There are certain plants, the leaves of which seem to be pierced with a multitude of small holes. Of this kind is the St. John’s Wort. If a fragment of this be viewed with a good microscope, the supposed holes are found to be vesicles, contained in the thickness of the leaf, and covered with an exceedingly thin membrane; and these are thought to be thereceptacles which contain the essential and aromatic oil peculiar to the plant. The view exhibited by those plants which have down, such as borage, nettles, &c. is exceedingly curious. When examined by a microscope, they appear to be covered with spikes. Those of borage are, for the most part, bent so as to form an elbow; and though really so close, they appear, by the microscope, to be at a considerable distance from each other. The entire appearance is very similar to that of the skin of a porcupine.
There are two kinds of sand, viz. the calcareous and the vitreous: the former, examined with a microscope, resembles large irregular fragments of rock; but the latter appears like so many rough diamonds. In some instances, the particles of sand seem to be highly polished and brilliant, like an assemblage of diamonds, rubies, and emeralds.
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 amultitude 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!
Their wings, all glorious to behold!Bedeck’d with azure, jet, and gold,Wide they display: the spangled dewReflects 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 space, 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 compass.
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 anus, 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 passage 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 attitude as we usually see it when alive. In this frame it must be held up by two threads, the one passing from the anus 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 attitude, 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 glass 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 Butterfly 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 butterfly, 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 butterfly, 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 balls, somewhat of the shape of those used by printers; have them covered with kid-skin, that being the best leather for the purpose. These balls may be made to any size. You must then procure some lamp-black, ground or mixed with drying oil, and having put a small quantity on one of the balls, 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-glass. 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.
“Thus fullers and dyers find that black cloths, of equal thickness with white ones, and hung out equally wet, dry in the sun much sooner than the white, being more readily heated by the sun’s rays. It is the same before a fire; the heat of which sooner penetrates black stockings than white ones, and is apt sooner to burn a man’s shins. Also beer much sooner warms in a black mug set before the fire, than in a white one, or in a bright silver tankard.
“My experiment was this: I took a number of little square pieces of broad cloth from a tailor’s pattern-card, of various colours. There were black, deep blue, lighter blue, green, purple, red, yellow, white, and other colours, or shades of colours. I laid them all out upon the snow in a bright sunshiny morning. In a few hours, (I cannot now be exact as to the time,) the black being warmed most by the sun, was sunk so low as to be below the stroke of the sun’s rays; the dark blue almost as low, the lighter blue not quite so low as the dark, the other colours less as they were lighter; and the quite white remained on the surface of the snow, not having entered it at all.
“What signifies philosophy that does not apply to some use? May we not learn from hence, that black cloths are not so fit to wear in a hot sunny climate, or season, as white ones; because, in such clothes the body is more heated by the sun when we walk abroad, and are at the same time heated by the exercise, which double heat is apt to bring on putrid dangerous fevers?—that soldiers and seamen, who must marchand labour in the sun, should, in the East or West Indies, have a uniform of white?—that summer hats for men or women, should be white, as repelling that heat which gives head-achs to many, and to some the fatal stroke that the French call thecoup de soliel?—that the ladies’ summer hats, however, should be lined with black, as not reverberating on their faces those rays which are reflected upwards from the earth or water?—that the putting a white cap of paper or linen, within the crown of a black hat, as some do, will not keep out the heat, though it would if placed without?—that fruit-walls being blackened, may receive so much heat from the sun in the day-time, as to continue warm, in some degree, through the night, and thereby preserve the fruit from frosts, or forward its growth?—with sundry other particulars, of less or greater importance, that will occur from time to time to attentive minds?”
Thirty Soldiers having deserted, so to place them in a Ring, that you may save any Fifteen you please, and it shall seem the Effect of Chance.
This recreation is usually proposed thus: Fifteen Christians and fifteen Turks being in a ship at sea, in a violent tempest, it was deemed necessary to throw half the number of persons overboard, in order to disburden the ship, and save the rest; to effect this, it was agreed to be done by lot, in such a manner, that the persons being placed in a ring, every ninth man should be cast into the sea, till one half of them were thrown overboard. Now, the pilot, being a Christian, was desirous of saving those of his own persuasion: how ought he therefore to dispose the crew, so that the lot might always fall upon the Turks?
This question may be resolved by placing the men according to the numbers annexed to the vowels in the words of the following verse:—
from which it appears, that you must place four of those you would save first; then five of those you would punish. After this, two of those to be saved, and one to be punished; and so on. When this is done, you must enter the ring, and beginning with the first of the four men you intend to save, count on to nine; and turn this man out to be punished; then count on, in like manner, to the next ninth man, and turn him out to be punished; and so on for the rest.
