Suppose the number chosen is 7 Which doubled 14 Add 4 to it, and it will make 18 Multiply 18 by 5, gives 90 To which add 12, is 102 Multiply that by 10, makes 1020 From which deducting 320, the remainder is 700 And by striking off the two ciphers, it becomes the number thought on 7

_To tell any Number a Person has fixed on, without asking him any Questions._

You tell the person to choose any number from 1 to 15; he is to add 1 to that number, and triple the amount. Then,

1. He is to take the half of that triple, and triple that half.

2. To take the half of the last triple, and triple that half.

3. To take the half of the last triple.

4. To take the half of that half.

Thus, it will be seen, there are four cases where the half is to be taken; the three first are denoted by one of the eight following Latin words, each word being composed of three syllables; and those that contain the letter i refer to those cases where the half cannot be taken without a fraction; therefore, in those cases, the person who makes the deduction is to add 1 to the number divided. The fourth case shows which of the two numbers annexed to every word has been chosen; for if the fourth half can be taken without adding 1, the number chosen is in the first column; but if not, it is in the second.

_The words._ _The numbers they denote._

Mi-se-ris 8 0 Ob-tin-git 1 9 Ni-mi-um 2 19 No-ta-ri 3 11 In-fer-nos 4 12 Or-di-nes 13 5 Ti-mi-di 6 14 Te-ne-ant 15 7

For example:

Suppose the number chosen is 9 To which is to be added 1 ---- 10 The triple of that number is 30 The half of which is 15 The triple of that half must be 45 And the half of that[A] 23 The triple half of that half 69 The half of that[A] 35 And the half of that half[A] 18

[A] At all these stages, 1 must be added, to take the half without a fraction.

While the person is performing the operation, you remark, that at the second and third stages he is obliged to add 1; and, consequently, that the word _ob-tin-git_, in the second and third syllables of which is an i, denotes that the number must be either 1 or 9; and, by observing that he cannot take the last half without adding 1, you know that it must be the number in the second column. If he makes no addition at any one of the four stages, the number he chose must be 15, as that is the only number that has not a fraction at either of the divisions.

_The Lamp Chronometer._

Figure 4 represents a chamber lamp, A, consisting of a cylindrical vessel made of tin, in the shape of a candle, and is to be filled with oil. This vessel should be about three inches high and one inch diameter, placed in a stand, B. The whole apparatus, of lamp and stand, can be purchased, ready-made, at any tin-shop in London. To the stand, B, is fixed the handle C, which supports the frame D, about 12 inches high, and four inches wide. This frame is to be covered with oiled paper, and divided into 12 equal parts by horizontal lines, at the end of which are written the numbers for the hours, from 1 to 12, and between the horizontal lines, and diagonals, divided into halves, quarters, &c. On the handle C, and close to the gla.s.s, is fixed the style or hand E.

[Ill.u.s.tration: Fig. 4.]

Now, as the distance of the style from the flame of the lamp is only half an inch, then, if the distance of the frame from the style be six inches, while the float that contains the light descends by the decrease on the oil, one inch, the shadow of the style of the frame will ascend 12 inches, being its whole length, and show by its progression, the regular increase of the hours, with their several divisions.

You must be careful always to burn the same oil, which must be the best; and the wick must never vary in size; if these precautions are not attended to, the dial never can be accurate.

_The Phial of the Four Elements._

Take a phial, six or seven inches long, and about three quarters of an inch in diameter. In this phial put, first, gla.s.s coa.r.s.ely powdered; secondly, oil of tartar per deliquum; thirdly, tincture of salt of tartar; and lastly, distilled rock oil.

The gla.s.s and the various liquors being of different densities, if you shake the phial, and then let it rest a few moments, the three liquors will entirely separate, and each a.s.sume its place; thus forming no indifferent resemblance of the four elements, earth, fire, water, and air: the powdered gla.s.s (which should be of some dark colour) representing the earth; the oil of tartar, water; the tincture, air; and the rock oil, fire.

_The Magic Bottle._

Take a small bottle, the neck of which is not more than the sixth of an inch in diameter. With a funnel, fill the bottle quite full of red wine, and place it in a gla.s.s vessel, similar to a show-gla.s.s, whose height exceeds that of the bottle about two inches; fill this vessel with water. The wine will shortly come out of the bottle, and rise in the form of a small column to the surface of the water; while at the same time, the water, entering the bottle, will supply the place of the wine. The reason of this is, that as water is specifically heavier than wine, it must hold the lower place, while the other rises to the top.

