eye glass, and a body glass; it is here shewn as screwed to the arm C D,
from whence it may be occasionally removed, either for the convenience
of packing, or when the instrument is to be used as a single microscope.
The eye glasses and the body glasses are contained in a tube which fits
into the exterior tube A B; by pulling out a little this tube, when the
microscope is in use, the magnifying power of each lens is increased.
The body A B of the microscope is supported by the arm C D; this arm is
moveable in a square socket cut in the head that is connected to the
main pillar E F, which is screwed firmly to the mahogany pedestal G H;
there is a drawer to this pedestal, which holds the apparatus. This arm
may be slid backwards and forwards in its socket, carrying the
magnifiers and the body of glasses, and also turned horizontally quite
round upon the pillar, giving a general motion all over the object on
the stage below; which is a material improvement and advantage of this
microscope over a similar one described in the former edition of this
work, as any unavoidable motion of the living object to be viewed may be
followed, by the observer’s hand moving the arm C D as the object
changes its place.
N I S is the plate or stage which carries the slider-holder K, this
stage is moved up or down the pillar E F, by turning the milled nut M;
this nut is fixed to a pinion, that works in a toothed rack cut on one
side of the pillar. By means of this pinion the stage may be gradually
raised or depressed, and the object adjusted to the focus of the
different lenses.
K is the slider-holder, which fits into a hole that is in the middle of
the stage N I S; it is used to confine and guide either the motion of
the sliders which contain the objects, or the glass tubes that are
designed to confine small fishes, for viewing the circulation of the
blood. The sliders and tubes are to be passed between the two upper
plates.
L is a brass tube, in the upper part of which is fixed the condensing
lens before spoken of; it screws into the wire arm a, which is placed in
the hole I of the stage, with the glass underneath, and may be set at
different distances from the object, according to its distance from the
mirror or the candle.
O is the frame which holds the two reflecting mirrors, one of which is
plane, the other concave. These mirrors may be moved in various
directions, in order to reflect the light properly, by means of the
pivots on which they move, in the semicircle Q, and the motion of the
semicircle itself on the pin R; the concave mirror generally answers
best in the day-time; the plane mirror combines better with the
condensing lens in L, and a lamp or candle at night.
At S is a hole and slit for receiving either the nippers _b_, or the
fish-pan _c_; when these are used, the slider-holder K must be removed.
T, a hole to receive the pin of the convex lens and illuminator _d_.
There are six magnifying lenses contained in a brass wheel screwed in a
circular brass box P; this wheel is moveable about its center with the
finger, and stops by a click when the magnifiers are each centrally
under the body A B above, or the hole in the arm C D. They are marked
from No. 1, to 6, and the proper number shewn in a small opening made in
the side of the brass box. This wheel P screws into the arm C D, and may
occasionally be taken off to admit of the silver speculum, or a single
magnifier, hereafter to be described.
There is a small line cut on the edge of the arm C D, which must be
brought to the right hand edge of its socket, in order to center the
magnifier to the body and the stage.
By unscrewing the body A B, the single magnifiers in the wheel P being
then only left, the instrument readily forms a single microscope.
A small pocket hand single or opake microscope may easily be extracted
from this apparatus. When the body A B is screwed off, and the arm C D
slipt away from its frame with the wheel of magnifiers, and the forceps,
wire, and joint _b_ applied to it, by a hole made in the arm for that
purpose, as represented at V, it is then ready for the examination of
any small object that may present itself in the garden, &c. and will be
found very convenient whenever the whole instrument is not required.
LIST OF APPARATUS GENERALLY MADE TO THIS MICROSCOPE.
The wheel, with the magnifiers, P. Fig. 1.
The body of the microscope, A B.
The slider-holder, K.
The tube, with the condensing lens L, to be used by candle-light.
The pin and arm _a_, either for the above lens, or for the silver
concave speculum _e_.
The silver concave speculum _e_, fitted to the arm above, and used
common to all the magnifiers in the wheel and body A B, it is to reflect
the light from the concave or plane mirror O below, upon the opake
objects, then called the compound opake microscope.
A silver concave speculum _f_, with a single magnifier; it screws to the
under part of the arm C D in room of the wheel of magnifiers, and forms
then the single opake microscope.
A brass cone _g_, to place under the stage N I S, and serves to diminish
the reflected light when necessary.
