THE MICROSCOPE.

BY THE REV. J. G. WOOD, M.A., F.L.S.

No. 1.

T any time of the year or hour of the day, there are few pursuits more interesting, and at the same time instructive, than the study of Nature by means of the Microscope.

This instrument has revolutionized science, solved many problems that had wearied the souls of older naturalists, and even in its simplest form is beyond all value to those who love Nature and the objects which they see around them. The microscope opens a new world to us. When the first telescope was directed to the heavens, and unlocked the mysteries of the skies, when it crumbled into dust all the theories of the past centuries, and told mankind that the planets were not merely instruments of fortune-telling, whose voices were intelligible to a chosen few, but orbs far vaster than our own; even then, the new world of thought into which man entered was no wider than that which is displayed by the poorest lens that possesses the power of magnifying.

All of us must admire the more than awful grandeur of that universe whereof we form so infinitesimal a part, wherein the stars are scattered as the sand on the sea-shore, and every star a sun, the centre of a system of orbs too distant for the eye of man to perceive. Looking at our nearest planet, and observing on her face vast mountain-chains, ravines into which the light of the sun can never penetrate, and volcanoes whose craters are so wide that they would take in the whole of London, the whole of Birmingham, and all the country between them, we can judge by analogy of the unseen wonders which must exist in the world beyond our ken.

But, to him who can read Nature rightly, the microscope is a teacher as grand as its sister instrument, and the awful magnificence of Nature is as evident in a midge's wing, as in the more patent glories of the sun, moon, and stars. In the following pages, I hope to put the readers of this Magazine in the way to read their microscope rightly-possibly to make it—and to show that much can be done with small means, when "there's a will," and to indicate to them that objects of no small interest

can be found without stirring from the room in which we sit, or even from the table on which our microscope is placed.

Some of my readers may say, when they read the heading of this paper, that they should like a microscope very much, but that they have no money to buy it, and that their parents cannot afford one.

This is just the feeling which I used to have when a boy, for in those days microscopes were microscopes indeed, and you had your choice between a little instrument, with a series of brass cups, having glasses in them, which magnified slightly but defined clearly, or a great composition of brass and iron, looking like a rocket-tube, with an eye-piece at one end and a glass shot at the other. It was very costly, very imposing, and magnified very highly; but it strained the eyes painfully, had no defining capacities, and made all the objects look as if they were seen through a thick fog. Practically, therefore, the former was the only instrument that was available.

A still more useful instrument, however, was that which can always be obtained for a few shillings, and which is now made wonderfully cheap and wonderfully good; I mean the double or treble pocket-lens. So I say, if you cannot afford a really good microscope, do not waste your money upon inferior and pretentious instruments, but get a sound pocket-lens.

It has a thousand advantages. It is portable, and is even more useful in the fields than in the house. It defines very clearly, and needs little trouble in manipulation. I need not say how difficult is the task of getting a complicated instrument to define properly, how impossible with a bad one. The object and the glass can be held in any light, a matter of no small consideration when examining anything new, and trying to make out its structure. It is not easily put out of order, and if treated with the most ordinary care, will last for a lifetime.

You can push it under water, and it will magnify as well as in the air, and if you are wandering on the river-side, you can lie down on the bank, dip the upper part of your head into the water, together with the glass, and watch carefully the subaquatic objects without removing them. The water will not hurt the eye in the least, though a non-swimmer may perhaps find a little difficulty in his first attempt. It makes a good burning-glass, should fire be needed, and no other means of procuring a spark be at hand. It can be used so as to show the principle of a camera obscura, and to illustrate the manner in which photographic portraits are taken. It can be made into an admirable dissecting microscope, and needs scarcely any practice in the manipulation. These are some of its advantages, and there are many others, which need not be mentioned.

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Even if you should be able to procure a good microscope, get a pocketlens as well, for you will want them both, and I may say that the most practised microscopists, and those who are possessors of the most elaborate instruments, are the very men who are most certain to have a pocket-lens about them, and to use it most frequently. Practice well with the pocket-lens before you meddle with the compound microscope. You will waste no time, but will rather gain by it; for you will be learning the rudiments of a new science, and laying a solid foundation on which to build. Whenever I see a lad take out his pocket-lens in a businesslike way, use it skilfully, and put it back with a mechanical facility that tells of constant practice, I know that there is a lad who has learned the chief lesson of a naturalist, namely, the art of observing. I speak highly of the pocket-lens, because I think highly of it and owe much to it. One or two practical remarks on the proper handling of the pocketDo not always employ the same eye in looking lens may be of use. through the lens, but use the eyes alternately. There is always a temptation to employ the same eye, which thus receives a kind of training in vision; but it is a temptation always to be resisted. With some persons the right eye is most in favour, and with others the left; favourite eye gets all the work, it too frequently suffers. look with the right or the left eye, keep both eyes open. It is a pitiful sight to see a human face all screwed up into a corner, the lids of the unused eye convulsively squeezed together, and the mouth slanting upwards, as if in sympathy with the eye. Not only does the human face become repulsively mean, and portentously ugly by such action, but the sight of the eye is seriously strained, and sometimes impaired for life. At first, the beginner will find a little difficulty in restricting his vision to one eye, while the other remains open, just as a beginner on the pianoforte feels himself puzzled when he tries to make his right hand go one way and his left hand another; but in either case, little practice and plenty of perseverance are sure to overcome all obstacles, and in a wonderfully short time the difficulty will not only be overcome, but forgotten.

