The apparatus represented in Fig. 4 is very curious, and might be put to some useful application, without mentioning that which wine merchants might make of it by changing the order of the liquids and leaving in view only the vessel, Α Β, and the cock.
“Being given,” says Heron again, “two vessels, one of them containing wine, it is required that whatever be the quantity of water poured into the empty one, the same quantity of a mixture of wine and water, in any proportion whatever (two parts of water to one of wine, for example), shall flow out through a pipe.
“Let Α Β be a vessel in the form of a cylinder, or of a rectangular parallelopipedon. At the side of it, and upon the same base, we place another vessel, Γ Δ, which is hermetically closed, and of cylindrical or parallelopipedal form, like Α Β. But the base of Α Β must be double that of Γ Δ if we desire that the quantity of water shall be double that of the wine in the mixture. Near Γ Δ we place another vessel, Ε Ζ, which is likewise closed, and into which we have poured wine. The vessels, Γ Δ and Ε Ζ, are connected by a tube, Η Θ Κ which traverses the diaphragms that close them at their upper part, and which is soldered to these. In the vessel, Ε Ζ, we place a bent siphon, Δ Μ Ν, whose inner leg should come so near to the bottom of the vessel as to leave just enough space for the liquid to pass, while the other leg runs into a neighboring vessel, Ξ Ο. From this latter there starts a tube, Π Ρ, which passes through all the vessels, or the pedestal that supports them, in such a way that it can be easily carried under and very near the bottom of the vessel, Α Β. Another tube, Σ Τ, traverses the partitions in the vessels, Α Β and Γ Δ. Finally, near the bottom of Α Β we adjust a small tube, Υ, which we inclose, with the tube Η Λ, in a pipe, Φ Ξ, that is provided with a key for opening or closing it at will. Into the vessel, Ε Ζ, we pour wine through an aperture, Ω, which we close after the liquor has been introduced.
“These arrangements having been made, we close the pipe, Ξ Φ and pour water into the vessel, Α Β. A portion, that is to say, one-half, will pass into the vessel, Γ Δ, through the tube, Σ Τ, and the water that enters Γ Δ will drive therefrom a quantity of air equal to itself into Ε Ζ, through the tube, Η Θ Κ. In the same way this air will drive an equal quantity of wine into the vessel, Ο Ξ, through the siphon, Λ Μ Ν. Now, upon opening the pipe, Φ Ξ, the water poured into the vessel, Α Β, and the wine issuing from the vessel, Ο Ξ, through the tube, Π Ρ, will flow together, and this is just what it was proposed to effect.”
| FIG. 5.—MAGICAL VESSELS OF THE EIGHTEENTH CENTURY. | FIG. 6.—SECTION OF A MAGICAL PITCHER. |
The accompanying figures, borrowed from a work on “Scientific Recreations,” by the late editor of La Nature, M. Gaston Tissandier, represents a magic vase and pitcher such as the ancients were accustomed to employ for the purpose of practicing a harmless and amusing deception on those who were not acquainted with the structure of the apparatus. For instance, if any one should attempt to pour wine or water from the pitcher shown in the cut, the liquid would run out through the apertures in the sides. But the person who knew how to use the vessel would simply place his finger over the aperture in the hollow handle (Fig. 6) and then suck through the spout, A, when the liquid would flow up through the handle and through a channel running around the rim of the vessel and so reach the spout. These magic vases, cups, pitchers, etc., were not only in use among the ancients, but were quite common in the eighteenth century, and numerous specimens are to be seen in European collections. The ones shown in the accompanying cuts are preserved in the Museum at Sèvres. These apparatus are all based on the use of concealed siphons, or, rather, their construction is based on the principle of that instrument. Devices of this kind admit of very numerous modifications. Thus tankards have been so contrived that the act of applying them to the lips charged the siphon, and the liquid, instead of entering the mouth, then passed through a false passage into a cavity formed for its reception below. By making the cavity of the siphon sufficiently large, a person ignorant of the device would find it a difficult matter even to taste the contents, however thirsty he might be. Dishonest publicans, whose signboards announced “entertainment for man and beast,” are said to have thus despoiled travelers in old times of a portion of their ale or mead, as well as their horses of feed. Oats were put into a perforated manger, and a large part forced through the openings into a receptacle below by the movements of the hungry animal’s mouth. Heron, in the eighth problem of his “Spiritalia,” figures and describes a magical pitcher in which a horizontal, minutely perforated partition divides the vessel into two parts. The handle is hollow and air-tight, and at its upper part a small hole is drilled where the thumb or finger can readily cover it. If the lower part of the pitcher be filled with water and the upper with wine, the liquids will not mix as long as the small hole in the handle is closed; the wine can then be either drunk or poured out. If the hole be left open for some time, a mixture of both liquids will be discharged. “With a vessel of this kind,” says an old writer, “you may welcome unbidden guests. Having the lower part already filled with water, call to your servant to fill your pot with wine; then you may drink unto your guest, drinking up all the wine; when he takes the pitcher, thinking to pledge you in the same, and finding the contrary, will happily stay away until he be invited, fearing that his next presumption might more sharply be rewarded.” Another old way of getting rid of an unwelcome visitor was by offering him wine in a cup having double sides and an air-tight cavity formed between them. When the vessel was filled, some of the liquid entered the cavity and compressed the air within, so that when the cup was inclined to the lips and partly emptied, the pressure being diminished, the air expanded and drove part of the contents in the face of the drinker. Another goblet was so contrived that no one could drink out of it unless he understood the art. The liquid was suspended in cavities, and discharged by admitting or excluding air through several secret openings.
