To Find The Difference Between Two Numbers The Greatest Of Which Is
unknown.
Take as many nines as there are figures in the smallest number, and
subtract that sum from the number of nines. Let another person add
that difference to the largest number, and, taking away the first
figure of the amount, add it to the last figure, and that sum will be
the difference of the two numbers.
For example: Robert, who is 22, tells George, who is older, that he
deducts 22 from 99, and the difference, which is 77, he tells George
to add to his age, and to take away the first figure from the amount,
and add it to the last figure, and that last sum will be the
difference of their ages. Thus, the difference between
Robert's age and 99, is 77
To which George adding his age 35
----
The sum will be 112
----
12
1
----
Then by taking away the first figure, 1, }
and adding it to the last figure, 2, } 13
the sum is }
Which added to Robert's age 22
----
Gives George's age, which is 35
More
-
The Solar Magic Lantern
Make a box, a foot high, eighteen inches wide, and about three inches deep. Two of the opposite sides of this box must be quite open, and in each of the other sides let there be a groove wide enough to admit a stiff paper or pasteboard. You fasten t... The Sublimated Tree
Into a large glass jar inverted upon a flat brick tile, and containing near its top a branch of fresh rosemary, or any other such shrub, moistened with water, introduce a flat thick piece of heated iron, on which place some gum benzoin, in gross pow... The Talking Busts
Procure two busts of plaster of Paris; place them on pedestals, on the opposite sides of the room. Let a thin tube, of an inch diameter, pass from the ear of one head through the pedestal, under the floor, and go up to the mouth of the other; taking... The Ten Duplicates
Select any twenty cards; let any person shuffle them; lay them by pairs on the board, without looking at them. You next desire several persons, (as many persons as there are pairs on the table,) each to look at different pairs and remember what card... The Three Magical Parties
Offer the long card to a person, that he may draw it, and replace it in any part of the pack he pleases. Make the pass, and bring that card to the top. Next divide the pack in three parcels, putting the long card in the middle heap. You then ask the... The Transmuted Cards
In a common pack of cards let the ace of hearts and nine of spades be something larger than the rest. With the juice of lemon draw over the ace of hearts a spade, large enough to cover it entirely, and on each side draw four other spades. Present... The Transposable Pieces
Take two guineas and two shillings, and grind part of them away, on one side only, so that they may be but half the common thickness; and observe, that they must be quite thin at the edge; then rivet a guinea and a shilling together. Lay one of thes... The Travelling Of Light
Light travels at the rate of a hundred and fifty thousand miles in a single second; and it is seven minutes in passing from the sun to the earth, which is nearly a distance of seventy millions of miles. Such is the rapidity with which these rays dar... The Travelling Of Sound Experimentally Proved
There is probably no substance which is not in some measure a conductor of sound; but sound is much enfeebled by passing from one medium to another. If a man, stopping one of his ears with his finger, stop the other also by pressing it against the e... The Unconscious Incendiary
Let a person stand upon a stool made of baked wood, or upon a cake of wax, and hold a chain which communicates with the branch. On turning the wheel he will become electrified; his whole body forming part of the prime conductor; and he will emit spa... The Water Sun
Provide two portions of a hollow sphere, that are very shallow; join them together in such a manner that the hollow between them be very narrow. Fix them vertically to a pipe from whence a jet proceeds. Bore a number of small holes all around that p... Three Objects Discernible Only With Both Eyes
If you fix three pieces of paper against the wall of a room at equal distances, at the height of your eye, placing yourself directly before them, at a few yards' distance, and close your right eye, and look at them with your left, you will see only ... To Cast Figures In Imitation Of Ivory
Make isinglass and strong brandy into a paste, with powder of egg-shells, very finely ground. You may give it what colour you please; but cast it warm into your mould, which you previously oil over. Leave the figure in the mould till dry, and you wi... To Cause A Brilliant Explosion Under Water
Drop a piece of phosphorus, the size of a pea, into a tumbler of hot water; and, from a bladder furnished with a stop-cock, force a stream of oxygen directly upon it. This will afford a most brilliant combustion under water. ... To Change Blue To White
