part thereof, A B C D, is conical, the other, C D E F, is cylindrical.
The cylindrical part receives the tube, G, of the opake object box, or
the tube, Y, of the single microscope, Fig. 2. At the large end, A B, of
the conical part there is a convex lens to receive the rays from the
mirror, and refract them convergingly into the box, H I K L.
N O P is a brass frame which is fixed to the moveable circular plate, _a
b c_; in this frame there is a plane mirror, to reflect the solar rays
through the afore-mentioned lens. This mirror may be moved into the
proper positions for reflecting the solar rays, by means of rack-work
turned by the nuts Q and R. By the nut Q, it may be moved from right to
left; it maybe elevated or depressed by the nut, R. _d_ _e_, two screws
to fasten the microscope to a window-shutter, or a board fitted entirely
before the window.
The box for opake objects is represented as open at H I K L; it contains
a plane mirror, M, for reflecting the light that it receives from the
large lens to the object, and thereby illuminating it; S is a screw to
adjust this mirror to its proper angle for reflecting the light. V X,
two tubes of brass, one sliding within the other, the exterior one in
the box, H I K L; these carry two magnifying lenses: the interior tube
is sometimes taken out, and the exterior one is then used by itself.
Part of this tube may be seen in the plate as within the box, H I K L.
At H, is a brass plate, the back part of which is fixed to a tube, _h_,
containing a spiral wire, which keeps the plate always bearing against
the side, H, of the brass box H I K L. The sliders, with the opake
objects, Fig. 5, pass between this plate and the side of the box; to
apply which, the plate is to be drawn back by means of the nut, g. _k
i_, a door to one side of the opake box, to be opened when adjusting the
mirror, M.
The foregoing pieces constitute the several parts necessary for viewing
opake objects. We shall now proceed to describe the single microscope,
which is used for transparent objects; but, in order to examine these,
the box, H I K L, must be first removed, and in its place we must insert
the tube, Y, of the single microscope, Fig. 2, now to be explained.
Fig. 2 represents a large tooth and pinion microscope; at _m_, within
the body of this microscope, are two thin plates that are to be
separated, in order to let the ivory sliders, Fig. 7, pass between them;
they are pressed together by a spiral spring, which bears up the under
plate, and forces it against the upper one. The slider, Fig. 3, that
contains the magnifiers, fits into a hole at _n_; any of the magnifiers
may be placed before the object, by moving the aforesaid slider: when
the magnifier is at the center of the hole P, a small spring falls into
one of the notches which is on the side of the slider, Fig. 3. At _h_,
slides a condenser, Fig. 4, for condensing the sun’s rays, and enlarging
the field of view on the screen: the number must correspond with that of
the magnifier used. This microscope is adjusted to the focus, while
exhibiting the object, by turning the milled nut O.
APPARATUS TO THE OPAKE SOLAR MICROSCOPE.
The mirror O P, Fig. 1, and square plate, and the tubular body of the
microscope, A F. The opake box and its tube, I K G. The tooth and pinion
or single microscope, Fig. 2. The slider of magnifiers, Fig. 3. The
megalascope magnifier, Fig. 6, fitted to P of Fig. 2. Six ivory sliders
with transparent objects, Fig. 7. Twelve wood sliders with opake
objects, and a brass frame to hold them, Fig. 5. A brass square-formed
slider case, Fig. 8, to hold any animal, piece of ore, or other opake
object, and is to be placed like the other slider at H, Fig. 1. A pair
of nippers and point, Fig. 9, the pin, _a_, of which fits into the hole
of the slider, Fig. 4, and holds before the magnifiers at P, Fig. 2, any
small fly or other complete object to be magnified. A four-glass slider
in a brass frame, Fig. 10, for any animalcula, &c. to be placed between
the plates at _m_, Fig. 2. A set of glass fish tubes, Fig. 11. A pair of
forceps, Fig. 12. Two brass nuts for the window-shutter or board, Fig.
13; and the two brass fastening screws, _d e_, Fig. 1, which may be
either used with or without the above two nuts.
The figures on the plate are about half the original size, and the
apparatus now made by Messrs. Jones packs into a case thirteen inches
long, nine inches broad, and four inches deep. For price, see the list
at the end.
TO USE THE SOLAR MICROSCOPE.