The apparatus represented in the illustration (Fig. 7) represents an arrangement similar to that of the inexhaustible bottle of Robert-Houdin, but it is more ingenious. The problem proposed, as enunciated by Heron, the Greek engineer, who describes the apparatus, is as follows: “Being given a vessel, to pour into it, through the orifice, wines of several kinds, and to cause any kind that may be designated to flow out through the same orifice, so that, if different persons have poured in different wines, each person may take out in his turn all the wine that belongs to him.
“Let Α Β be a hermetically closed vessel whose neck is provided with a diaphragm, Ε Ζ, and which is divided into as many compartments as the kinds of wine that it is proposed to pour into it. Let us suppose, for example, Η Θ and Κ Α are diaphragms forming the three compartments, Μ, Ν, and Ξ, into which wine is to be poured. In the diaphragm, Ε Ζ, there are formed small apertures that correspond respectively to each of the compartments. Let Ο, Π, and Ρ be such apertures, into which are soldered small tubes, Π Σ, Ο Τ, and Ρ Υ, which project into the neck of the vessel. Around each of these tubes there are formed in the diaphragm small apertures like those of a sieve, through which the liquids may flow into the different compartments. When, therefore, it is desired to introduce one of the wines into the vessel, the vents, Σ, Τ, and Υ are stopped with the fingers, and the wine is poured into the neck, Φ, where it will remain without flowing into any of the compartments, because the air contained in the latter has no means of egress. But, if one of the said vents be opened, the air in the compartment corresponding thereto will flow out, and the wine will flow into such compartment through the apertures of the sieve. Then, closing this vent in order to open another, another quantity of wine will be introduced, and so on, whatever be the number of wines and that of the corresponding compartments of the vessel, Α Β.
“Let us now see how each person in turn can draw his own wine out through the same neck. At the bottom of the vessel, Α Β, there are arranged tubes which start from each of the compartments, to wit: The tube χ ψ from the compartment, Μ; the tube ω σ, from Ν, and the tube λ μ, from Ξ. The extremities, ψ, σ, and μ, of these tubes should communicate with another tube, α, in which is accurately adjusted another, β Γ, closed at Γ at its lower extremity and having apertures to the right of the orifices, ψ, σ, and μ, so that such apertures may, in measure, as the tube revolves, receive respectively the wine contained in each of the compartments and allow it to flow to the exterior through the orifice, β, of the said tube, β Γ. To this tube is fixed an iron rod, δ ε, whose extremity, ε, carries a lead weight, η. To the extremity, δ, is fixed an iron pin supporting a small conical cup whose concavity points upward. Let us therefore suppose this truncated cone established, its wide base at ξ, and its narrow one (through which the pin passes) at θ.[2] Again, one must have small leaden balls of different weights, and in number equal to that of the compartments, Μ, Ν, and Ξ. If the smallest be placed in the cup, ξ θ, it will descend on account of its weight until it applies itself against the internal surface of the cup, and it will be necessary to so arrange things that it may thus cause the tube, β Γ, to turn so as to bring beneath ψ that one of the apertures that corresponds to it, and that will thus receive the wine of the compartment, Μ. This wine will then flow as long as the ball remains in the cup. If, now, the ball be removed, the weight, η, in returning to its first position, will close the orifice, ψ, and stop the flow. If another ball be placed in the cup, a further inclination of the rod, ε δ, will be produced, and the tube, β Γ, will revolve further, so as to bring its corresponding aperture beneath σ. Then the wine contained in the compartment, Ν, will flow. If the ball be removed, the weight, η, will redescend to its primitive place, the aperture, σ, will be closed, and the wine will cease to flow. Finally, upon placing the last ball (which is the heaviest), the tube, β Γ, will turn still more, so as to cause the flow of the wine contained in the compartment, Ξ.
[2] The text does not agree with the figure given by the MSS. Moreover, there is an arrangement here that it is difficult to understand from Heron’s description.
“It must be remarked that the smallest of the balls should be so heavy that when placed in the cup it shall outweigh the weight, η, and consequently bring about the revolution of the tube, β Γ. The other balls will then be sufficient to cause the revolution of the said tube.”
