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I C micro- them as you move it in or out. A few turns of the 2. Single Microscope by reflection. In fig. 2. A is a Microscope. screw CC will easily prevent this mischief, by giving scroll of brass fixed upright upon a round wooden
them room enough.' You may change the objects in base B, or a malogany drawer or case, so as to stand your sliders for any others you think proper, by taking perfectly firm and steady. C is a brass screw, that pas
. out the brass rings with the point of a penknife; ses through a hole in the upper limb of the scroll inthe talcs will then fall out, if you but turn the sliders; to the side of the microscope D, and screws it fast to and after putting what you please between them, by the said scroll E is a concave speculum set in a replacing the brass rings you will fasten them as they box of brass, which hangs in the arch G by two small were before. It is proper to have some sliders furnish
screws ff, that screw into the opposite sides thereof. ed with talcs, but without any object between them, At the bottom of this arch is a pin of the same metal, to be always in readiness for the examination of fluids, exactly fitted to a hole h in the wooden pedestal, made salts, sands, powders, the farina of flowers, or any for the reception of the pin. As the arch turns on other casual objects of such sort as need only be applied this pin, and the speculum turns on the end of the to the outside of the talc.
arch, it may, by this twofold motion, be easily adjustThe circulation of the blood may be easiest seen in ed in such a manner as to reflect the light of the sun, the tails or fins of fishes, in the fine membranes be- of the sky, or of a candle, directly upwards through tween a frog's toes, or best of all in the tail of a the microscope that is fixed perpendicularly over it; water-newt. If your object be a small fish, place it and by so doing may be made to answer many purwithin the tube N, and spread its tail or fin along the poses of the large double reflecting microscope. The side thereof: if a frog, choose such a one as can bút body of the microscope may also be fixed horizonjust be got into your tube; and, with a pen, or small tally, and objects viewed in that position by any light stick, expand the transparent membrane between the you choose; which is an advantage the common double toes of the frog's bind foot as much as you can. When reflecting microscope bas not. It may also be renderyour object is so adjusted that no part of it can inter- ed further useful by means of a slip of glass ; one end cept the light from the place you intend to view, un- of which being thrust through between the plates where screw the long screw CC, and thrust your tube into the sliders go, and the other extending to some distance, the arched cavity, quite through the body of the mi- such objects may be placed thereon as cannot be apcroscope ; then screw it to the true focal distance, and plied in the sliders : and then, baving a limb of brass you will see the blood passing along its vessels with a that may fasten to the body of the microscope, and exrapid motion, and in a most surprising manner.
tend over the projecting glass a hollow sing wherein The third or fourth magnifiers may be used for to screw the magnifiers, all sorts of subjects may be frogs or fishes : but for the tails of water-newts, the examined with great convenience, if a hole be made in fifth or sixth will do ; because the globules of their the pedestal, to place the speculum exactly underneath, blood are twice as large as those of frogs or fish. The and thereby throw up the rays of light. The pocketfirst or second magnifier cannot well be employed for microscope, thus mounted, says Mr Baker, " is as easy this purpose; because the thickness of the tube in and pleasant in its use; as fit for the most curious exwhich the object lies, will scarce admit its being amination of the animalcules and salts in fluids, of the brought so near as the focal distance of the magni- farinæ in vegetables, and of the circulation in small fier.
animals ; in short, is as likely to make considerable
It is easy to
the light as reflected obliquely from it: the silver speconceive, therefore, that the arm at R, which turns culum screwed into R will then reflect the light, which by a twofold joint at a and b, may be brought with it receives from the glass speculum, 'strongly upon the its magnifier over the object, the light reflected upon object that is applied upon the wire T underneath: it by the application of the speculum, and the true This miscroscope; however, is not upon the most focus obtained by turning of the male screw CC as convenient construction, in comparison with others now before directed.As objects are sometimes not well made: it has been esteemed for many years past from fixed for view, either by the forceps or point, the its popular name, and recommendation by its makers. small piece shown at Vis added, and in such cases Its portability is certainly a great advantage in its faanswers better : it serews over the point of T; it con- vour ; but in most respects it is superseded by the mitains a small round piece of ivory, blackened on one croscopes herealter described. ; side, and left white upon the other as a contrast to 3: Microscope for Opaque Objects, called the Single Fig. 3. coloured objects, and by a small piece of watch-spring Opaque Microscope. This microscope remedies the infastens down the objects upon the ivory.
