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mirrors may be moved in various directions, in order glasses fitted to the stage, as well as those put into the scope.
concave speculum, for reflecting light on opaque objects, in the slider E are mounted in a wheel case, which perPlate, is fixed. At S is a hole and slit for receiving either the baps prevents its being in the way so much as the long CCCXLI.
nippers L (fig. 31.) or the fish-pan I, when these are slider E before described.--This contrivance is repre-
4. Martin's New Universal Compound Microscope.-
fig. 13. each magnifier in this slit there is a notch, and in piece, or that containing the eye-glasses, and is screwthe dove-tailed part of the arm CD there is a spring, ed into C, which is a moveable or sliding tube on the which falls into the above-mentioned potch, and tbus top ; this inner tube contains the body-glass screwed makes each magnifier coincide with the centre of the into its lower part. D is the exterior tube or case, hody. Pass the ivory slider you intend to use between in which the other slides up and down in an easy and the upper plates of the slider-holder KL, and then steady manner. This motion of the tube C is useful reflect as strong a light as you can on the subject by to increase and decrease the magnifying power of the means of one of the mirrors ; after this, adjust the ob- body-glass when thought necessary, as before mentionject to the focus of the magnifier and your eye, by ed." E is a pipe or snout screwed on to the body of the turning the milled screw M, the motion of which raises microscope D, and at its lower part, over the several and depresses the stage NIS. The degree of light magnifying lenses bereafter described. FGHI is the necessary for each object, and the accuracy required in square stem of the microscope, upon which the stage the adjustment of the Jenses to their proper focal di- R moves in an horizontal position, upwards or downstance from the object, will be easily attained by a little ward, by means of the fine rack work of teeth and pinion. practice.
KL is a strong solid joint and pillar, by which the po-
frame, that contains the condensing lens, and acts in
pin, and to slide backwards and forwards in a socket round bole in the upper plate of it. To the upper side
Micro- brass arm. R is a fixed stage, upon which the objects ing of a concave glass with a plane ono screwed over Micre
to be viewed are to be placed : it is firmly fastened to it; by means of which a bug, louse, flea, &c. may be seope.
In this slider small concave glasses are cemented; and
viewed therewith as a single microscope. This magni-
X (fig. 13.).
quire a great space to move in, are to be viewed, then
by putting the arm abcd forward or backward in N° 12. is what is usually called a bug-box, consist- its socket ef, the view is extended in the coptrary
direction equally well; and in this manner the whole two screws (11). N° 6. (fig. 16.) represents a move- Micro of the objects may be viewed without the least disturb- able stage, which is placed in the spring socket m.
It scope. contains a concave glass, for the reception of animal
If living by means of the rack-work motion of the stage, a and moving objects are required to be shown, the must lens of a greater focal distance than the greatest in be confined in the concave, by putting a glass cover, the wheel Q may be occasionally applied in place of N° 7. upon the stage ; and then a small spider, a louse, the wheel, and thereby the larger kind of objects be a flea, bug, &c. may be seen, and the motion or cirviewed; the instrument becoming, in this case, what is culation of the blood, &c. observed with surprising dicalled a megalascope.
stinctness. In viewing moving living objects, or even fixed ones, To view the circulation of the blood in the most when nice motions are requisite, a rack-work and pi- eminent degree, it must be done by placing small frogs, nion is often applied to the arm abcd: the arm is tadpoles, water-newts, fishes, &c. in a tube as reprecut out with teeth ; and the pinion, as shown at Y, is sented No 8. (fig. 17.); which tube is placed in the Fig. 17. applied to work it. This acts but in one direction ; holes o in the opposite sides of the case a b, fig. 15. in and, in order to produce an equally necessary motion the lower part --No 9. (fig. 16.) is a pair of pincers perpendicular to this, rack-work and pinion is applied or pliers d, for liolding any object; the other end of tangent-wise to the stage, which is then jointed. the steel wire is pointed to receive a piece of ivory b,
with one end black, and the other white, on which you What has been related above respects the construc- stick objects of different hue : . this also, when used, is tion of those denominated parlour microscopes, in con placed in the spring socket m. tradistinction to those which are portable: their di- To use this instrument as a compound opaque, you mensions, however, have been considerably reduced by screw off the body part a b, and screw to it the bandle opticians, in order to render them fit for the pocket; po (fig. 16.); by this means you may hold the microand as they are for the most part constructed on nearly scope in a horizontal position, as shown in the figure. the same principles as those wbich bave been already The silver dish or speculum (which is contained in the described, what has been said will sufliciently instruct bottom or base k, fig. 15.), is then screwed on at b. our readers in using any pocket microscope whatever. N° 9. is placed in the spring soeket m, and adjusted Only it may be observed, that in those reduced instru- backward and forward in m, till the reflected light from ments, both the field of view and the magnifying the speculum falls in a. proper manner on the opaque power are proportionably diminished.