It is reported that Josephus, the author of the Jewish History, escaped the danger of death by means of this problem;for being governor of Joppa, at the time that it was taken by Vespasian, he was obliged to secrete himself with thirty or forty of his soldiers in a cave, where they made a firm resolution to perish by famine rather than fall into the hands of the conqueror; but being at length driven to great distress, they would have destroyed each other for sustenance, had not Josephus persuaded them to die by lot, which he so ordered, that all of them were killed except himself and another, whom he might easily destroy, or persuade to yield to the Romans.
Three Persons having each chosen, privately, one out of three Things,—to tell them which they have chosen.
Let the three things, for instance, be a ring, a guinea, and a shilling, and let them be known privately to yourself by the vowelsa,e,i, of which the first,a, signifies one, the second,e, two, and the third,i, three.
Then take 24 counters, and give the first person 1, which signifiesa, the second 2, which representse, and the third 3, which stands fori; then, leaving the other counters upon the table, retire into another room, and bid him who has the ring take as many counters from the table as you gave him; he that has the guinea, twice as many, and he that has the shilling four times as many.
This being done, consider to whom you gave one counter, to whom two, and to whom three; and as there were only twenty-four counters at first, there must necessarily remain either 1, 2, 3, 5, 6, or 7, on the table, or otherwise they must have failed in observing the directions you gave them.
But if either of these numbers remain, as they ought, the question may be resolved by retaining in your memory the six following words:—
As, for instance, suppose the number that remained was 5; then the word belonging to it is semita; and as the vowels in the first two syllables of this word areeandi, it shews, according to the former directions, that he to whom you gave two counters has the ring; he to whom you gave three counters, the gold; and the other person, of course, the silver, it being the second vowel which represents 2, and the third which represents 3.
How to part an Eight Gallon Bottle of Wine equally between two Persons, using only two other Bottles, one of Five Gallons, and the other of Three.
This question is usually proposed in the following manner:A certain person having an eight-gallon bottle filled with excellent wine, is desirous of making a present of half of it to one of his friends; but as he has nothing to measure it out with, but two other bottles, one of which contains five gallons, and the other three, it is required to find how this may be accomplished?
In order to answer the question, let the eight-gallon bottle be called A, the five-gallon bottle B, and the three-gallon bottle C; then, if the liquor be poured out of one bottle into another, according to the manner denoted in either of the two following examples, the proposed conditions will be answered.
A Quantity of Eggs being broken, to find how many there were without remembering the Number.
An old woman, carrying eggs to market in a basket, met an unruly fellow, who broke them. Being taken before a magistrate, he was ordered to pay for them, provided the woman could tell how many she had; but she could only remember, that in counting them into the basket by twos, by threes, by fours, by fives, and by sixes, there always remained one; but in counting them in by sevens, there were none remaining. Now, in this case, how was the number to be ascertained?
This is the same thing as to find a number, which being divided by 2, 3, 4, 5, and 6, there shall remain 1, but being divided by 7, there shall remain nothing; and the least number, which will answer the conditions of the question, is found to be 301, which was therefore the number of eggs the old woman had in her basket.
To find the least Number of Weights, that will weigh, from One Pound to Forty.
This problem may be resolved by the means of the geometrical progression, 1, 3, 9, 27, 81, &c. the property of which is such, that the last sum is twice the number of all the rest,and one more; so that the number of pounds being forty, which is also the sum of 1, 3, 9, 27, these four weights will answer the purpose required. Suppose it was required, for example, to weigh eleven pounds by them: you must put into one scale the one-pound weight, and into the other the three and nine-pound weights, which, in this case, will weigh only eleven pounds, in consequence of the one-pound weight being in the other scale; and therefore, if you put any substance into the first scale, along with the one-pound weight, and it stands in equilibrio with the three and nine in the other scale, you may conclude it weighs eleven pounds.
In like manner, to find a fourteen-pound weight, put into one of the scales the one, three, and nine-pound weights, and into the other that of twenty-seven pounds, and it will evidently outweigh the other three by fourteen pounds; and so on for any other weight.
To break a Stick which rests upon two Wine Glasses, without injuring the Glasses.
Take a stick, (see Plate,) AB. fig. 1, of about the size of a common broomstick, and lay its two ends, AB, which ought to be pointed, upon the edges of two glasses placed upon two tables of equal height, so that it may rest lightly on the edge of each glass. Then take a kitchen poker, or a large stick, and give the other a smart blow, near the middle pointc, and the stick AB will be broken, without in the least injuring the glasses: and even if the glasses be filled with wine, not a drop of it will be spilt, if the operation be properly performed. But on the contrary, if the stick were struck on the underside, so as to drive it up into the air, the glasses would be infallibly broken.
A Number of Metals being mixed together in one Mass, to find the Quantity of each of them.