The jointed nippers _b_, fitted to the stage, to hold any small insect,
or other opake object.
A cylinder of ivory _h_, to fix on the pointed end of the nippers, black
on one side and white on the other, to make a contrast to the opake
object used.
Six ivory sliders, _i_, each having four holes, and objects contained
between two talcs confined together by brass circular wires. One of the
sliders is usually sent without objects, to be supplied at pleasure.
When used, they are placed between the perforated plates of the
slider-holder K; where also is to be applied the brass frame slider _k_,
containing in one brass piece four small concave glasses fixed; a narrow
slip of glass slides over these, all within the frame; so that any very
small living object, as a mite, &c., may be viewed with the proper
security.
A set of glass tubes, _l_, three in number, to contain tadpoles, water
newts, small frogs, eels, &c. which are curious objects for affording a
fine view of the circulation of the blood, &c. They are also to be
placed in the slider-holder K. There is a small hole at one end to admit
air, the other end is to be stopped with cork, to contain the fluid and
prevent the escape of the animal. A brass twisted wire is sent, to
assist in the cleaning of these tubes.
A small ivory box, _m_, containing talcs and wires to supply the ivory
sliders with, should any be lost or damaged.
A lens set in a brass cell, _n_, of such a focus as to view objects
under a magnifying power sufficient for the applying them to the
instrument for further inspection; hence it has been called the
explorator. It may occasionally be screwed to the arm C D, and is then
well adapted for viewing objects of the larger kind, or the whole of an
insect, &c. before the observing of it in part under the regular
magnifiers.
A concave, or a circular plane glass, _o_, for transparent objects, or
animalcula in fluids, &c. it is fitted to the side, I, of the stage.
It is necessary to describe the lens and frame, _d_, noticed at page 95;
it is either for converging the sun’s rays upon opake objects laid upon
the stage, or for magnifying a flower, or other large objects applied to
the stage, or on the nippers or point, _b_. By its pin and spring socket
it is easily raised to any height, for the sun, candle, or the eye of
the observer.
A brass insect box, _h_, consisting of a concave and plane glass that
screw close together; by means of which a louse, flea, &c. may be
secured, viewed alive, and retained for any time. It is applied to the
hole I, of the stage, Fig. 1.
A pair of small brass forceps, _q_, by which any small object may be
conveniently taken up or moved.
This microscope packs into a mahogany pyramidical shaped case, about
seven inches square at its base, and fourteen inches in height. For its
price, see the general list annexed to this work.
TO USE THIS MICROSCOPE.
It will be obvious to the reader from the preceding description that it
must be put together as represented in the figure; that he has to place
the slider-holder, K, to the stage, N I S, with one slider of objects;
to reflect as strong a light as possible from the concave mirror, O,
below, by turning it into the best position, and moving it upwards or
downwards all the while he is looking down the body, A B. Then, for a
distinct view of the object, to turn the pinion, M, in a slow and gentle
manner. A small degree of practice will render the management very
familiar.
For opake objects, the slider-holder, K, is to be removed; the silver
speculum, _e_, screwed to the arm, _a_, and by its pin placed in the
hole, I, of the stage, with the concave part downward above the stage;
the glass, _o_, or the nippers, _b_, with ivory, _h_, placed at the
stage: then the light reflected from the mirror, O, up to the speculum
above, which will again reflect the light very strongly upon the object.
Practice also in this case can make it easy to the beginner. The use of
the rest of the apparatus has been sufficiently explained.
OF THE MOST IMPROVED COMPOUND MICROSCOPE, BEING UNIVERSAL IN ITS USES,
AND FORMING THE SINGLE, COMPOUND, OPAKE, AND AQUATIC MICROSCOPES.
A person much accustomed to observations by the microscope, will readily
discern the several advantages of this instrument over the preceding
one. Besides its containing an additional quantity of useful apparatus,
it is more commodious and complete for the management while observing,
as it may instantly be placed in a vertical, oblique, or horizontal
situation, turned laterally at the ease of the observer, and the objects
viewed by the primary direct light, or reflected as usual, at pleasure.
These particulars the following description will clearly shew. I shall
not again so fully describe the same apparatus, as the reader must
already understand their uses from the preceding references.