Make a round hole in a window-shutter or window-board, that is opposite
to the meridian sun, or as nearly so as possible, a little larger than
the circle _a b c_; pass the mirror, N O P, through this hole, and apply
the square plate to the shutter; then mark with a pencil the places
which correspond to the two holes through which the screws are to pass;
take away the microscope, and bore two holes at the marked places, large
enough to admit the milled screws, _d e_, to pass through them. These
screws are to pass from the outside of the shutter, to go through it,
and being then screwed into their respective holes in the square plate,
they will, when screwed home, hold it fast against the inside of the
shutter, and thus support the microscope.
Another way, and perhaps more convenient, is to previously screw the two
brass nuts, Fig. 13, to the shutter or window-board, at the inside at a
suitable distance, to receive the two milled screws; these nuts will
always be ready for use, and the operator may in a minute, within his
room, fasten the plate, _a b c_, to the shutter by the two milled
screws, being placed contrarywise.
Screw the conical tube, A B C D, to the circle, _a b c_, and then slide
the tube, G, of the opake box into the cylindrical part, C D E F, of
the body, if opake objects are to be examined; but if transparent
objects are intended to be shewn, then place the tube Y, Fig. 2, within
the tube C D E F. The room is to be darkened as much as possible, that
no light may enter but what passes through the body of the microscope;
for, on this circumstance, together with the brightness of the sun, the
perfection and distinctness of the image in a great measure depend.
We shall first consider the microscope as going TO BE USED FOR OPAKE
OBJECTS. Adjust the mirror, N O P, so as to receive the solar rays, by
means of the two finger-screws or nuts, Q, R; the first, Q, turns the
mirror to the right or left; the second, R, raises or depresses it: this
you are to do, till you have reflected the sun’s light through the lens
at A B, strongly upon a white-paper screen or cloth, from four to eight
feet square (about the latter dimensions for transparent objects) placed
from about five to eight feet distance from the window, and formed
thereon a round spot of light: a white wainscot or wall at a suitable
distance answers very well. An unexperienced observer will find it more
convenient to obtain the light by first forming this spot, before he
puts on either the opake box, or the tooth and pinion microscope, Fig.
2.
Now apply the opake box, and place the object between the plates at H;
open the door, _k i_, and adjust the mirror, M, till you see you have
illuminated the object strongly. If you cannot effect this by the screw
S, you must move the screws Q, R, in order to get the light reflected
strongly from the mirror, N O P, on the mirror M; without which the
latter cannot illuminate the object. The object being strongly
illuminated, shut the door, _k i_, and a distinct view of the object
will soon be obtained on your screen, by adjusting the tubes V X, with
the magnifiers, which is effected by moving them backwards or forwards.
A perfectly round spot of light cannot always be procured in northern
latitudes, the altitude of the sun being often too low; neither can it
be obtained when the sun is directly perpendicular to the front of the
room. As the sun is continually changing its place, it will be
necessary, in order to keep his rays full upon the object, to keep them
continually directed through the axis of the instrument, by turning the
two screws Q and R.
To view transparent objects, remove the opake box, and insert the tube,
Y, of Fig. 2, in its place; put the slider, Fig. 3, into its place at
_n_, a condenser, Fig. 4, at _h_, and the slider with the objects
between the plates at _m_; then adjust the mirror, N O P, as before
directed, by the screws, Q, R, so that the light may pass through the
object; regulate the focus of the magnifier by the pinion, O. The most
pleasing magnifiers in use are the fourth and fifth. The size of the
object is generally from four to eight feet, and may be increased or
diminished by altering the distance of the screen from the microscope;
five or six feet is a convenient distance.
The effect by this sort of microscope is stupendous, and never fails to
excite wonder in an observer at the first view, in seeing a flea, &c.
augmented in appearance to SEVEN, EIGHT, or even TEN FEET in length,
with all its colours, motions, and animal functions, distinctly and
beautifully exhibited.
TO EXAMINE TRANSPARENT OBJECTS OF A LARGER SIZE, or to render the
instrument what is usually called a megalascope, take out the slider,
Fig. 3, from its place at _n_; screw the cell and lens, Fig. 6, into the
hole at P, Fig. 2; remove the glass which is placed at _h_, and regulate
the light and focus agreeable to the foregoing directions.
At C D, is placed a lens for increasing the density of the rays, for the
purpose of burning or melting any fusible substance; this lens must be
removed in most cases, lest the objects should be burnt. The intensity
of the light is also varied by moving the tube G, and Fig. 2, Y, inwards
or outwards.