Vitruvius, in his Architecture, reports, that Hiero, king of Sicily, having employed an artist to make a crown of pure gold, which was designed to be dedicated to the gods, suspected that the goldsmith had stolen part of the gold, and substituted silver in its place: being desirous of discovering the cheat, he proposed the question to Archimedes, desiring to know if he could, by his art, discover whether any other metal were mixed with the gold. This celebrated mathematician being soon afterwards bathing himself, observed, that as he entered the bath, the water ascended, and flowed out of it; and as he came out of it, the water descended in like manner: from which he inferred, that if a mass of pure gold,silver, or any other metal, were thrown into a vessel of water, the water would ascend in proportion to the bulk of the metal. Being intensely occupied with the invention, he leaped out of the bath, and ran naked through the streets, crying, “I have found it, I have found it!”
The way in which he applied this circumstance to the solution of the question proposed was this: he procured two masses, the one of pure gold, and the other of pure silver, each equal in weight to the crown, and consequently of unequal magnitudes; then immersing the three bodies separately in a vessel of water, and collecting the quantity of water expelled by each, he was presently enabled to detect the fraud, it being obvious, that if the crown expelled more water than the mass of gold, it must be mixed with silver or some baser metal. Suppose, for instance, in order to apply it to the question, that each of the three masses weighed eighteen pounds; and that the mass of gold displaced one pound of water, that of silver a pound and a half, and the crown one pound and a quarter only: then, since the mass of silver displaced half a pound of water more than the same weight of gold, and the crown a quarter of a pound more than the gold, it appears, from the rule of proportion, that half a pound is to eighteen pounds, as a quarter is to nine pounds; which was, therefore, the quantity of silver mixed in the crown.
Since the time of Archimedes, several other methods have been devised for solving this problem; but the most natural and easy is, that of weighing the crown both in air and water, and observing the difference.
To make a mutual Exchange of the Liquor in two Bottles, without using any other Vessel.
Take two bottles, which are as nearly equal as possible, both in neck and belly, and let one be filled with oil, and the other with water; then clap the one that is full of water dexterously upon the other, so that the two necks shall exactly fit each other; and as the water is heavier than the oil, it will naturally descend into the lower bottle, and make the oil ascend into its place. In order to invert the bottle of water without spilling the contents, place a bit of thin writing paper over the mouth of the bottle; and when you have placed the bottle in the proper position, draw out the paper quickly and steadily.
How to make a Peg that will exactly fit Three different Holes.
Let one of the holes be circular, the other square, and the third an oval; then it is evident, that any cylindrical body,of a proper size, may be made to pass through the first hole perpendicularly; and if its length be just equal to its diameter, it may be passed horizontally through the second, or square hole; also, if the breadth of the oval be made equal to the diameter of the base of the cylinder, and its longest diameter equal to the diagonal of it, the cylinder, being put in obliquely, will fill it as exactly as any of the former.
To place Three Sticks, or Tobacco Pipes, upon a Table, in such a manner that they may appear to be unsupported by any thing but themselves.
Take one of the sticks, or pipes, (see Plate,) AB, fig. 2, and place it in an oblique position, with one of its ends, B, resting on the table; then put one of the other sticks, as CD, across this in such a manner that one end of it, D, may be raised, and the other touch the table at C. Having done this, take the third stick E, and complete the triangle with it, making one of its ends E rest on the table, and running it under the second, CD, in such a manner that it may rest upon the first, AB; then will the three sticks, thus placed, mutually support each other; and even if a small weight be laid upon them, it will not make them fall, but strengthen, and keep them firmer in their position.
How to prevent a heavy Body from falling, by adding another heavier Body to it on that side towards which it inclines.
On the edge of a shelf, or table, or any other horizontal surface, lay a key, (see Plate,) CD, fig. 3, in such a manner, that, being left to itself, it would fall to the ground; then, in order to prevent this, take a crooked stick DFG, with a weight, H, at the end of it; and having inserted one end of the stick in the open part of the key, at D, let it be so placed, that the weight H may fall perpendicularly under the edge of the table, and the body by these means will be effectually prevented from falling.
The same thing may be done by hanging a weight at the end of a tobacco-pipe, a stick, or any other body; the best means of accomplishing which will be easily known by a few trials.
To make a false Balance, that shall appear perfectly just when empty, or when loaded with unequal Weights.
Take a balance, (see Plate,) DCE, fig. 4, the scales and arms of which are of such unequal weights and lengths, that the scale A may be in proportion to the scale B, as the lengthof the arm CE is to the length of the arm CD; then will the two scales be exactly in equilibrio about the point C; and the same will be the case, if the two arms CD, CE, are of equal length, but of unequal thickness, provided the thickness of CD is to that of CE, as the weight of the scale B is to that of A.