Dissolve copper filings in a phial of volatile alkali; when the phial is unstopped, the liquor will be blue; when stopped, it will be white. ... To Change The Cards Which Several Persons Have Drawn From The Pack
On the top of the pack put any card you please--suppose the queen of clubs; make the pass, bring that card to the middle of the pack, and offer it to a person to draw. Then, by cutting the cards, bring the queen again to the middle of the pack. Make... To Construct Paper Balloons
Take several sheets of silk paper; cut them in the shape of a spindle; or, to speak more familiarly, like the coverings of the sections of an orange; join these pieces together, into one spherical or globular body, and border the aperture with a rib... To Construct The Camera Obscura
Make a circular hole in the shutter of a window, from whence there is a prospect of some distance; in this hole place a magnifying glass, either double or single, whose focus is at the distance of five or six feet; no light must enter the room but t... To Discover The Card Which Is Drawn By The Throw Of A Die
Prepare a pack of cards, in which there are only six sorts of cards. Dispose these cards in such manner that each of the six different cards shall follow each other, and let the last of each suite be a long card. The cards being thus disposed, it fo... To Diversify The Colours Of Flowers
Fill a vessel of what size or shape you please, with good rich earth, which has been dried and sifted in the sun, then plant in the same a slip or branch of a plant bearing a white flower, (for such only can be tinged,) and use no other water to wat... To Draw Easily And Correctly A Landscape Or Any Other Object
without being obliged to observe the Rules of Perspective, and without the Aid of the Camera Obscura. Procure a box of pasteboard, A B C D, Fig. 13, of about a foot and a half long, and made in the shape of a truncated pyramid, whose base, B D F... To Drive Or Ram Rockets Rockets Are Filled Hollow Otherwise They
would not ascend, and there is not a part that requires greater attention than this stage of the process. One blow more or less with the mallet will spoil the ascent. The charge of rockets must always be driven above the piercer, and on it must be ... To Extract The Silver Out Of A Ring That Is Thick Gilded So That The
Gold may remain entire. Take a silver ring that is thick gilded. Make a little hole through the gold into the silver; then put the ring into aqua fortis, in a warm place: it will dissolve the silver, and the gold will remain whole. ... To Fill A Bladder With Hydrogen Gas
Apply a bladder, previously wetted and compressed, in order to squeeze out all the common air, to the piece of tobacco-pipe inserted in the cork stopper of the phial, (as described in the experiment above.) The bladder will thus be filled with hydro... To Find How Many Square Yards It Would Require To Write All The
Changes of the Twenty-four Letters of the Alphabet, written so small, that each Letter should not occupy more than the hundredth part of a square Inch. By adopting the plan of the preceding article, the changes of the twenty-four letters will be fo... To Find The Difference Between Two Numbers The Greatest Of Which Is
unknown. Take as many nines as there are figures in the smallest number, and subtract that sum from the number of nines. Let another person add that difference to the largest number, and, taking away the first figure of the amount, add it to the la... To Find The Number Of Changes That May Be Rung On Twelve Bells
Multiply the numbers from 1 to 12 continually into each other, as follow: and the last product will give the number required. 1 2 -- 2 3 -- 6 4 ... To Fire Rockets Without Sticks You Must Have A Stand Of A Block
of wood, a foot diameter, and make the bottom flat, so that it may stand steady: in the centre of the top of this block draw a circle two inches and a half diameter, and divide the circumference of it into three equal parts; then take three pieces of ... To Fire Sky-rockets Under Water
You must have stands made as usual, only the rails must be placed flat instead of edgewise, and have holes in them for the rocket-sticks to go through; for if they were hung upon hooks, the motion of the water would throw them off: the stands being ... To Fix One Rocket On The Top Of Another When Sky-rockets Are Fixed
one on the top of another, they are called towering rockets, on account of their mounting so very high. Towering rockets are made after this manner: Fix on a pound rocket a head without a collar; then take a four-ounce rocket, which may be headed or b... To Fix Several Rockets To The Same Stick Two Three Or Six
sky-rockets, fixed on one stick, and fired together, make a grand and beautiful appearance; for the tails of all will seem but as one of an immense size, and the breaking of so many heads at once will resemble the bursting of an air-balloon. The manag... To Form Figures In Relief On An Egg
