Charcoal is a fine object for the microscope: it is found to be full of pores, regularly arranged, and passing through its whole length.
Those who wish to observe the circulation of the blood, by means of the microscope, may readily obtain the desired satisfaction. An object employed chiefly for this purpose is the delicate transparent membrane which unites the toes of the frog; another object is the tail of the tadpole. If this membrane be extended, and fixed on a piece of glass illuminated below, the motion of the blood in the vessels will be distinctly visible; the appearance resembles a number of small islands, with a rapid current flowing between them.
Take a small tadpole, and, having wrapped its body in a piece of moist cloth, place its tail on the object-plate of the microscope, and enlighten it below, and you will see very distinctly the circulation of the blood; which in some of the vessels proceeds by a kind of undulation, and in others with a uniform motion. The former are thought to be the arteries in which the blood moves, in consequence of the alternate pulsation of the heart; the latter are said to be the veins. The circulation of the blood may be seen also in the legs and tails of shrimps. The transparent legs of small spiders, and those of bugs, will also afford the means of observing the circulation of the blood to very great advantage. The latter are said, by Mr. Baker, to exhibit an extraordinary vibration of the vessels, which he never saw any where else. Very small fish are good objects for this purpose; but the most curious of all spectacles of this kind, is that exhibited by the mosentery of a living frog, applied in particular to the solar microscope.
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 multitude 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, scrape 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-glass 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 coarser 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 God, 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!