Encyclopaedia Britannica, or, a Dictionary of arts, sciences, and miscellaneous literature : enlarged and improved. Illustrated with nearly six hundred engravings > Volume 14, MIC-NIC

MIC
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M I C
Microfeope. The opaque part may be ufed in the daytime without
a lamp^ provided the large lenfes at AJB are fcreened
from the light.
To ufe the Lucernal Microfeope in the examination of
Tranfparent Oijccls.—The inftrument is to remain as
before : the upper part fg s of the opaque flage Jnuft
be removed, and the ftage for tranfparent objtdb, re-
prefented at fig. 28. put in its place ; the end 910
to be next the lamp.
Place the grayed glafs in its groove at the end AB,
and the objects in the Aider-holder at the front of the
flage ; then tranfmit as ftrong a light as you are able
on the obiedt, which you will eafily do by railing or
lowering the lamp.
The objedl will be beautifully depleted on the gray
glafs j it mull be regulated to the focus of the magni¬
fier, by turning the pinion a.
The objeff may be viewed either with or without
the guide for the eye. A Angle obferver will fee an
objeft to the greatefl advantage by uling this guide,
which is to be adjufled as we have deferibed above. If
two or three wifh to examine the object at the fame
time, the guide for the eye mull be laid afide.
Take the large lens out of the groove, and receive
the image on the gray glafs; in this cafe, the guide
for the eye is of no ufe : if the gray glafs be taken
away, the image of the objcdl may be received on a
paper fereen.
Take out the gray glafs, replace the large lenfes,
and ufe the guide for the eye ; attend to the forego¬
ing direflions, and adjuft the object to its proper fo¬
cus. You will then fee the objedl in a blaze of light
almofl too great for the eye, a circumftanee that will
be found very ufeful in the examination of particular
objedls. The edges of the object in this mode will be
fomewhat coloured : but as it is only ufed in this full
light for occafional purpofes, it has been thought bet¬
ter to leave this fmall imperfe&ion, than, by remedying
it, to facrifice greater advantages ; the more fo, as this
fault is eafily correfted, a new and intereifing view
of the objeft is obtained, by turning the infirument
out of the direft rays of light, and permitting them to
pafs through only in an oblique direction, by which
the upper furface is in fome degree illuminated, and
the objeft is feen partly as opaque, partly as tranfpar¬
ent. It has been already obferved, that the tranfparent
objefts might be placed between the Aider-holders of
the ftage for opaque objects, and then be examined as
if opaque.
Some tranfparent obje<fls appear to the greateft ad¬
vantage when the lens at 9 10 is taken away 5 as, by
giving too great a quantity of light, it renders the
edges lefs {harp.
The variety of views which may be taken of every
objeft by means of the improved lucernal microfeope,
will be found to be of great ufe to an accurate obferv¬
er : it will give him an opportunity of corre&inar or
Vol. XIV. Part I.
confirming his difeoveries, and inveftigating thofe parts Micrcfcopc
in one mode which are invifible in another. 1-
To throw the image oj tranfparem ot jecis on a fereen
as in the folar microfeope.—It has been long a microfco-
pieal defideratum, to have an inftrument by which
the image of tranfparent objefts might be thrown on
a fereen, as in the common folar microfeope : and this
not only becauie the fun is fo uncertain in this cli¬
mate, and the ufe of the folar microfeope requires
confinement in the fineft part of the day, when time
feldom hangs heavy on the mind ; but as it alio affords
an increafe of pleafure, by difplaying its wonders to
feveral perfjns at the fame inftant, without the leaft
fatigue to the eye.
This purpofe is now effe&ually anfwered, by affix¬
ing the tranfparent ftage of the lucernal to a lanthorn,
with, one of Argand’s lamps.—The lamp is placed
within the lanthorn, and the end 9 10 of the tranf¬
parent ftage is ferewed into a female ferew, which is
rivetted in the Aiding part of the front of the lan¬
thorn ; the magnifying lenfes are to be ferewed into
the hole repreiented at 12, and they are adjufted by
turning the milled nut. The quantity of light is to be
regulated by railing and lowering the Aiding-plate or
the lamp.
Apparatus which ufually accompanies the improved
Lucernal Microfeope.—The ftage for opaque objects,
with its femicircular lump of glafs, and concave mirror.
The ftage for tranfparent objects, which fits on the
upper part of the foregoing ftage. The Aiding tube,
to which the magnifiers are to be affixed : one end of
thefe is to be ferewed on the end D of the wooden
body } the magnifier in ufe is to be ferewed to the
other end of the inner tube. Eight magnifying
lenfes : thefe are fo conftrudted that they may be
combined together, and thus produce a very great
variety of magnifying powers. A fifti-pan, fuch as
is reprefented at I. A fteel wire L, with a pair of
nippers at one end, and a fmall cylinder of ivory / at
the other. A Aider of brafs N, containing a flat
glafs Aider, and a brafs Aider into which are fitted
fome fmall concave glaffes. A pair of forceps. Six
large and fix fmall ivory Aiders, with tranfparent
objects. Fourteen wooden Aiders, with four opaque '
objefts in each Aider ; and two fpare Aiders. Some
capillary tubes for viewing fmall animalcula.
Ingenious men feldom content themfelves with an
inftrument under one form ; hence fuch a variety of
microfcopes, hence many alterations in the Lucernal
Microfeope. Mr Adams himfelf, we underftand, has
fitted up this laft in a great many different ways j and
it is reafonable to think that no perfon was more likely
to give it every improvement of which it is fufceptible.
Of the alterations by other hands we ftiall only parti¬
cularize one, made by Mr Jones of Holborh (b),
whofe defeription is as follows :
A (fig. 30.) reprefents a portion of the top of the ma-Fig. 3*,
C hogany
(b) We truft the reader will never confider any paragraph wherein the name of an inftrument-maker or
other artift is inferted, as a recommendation of thofe artifts by the editors of this wrork. In the courfe of a
pretty extenfive correfpondence, they have been favoured with very liberal communications from various artifts,
*or which they are greatly indebted to them ; the inferting their names in this work is therefore to be confidered
as