Design on the shell any figure or ornament you please, with melted tallow, or any other fat oily substance; then immerse the egg into very strong vinegar, and let it remain till the acid has corroded that part of the shell which is not covered with ... To Give A Ghastly Appearance To Persons In A Room
Dissolve salt in an infusion of saffron and spirits of wine. Dip some tow in this solution, and, having set fire to it, extinguish all other lights in the room. ... To Give Silver The Colour Of Gold
Dissolve in common aqua fortis as much silver as you please. To eight ounces of silver, take four ounces of hepatic aloes, six ounces of turmeric, and two ounces of prepared tutty, that has been several times quenched in urine. Put these to the solu... To Give Silver-plate A Lustre
Dissolve alum in a strong ley, and scum it carefully; then mix it up with soap, and wash your silver utensils with it, using a linen rag. ... To Load Air Balloons With Stars Serpents &c &c When You Fill
your shells, you must first put in the serpents, rains, &c., or whatever they are composed of, then the blowing powder; but the shells must not be quite filled. All those things must be put in at the fuse-hole, but marrons being too large to go in at ... To Make A Ring Suspend By A Thread After The Thread Has Been
burned. Soak a piece of thread in urine, or common salt and water. Tie it to a ring, not larger than a wedding-ring. When you apply the flame of a candle to it, it will burn to ashes, but yet sustain the ring. ... To Make A Rocket Form An Arch In Rising Having Some Rockets Made
headed according to fancy, and tied on their sticks, get some sheet tin, and cut it into round pieces about three or four inches diameter; then on the stick of each rocket, under the mouth of the case, fix one of these pieces of tin 16 inches from the... To Make An Eolian Harp
This instrument may be made by almost any carpenter: it consists of a long narrow box of very thin deal, about five or six inches deep, with a circle in the middle of the upper side, of an inch and a half in diameter, in which are to be drilled smal... To Make An Old Gold Chain Appear Like New
Dissolve sal ammoniac in urine, boil the chain in it, and it will have a fine gold colour. ... To Make Any Number Divisible By Nine By Adding A Figure To It
If (for example) the number named be 72,857, you tell the person who names it to place the number 7 between any two figures of that sum, and it will be divisible by 9; for if any number be multiplied by 9, the sum of the figures of the product will ... To Make Artificial Coruscations
There is a method of producing artificial coruscations, or sparkling fiery meteors, which will be visible, not only in the dark but at noon-day, and that from two liquors actually cold. The method is this:--Fifteen grains of solid phosphorus are to ... To Make Beautiful Transparent Coloured Water
The following liquors, which are coloured, being mixed, produce colours very different from their own. The yellow tincture of saffron, and the red tincture of roses, when mixed, produce a green. Blue tincture of violets, and brown spirit of sulphur,... To Make Crackers
Cut some stout cartridge-paper into pieces three inches and a half broad, and one foot long; one edge of each of these pieces fold down lengthwise about three-quarters of an inch broad; then fold the double edge down a quarter of an inch, and turn t... To Make Luminous Writing In The Dark
Fix a small piece of solid phosphorus in a quill, and write with it upon paper; if the paper be carried into a dark room, the writing will appear beautifully luminous. ... To Make Moulds Of Horn
If you wish to take the impression of any coin, medal, &c., previously anoint it with oil; then lay the horn shavings over it in its softened state. When dry, the impression will be sunk into the horn; and this will serve as a mould to re-produce, e... To Make Pictures Of Birds With Their Natural Feathers
First take thin board or panel, of deal or wainscot, well seasoned, that it may not shrink; then paste white paper smoothly on it, and let it dry; if the colour of the wood show through, paste a second paper over it. When the paper is dry, get ready... To Make Pomatum With Water And Wax
Water and wax are two substances that do not naturally unite together; therefore, to those who witness the following process, without knowing the cause, it will have the appearance of marvellous. Put into a new glazed earthen pot, six ounces of rive... To Make Several Rockets Rise Together Take Six Or Any Number Of
sky-rockets, of any size; then cut some strong packthread into pieces of three or four yards long, and tie each end of these pieces to a rocket in this manner: Having tied one end of the packthread round the body of one rocket, and the other end to... To Make Squibs And Serpents
First make the cases, of about six inches in length, by rolling slips of stout cartridge-paper three times round a roller, and pasting the last fold; tying it near the bottom as tight as possible, and making it air-tight at the end, by sealing-wax. ...