For example; suppose the arm CD is equal to three ounces, and the arm CE to two, and that the scale B weighs three ounces, and the scale A two; then the balance, in this case, will be exactly true when empty; and if a weight of two pounds be put into the scale A, and one of three pounds into B, they will still continue in equilibrio. But the fallacy in this, and all other cases of the same kind, may be easily detected, in shifting the weights from one scale to the other.
How to lift up a Bottle with a Straw, or any other slight Substance.
Take a straw, (see Plate,) AB, fig. 5, which is not broken or bruised, and bend one end of it into a sharp angle ABC; then if this end of the straw be put into the bottle, so that the bent part of it may rest against either of its sides, you may take the other end in your hand, and lift up the bottle by it without breaking the straw; and this will be the more easily done, according as the angular part of the straw approaches nearer to that which comes out of the bottle.
How to make a Cone, or Pyramid, move upon a Table without Springs, or any other artificial Means.
Take a cone, or pyramid, of paper, or any other light substance, and put a beetle, or some such small insect, privately under it; then, as the animal will naturally endeavour to free itself from its captivity, it will move the cone towards the edge of the table, and as soon as it comes there, will immediately return for fear of falling; and by moving backwards and forwards in this manner, will occasion much diversion to those who are ignorant of the cause.
To make a Pen, which holds One Hundred Sheep, hold double the Number, by only adding two Hurdles more.
In the first pen, or that which holds one hundred sheep, the hurdles must be so disposed, that there shall be only one at the top and bottom, and the rest in equal numbers on each side; then it is obvious, that if one hurdle more be placed at each end, the space enclosed must necessarily be double the former, and consequently will hold twice the number of sheep.
An ingenious Recreation, called the Two Communicative Busts.
Take two heads of plaster of Paris, and place them on pedestals on the opposite sides of a room. Then take a tin tube, of an inch in diameter, and let it pass from the ear of one head through the pedestal, and under the floor, to the mouth of the other, observing, that the end of the tube which is next the ear of one head, should be considerably larger than that which comes to the mouth of the other.
The whole being so disposed that there may be no suspicion of a communication, let any person speak with a low voice into the ear of one bust, and the sound will be distinctly heard by anyone who shall place his ear to the mouth of the other; and if there be two tubes, one going to the ear, and the other to the mouth of each head, two persons may converse together, by applying their mouth and ear reciprocally to the mouth and ear of the busts, without being heard by any other persons in the room.
Another Recreation of the same kind, called the Oracular Head.
Place a bust on a pedestal in the corner of a room, and let there be two tubes, one of which goes from the mouth, and the other from the ear of the bust, through the pedestal and floor, to an under apartment.
Then if a person be placed in the under room, by applying his ear to one of the tubes as soon as a proper signal is given, he will hear any question that is asked, and can immediately return an answer; and if wires be contrived to go from the under jaw and eyes of the bust, they may be made to move at the same time, and by these means appear to deliver the answer.
It was by a contrivance of this kind, that Don Antonio de Moreno so much astonished the celebrated Knight of the Woeful Countenance, and his facetious squire Sancho Panza, by resolving certain doubts proposed by the former concerning his adventures in the cave of Montesinos, and the disenchantment of my lady Dulcinea.
How to make a Piece of Metal, or any other heavy Body, swim upon the Surface of Water, like a Cork.
The specific gravity of water is inferior to that of metals, and consequently water, absolutely speaking, cannot support a ball of iron or lead; but if this ball be flattened, and beat out to a very thin plate, it will, if put softly upon still water, be prevented from sinking, and will swim upon its surface like any light substance. In like manner, if a fine steel needle,which is perfectly dry, be placed gently upon some still water in a vessel, it will float upon the surface without sinking.
But if you would have a metallic body of large dimensions to swim upon water, you must reduce it into a thin concave plate, like a kettle; in which case, as the air it contains, together with the body itself, weighs less than the same bulk of water, it cannot possibly sink; as is evident from large copper boats, or pontoons, by which whole armies have frequently passed over rivers without danger.
If this concave metallic vessel be placed upon the water with its mouth downwards, it will swim as before, and the contained air will keep the bottom of it from being wet; for that the water will not rise into any hollow vessel which is immersed into it, may be made evident thus:—Take a glass tumbler, and plunge it into water with its mouth downwards, and you will find, when you take it out, that the inside of the vessel is perfectly dry, so that if a live coal were put there, it would not be extinguished.
A curious Experiment, to prove that Two and Two do not make Four.