DESCRIPTION OF THE TRANSPARENT SOLAR MICROSCOPE AND APPARATUS. Plate VI.
Fig. 4, to 14.
The foregoing description will, in great part, answer for this
microscope; but, the dimensions, apparatus, &c. varying in a small
degree from the preceding, a distinct description here, may be
acceptable to those, who possess this sort of microscope only.
A B C D, Fig. 4, represents the body of the microscope, consisting of
two brass tubes. E F is the end of the inner moveable tube; _e f_, that
of the single tooth and pinion microscope. Fig. 5, screws into the end
of this inner tube; at the end, A B, of the external tube there is a
convex lens, to receive the sun’s rays from the mirror, K L, and to
condense them on the object; the end, A B, screws into the circular
plate, G H I. This part may also be used as a single microscope, and may
have at _m_ the handle, _c_, screwed to it. K L, a long frame fixed to
the moveable circular plate, with a plane mirror, to reflect the rays of
the sun on the lens at A B. An endless worm or screw, which is cut on
the lower part of the nut, M, works in a small wheel which is fixed to
the frame, K L, so that by turning the nut, the frame, K L, is moved up
or down: the nut, N, moves the mirror to the right or left. O, P, two
screws to fasten the square plate to the window-shutter.
Fig. 5, the single microscope; _e f_, the end which screws on to the
part, E F, Fig. 4, of the internal tube of the body; _q_, the
dove-tailed slit for receiving the slider, Fig. 8; _g_, the hole in
which the megalascope magnifier, Fig. 6, is to be screwed, when the
slider, Fig. 8, is removed. At _h_, are the moveable plates, between
which the object sliders are placed; under the lowermost of these, the
lens represented at Fig. 11 is to be placed, when the magnifiers in the
slider, Fig. 8, are to be used, _a k_ is a small piece of rack-work,
which is moved backwards and forwards by the pinion fixed to the milled
nut, _b_; by the gradual motion of this rack, the objects are adjusted
to the foci of the different lenses. Fig. 8 is a brass slider, with six
lenses, or magnifying glasses; it is to be inserted into the hole at
_q_; either of the magnifiers may be placed before the object, by
sliding it one way or the other: you may perceive when the glass is in
the center of the eye-hole by a small spring acting upon a notch which
is made on the side of the slider opposite to each lens.
APPARATUS BELONGING TO THIS SOLAR MICROSCOPE.
Square plate and mirror. The body, A D, consisting of two tubes, one
within the other. The single microscope, Fig. 5. The megalascope lens,
Fig. 6. The slider, Fig. 8, with six lenses. The two screws O, P. Six
ivory sliders and a talc box, Fig. 7 and 13. Some glass tubes, Fig. 9. A
slider or brass case, Fig. 10, containing a plane piece of glass, and a
brass slider with holes, into which are cemented small concave glasses,
designed for confining minute insects between the plane and concave
glasses, which are thus preserved from being crushed, or from moving out
of the field of view. Three condensing lenses to enlarge the field of
view, such as Fig. 11, that are fitted to the hole, _l_, of Fig. 5.
Their numbers correspond with the numbers used. Fig. 12, two brass nuts
for the window-shutter or board, to receive the two screws, O and P.
TO USE THE TRANSPARENT SOLAR MICROSCOPE. Fasten the square plate against
the inside of a window-shutter, by the two screws O, P, which are to go
from the outside of the window-shutter through it, and then be screwed
into their respective holes in the square plate at G H I. The mirror is
to be on the outside of the shutter, passing through a hole made for
that purpose. Darken the room; then place a screen at about six or eight
feet distance from the window, the farther it is from it the larger is
the image: now move the mirror, K L, by the two nuts M N, till the sun’s
rays come through the instrument in an horizontal direction to the
screen, forming a round spot thereon; screw the microscope, Fig. 5, into
its place E F; put the slider with the lenses, Fig. 8, at _q_, Fig. 5,
and the object slider between the plates at _h_; adjust the object to
the focus of the magnifying lens by the screw _b_, till the object
appears distinct and clear on the screen. By moving the internal tube of
the body, the object may be placed at different distances from the lens
which is fixed at A B, so as to be sufficiently illuminated, and not
burnt by the solar rays. If the screws O, P, are to pass inside the
room, the two nuts, Fig. 12, must be previously fixed.
THE SCREW BARREL, OR WILSON’S SINGLE POCKET MICROSCOPE. Plate II. B.