Fig. 2 is a representation of this instrument as placed up for use. A B
is the compound body. The eye-glasses are contained in an inner tube
that slides outwards or inwards, thus altering its distance from a glass
at B, and thereby increasing or diminishing the magnifying power, when
thought necessary. This body may be screwed on or off to the arm C D, as
in the microscope just described; the arm C D may also be moved in any
direction over the object. E F is the square stem or bar, on which is
moved by the rack-work and pinion M, the stage N I S, to adjust a
distinct view to any of the magnifiers, or apparatus used. V is a strong
brass pillar with a joint-piece at top, connected to the stem E F; by
means of this joint the position of the microscope is readily altered
from a vertical to an oblique or horizontal one, as may be desired or
found most easy and convenient to the observer, while sitting or
standing; it will also enable him to view objects by direct unreflected
light; for, when the stem, E F, is put into an horizontal position, the
mirrors, O, R, may be drawn off and laid aside. Against or before the
condensing lens, U, the common day-light or the light of a candle may
then be directed.
At the stage N I S, is a sliding brass spring, N, serving to confine
down slips of glass or large sliders, when objects placed thereon are
intended to be viewed out of the horizontal position of the stage. A
lens, U, called the condensing lens, fixed in a frame connected to a
socket, is for condensing and modifying the rays of light reflected from
the concave or plane mirror, O, below; it may be set to a proper
distance by raising it up by two little screws, one of which is shewn at
_u_. This lens is of considerable use by candle-light, as it serves to
fill the whole body, A B, beautifully with light on the object. It is
turned aside on a joint pin, when not in use. Six magnifiers are
contained in the wheel at P, as in the former microscope. The mirrors,
O, below may also be slid upwards or downwards on the stem, by pushing
against the screws at _r_. Thus the stage, lens U, and mirrors below,
being all in one axis of motion, admit the adjustment of the distinct
view, light, &c. in the most accurate and pleasing manner. When the
instrument is packed into its case, the feet, G G H, may all be folded
together as one, and the body A B, screwed off, for the advantage of
being portable. The body, as screwed off, leaves the instrument a single
microscope.
THE GENERAL APPARATUS TO THIS MICROSCOPE IS AS FOLLOWS.
First, such as accompany the preceding microscope. The brass wheel with
magnifiers, P, Fig. 2. The slider-holder, K. The brass pin and arm, _a_,
for receiving the concave speculum, _e_, which is applied to the upper
side of the stage, and used common to all the magnifiers. The silver
concave speculum, _f_, with a magnifier set therein, used by itself in
the arm C D. These two speculums form the instrument into what is called
an OPAKE MICROSCOPE.
A brass cone, g, fitting the under side of the stage, N I S, to exclude
superfluous light. The illuminator, or convex lens, _d_, Fig. 1, fitted
to T of the stage. The jointed nippers, _b_, fitted to the stage, and
either on the point or nippers to hold any small insect, or other opake
object. An ivory black and white piece, _h_, is also fitted to the point
to contrast the colour of any object laid thereon; the light upon this
is reflected from the silver concaves placed above, which reflect the
light downwards received from the mirrors at O. Six ivory sliders as
shewn at _i_, containing a selection of objects, placed between Muscovy
talc, and fastened by spring wires; and a brass frame slider, _k_: all
for the stage, K, when in use. A set of glass tubes for fish or liquids,
_l_, to be filled with water and stopped with cork, for the
slider-holder K. A pan, _c_, for fish or frogs, fitted to the stage at
S. A small ivory box, _m_, with spare talcs and wires. The explorator,
_n_, a lens set in a brass cell, for viewing the larger sort of objects
either by the hand, or from the arm C D, Fig. 2. A plane glass, _o_, and
a concave ditto, _s_, both fitted to the hole of the stage, N I S, for
viewing fluids, and confining the animalcula, &c. between them, and so
forming what is called the AQUATIC MICROSCOPE.
A brass box, _p_, with a concave and plane glass, for insects and other
objects, fitted to the stage N I S, when they are to be examined by the
instrument. A pair of brass forceps, _q_, to take or hold any object by.
A camel hair brush, _t_.
ADDITIONAL APPARATUS TO THIS BEST MICROSCOPE.
