DOI Page / Citation link:
https://doi.org/10.11588/diglit.68888#0220
I$o MlCROGRAPHIA.
fented in the 4-Figurc of the 15. Scheme. Or,is you intend to make ufe of
many of these small Beards join’d together, you may have a small long
Case of Ivory, whose sides are turn’d of Basket-work, full of holes, which
may be fcrew’d on to the underside of a broad Plate of Ivory,on the other
side of which is to be made the divided Ring or Circle, to which divisi-
ons the pointing of the Hand or Index, which is moved by the conjoin'd
Beard, may shew all the Minute variations of the Air.
There may be multitudes of other ways for contriving this small Instru-
ment, so as to produce this effest, which any one may, according to his
peculiar use, and the exigency of his present occasion, easily enough con-
trive and take, on which I (hall not therefore insift. The whole manner of
making any one of them is thus: Having your Box or frame A A B B, fitly
adapted for the sree passage of the Air through it,in the midst of the bot-
tom B B B, you musthave a very small hole C, into which the lower end os
the Beard is to be fi’xd,the upper end of which Beard a is to pals through
a small hole of a Plate, or top A A, if you make use onely of a single one,
and on the top of it e, is to be fix’d a small and very light Indexsg, made
of a very thin (liver of a Reed or Cane 5 but if you make use of two or
more Beards, they must be fix’d and bound together, either with a very
fine piece of Silk, or with a very small touch of hard Wax, or Glew,which
is better, and the Index sg} is to be fix’d on the top of the fecond,third,
or fourth in the same manner as on the single one.
Now,because that in every of thefe contrivances, the Index sg> will
with feme temperatures of Air, move two, three, or more times round,
which without some other contrivance then this,will be difficult to distin-
guish,therefore I thought of this Expedient: The Index or Handsg, be-
ing rais’d a pretty way above the surface of the Plate A A, fix in at a
little distance from the middle of it a small Pin so as almost to touch
the surface of the Plate A A, and then in any convenient place of the
surface of the Plate,fix a small Pin, on which put on a small piece of Paper,
or thin Past-board, Vellom, or Parchment, made of a convenient cize,
and shap’d in the manner of that in the Figure express’d by i 4, so
that having a convenient number of teeth every turn or return of the
Pin Z», may move this small indented Circle, a tooth forward or back-
wards, by which means the teeth of the Circle, being mark’d, it will be
thereby very easie to know certainly, how much variation any change
of weather will make upon the small wreath’d body. In the making of
this Secundary Circle of Vellom, or the like, great care is to be had, that
it be made exceeding light, and to move very easily, for otherwife a small
variation will spoil the whole operation. The Box may be made ofBrass,
Silver, Iron, or any other sobstance, if care be taken to make it open
enough, to let the Air have a sufficiently free access to the Beard. The
Index also may be various ways contrived, so as to shew both the number
of the revolutions it makes, and the Minute divisions of each revolution.
I have made feveral trials and Instruments for difeovering the driness
and moisture of the Air with this little wreath’d body,and find it to vary
exceeding fensibly with the least change in the coastitution of the Air, as
to
fented in the 4-Figurc of the 15. Scheme. Or,is you intend to make ufe of
many of these small Beards join’d together, you may have a small long
Case of Ivory, whose sides are turn’d of Basket-work, full of holes, which
may be fcrew’d on to the underside of a broad Plate of Ivory,on the other
side of which is to be made the divided Ring or Circle, to which divisi-
ons the pointing of the Hand or Index, which is moved by the conjoin'd
Beard, may shew all the Minute variations of the Air.
There may be multitudes of other ways for contriving this small Instru-
ment, so as to produce this effest, which any one may, according to his
peculiar use, and the exigency of his present occasion, easily enough con-
trive and take, on which I (hall not therefore insift. The whole manner of
making any one of them is thus: Having your Box or frame A A B B, fitly
adapted for the sree passage of the Air through it,in the midst of the bot-
tom B B B, you musthave a very small hole C, into which the lower end os
the Beard is to be fi’xd,the upper end of which Beard a is to pals through
a small hole of a Plate, or top A A, if you make use onely of a single one,
and on the top of it e, is to be fix’d a small and very light Indexsg, made
of a very thin (liver of a Reed or Cane 5 but if you make use of two or
more Beards, they must be fix’d and bound together, either with a very
fine piece of Silk, or with a very small touch of hard Wax, or Glew,which
is better, and the Index sg} is to be fix’d on the top of the fecond,third,
or fourth in the same manner as on the single one.
Now,because that in every of thefe contrivances, the Index sg> will
with feme temperatures of Air, move two, three, or more times round,
which without some other contrivance then this,will be difficult to distin-
guish,therefore I thought of this Expedient: The Index or Handsg, be-
ing rais’d a pretty way above the surface of the Plate A A, fix in at a
little distance from the middle of it a small Pin so as almost to touch
the surface of the Plate A A, and then in any convenient place of the
surface of the Plate,fix a small Pin, on which put on a small piece of Paper,
or thin Past-board, Vellom, or Parchment, made of a convenient cize,
and shap’d in the manner of that in the Figure express’d by i 4, so
that having a convenient number of teeth every turn or return of the
Pin Z», may move this small indented Circle, a tooth forward or back-
wards, by which means the teeth of the Circle, being mark’d, it will be
thereby very easie to know certainly, how much variation any change
of weather will make upon the small wreath’d body. In the making of
this Secundary Circle of Vellom, or the like, great care is to be had, that
it be made exceeding light, and to move very easily, for otherwife a small
variation will spoil the whole operation. The Box may be made ofBrass,
Silver, Iron, or any other sobstance, if care be taken to make it open
enough, to let the Air have a sufficiently free access to the Beard. The
Index also may be various ways contrived, so as to shew both the number
of the revolutions it makes, and the Minute divisions of each revolution.
I have made feveral trials and Instruments for difeovering the driness
and moisture of the Air with this little wreath’d body,and find it to vary
exceeding fensibly with the least change in the coastitution of the Air, as
to