Take a glass vessel with a long narrow neck, which, being filled with water, will hold exactly a quart; then put into this vessel a pint of water, and a pint of acid of vitriol, and you will presently perceive, that the mixture will not fill the vessel, as it did when a quart of water only was put into it. The acid of vitriol must be put in gradually, by little and little at a time, mixing each portion with the water before you add more, by shaking the bottle, and leaving its mouth open, otherwise the bottle will burst. The mixture in this case also possesses a considerable degree of heat, though the two ingredients of themselves are perfectly cold; and this phenomenon is not to be accounted for, by supposing that the acid of vitriol is received into the pores of the water, for then a small portion of it might be absorbed by the water, without augmenting its bulk, which is known not to be the case; but the very form of the bodies in this experiment is changed, there being, as Dr. Hooke, who first noticed the fact, observes, an actual penetration of dimensions. Chemistry also furnishes a number of other instances, which shew that two bodies, when mixed together, possess less space than when they are separate.
An ingenious Method of Secret Writing, by means of corresponding Spaces.
Take two pieces of pasteboard, or stiff paper, out of which cut a number of oblong figures, at different distances fromeach other, as in the following example. Keep one of these pieces for yourself, and give one to your correspondent; and when you are desirous of sending him any secret intelligence, lay the pasteboard upon a sheet of paper of the same size, and in the spaces which are cut out, write what you would have him only to understand, and fill up the intermediate parts of the paper with something which makes with these words a different sense. Then, when your correspondent receives this letter, by applying it to his pasteboard, he will be able to comprehend your meaning.
Example.
A curious Experiment, which depends on an Optical Illusion.
On the bottom of the vessel, (see Plate,) AIBD, fig. 6, place three pieces of money, as a half-crown, a shilling, and a sixpence; the first at E, the second at F, and the third at G. Then let a person be placed with his eye at H, so that he can see no farther into the vessel than I; and tell him, that by pouring water into the vessel, you will make him see three different pieces of money, which he may observe are not poured in with the water.
For this purpose, desire him to keep himself steady in the same position, and, pouring the water in gently, that the pieces of money may not be moved out of their places, when it comes up to K, the piece G will become visible to him; when it comes up to L, he will see the two pieces G and F; and when it rises to M, all the three pieces will become visible: the cause of which is owing to the refraction of the rays of light, in their passage through the water; for while the vessel is empty, the ray HI will proceed in a straight line; but in proportion as it is filled with water, the ray will be bent into the several directions NG, OF, PE, and by these means the pieces are rendered visible.
A curious Experiment, of nearly the same kind as the last, called Optical Augmentation.
Take a large drinking-glass, of a conical figure, and having put a shilling into it, fill the glass about half full with water;then place a plate on the top of it, and turn it quickly over, so that the water may not get out. This being done, look through the glass, and you will now perceive a piece of money of the size of half-a-crown; and somewhat higher up, another piece of the size of a shilling. But if the glass be entirely filled with water, the large piece at the bottom only will be visible.
This phenomenon is occasioned by your seeing the piece through the conical surface of the water, at the side of the glass, and through the flat surface at the top of the water, at the same time; for the conical surface dilates the rays, and makes the piece appear larger, while the flat surface only refracts them, and occasions the piece to be seen higher up in the glass, but still of its natural size.
Another curious Experiment, called Optical Subtraction.
Against the wainscot of a room fix three small pieces of paper, as A, B, C, fig. 7, (see Plate,) about a foot and a half or two feet asunder, at the height of your eye; and placing yourself directly before them, about five times the distance from them that the papers are from each other, shut one of your eyes and look at them with the other, and you will then see only two of those papers, suppose A and B; but altering the position of your eye, you will now see the third, and one of the first, suppose A; and by altering its position a second time, you will see B and C, but in neither case all three of them together.
The cause of this phenomenon is, that one of the three pencils of rays, which come from these objects, falls on the optic nerve at D, whereas, to produce distinct vision, it is necessary that the rays of light fall on some part of the retina E, F, G, H.
From this experiment, the use of having two eyes may be easily perceived; for he that has only one can never see three objects placed in this position; or all the parts of one object, of the same extent, without altering the situation of his eye.
An Optical Experiment, shewing how to produce an Artificial Rainbow.
In any room which has a window facing the sun, suspend a glass globe, filled with water, by a string which runs over a pulley, so that the sun’s rays may fall directly upon it; then drawing the globe gradually up, when it comes to the height of about forty degrees above the horizon, you will see, by placing yourself in a proper situation, the glass tinged with a purple colour; and by drawing it gradually higher up, theother prismatic colours, blue, green, yellow, and red, will successively appear; but after this they will all vanish, till the globe is raised to about fifty degrees, when they will again be seen, but in an inverted order, the red appearing first, and the blue, or violet, last; and when the globe comes up to little more than fifty-four degrees, they will entirely vanish.
These appearances serve to illustrate the phenomena of natural rainbows, of which there are generally two, the one being about eight degrees above the other, and the order of their colours inverted, as in this experiment; the red being the uppermost colour in the lower bow, and the violet in the other.
An artificial Rainbow may also be produced as follows.