convenience of having the dark side of an object next 3
Miero. the eye, which formerly was an insurmountable ob- scope, screw the speculum, with the magnifier you Micro scope . jection to the making observations on opaque objects think proper to use, into the brass ring 1. Place your scope. with
any considerable degree of exactness or satisfac- object, either on the needle G in the pliers H, on the tion : for, in all other contrivances commonly known, object-plate M, or in the hollow brass box O, as may the nearness of the instrument to the object (when be most convenient ; then holding up your instrument glasses that magnify much are used) unavoidably over- by the handle P, look against the light through the shadows it so much, that its appearance is rendered ob- magnifying lens ; and by means of the nut D, together scure and indistinct. And, notwithstanding ways have with the motion of the needle, by managing its lower been tried to point light upon an object, from the sun. end, the object may be turned about, raised, or deor a candle, by a convex glass placed on the side there pressed, brought nearer the glass, or removed farther of, the rays from either can be thrown upon it in such from it, till you find the true focal distance, and the an acute angle only, that they serve to give a confused light be seen strongly reflected from the speculum upglare, but are insufficient to afford a clear and perfect on the object, by which means it will be shown in a view of the object. But in this microscope, by means of manner surprisingly distinct and clear; and for this
concave speculum of silver highly polished, in whose purpose the light of the sky or of a candle will answer centre a magnifying lens is placed, such a strong and very well
. Transparent objects may also be viewed by direct light is reflected upon the object, that it may be this microscope , only observing, that when such come examined with all imaginable ease and pleasure. The under examination, it will not always be proper to several parts of this iostrument, made either of brass or throw on them the light reflected from the speculum ; silver, are as follow.
for the light transmitted through them, meeting the reThrough the first side A, passes a fine screw B, the flected light, may together produce too great a glare. other end of which is fastened to the moveable side C. A little practice, however, will show how to regulate D is a nut applied to this screw, by the turning of both lights in a proper manner. wbich the two sides A and C are gradually brought 4. Ellis's single and Aquatic Microscope. Fig. 4. re- Fig. 4. together. E is a spring of steel that separates the presents a very convenient and useful microscope, contwo sides when the nut is unscrewed. F is a piece of trived by Mr John Ellis, author of An Essay upon Cobrass, turning round in a socket, whence proceeds a rallines, &c. To practical botanists, observers of apismall spring tube moving upon a rivet; through which malcula, &c. it possesses many advantages above those tube there runs a steel wire, one end whereof termi- just described. It is portable, simple in its construcnates in a sharp point G, and the other with a pair of tion, expeditious, and commodious in use.