object. Either of the four magnifiers, 2, 3, 4, 5, may be
used, and brought to a proper focus, as before describWe shall conclude the account of this sort of mi- ed by the tooth and pinion e (fig. 15.). If you take eroscope with descriptions of a very portable pocket off the opaque apparatus, and apply the stage No 1. (fig. apparatus of microscopic instruments, and of a new mi- 16.) with an ivory slider, and at the end b screw in either croscopic pocket telescope, both invented by the late of the two lenses, No 10. (which are distinguished by Mr B. Martin, and since made by most instrument- the name of illuminators), the microscope being held up makers in London.
to the light (and properly adjusted), the whole field of The former is represented at. fig. 15. It consists view will be strongly illuminated, and present a most: of two parts, viz. the body a b, and the pedestal i k, pleasing appearance of any transparent object. These which is joined by a screw at the part between b and two convex lenses are of diferent focuses, and are to be i. It consists of three cylindric tubes, viz. (1.) the used singly or together ; N° 2. being the greatest magniexterior tube, or case, ab; ( 2.) a middle tube cb; fier, will require the object to be strongly illuminated, and (3.) the interior tube f g. The middle tube and of course both the lenses must be used together. cd is the adjueter; and is connected with the outer By candle-light, this method of viewing transparent olitube by the rack-work of teeth and pinion, as shown jects will prove very entertaining ; by screwing the at e : by which means it is moved up and down at handle r into the part s of No 10. it becomes a delightpleasure through the smallest space, and carries with ful hand megalascope for viewing flowers, fossils, shells, it the internal tube fg. The interior tube f g receives &c,; and each lens, as before mentioned, baving a on its lower part at the several capsules or boxes 2, different focus, produces two magnifying powers used 3, 4, 5, (fig. 16.) which contain the object lenses or singly, and when combined a third.
The manner of using this instrument as a single mi. The method of using this compound microscope in croscope (like Wilson's) is represented in fig. 17. where the perpendicular position, is as follows: The stage the button or magnifier at each is to be screwed off, and No 1. is put within the exterior tube at b. Un- the circular piece N° 11. is screwed in its place. This der the springs are applied the four ivory sliders, piece has a spring socket made to receive the slider-hclwhich contain a variety of transparent objects; then
der No 12.
13. is a circular piece of brass, with a. move the interior tube f g up and down with the hand, long shank and spring, and is introduced through the till you discern the object in the slider, and there let outside tube ab at to N° 2, 3, 4, 5, are screwed occait rest. After this, turn the pinion at'e very tenderly sionally in the centre of this piece, and used as single one way or the other, till you obtain a perfect view lenses with ivory sliders, &c. N° 14. contains a lens of of the transparent objects properly. illuminated, from a great magnifying power, for viewing very minute oba mirror contained in the pedestal or stand ik, sus- jects : to render this instrument the most complete single pended upon, and moveable about, the points of opaque microscope, you have only to screw into N° 13. Vol. XIV. Part I.
Micm. the silver speculum No 15. which has a small lens set in and the mirror B placed therein, and the wheel with Micra. its centre.