Take some water in your mouth, and turn your back to the sun; then if it be blown forcibly out against some dark or shady place, you will see the drops formed by the beams of the sun into an apparent rainbow, which, however, soon vanishes.
A curious Optical Illusion, produced by means of a Concave Mirror.
Take a glass bottle, (see Plate,) ABC, fig. 8, and fill it with water to the point B; leave the upper part, BC, empty, and cork it in the common manner; place this bottle opposite a concave mirror, and beyond its focus, so that it may appear reversed; then if you place yourself still farther from the mirror, the bottle will appear to you in the situationa b c.
And in this apparent bottle it is remarkable, that the water, which, according to the laws of catoptrics, and all other experiments of this kind, should appear ata b, appears, on the contrary, atb c, the parta bseeming to be entirely empty.
And if the bottle be inverted, and placed before the mirror, as in the under part of the figure, its image will appear in its natural erect position, but the water, which is in reality atb c, will appear ata b.
And if, while the bottle is inverted, it be uncorked, and the water suffered to run gently out, it will appear, that while the part BC is emptying, the parta bin the image is filling; and if, when the bottle is partly empty, some drops of water fall from the bottom A, towards BC, it seems in the image as if there were formed at the bottom of the parta bbubbles of air arising fromatob, which is the part that seems full.
The circumstances most remarkable in this experiment, are, first, not only to see an object where it is not, but also where its image is not; and, secondly, that of two objects, whichare really in the same place, as the surface of the bottle and the water it contains, the one should be seen at one place, and the other at another; and also that the bottle should be seen in the place of its image, and the water where neither it nor its images are.
It is, however, to be noted, that if any coloured liquor be put into the bottle instead of water, no such illusion will take place.
There is one phenomenon more of this kind, which ought not to be omitted; for though it be common enough, it is also extremely pleasing, and easy to be performed.
If you place yourself before a concave mirror, at a proper distance, your figure will appear inverted; and if you stretch out your hand towards the mirror, you will perceive another hand, which seems to meet and join it, though imperceptible to the touch.
And if, instead of your hand, you make use of a drawn sword, and present it in such a manner that its point may be directed towards the focus of the rays reflected by the mirror, another sword will appear, and seem to encounter that in your hand. But it is to be observed, that to make this experiment succeed well, you must have a mirror of at least a foot in diameter, that you may see yourself in part; and if you have a mirror large enough to see your whole person, the illusion will be still more striking.
How to make a violent Tempest, by means of artificial Rain and Hail.
Make a hollow cylinder of wood, very thin at the sides, about eight or ten inches long, and two or three feet in diameter. Divide its inside into five equal partitions, by means of boards of about six inches wide; and let there be a space between them and the wooden circle, of about one-sixth of an inch; observing, that the boards are to be placed obliquely to each other.
This being done, put into the cylinder four or five pounds of leaden shot, of a size that will easily pass through the opening left for this purpose; then turn the cylinder on its axis, and the sound of the machine, when in motion, will represent that of rain, which will increase with the velocity of the motion; and if a larger sort of shot be used, it will produce the sound of hail.
Magic Square.
This, in arithmetic, is a square figure made up of numbers in arithmetical proportion, so disposed in parallel and equalranks, that the sums of each row, taken either perpendicularly, horizontally, or diagonally, are equal: thus—
Magic squares seem to have been so called, from their being used in the construction of talismans.
Take another instance:—
where every row and diagonal in the magic square, makes just the sum 65, being the same as the two diagonals of the natural square.
It is probable that these magic squares were so called, both because of this property in them, viz. that the ranks in every direction make the same sum, which appeared extremely surprising, especially in the more ignorant ages, when mathematics passed for magic; and because also of the superstitious operations they were employed in, as, the construction of talismans, &c.; for, according to the childish philosophy of those days, which ascribed virtues to numbers, what might not be expected from numbers so seemingly wonderful? The magic square was held in great veneration among the Egyptians, and the Pythagoreans their disciples, who, to add more efficacy and virtue to this square, dedicated it to the then known seven planets, divers ways, and engraved it upon a plate of the metal that was esteemed in sympathy with the planet. The square, thus dedicated, was enclosed by a regular polygon, inscribed into a circle, which was divided into as many equal parts as there were units in the side of the square; with the names of the angels of the planet, and the signs of the zodiac written upon the void spaces between the polygon and the circumference of the circumscribed circle. Such a talisman,or metal, they vainly imagined would, upon occasion, befriend the person who carried it about him. To Saturn, they attributed the square of 9 places, or cells, the side being 3, and the sum of the number in every row 15: to Jupiter, the square of 16 places, the side being 4, and the amount of each row 34: to Mars, the square of 25 places, the side being 5, and the amount of each row 65: to the Sun, the square with 36 places, the side being 6, and the sum of each row 111: to Venus, the square of 49 places, the side being 7, and the amount of each row 175: to Mercury, the square with 64 places, the side being 8, and the sum of each row 260: and to the Moon, the square of 81 places, the side being 9, and the amount of each row 369. Finally, they attributed to imperfect matter, the square with 4 divisions, having 2 for its side: and to God, the square of only one cell, the side of which is also an unit, which, multiplied by itself, undergoes no change.