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and when the Whether you

I speak here with some feeling, because, while engaged on the "Common Objects of the Microscope," I was necessarily obliged to work much at night, and inadvertently employed the left eye more than the right; the consequence of which imprudence was that I have been obliged ever since that time to give the left eye perfect rest, as far as artificial vision goes, and, except when looking through a binocular instrument, I have not ventured to use it either to a microscope or telescope. The vision accommodates itself to circumstances with wonderful

ease, and the observer learns the curious art of cutting off all communication between the unused eye and the brain; so that, although the objects around may imprint themselves upon the retina, the mind is as totally unconscious of them as if they had no existence.

If possible, always examine an object without removing it, as thereby you see it as it is, without altering any of the conditions with which it is surrounded. Should this not be practicable, take the object to be viewed in the left hand and the lens in the right. Place the wrists of the two hands together, and then you will find that one supports the other, and that the lens can be held in the proper focus without the least difficulty: After you have used the lens for some little time, you will learn to hit upon the right focus almost to a hair's-breadth, so as to lose no time, a matter of some importance when a living creature is to be examined, especially if it be in motion.

As to the selection of objects, none is necessary. Look at everything, and the uglier and more unpromising it is, let it be the closer examined. We do not merely use our aids to vision for the sake of seeing beautiful things, though the microscopist sees more beauty in a day than others will see in a year. We want to see how the world and its constituent parts are made; and though admiration will not be wanting, yet it does not, or ought not, to hold the first place. Always have a motive for looking at every object, and if you have none, try to make one. One of my friends, known by name at least to most of my readers, struck out, some years ago, a most curious train of thought while looking at an object which is seen daily by thousands of human beings, and will probably soon give the public the benefit of it. I have seen the object hundreds of times, but the ideas which it suggested did not happen to occur to me.

I am now about to suggest a very simple piece of mechanism, by which the pocket-lens can be converted into a microscope, that will serve for dissection, and many other purposes. The accompanying sketch is taken from an instrument of my own manufac

ture. It is of very rough make, and by an old Indian officer would be contemptuously termed "cutcha." Measured, however, by its performance, it is quite as satisfactory as those instruments which are made by professed opticians, and which the same old Indian would class under the honoured title of "pucka."

Melt three or four pounds of lead in an iron ladle, and make a mould, consisting of a hollow hemisphere of paper or cardboard, through the

centre of which an iron rod has been passed. The hollow of the paper should resemble an ordinary saucer. Pour the lead into the saucer, and

let it cool. The paper mould will be scorched by the heat and rendered useless, but an outer coating of lead will be cool and hard before the paper is quite destroyed. The rod and leaden stand will now appear as in the illustration. Next, take a piece of stout brass wire and a winecork; twist the wire round the cork several times; cut off one end close to the cork; sharpen the other, and turn it up as seen in the engraving. Bore a hole through the cork, just large enough to allow the upright rod to slip through it, and there is the "stand" of your microscope. Now take your pocket-lens, and get an optician to bore a hole through one end of it, just large enough to receive the upturned end of the wire; slip the lens on the wire, and the microscope is complete.

The cork, though grasping the upright stem with tolerable firmness, can be slid up and down so as to insure the correct focus, and can be pushed aside whenever the object has to be viewed with the naked eye and must not be removed from its place. This instrument is a capital one for dissecting purposes, and will answer quite as well as those expen

I

ROSS'S DISSECTING MICROSCOPE.

sive affairs that are to be purchased in the shops. If, however, my readers would like to possess a real and wellmade instrument, he cannot do better than get one of Ross's Dissecting Microscopes, which are very steady, and, as may be seen, can be adjusted to almost any position. A rack-andpinion movement for elevating or lowering the sliding pillar would be useful.

If the object be transparent, and requires to be seen by transmitted light, the following plan will answer:-Take a thin piece of wood, cut or punch a round hole out of the middle, and support it on four legs. Wires or wooden pegs fixed in corks will answer the purpose well, and if the corks be glued to the corners of the board, the legs can be inserted or removed at pleasure. The wood of which cigar-boxes are made will answer the purpose very well. Its dimensions should be about three inches in length by two in width. Now buy one of the doll's lookingglasses that are sold for a penny, and put it under the stand. Lay a flat piece of glass over the hole, place the object upon it, and direct the light through it by means of the mirror below. If such a mirror cannot