K repliers H fastened to it. The point and pliers are to presents the box containing the whole apparatus : it thrust into, or take up and hold, any insect or object; is generally made of fish-skin; and on the top there and either of them may be turned upwards, as best is a female screw, for receiving the screw that is at the suits the purpose. I is a ring of brass, with a female bottom of the pillar A: this is a pillar of brass, and screw within it, mounted on an upright piece of the is screwed on the top of the box. Dis a brass piu same metal; which turns round on a rivet, that it may which fits into the pillar; on the top of this pin is a be set at a due distance when the least magnifiers are hollow socket to receive the arm which carries the employed. This ring receives the screws of all the magnifiers; the pin is to be moved up and down, in magnifiers. K is a concave speculum of silver, po- order to adjust the lenses to their focal or proper dislished as bright as possible ; in the centre of which is tance from the object. (N. B. In the representaplaced a double convex lens, with a proper aperture tions of this microscope, the pin D is delineated as to look through it. On the back of this speculum a passing through a socket at one side of the pillar A; male screw L is made to fit the brass ring I, to screw whereas it is usual at present to make it pass down a into it at pleasure. There are four of these concave hole bored through the middle of the pillar.] E, the specula of different depths, adapted to four glasses of bar which carries the magnifying lens; it fits into the different magnifying powers, to be used as the ob- socket X, which is at the top of the pin or pillar D. jects to be examined may require. The greatest mag- This arm may be moved backwards and 'forwards in nifiers have the least apertures. M is a round object- the socket X, and sideways by the pin D; so that the plate, one side of which is white and the other black: magnifier, which is screwed into the ring at the end The intention of this is to render objects the more vi- E of this bar, may be easily made to traverse over any sible, by placing them, if black, on the white side, part of the object that lies on the stage or plate B. or, if white, on the black side. A steel spring N turns FF is a polished silver speculum, with a magnifying down on each side to make any object fast; and is- lens placed at the centre thereof, wbich is perforated suing from the object-plate is a hollow pipe to screw for this purpose. The silver speculum screws into the it on the needle's point G. O is a small box of brass, arm E, as at F. G, another speculum, with its lens, with a glass on each side, contrived to confine any li- which is of a different magnifying power from the ving object, in order to examine it: this also has a former. H, the semicircle which supports the mirror I; pipe to screw upon the end of the needle G, P is a the pin R, 'affixed to the semicircle H, passes through turned handle of wood, to screw into the instrument the hole which is towards the bottom of the pillar A. when it is made use of. R, a pair of brass pliers to B, the stage, or the plane, on which the objects are to take up any object, or manage it with conveniency. be placed ; it fits into the small dove-tailed arm whick R is a soft hair-brush for cleaning the glasses, &c. Sis is at the upper end of the pillar DA. C, a plane a small ivory box for talcs, to be placed, when wanted, glass, with a small piece of black silk stuck on it; this in the small brass box 0.
glass is to lay in a groove made in the stage C. M, When you would view any object with this micro- a hollow glass to be laid occasionally on the stage-in
to the stage.
Micro. stead of the plane glass C. I, a pair of vippers, be fixed in the nippers MN, and then brought under the Microseope. These are fixed to the stage by the pin at bottom; eye-glasses; or they may be laid on one of the glasses scope.
the steel wire of these nippers slides backwards and which fit the stage. The apparatus to this instrument
6. Withering's portable Botanic Microscope. Fig. 6. Fig. 6.
sockets which are fixed to it. The two upper plates
e with f a third ; which, with the three singly, make
de saule, 4to.
Micro- ing glasscs that may be used either separately or com- The particular and chief advantages which the conscope bined. In the inside, at the bottom, is a piece of ivory, pound microscopes have over the single, are, that the scope.
black and white on opposite sides, that is occasionally objects are represented under a larger field of view, and removed, and admits a point to be screwed into the with a greater amplification of reflected light. centre. The cap unscrews at I), to admit the placing 1. Culpeper's Microscoppom. The compound microscope, of the object : the proper distance of the glasses from originally contrived by Mr Culpeper, is représented at the object is regulated by pulling up or down the brass fig. 10. It consists of a large external brass body A, Fig. 10. tube É at top containing the eye-glasses.
B, C, D, supported upon three scrolls, which are fixed This microscope is particularly useful for exhibiting to the stage EF; the stage is supported by three larthe well-known curicus curculio imperialis, vulgarly ger scrolls, that are screwed to the mahogany pedestal called the diamond beetle, to the greatest advantage; GH. There is a drawer in the pedestal, which holds for which, as well as for other objects, a glass bottom, the apparatus. The concave mirror I is fitted to a and a polished reflector at the top, are often applied, socket in the centre of the pedestal. The lower part to condense the light upon the object. In this case, LMCD of the body forms an exterior tube, into which the stand and brass-bottom F, as shown in the figure, the upper part of the body ABLM slides, and may are taken away by unscrewing.