It never was the intention of the compiler of this work to give an account ofallthe curious and remarkable persons that have figured on this mortal stage, but only such as have not been usually incorporated in works of this kind; it has been thought advisable, however, to make the following additions to this department, with which, it is hoped, the reader will be amused and instructed.
An account ofthat celebrated extraordinary Genius, John Henderson, B. A.—Of this much celebrated young man, whose extraordinary acquirements attracted the notice, and even commanded the respect, of Dr. Johnson, several accounts have been published, and much eulogium has been pronounced. By many he has been supposed to emulate the variety and extent of knowledge possessed by the admirable Crichton; and, like that eccentric character, he has left little for posterity to form a judgment of the truth of those praises which have been bestowed upon him.
He was born at Bellegarance, near Limerick, in the kingdom of Ireland, on the 27th of March, 1757, of very pious and respectable parents. He received his education among the Methodists; and at eight years of age he understood Latin so well, as to be able to teach it at Kingswood school. At twelve, he taught the Greek language, in the school of Trevecka, in Wales, to men, several of whom were double his age. The governor of the college, at that time, was the Rev. Mr. Fletcher, late Vicar of Madeley, a clergyman highly distinguished for the fervour of his piety and the liveliness of his imagination. Some disagreement taking place with this gentleman and those who had the superintendence of the college, he was dismissed, together with young Henderson, who soon after, at the age of twenty-four years, went to Oxford, was entered of Pembroke college, and, in due time, took the degree of Bachelor of Arts. From the time of his entrance into the college, his life passed with little variety, and no adventure. His thirst after knowledgeappears to have been unabated and unobtruded; he was admired, and generally respected; and he acquired habits, some of which brought him into the notice of the world, almost as much as his talents. Some of these traits of character having been depicted by one who appears to have known him well, we shall give nearly in the words of their author, who was also of Pembroke college, and thus describes Mr. Henderson’s appearance when he was first introduced to him.
His clothes were made in a fashion peculiar to himself; he wore no stock nor neckcloth; his buckles were so small as not to exceed the dimensions of an ordinary knee-buckle, at a time when very large buckles were in vogue. Though he was then twenty-four years of age, he wore his hair like a schoolboy of six.
Mr. H.’s temper was mild, placable, and humane. He professed that he was ready to serve any individual as far as lay in his power. His benevolence knew no bounds; and his liberality was so diffusive, that it submitted with difficulty to the circumscription of a narrow income. He was fond of society, and well qualified to shine in it. He was frank, open, and communicative, averse to suspicion, and untinctured with pride and moroseness. His mode of life was singular. He generally retired to rest about daybreak, and rose in the afternoon; a practice, however, that was frequently interrupted by the occasional attendance he was obliged to give to the morning service of the college chapel. He spent a great part of the day in smoking; and, except when in company, he usually read while he smoked.
With regard to his moral and religious character, he was a pattern highly worthy of imitation. He shewed a constant regard to the obligations of honour and justice; and commended, both by precept and example, an attention to moral rectitude in all its ramifications. He had the courage to reprove vice and immorality wherever they appeared; and though he was sometimes treated on these occasions with contumely and insult, he bore with a moderation truly christian, so ill a return for his well-meant endeavours. He was perfectly acquainted with the religious dogmas of every different sect, and could readily detect the respective fallacies of each.
His abilities and understanding were eminently conspicuous. His penetration was so great, as to have the appearance of intuition. So retentive was his memory, that he remembered whatever he heard; and this faculty of recollection, combined with a pregnancy of imagination and solidity of judgment, enabled him to acquire an amazing fund of erudition and argument, a fund ready at every call, and adequate to every emergency.
His learning was deep and multifarious. He was admirably skilled in logic, ethics, metaphysics, and scholastical theology. He had studied the healing art with particular attention, and added to a sound theoretic knowledge of it, some degree of practice. His skill in this art he rendered subservient to his philanthropy; for he gratuitously attended the valetudinarian poor wherever he resided, and favoured them with medical advice, as well as pecuniary assistance. He had a competent knowledge of geometry, astronomy, and every branch of natural and experimental philosophy. He was well acquainted with the civil and canon laws, and the law of nature and nations. In classical learning and the belles lettres, he was by no means deficient. He was master of the Greek and Latin, as well as of several modern languages.