Fig. 1 and 2.
This microscope of Mr. Wilson’s is an invention of many years standing,
and was in some measure laid aside, till Dr. Lieberkühn introduced the
solar apparatus to which he applied it, there being no other instrument
at that time which would answer his purpose so well; it is much esteemed
in particular cases. The body of the microscope is represented at A B,
Fig. 1, and is made either of silver, brass, or ivory. C C is a long
fine-threaded male screw, that turns into the body of the microscope. D,
a convex glass at the end of the said screw, on which may be placed, as
occasion requires, one of the two concave apertures of thin brass to
cover the said glass, and thereby diminish the aperture when the
greatest magnifiers are used. E, three thin plates of brass within the
body of the microscope, one whereof is bent to an arched cavity for the
reception of a tube of glass. F, a piece of wood or brass, curved in the
manner of the said plate, and fastened thereto. G, the other end of the
microscope, where a female screw is adapted to receive the different
magnifiers. H, a spiral spring of steel, between the said end, G, and
the plates of brass, E, intended to keep the plates in a due position,
and counteract against the long screw, C. I, a small ivory handle. To
this microscope belong seven different magnifying glasses, six of which
are set in cells, as in Fig. K, and are marked from 1, to 6: the lowest
numbers to the greatest magnifiers. L is the seventh magnifier, set in
the manner of a little barrel, to be held in the hand for viewing any
large object. M is an ivory slider with the objects. Six of these, and
one of brass, are usually sold with this microscope. There is also a
brass slider not shewn in the figure, to confine any small object, that
it may be viewed without crashing or destroying it. N, a pair of
forceps, or pliers, for the taking up of insects or other objects, and
applying them to the sliders or glasses. O, a camel hair brush, to take
up and examine a small drop of liquid, brush the dust away, &c. P is a
glass tube to confine living objects, such as frogs, fishes, &c.
When you view an object, push the ivory slider, in which the said object
is placed, between the two flat brass plates, observing always to put
that side of the slider, where the brass rings are, farthest from the
eye; then screw in the magnifying glass you intend to use at the end of
the instrument G, and looking through it against the light, turn the
long screw, C C, till your object is brought to appear distinct, or to
the true focal distance. To examine any object accurately, view it first
through a magnifier that will shew the whole at once, and afterwards
inspect the several parts more particularly with one of the greatest
magnifiers; for thus you will gain a true idea of the whole, and all
its parts: and, though the greatest magnifiers can shew but a minute
portion of any object at once, such as the claw of a flea, the horn of a
louse, &c. yet by gently moving the slider that contains your object,
the eye will gradually see the whole; and if any part should be out of
the focal distance, the screw, C C, will easily bring it to the true
focus. As objects must be brought very near the glass, when the greatest
magnifiers are used, be particularly careful not to rub the slider
against the glasses as you move it in or out. A few turns of the screw,
C C, will easily obviate this.
DESCRIPTION OF A SCROLL FOR FIXING WILSON’S POCKET MICROSCOPE, AND A
MIRROR FOR REFLECTING LIGHT INTO IT.
A B C, Fig. 2, is a brass scroll, which, for the better conveniency of
carriage, is made to unscrew into three parts, and may be put into the
drawer upon which it stands, with its reflecting mirror D, and Wilson’s
pocket microscope, G. The upper part of the scroll is taken off at B, by
unscrewing half a turn of the screw; then, if lifted up, it will come
out of the socket. The lower part unscrews at C, and the base at E. The
mirror lifts out at F, which, with the scroll, lies in one partition of
the box.
To apply this scroll for use, fix the body of the microscope to the top
thereof by the screw, A, as in Fig. 2, by screwing it in the same hole
as the ivory handle was applied to before. The brass or ivory slider
being fixed as before described, and the microscope placed in a
perpendicular position, move the mirror, D, in such a manner as to
reflect the light of the sky, of the sun, or a candle, directly upwards
through the microscope; by which means the object will be most
conveniently viewed. It is further useful for viewing opake objects, by
screwing the arm, Q R, Fig. 1, into the body of the microscope at G;
then screwing into the round hole, R, that magnifier which you think
will best suit your object, and putting the concave speculum, S, on the
outside of the ring, R, you will observe in the body of the microscope,
between the wood or brass, F, and the end of the male screw, C C, a
small hole, _u_, through which slides the long wire, T, which has a
point at one end, and forceps at the other, that may be used
occasionally as your objects require. When you have fixed this, and your
object on it, turn the arm, R, till the magnifier is brought over the
object; it may be then adjusted to the true focus, by turning the screw,
as before. It must also be brought exactly over the speculum, by turning
the upper part of the scroll to one side, till your object and the two
specula are in one line, as will be found by trial; and then fix it by
the screw, B, at which time the upper surface of the object will be
enlightened by the light reflected from the mirror, D, to the concave
speculum.