be moved up or down, so as to bring the magnifiers, 9. Bir Lyonet's Single Anatomical Dissecting Micro which are screwed on at N, nearer to or farther from Fig. 9. scope.--Fig . 9. represents a curious and extremely use
the object. ful microscope, invented by that gentleman for the pur- To use this microscope: Screw one of the buttons, pose of minute dissections, and microscopic prepara- which contains a magnifying lens, to the end N of the tions. This instrument must be truly useful to ama. body : place the slider, with the objects, between the teurs of the minutiæ of insects, &c. being the best plates of the slider-holder. Then, to attain distinct adapted of any for the purposes of dissection. With vision, and a pleasing view of the object, adjust the this instrument Mr Lyonet made his very curious mi- body to the focus of the lens you are using, by moving croscopical dissection of the chenille de saule, as related the upper part gently up and down, and regulate the in his Traité Anatomique de la chenille qui ronge le bois light by the concave mirror.
For opaque objects, two additional pieces must be AB is the anatomical table, which is supported
by used. The first is a cylindrical tube of brass (representa pillar NO; this is screwed on the foot CD. The ;
ed at L, fig: 11.), which fits on the cylindrical part at Fig. 18. table AB is prevented from turning round by means N of the body. The second piece is the concave spect of two steady pins. In this table or board there is a lum h; this is to be serewed to the lower end of the bole G, which is exactly over the centre of the mirror aforesaid tube: the upper edge of this tube should be EF, that is to reflect the light on the object; the hole
made to coincide with the line which has the same numG is designed to receive a flat or concave glass, on a
ber affixed to it as to the magnifer you are using ; e. g. which the objects for examination are to be placed. you are making use of the magnifier marked S, slide
S RXZ is an arm formed of several balls and sockets, the tube to the circular line on the tube N that is by which means it may be moved in every possible si- marked also with No 5 The slider-bolder should be tuation; it is fixed to the board by means of the screw removed when you are going to view opaque oba H. The last arm IZ has a female serew, into which jects, and a plane glass sbould be placed on the stage a magnifier may be screwed as at Z. By means of the in its stead to receive the object; or it may be placed screw H, a small motion may be occasionally given to in the nippers, the pin of which fits into the hole in the the arm 12, for adjusting the lens with accuracy to its stage. focal distance from the object.
The apparatus belonging to this microscope consists Anotber chain of balls is sometimes used, carrying a of the following particulars : viz. Five magnifiers, each lens to throw light upon the object ; the mirror is like- fitted in a brass button ; one of these is seen at N, wise so mounted, as to be taken from its place at K, and fig. 10. Six ivory sliders, five of them with objects. fitted on a clamp, by which it may be fixed to any part A brass tube to hold the concave speculum, The of the table AB.
concave speculum in a brass box. A fish
pan. To use the Dissecting Table.—Let the operator sit of glass tubes. A flat glass fitted to the stage. Az with his left side near a light window; the instrument concave glass fitted to the stage. A pair of forceps. being placed on a firm table, the side DH towards the A steel wire, with a pair of pippers at one end and a stomach, the observations should be made with the point at the other. A small ivory cylinder, to fit on left eye. In dissecting, the two elbows are to be sup- the pointed end of the aforesaid nippers.
A convex ported by the table on which the instrument rests, the lens, movcable in-a brass semicircle ; this is affixed to hands resting against the board. AB; and in order to a long brass pin, which fits into a hole on the stages give it greater stability (as a small shake,, though. im- The construction of the foregoing microscope is very perceptible to the naked eye, is very visible in the mi- simple, and it is easy in use; but the advantages of the croscope), the dissecting instruments are to be held stage and mirror are too much confined for an extensive one in each band, between the thumb, and two fore- application and: management of all kinds of objects. Its fingers:
greatest recommendation is its cheapness; and to those II. OF DOUBLE Microscopes, commonly called Com
who are desirous of traving a compound microscope at
a low price, it may be acceptable. POUND Microscopes.