The slider-holder No 12. is taken out of transparent objects. C (fig. 20.) represents the wheel scope. No 11, and the pincers or nippers db, being detached with transparent objects, and D the wheel with opaque from the other part of No 9. are passed through the objects. They are both made of ivory; and turn long spring socket N° 11. and ready to receive any round upon a centre brass pin slit upon the top, which opaque body in the pincers, or on the black and white fits upon the edge of the tube ; which tube is then to piece of ivory. To the large screw of N° 13. are applied be pushed up into the telescope tube, so that its lower the two lenses N° 10. which make it the completest end may rest upon the upper edge of the wheel acmegalascope that can be desired.
cording to its view at a, fig. 18. The handle r contains the four ivory sliders with In viewing the objects, the second brass tube of the objects.
telescope must be pushed down, till its milled edge at The shagreen case which contains this universal mi- top falls upon that of the exterior tube ; taking care croscope and its apparatus, is six inches long, three that the circular hole is duly placed to the exterior one. inches wide, tıro inches deep; and weighs together 16 These circular holes are not seen in fig. 18. being supounces. “Thus (says Mr Martin) so small, so light, posed in the opposite side, where the wheel is fixed. so portable, and yet so universally complete, is this The adjustment for the focus is now only necessary; pocket microscopic apparatus, that you find nothing which is obtained by pushing downwards or upwards material in the large three-pillared microscope, the the proper tube, till the object appear quite distinct. opaque microscope, Wilson's single microscope, and In viewing transparent objects
, the instrument may be the aquatic microscope, all, together, which you bave used in two positions ; one vertical, when the light is to not in this ; besides some very considerable advantages be reflected upon the object by the mirror; the other, in regard to the field of view, &c. which they bave by looking up directly against the light of a candle, not (A).”
common light, &c.; in which case the mirror must be This inventive artist having contrived a construc
In viewing opaque objects, the mirror is tion of the compound microscope so small as to admit of not used; but as much common light as possible must be being packed in a common walking cane, thought next admitted through the circular holes in the sides of the of introducing the same instrument into the inside of tubes. what be called his Pocket Three-brass drawer Achro- There is a spare hole in the transparent wheel, and matic Telescope. The same eye glasses that serve the also one in the opaque, to receive any occasional object purpose of a telescope, answer as the compound magni-' that is to be viewed. Any sort of object whatsoever fier, for viewing transparent and opaque objects in a may be viewed, by only pushing up the microscope microscope.
tube into its exterior, and bringing the first eye-tube Fig. 18, 19, 20, represent the telescope separated to its focal distance from the object. by unscrewing it at m, in order that the whole of The brass tubes are so contrived, that they stop the necessary parts in use may be exhibited. Fig. 19. when drawn out to the full length : so that by represents the exterior tube, which is of mahogany, applying one hand to the outside tube, and the and its rinus of brass. It is detached from the rest of other to the end of the smallest tube, the telescope at the telescope, as not making any part of the micro- one pull may be drawn out; then any of the tubes scope. The brass cover k l, that shuts up the object- (that next to the eye is best) may be pushed in graglass of the telescope, is also the box which contains dually, till the most distinct view of the object be obthe two-wheel object frames, and a small plain reflect
tained. ing mirror.
The tubes all slide through short brass spring tubes,
, by unscrew
may be unscrewed from the ends of the ing the top part : The mirror B is taken out; and al- sliding tubes by means of the milled edges which proso, by unscrewing the bottom part, the two circular ject above the tubes, taken from each other, and the wheels, with the objects sbown in C and D.
springs set clear if required. Fig. 18. is a representation of the three internal brass sliding tubes of the telescope, which form the
III. Of Solar Microscopes. microscopic part. The tubes are to be drawn out as shown in this figure; then, at the lower end of the This instrument, in its principle, is composed of a large tube in the inside, is to be pulled out a short tube, a looking-glass or mirror, a convex lens, and tube b c, that serves as a kind of stage to bold the Wilson's single microscope before described. The sun's wheels, with objects
, and support the reflecting mirror. rays being reflected through the tube by means of the This tube is to be partly drawn out, and turned so mirror upon the object, the image or picture of that the circular hole that is pierced in it may coin- the object is thrown distinctly and beautifully upon ·cide with a similar hole that is cut in the exterior tube. a screen of white paper or a white linen sheet, placed This tube is represented as drawn out in the figure ; at a proper distance to receive the same; and may be
any of which
(A) Notwithstanding the properties that have been ascribed to the above instrument, and the praises bestowed upon it by some, which induced us to admit so minute a description, we must apprise our readers, that it has been omitted in Mr Adams's enumeration; and upon inquiry we learn, that it has fallen into neglect among the most judicious opticians, being found too imperfect to serve the purposes of science, and too complicated for the use of persons who seek only entertainment.