DESCRIPTION OF A SMALL MICROSCOPE FOR OPAKE OBJECTS. Plate II. B. Fig. 3
and 4.
A, Fig. 3, is a fixed arm, through which passes a screw, B, the other
end is fastened to the moveable arm, C. D, a nut fitted to the said
screw, which, when turned, will either separate or bring together the
two arms, A C. E, a steel spring, that separates the two sides when the
nut is unscrewed. F, a piece of brass turning round in a spring socket,
moving on a rivet, in which moves a steel wire pointed at the end G, and
the other end a pair of pliers, H: these are either to thrust into, or
take up and hold any object, and may be turned round as required. I, a
ring of brass, with a female screw fixed on an upright piece of the same
metal, turning on a rivet, that it may be set at a due distance when the
least magnifiers are used, and is adapted to the screws of all the
magnifiers.
Fig. 4, K, a concave speculum of polished silver, in the center of which
a lens is placed. On the back of this speculum a male screw, L, is made
to fit the brass ring I, Fig. 3. Four of these specula of different
concavities, with four glasses of different magnifying powers, as the
objects may require. The greatest magnifiers have the least apertures.
M, a round object plate, one side white and the other black, intended to
render objects the more visible, by placing them, if black, upon the
white, and if white, on the black side. A steel spring, N, turns down on
each side, to secure any object; from the object plate there is a hollow
pipe, to screw it on the needle’s point G, Fig. 3. O, a small box of
brass, with a glass on each side, to confine any living object in order
to examine it, having a pipe to screw upon the end of the needle at G.
P, an ivory handle. Q, a pair of pliers to take up any object. R, a soft
hair brush.
To view any object, screw the speculum, with the magnifier you intend to
use, into the brass ring, I; place your object either on the needle G,
in the pliers H, on the object plate M, or in the brass hollow box O, as
may be most convenient; then holding up your instrument by the handle P,
look against the light through the magnifying lens, and by means of the
nut, D, together with moving of the needle at its lower end, the object
may be turned about, raised or depressed, brought nearer the glass, or
put farther from it, till you have the true focal distance, and the
light be seen reflected from the speculum strongly upon the object.[35]
[35] Opake microscopes are now constructed more elegantly and simply.
The chief merit of Wilson’s microscope appears, in being particularly
adapted to minute objects, and these principally of the transparent
kind; the barrel form is useful for excluding adventitious light.
Excepting these peculiarities, its general utility is considered far
short of the universal pocket microscope hereafter to be described.
EDIT.
OF ELLIS’S SINGLE OR AQUATIC MICROSCOPE. Plate VII. B.
This instrument takes its name from Mr. John Ellis, author of “An Essay
towards a Natural History of Corallines,” and of the “Natural History
of many curious and uncommon Zoophytes.” By this instrument he was
enabled to explain many singularities in the œconomy and construction of
these wonderful productions of nature. To the practical botanist this
instrument is recommended by the respectable authority of Mr. Curtis,
author of the Flora Londinensis, a work which does credit to the author
and the nation. This microscope is simple in its construction, easy in
its use, and very portable; these advantages, as well as some others
which it also has over other portable microscopes, have accelerated the
sale thereof, and caused it to be very much adopted.
DESCRIPTION OF THE VARIOUS PARTS OF THE MICROSCOPE.
K, the box which contains the whole apparatus; it is generally made of
fish-skin; on the top of the box there is a female screw, for receiving
the screw which is at the bottom of the brass pillar A, and which is to
be screwed on the top of the box, K. D, a brass pin which fits into the
pillar; on the top of this pin is a hollow socket to receive the arm
which carries the magnifiers; the pin is to be moved up and down, in
order to adjust the lenses to their focal or proper distance from the
object.
In the representation of this microscope, Plate VII. B. Fig. 1, the pin,
D, is delineated as passing through a socket at one side of the pillar,
A; it is now usual to make it pass down a hole bored through the middle
of the pillar.