An effect equally pleasing will be produced, if the bottle be filled with water, and the vessel with wine.

_The Globular Fountain._

Make a hollow globe, of copper or lead, and of a size adapted to the quant.i.ty of water that comes from a pipe (hereafter mentioned) to which it is to be fixed, and which may be fastened to any kind of pump, provided it be so constructed, that the water shall have no other means of escape than through the pipe. Pierce a number of small holes through the globe, that all tend towards its centre, and annex it to the pipe that communicates with the pump. The water that comes from the pump, rushing with violence into the globe, will be forced out at the holes, and form a very pleasing sphere of water.

_The Hydraulic Dancer._

Procure a little figure made of cork, which you may dress as your fancy dictates. In this figure place a small hollow cone made of thin leaf bra.s.s.

When the figure is placed on a jet d'eau, that plays in a perpendicular direction, it will be suspended on the top of the water, and perform a great variety of amusing motions.

If a hollow ball of very thin copper, of an inch diameter, be placed on a similar jet, it will remain suspended, turning round, and spreading the water all about it.

_A Person having put a Ring an one of his Fingers, to name the Person, the Hand, the Finger, and the Joint on which it is placed._

Let a third person double the number of the order in which he stands who has the ring, and add 5 to that number; then multiply that sum by 5, and to the product add 10. Let him next add 1 to the last number, if the ring be on the right hand, and 2 if on the left, and multiply the whole by 10: to the product of this he must add the number of the finger, (counting the thumb as the first finger,) and multiply the whole again by 10. Let him then add the number of the joint, and, lastly, to the whole join 35.

He is then to tell you the amount of the whole, from which you are to subtract 3535, and the remainder will consist of four figures; the first of which will express the rank in which the person stands, the second the hand, (number 1 signifying the right, and 2 the left,) the third number the finger, and the fourth the joint.--For example:

Suppose the person who stands the third in order has put the ring upon the second joint of the thumb of his left hand; then,

The double of the rank of the third person is 6 To which add 5 ____ 11 Multiply the sum by 5 ____ 55 To which add 10 And the number of the left hand 2 ____ 67 Which being multiplied by 10 ____ 670 To which add the number of the thumb 1 ____ 671 And multiply again by 10 ____ 6710 Then add the number of the joint 2 And lastly the number 35 ____ 6747 From which deducting 3535 ____ The remainder is 3212 ____

Of which, as we have said, the 3 denotes the third person, the 2 the left hand, the 1 the thumb, and the last 2 the second joint.

_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 part where the two pieces are joined together. The water rushing through the holes will form a very pleasing water sun, or star.

_The Magical Cascade._

Procure a tin vessel, shaped like Fig. 5, about five inches high and four in diameter, with a cover, C, closed at top. To the bottom of this vessel, let the pipe D E be soldered. This pipe is to be ten inches long, and half an inch in diameter, open at each end, and the upper end must be above the water in the vessel. To the bottom also fix five or six small tubes, F, about one-eighth of an inch in diameter. By these pipes, the water in the vessel is to run slowly out.

[Ill.u.s.tration: Fig. 5.]

Place this machine in a tin basin, G H, with a hole in the middle, about a quarter of an inch in diameter. Fix to the tube D E, any sort of ornament that will keep the machine firm on the basin, observing, that these supports are sufficiently long to leave about a quarter of an inch between the end of the tube and the orifice in the basin; and let there be a vessel under the basin to catch the water that runs out.

As the small pipes discharge more water into the basin than can run out of the central orifice, the water will rise in the basin above the lower end of the pipe, and prevent the air from getting into the vessel, by which the water will cease to flow from the small pipes.

But as the water continues to flow from the basin, the air will have liberty again to enter the vessel by the tube, and the water will again flow from the small pipes, and alternately stop and flow, while any water remains in the vessel.

As you can guess when the pipes will flow, and when they will stop, you may so manage it, that they will appear to act by word of command.

_The illuminated Fountain, that plays when the Candles are lighted, and stops when they are extinguished._