Three large wood sliders, as shewn at X, with talcs and wires, for the
larger sort of wings of flies, and other objects which are too large for
the small ivory sliders, _i_; they are to be placed in the slider-holder
K, when on the stage N I S, and the objects to be magnified either by
the magnifiers in the wheel P, or the lens shewn at _n_, screwed on the
arm C D. A brass cell, _y_, with a very small globule or lens, or an
extraordinary great magnifier, usually about the 30th or 40th of an inch
focus; it is to be screwed into the arm C D, when the wheel, P, is first
unscrewed away. It is for the purpose of viewing extreme minute objects,
which may be so small as to elude the power of the magnifiers in the
wheel, P.
A moveable stage, W, which by the pin, _a_, is applied to the hole, S,
of the stage Fig. 2, and thereby has an horizontal motion under the
whole field of view, without disturbing any other part of the
instrument. To the large hole of this stage are fitted a deep concave
glass, _r_, and the concave and plane glasses, _s_ and _o_; and to the
small holes, _x_ _x_, a black and white piece of ivory, _w_, for opake
objects, and a concave and plane glass similar to _o_ and _s_. An extra
concave silver speculum with a less magnifier than the other, as shewn
at _f_, used for the larger kind of opake objects, like the other,
fitted to the arm C D, and used instead of the magnifiers in the wheel,
P.
Rack-work is sometimes cut in the arm C D, to turn the pinion above, so
as to move the magnifiers in a linear direction over the objects in the
most accurate degree; and also the stage N I S jointed, to turn by a
screw and teeth in an horizontal direction at right angles to the above,
thereby rendering a slow and accurate motion, perfectly suitable to the
various positions of any living animal under examination.
Six or more larger ivory sliders, with cuttings of different woods, &c.
are also frequently added; but as these enhance the expense, and may be
extended to the desire of the purchaser, his choice, and not my
description here, will determine the extent of the apparatus to the
microscope. When packed up into its mahogany, or black shagreen case,
the outside dimensions are about twelve inches and an half long, nine
inches broad, and three inches three-quarters deep.
A microscope from this plan is frequently made of smaller dimensions,
for the convenience of persons who frequently travel, and is contained
in a fish-skin case about seven inches long, four inches and an half
broad, and two inches deep, and is the most complete instrument of the
sort.
TO USE THIS MICROSCOPE.
As in the former one, place the slider-holder K, with a slider of
objects in it, in the stage N I S; move the arm C D, in its socket, so
that a mark on the side is brought to the edge of the socket; then turn
the arm till the magnifier is directly central over the object; look
down the tube A B, and during that time, reflect the light strongly and
clearly up into it from the mirror O below; and then, while you are
looking through the body, gently turn the pinion at M to the right or
left, till you see the object magnified in the most distinct and
well-defined manner. Attending properly to this mode is the only care
necessary to use any microscope whatsoever; and for want of doing which,
many a beginner finds a difficulty in using properly his instrument. For
price, see the list at the end.
For opake objects, you take away the slider-holder, K; place on the
stage either the concave glass, _s_, or the nippers, _b_; screw the
concave speculum, _e_, to the arm, _a_, which place on the stage with
the arm in the hole, I. The light is now to be reflected into this
concave dish from one of the mirrors, O, below, and it will thus be
strongly condensed upon the object. With this concave speculum any of
the magnifiers in the wheel, P, may be used. When the single silver
concave, _f_, is used, it is screwed to the arm C D, and the one, _e_,
and arm, _a_, are not then applied.
For further directions for the management of microscopes, the light, &c.
see Chap. IV. p. 129, and sequel.
A DESCRIPTION OF CULPEPER’S, OR THE COMMON THREE-PILLARED MICROSCOPE.
Plate IV. Fig. 3.
The only recommendations of this original instrument are, its simple
construction and lowness of price. It gives a pleasing view of the
object. It is precluded by its form from some of the advantages of the
two foregoing instruments, because both the stage and the mirror are
confined. This microscope consists of a large exterior brass body, A B,
supported on three brass scrolls, which are fixed to the stage F; the
stage is supported by three larger scrolls that are screwed to the
mahogany pedestal G H. There is a drawer in the pedestal which holds the
apparatus. The concave mirror, I, is fitted to a socket in the center of
the pedestal. The lower part, B, of the body forms an exterior tube,
into which the upper part of the body, C, slides, and may be moved up or
down by the hand, so as to bring the magnifiers which are screwed on at
D, nearer to, or further from the object.