Micro- magnified to a size not to be conceived by those light upon the screen before you apply the micro-
moved, the larger will the object appear; insomuch, right, that proof must not always be expected : for the
round spot may be obtained, even in December. As
collar provided for it in the middle of your wood-work, fig. 21.
I. The old construction is represented in fig. 21. A taking care not to alter your looking-glass: then is a square wooden frame, through which pass two screwing the magnifier you choose to employ to the long screws assisted by a couple of nuts 1, 1. By these end of your microscope in the usual manner, take away it is fastened firmly to a window shutter, wherein a hole the lens at the other end thereof, and place a slider, is made for its reception ; the two nuts being let into containing the objects to be examined, between the the shutter, and made fast thereto. A circular hole thin brass plates, as in the other ways of using the miis made in the middle of this frame to receive the piece croscope. of wood B, of a circular figure ; whose edge, that Things being thus prepared, screw the body of projects a little beyond the frame, composes a shallow the microscope over the small end E of the brass tube groove 2, wherein runs a catgut 3 ; which, by twist- F; which slip over the small end E of the tube D, ing round, and then crossing over a brass pulley 4, and pull out the said tube D less or more as your
ob(the handle whereof s, passes through the frame), ject is capable of enduring the sun's heat. Dead obaffords an easy motion for turning round the circular jects may be brought within about an inch of the piece of wood B, with all the parts affixed to it. C focus of the convex lens 5; but the distance must is a brass tube, which, screwing into the middle of the be shortened for living creatures, or they will soon be
, circular piece of_wood, becomes a case for the unco- killed. vered brass tube D to be drawn backwards or forwards If the light fall not exactly right, you may casily, in. E is a smaller tube, of about one inch in length, by a gentle motion of the jointed wire and pulley, dicemented to the end of the larger tube D. F is rect it through the axis of the microscopic lens. The another brass tube, naade to slide over the above de- short tube F, to which the microscope is screwed, scribed tube E; and to the end of this the microscope renders it easy, hy sliding it backwards or forwards on must be screwed, when we come to use it. 5. A con- the otber tube E, to bring the objects to their focal res lens, whose focus is about 12 inches, designed to distance ; which will be known by the sharpness and collect the sun's rays, and throw them more strongly clearness of their appearance: they may also be turn; upon the object. G is a looking-glass of an oblong ed round by the same means without being in the least figure, set in a wooden frame, fastened by hinges in disordered. the circular piece of wood B, and turning about The magnifiers most useful in the solar microscope therewith by means of the above-mentioned catgut. are in general, the fourth, fifth, or sixth. The screen H is a jointed wire, partly brass and partly iron ; on which the representations of the objects are thrown, the brass part whereof 6, which is flat, being fastened is usually composed of a sheet of the largest elephant to the mirror, and the iron part 7, which is round, paper, strained on a frame which slides up or down, or passing through the wooden frame, enable the observer, turns about at pleasure on a round wooden pillar, after by putting it backwards or forwards, to elevate or de- the manner of some fire screens. Larger screens may press the mirror according to the sun's altitude. There also be made of several sheets of the same paper pasted is a brass ring at the end of the jointed wire 8, where- together on cloth, and let down from the ceiling with a by to manage it with the greater ease. The extremi- roller like a large map. ties of the catgut are fastened to a brass pin, by turn- “ This microscope (says Mr Baker) is the most ening of which it may be braced up, if at any time it beu tertaining of any; and perhaps the most capable of comes too slack.
making discoveries in objects that are not too opaque :. When this microscope is employed, the room must as it shows them much larger than can be done any
as dark as possible ; for on the darkness other way. There are also several conveniences atof the room, and the brightness of the sunshine, de- tending it, which no other microscope can have : for pend the sharpness and perfection of your image. the weakest eyes may use it without the least straining Then putting the looking-glass G through the hole in or fatigue : numbers of people together may view any your window shutter, fasten the square frame A to the object at the same time ; and by pointing to the partichuiter by its two serews and nuts 1, 1. This done, cular parts thereof, and discoursing on what lies before
your looking-glass to the elevation and situation them, may be able better to understand one another,
For the first of microscopes, where they must peep one after another,
serve a picture of; since they need only fasten a paper