If you take off a small piece of the epidermis, or scarf skin, of the hand, by means of a sharp razor, and place it on the object-plate of the microscope, you will see it covered with a mult.i.tude of small scales, so exceedingly minute, that, according to Leuwenhoek, a grain of sand would cover two hundred of them. These scales are arranged like those on the back of fishes, like the tiles of a house, each in part covering the other. To ascertain the form of these little scales, sc.r.a.pe the skin with a penknife, and put this dust into a drop of water, and it will be seen that these scales, small as they are, have, in general, five planes, and that each consists of several strata. Underneath these scales are the pores of the epidermis, which, when the former are removed, may be distinctly seen, apparently like small holes, pierced with an exceedingly fine needle. In the length of an inch, twelve hundred have been counted, so that, in a surface equal to a square inch, there are fourteen thousand; and as there are one hundred and forty-four inches in a square foot, the number of pores in a square foot of surface would be more than two millions; and as the surface of the human body is reckoned at fourteen feet, the number of pores in its surface, through which there is a perpetual perspiration going on, must be more than twenty-eight millions.

The hairs of animals, seen through a microscope, appear to be organized bodies: they are composed of long, slender, hollow tubes; some seem to be composed of several small hairs, covered with a common bark; others are hollow throughout. The bristles of a cat's whisker, when cut transversely, exhibit the appearance of a medullary part, which occupies the middle, like the pith in the twig of the elder-tree. A human hair, cut in the same manner, shews a variety of vessels in very regular figures. Hair taken from the head, the eyebrows, the nostrils, the beard, the hand, &c. appear unlike, as well in the roots as in the hairs themselves, and vary as plants do of the same genus, but of different species. Those of the hedgehog contain a kind of real marrow, which is whitish, and formed of radii meeting in a centre. A split hair appears like a stick shivered with beating.

Nothing can be more curious than the appearance exhibited by mouldiness, when viewed through a microscope. If looked at by the naked eye, it seems nothing but an irregular tissue of filaments; but the magnifying-gla.s.s shews it to be a forest of small plants, which derive their nourishment from the moist substance which serves them as a base. The stems of these plants may be plainly distinguished, and sometimes their buds, some shut, and some open. They have much similarity to mushrooms, the tops of which, when they come to maturity, emit an exceedingly fine dust, which is their seed.

Upon examining the edge of a very keen razor with a microscope, it will appear as broad as the back of a thick knife, rough, uneven, full of notches and furrows. An exceedingly small needle resembles a rough iron bar. But the sting of a bee, seen through the same instrument, exhibits every where a polish exceedingly beautiful, without the least flaw, blemish, or inequality, and ends in a point too fine to be discerned.

A small piece of exceedingly fine lawn, appears, through a microscope, like a hurdle or lattice, and the threads themselves seem coa.r.s.er than the yarn with which ropes are made for anchors. But a silkworm's web appears perfectly smooth and shining, and every where equal.

The smallest dot that can be made with a pen, appears, when viewed by the microscope, an irregular spot, rough, jagged, and uneven. But the little specks on the wings or bodies of insects, are found to be most accurately circular.

A microscope will prove the most boasted performances of art to be ill-shaped, rugged, and uneven. The finest miniature paintings appear before this instrument as mere daubings, plastered on with a trowel, entirely void of beauty, either in the drawing or the colouring. The most even and beautiful varnishes and polishings will be found to be mere roughness, full of gaps and flaws. Thus sink the works of art, before the microscopic eye. But the nearer we examine the works of G.o.d, even in the least of his productions, the more sensible shall we be of his wisdom and power. Apply the microscope to any, the most minute of his works, nothing is to be found but beauty and perfection. If we examine the numberless species of insects that swim, creep, or fly around us, what proportion, exactness, uniformity, and symmetry, shall we perceive in all their organs! what a profusion of colouring! azure, green, and vermilion, gold, silver, pearls, rubies, and diamonds; fringe and embroidery on their bodies, wings, heads, and every other part! how high the finishing, how inimitable the polish, we every where behold!

Their wings, all glorious to behold!

Bedeck'd with azure, jet, and gold, Wide they display: the spangled dew Reflects their eyes and various hue.

_Gay._

The most perfect works of art betray a meanness, a poverty, an inability in the workman; but the works of nature plainly prove, that "the hand which formed them was divine."

_Amusing Experiments with the Thermometer._

A thermometer is amusing in a room, to enable us to know with accuracy the real degree of heat, as our own feelings are so very deceptive. According to their state of health at the time, different persons will give a different judgment on the subject. After hot weather, a day which is not very cold, will yet feel so to us, and after cold weather we shall be ready to think a day warm, which is not so severe as the preceding. In winter, a thermometer in a sitting-room enables us to regulate its heat.

Too great warmth produced by a fire is injurious to health, as it relaxes the strength, and consumes the pure oxygenous air, so necessary for respiration.

Experiments will shew how differently the feelings of different individuals may be affected by the same degree of heat.

Let one person go out into the cold air in winter for a few minutes, and let another sit by a warm fire; then introduce both into a room without a fire: the person from the cold will feel it warm, and the other will feel it cold.

A much more entertaining experiment will shew, that what will be cold to the one hand, will be warm to the other. Pour warm water into one basin, cold water into a second, and a mixture of hot and cold water into a third; then put the one hand into the cold water, and the other into the warm, for two minutes, and after that put both hands into the lukewarm water, and to the one hand it will feel cold, and to the other hot.

THE BAROMETER.

_Rules for judging of and predicting the State of the Weather by the Barometer._

The rising of the mercury presages, in general, fair weather, and its falling, foul weather, as rain, snow, high winds, and storms.