A LIST OF THE APPARATUS TO CULPEPER’S MICROSCOPE.
Five magnifiers, each fitted in a brass cell; one of these is seen
screwed on at D. Six ivory sliders, _k_, five of them with objects; and
a small ivory box, _m_, containing some spare talcs, and wires for them.
A brass tube, N, to hold the concave speculum. A brass box, M, for the
same speculum. A fish-pan, _c_. A set of glass tubes, _b_. A flat and a
concave glass, both fitted to the stage. A brass cone, _g_, to exclude
superfluous light; it applies at the under side of the stage, F. A brass
box, _p_, with plane and concave glasses for living objects. A pair of
forceps, _q_. A steel wire, _b_, with a pair of nippers at one end, a
point at the other, and a small ivory cylinder, _h_, to fit on the
pointed end of the nippers. A convex lens, E, moveable in a brass
semicircle; this is affixed to a long brass pin, which fits into a hole,
F, on the stage. The uses of the above apparatus have been sufficiently
described in the preceding pages.
TO USE THIS MICROSCOPE.
Screw one of the five cells, which contains a magnifying lens, to the
end, D, of the body; place the slider _i_ or _k_, with the objects,
between the plates of the slider-holder, K. Then, to attain distinct
vision and a pleasing view of the object, adjust the sliding body to the
focus of the lens you are using, by moving the upper part, C, gently up
and down while you are looking at the object, and regulate the light by
the concave mirror, I, below. The image of the objects in this
microscope is seen in a field of view of about six inches in diameter;
but, in the improved ones before described, it is from about twelve to
fifteen inches.
For opake objects, two additional pieces must be used; the first is a
cylindrical tube of brass, represented at N, which fits on the
cylindrical snout above D of the body: the second piece is the concave
speculum, L; this is to be screwed to the lower end of the aforesaid
tube. The upper edge of this tube should be made to coincide with the
line which has the same number affixed to it as the magnifier you are
using; that is, if you are making use of the magnifier marked 5, slide
the tube to the circular line on the tube above D, that is marked also
with No. 5.
The slider-holder, K, should be removed when you are going to view opake
objects, and a plane glass should be placed on the stage in its stead to
receive the object; or it may be placed on the nippers, _b_, the pin of
which fits into the hole in the stage.
A DESCRIPTION OF MARTIN’S IMPROVED SOLAR MICROSCOPE, WHICH IS
CONSTRUCTED TO EXHIBIT TRANSPARENT AND OPAKE OBJECTS. Plate V.
The solar microscope is generally supposed to afford the most
entertainment, on account of the wonderful extent of its magnifying
power, and the ease with which several persons may view each single
object at the same time. The use of it was, however, confined for many
years only to transparent objects. About the year 1774, Mr. B. Martin so
far improved this instrument, as to render it applicable to opake, as
well as to transparent objects, exhibiting the magnified image of either
kind on a large screen. Treating of it himself, he says[34], “With this
instrument all opake objects, whether of the animal, vegetable, or
mineral kingdom, may be exhibited in great perfection, in all their
native beauty; the lights and shades, the prominences and cavities, and
all the varieties of different hues, teints, and colours, heightened by
the reflection of the solar rays condensed upon them.” From its enlarged
dimensions, transparent objects are also shewn with greater perfection
than in the common solar microscope.
[34] Description and Use of an Opake Solar Microscope. 8vo. 1774.
Plate V. Fig. 1, represents the solar opake microscope, placed together
for exhibiting opake objects.
Fig. 2, is that part called the single tooth and pinion microscope,
which is used for shewing transparent objects; the cylindrical tube, Y,
thereof, being made to fit into the tube E F, Fig. 1. It may be
occasionally used as a hand single, or Wilson’s microscope, and for
which purpose, the handle, _c_, is fitted by a screw to the body at _g_,
and the tube, Y, screwed away.
Fig. 3, the slider which contains the six magnifiers; it fits into a
dove-tail under P, Fig. 2, at the upper part of the microscope.
Fig. 4 represents a brass dove-tail slider, containing a small lens: it
is called a condenser. There are three in number, marked 1 and 2, &c.
corresponding to the number of the magnifiers used: they serve to
condense the sun’s rays strongly upon the object, and enlarge the circle
of light. They slide in at _h_, Fig. 2.