He spoke of physiognomy as a science with all the confidence of a Lavater. He pretended to a knowledge of the occult sciences of magic and astrology. Whether this was or was not a mere pretence, we leave to the judgment of the enlightened reader. Suffice it to remark, that his library was well stored with the magical and astrological books of the last century.
His talents of conversation were so attractive, so various and multiform, that he was a companion equally acceptable to the philosopher and the man of the world, to the grave and the gay, the learned and the illiterate, the young and the old of both sexes.
Henderson, like many other great characters, had his little peculiarities. The following remarkable custom was frequently observed by him before he retired to repose:—He used to strip himself naked as low as the waist, and taking his station at a pump near his rooms, would completely sluice his head and the upper part of his body; after which he would pump over his shirt so as to make it perfectly wet, and putting it on in that condition, would immediately go to bed. This he jocularly termed “an excellent cold bath.” The latter part of this ceremony, however, he did not practise with such frequency as the former.
There is great reason to think that he materially injured a good natural constitution by the capriciousness of his conduct, and particularly by the bold and strange experiments which he was accustomed to be always making upon himself. He used to swallow large quantities of noxious drugs, and quicksilver; and what seemed very rash, such doses of opium, like the famous Psalmanazar, as were apparently sufficient to send a dozen men to the grave.
His external appearance was as singular as his habits of life. He would never suffer his hair to be strewed with white dust, (to use his own expression,) daubed with pomatum, ordistorted by the curling-irons of the friseur. Though under two-and-thirty years of age at his death, he walked, when he appeared in public, with as much apparent caution and solemnity as if he had been enfeebled by the co-operation of age and disease.
His learning was truly astonishing: scarcely a book, however obscure, could be mentioned, but he could give some account of it; nor any subject started, but he could engage in the discussion of it. He had a very deep and extensive knowledge of the learned languages; the Arabic and Persian were familiar to him. He delighted much in parodoxes, and his intimate acquaintance with the schoolmen brought him much into the habit of disputation. At one time he was profoundly plunged in the study of the writings of the illumined Jacob Behmen; and he then, and afterwards, warmly vindicated the system, if system it may be called, of that wonderful man.
Many surprising cures, accomplished by means of his prescriptions, might be produced: one upon a very ingenious and valuable youth in the neighbourhood of Taunton, deserves notice, as the patient had been in an alarming decline for the long space of four years, and seemed just verging to thehouse appointed for all living. Mr. Henderson attended him with the utmost assiduity and tenderness, and saw, at last, his patient in a state of perfect health. The benevolent man had then a presentiment of his own approaching change, and addressed himself to his young friend to this effect: “My young and beloved friend, your cure, in all human probability, is now certain, and you will live, but I shall die. Remember, to be pious, is to be happy; to be sober, is to live long; and to practise the moral virtues, is to become great.”—Mr. Henderson died a few months after, November 2, 1788. His connections with the Methodists continued till the last. The late venerable and truly great John Wesley had a very great regard for him. The father of Mr. Henderson was for some time one of Mr. Wesley’s itinerant preachers in Ireland, from whence he came over to Bristol, and soon after settled at Hanham, a village about four miles from that city, where he set up a very respectable boarding-school, for the instruction of youth in classical learning. A few years previous to his death, he left off keeping school, and opened his house for the reception of insane persons. The death of his favourite and only child, made a deep and lasting impression on him; and so strongly was he affected by his loss, that he caused the corpse to be taken up again some days after the interment, to be satisfied whether he was really dead. The following is taken from the sermon that was preached by his friend, Mr. Agutter:—“When we consider the strength of his mind, thevariety of his knowledge, and the excellencies of his soul, we may justly declare, that he was a truly great character, and an original genius. The partiality of friendship must give place to the sacredness of truth; and I do not mean to describe him as a perfect man: his friends lamented his failings, and he himself sincerely repented of them. The God of heaven does not require more of his fallen creatures; and let us remembernot to be extreme to mark all that is done amiss, seeing we have much cause for shame and repentance. He was a meek sufferer through this world of misery; a sincere and contrite penitent for time mispent and talents misapplied; an humble believer in Christ his Saviour. I saw him in his last sufferings; I heard his last words; he languished under extreme weakness; he laboured under most grievous pains. He was wonderfully patient and resigned; forhe knew in whom he believed, and his hope was full of immortality. He prayed with uncommon fervour to his good God, even to Jesus Christ, in whom all his hopes were placed; and “without whom,” says he, “heaven would be no heaven to me.” Death was the wished-for messenger, whom he earnestly expected. Three days before that awful event, his pulse ceased to beat, andthe sight of his eyes went from him—the last struggle is over;the bitterness of death is past. There was an humble dignity and composure in thathour of trial, worthy the man and Christian.Let me die the death of the righteous, and let my last end, or more properly,my hereafter, be like his.”