres.
* Pneumaticks, Expl. 6th Plate:
* [Fig. 6]: througn Muslin → through Muslin