2. Cuf"'s. Microscope. The improved microscope Double microscopes are so called, from being a com
next in order is that of Mr Cuff. Besides remedying kination; of two or more lenses.
the disadvantages above meutioned, it contains the
Alicro- addition of an adjusting screw, which is a consider- ivory box, to hold a supply of talc and rings for the Mirro.
able improvement, and highly necessary to the ex- sliders. V, a small ivory cylinder, that fits on the scope.
amination of objects under the best defined appear. pointed end of the steel wire : it is designed for opaque Fig. 11. ance from the glasses. It is represented at fig. 11. objects. Light-coloured ones are to be stuck upon
with the apparatus that asually accompanies it. A, the dark side, and vice versa. M, a fish-pan, whereon
suitably varied. A condensing glass is applied under
the stage in the slider-holder, in order to modify and To use this microscope : Screw the magnifier you increase the light that is reflected by the mirrors beintend to use to the end of the body; place the low from the light of a candle or lamp. It is furnishslider-bolder P in the hole n, and the slider with the ed also with two mirrors in one frame, one concave object between the plates of the slider-holder; set tbe and the other plane, of glass silvered; and by simply upper edge of the bar DE to coincide with the di unscrewing the body, the instrument, when desired, may visions which correspond to the magnifier you have in be converted into a single microscope. Fig. 12. is a Fig. 1 22 use, and pinch it by the milled nut; now reflect a representation of the instrument thus improved; and proper quantity of light upon the object, by means of the following is the description of it, as given by the concave mirror G, and regulate the body exactly Mr Adams in his Essays. to the eye and the focus of the glasses by the adjusting AB represents the body of the microscope, conscrew cg
taining a double eye-glass and a body-glass; it is To view opaque objects, take away the slider-holder here shown as screwed to the arm CD, from whence P, and place the object on a flat glass under the cen- it may be occasionally removed, either for the convetre of the body, or on one end of the jointed nippers nience of packing, or when the instrument is to be used op. Then screw the silver concave speculum h to the as a single microscope. end of the cylinder L, and slide this cylinder on the The eye-glasses and the body-glasses are contained lower part of the body, so that the upper edge thereof in a tube which fits into the exterior tube AB ; by may coincide with the line which has the same mark pulling out a little this tube when the microscope is in with the magnifier that is then used : reflect the light use, the magnifying power of each lens is increased. from the concave mirror G to the silver speculum, The body AB of the microscope is supported by from which it will again be reflected on the object. the arm CD; this arm is fixed to the main pillar CF, The glasses are to be adjusted to their focal distance as which is screwed firmly to the mabogany pedestal before directed.
GH; there is a drawer to this pedestal, which holds The apparatus consists of a convex lens H, to col- the apparatus. lect the rays of light from the sun or a candle, and NIS, the plate or stage which carries the slider-bolder condense them on the object. La cylindrical tube, KL; this stage is moved up or down the pillar CF, by open at each side, with a concave speculum screwed to turning the milled nut M; this nut is fixed to a pinion, the lower end h. P the slider-bolder: this consists of a that works in a toothed rack cut on one side of the pilcylindrical tube, in which an inner tube is forced up- lar. By means of this pinion, the stage may be graduwards by a spiral spring; it is used to receive an ivory ally raised or depressed, and the object adjusted to the slider K, which is to be slid between the plates h focus of the different lenses. and i. The cylinder P fits the hole n in the stage ; KL is a slider-holder, which fits into a hole that is in and the hollow part at k is designed to receive a glass the middle of the stage NIS; it is used to confine and tube. R is a brass cone, to be put under the bottom guide either the motion of the sliders which contain the of the cylinder P, to intercept occasionally some of objects, or the glass tubes that are designed to contine the rays of light. S, a box containing a concave and small fishes for viewing the circulation of the blood. a flat glass, between which a small living insect may The sliders are to be passed between the two upper be confined: it is to be placed over the hole n. T, plates, the tubes through the bent plates. a fiat glass, to lay any occasional object upon ; there L is a brass tube, to the upper part of which is fixed is also a concave one for fluids. O is a long steel wire, the condensing lens before spoken of; it fits into the with a small pair of pliers at one end, and a point at under part of the slider-holder KL, and may be set at the other, designed to stick or hold objects : it slips different distances from the object, according to its disbackwards and forwards in the short tube o; the pin tance from the mirror or the candle. p fits into the hole of the stage. W, a little round O is the frame which holds the two reflecting mir