When the surface of the mercury is convex, or stands higher in the middle than at the sides, it is a sign the mercury is then in a rising state; but if the surface be concave, or hollow in the middle, it is then sinking.

In very hot weather, the falling of the mercury indicates thunder.

In winter, the rising presages frost; and in frosty weather, if the mercury falls three or four divisions, there will be a thaw. But in a continued frost, if the mercury rises, it will certainly snow.

When wet weather happens soon after the depression of the mercury, expect but little of it; on the contrary, expect but little fair weather, when it proves fair shortly after the mercury has risen.

In wet weather, when the mercury rises much and high, and so continues for two or three days before the bad weather is entirely over, then a continuance of fair weather may be expected.

In fair weather, when the mercury falls much and low, and thus continues for two or three days before the rain comes, then a deal of wet may be expected, and probably high winds.

The unsettled motion of the mercury denotes unsettled weather.

The words engraved on the scale are not so much to be attended to, as the rising and falling of the mercury; for if it stands at much rain, and then rises to changeable, it denotes fair weather, though not to continue so long as if the mercury had risen higher.

If the mercury stands at fair, and falls to changeable, bad weather may be expected.

In winter, spring, and autumn, the sudden falling of the mercury, and that for a large s.p.a.ce, denotes high winds and storms; but in summer it presages heavy showers, and often thunder. It always sinks very low for great winds, though not accompanied with rain; but it falls more for wind and rain together, than for either of them alone.

If, after rain, the wind change into any part of the north, with a clear and dry sky, and the mercury rise, it is a certain sign of fair weather.

After very great storms of wind, when the mercury has been low, it commonly rises again very fast.

In settled fair weather, except the mercury sink much, expect but little rain.

In a wet season, the smallest depression must be attended to; for when the air is much inclined to showers, a little sinking in the barometer denotes more rain. And in such a season, if it rise suddenly fast and high, fair weather cannot be expected to last more than a day or two.

The greatest heights of the mercury are found upon easterly and north-easterly winds; and it may often rain or snow, the wind being in these points, while the barometer is in a rising state, the effects of the wind counteracting its influence. But the mercury sinks for wind as well as rain in all other points of the compa.s.s.

_New Method of Preserving Birds._--(_From the Annual Register._)

When I receive a bird fresh taken, (says the author,) I open the venter, from the lower part of the breast-bone down to the a.n.u.s, with a pair of scissars, and extract all the contents. This cavity I immediately fill up with the following mixture, and then bring the wound together by a suture, so as to prevent the stuffing from coming out. The gullet or pa.s.sage I fill, from the beak down to where the stomach lies, with the mixture finer ground, which must be forced down a little at a time, by the help of a quill or wire: the head I open near the root of the tongue, with the scissars, and, after having turned out the brains, I fill the cavity with the same mixture.

The bird being thus filled, must now be hung up by the legs to dry for two days, to let the spice settle; after which it may be placed in a frame to dry, in the same att.i.tude as we usually see it when alive. In this frame it must be held up by two threads, the one pa.s.sing from the a.n.u.s to the lower part of the back, and the other through the eyes: the ends of these threads are to brace the bird up to its proper att.i.tude, fasten them to the side of the frame, and place it on a chip pill-box. It will now require no other support than a pin through each foot, fastened into the box: it must remain a month or two to dry. The eyes must be supplied by proportional gla.s.s beads, fixed in with strong gum-water.

The mixture is: common salt, one pound; alum, powdered, four ounces; ground pepper, two ounces; all blended together.

_To take the Impression of the Wings of a b.u.t.terfly in all their Colours._

Kill it without spoiling; cut off the body close to the wings, which contrive to spread in a flying position; then take a piece of white paper, wash part of it with thick gum-water; when dry, lay it on a smooth board, with the wings on the gum-water; lay another paper over this, press both very hard, let them remain under pressure for an hour; afterwards take off the wings of the b.u.t.terfly, and you will find a perfect impression of them, with all their various colours, remaining on the paper. Draw, between the wings of the impression, the body of the b.u.t.terfly, and colour it after life.

_To take the Impression of a Leaf of any Tree, Plant, or Shrub, with all its Veins._

Having put the intended leaf into a book for a few minutes, which will cause it to lie very flat, you must have a pair of b.a.l.l.s, somewhat of the shape of those used by printers; have them covered with kid-skin, that being the best leather for the purpose. These b.a.l.l.s may be made to any size. You must then procure some lamp-black, ground or mixed with drying oil, and having put a small quant.i.ty on one of the b.a.l.l.s, spread it all over with the other till they are both black; then laying the leaf on one of them, place the other over it, and press both very hard together. When the leaf is sufficiently black, take it off the ball, and place it between a sheet of white paper. Press it gently with your hand, the heat and pressure of which will cause it to receive an accurate delineation of all its veins.

Instead of black, any other colour may be used. Verdigris makes a pleasant green; and by adding yellow ochre, or Prussian blue, you may approach the original tint of the leaf, and your impression will almost equal that of nature.

_Curious Experiments respecting Colours._

The following curious and useful remarks on the different degrees of heat imbibed from the sun's rays, &c. by cloths of different colours, were extracted from "Experiments and Observations," by that famous American philosopher and politician, Dr. B. Franklin.

"First, let me mention an experiment you may easily make yourself. Walk but a quarter of an hour in your garden when the sun shines, with a part of your dress white, and a part black; then apply your hand to them alternately, and you will find a very great difference in their warmth.

The black will be quite hot to the touch, the white still cool.

"Another. Try to fire paper with a burning-gla.s.s. If it be white, you will not easily burn it; but if you bring the focus to a black spot, or upon letters written or printed, the paper will immediately be on fire under the letters.