ANCIENT ORGANS.
The hydraulic organ filled with its powerful voice the vast arenas in which the gladiators fought, and Petronius relates that Nero one day made a vow to play one of them himself in public if he escaped a danger that threatened him. The invention of them is attributed to Ctesibius.
Fig. 1 gives a reproduction of one of these instruments as described by Heron in his “Pneumatics.”
Let Β Δ be an altar[3] of bronze containing water. Let there be in the latter an inverted hollow hemisphere, Ε Ζ Η (called a damper), that allows the water to pass all around its bottom, and from the top of which rise two tubes that communicate with the interior. One of these tubes, Η Κ, is bent in the interior and communicates with a small inverted box,[4] Ν Η, the aperture of which is at the bottom, and the interior of which is bored out so that it may receive a piston, Ρ Ι, which should fit very accurately so as to allow no air to pass. To this piston is fixed a very strong rod, Τ γ, with which is connected another rod, γ Φ, movable around a pin at γ.[5] This lever moves upon a fixed vertical rod, Ψ Χ. Upon the bottom of the box, Ν Π, is placed another box, Ω, which communicates with the first, and which is closed at the upper part by a cover that contains an aperture to allow of the passage of the air into the box, Ν Π. Under the aperture of this cover, and in order to close it, there is arranged a thin disk, held by means of four pins which pass through apertures in the disk, and are provided with heads in order to hold it in place. This disk is called a platysmatim (Fig. 2). The other tube, Ζ Ζ′, is carried by the hemisphere, Ε Ζ Η, and ends in a transverse tube, Α Α′,[6] upon which rest pipes communicating with it and having at their extremities glossocomiums[7] that communicate with these pipes, and the orifices, Β′, of which are open. Across these orifices, covers provided with holes[8] slide in such a way that when they are pushed toward the interior of the organ their holes correspond to the orifices of the pipes (and to those of the tube Α Α′), and that when they are pulled back, the pipes are closed, since there is no longer any correspondence.
[3] Altars were cylindrical or square pedestals, characterized by a cavity in the upper platform, in which a fire was lighted.
[4] This box performs here the office of a pump chamber.
[5] The figure shows another arrangement.
[6] Called a wind-chest in modern organs.
[7] Flute mouths.
[8] Registers.
If, now, the transverse rod, γ Φ, be lowered at Φ the piston, Ρ Σ, will rise and compress the air in the box, Ν Σ Ο Π, and such air will close the aperture of the small box through the intermedium of the platysmatim described above. It will then pass into Ε Ζ Η by means of the tube, Κ Η, then into the transverse tube Α Α′, through the tube Ζ Ζ′, and finally from the transverse tube into the pipes, if the orifices correspond to those of the covers, and this will occur when all the covers (or only a few of them) have been pushed toward the interior.
In order that their orifices may be open when it is desired to make certain pipes resound, and that they may be closed when it is desired to cause the sound to cease, the following arrangement is employed: Let us consider isolately one of the mouths placed at the extremity (Fig. 3). Let γ δ be this mouth, δ its orifice, Α Α′ the transverse tube, and σ the cover that is adapted and the aperture of which does not coincide with the apertures of the pipes at this moment. Let us now suppose a jointed arrangement composed of three rods, δ, μ, and ν, the rod, ε δ, being attached to the cover, σ, and the system as a whole moving around a pin, μ. It will be seen that if we lower with the hand the extremity, ν, of the system toward the orifice of the glossocomiums, we shall cause the cover to move toward the interior, and that, when it arrives there, its orifice will coincide with the orifices of the pipes. In order that, upon removing the hand, the cover may be carried back toward the exterior and close all communication, an arrangement such as the following may be employed. Beneath a number of glossocomiums, there is established a bar equal in length to and parallel with the tube, Α Α′, and to which are fixed strong curved plates of horn, such as γ, placed opposite γ δ. A cord is fixed to the end of this plate and winds around the extremity, δ, in such a way that when the cover is moved toward the exterior the cord shall be taut. If the extremity, ν, then be lowered, and the register be thus pushed into the interior, the cord will draw upon the horn plate, and by its force, right it. But as soon as the pressure ceases, the plate will resume its former position and draw the cover back in such a way as to prevent its orifice from establishing a communication. This arrangement being adopted for all the glossocomiums, it will be seen that in order to cause any one of the pipes to resound, it will suffice to depress the corresponding key with the finger. When, on the contrary, it is desired to cause the sound to cease, we shall merely have to lift the finger, and the effect will be produced by the motion of the cover.
Water is poured into the small altar in order that the compressed air that is driven from the box, Ν Π, may, owing to the pressure of the liquid, be retained in the damper, Ε Ζ Η, and thus supply the pipes. When the piston, Ρ Σ, is raised, it therefore expels the air from the box into the damper, as has been explained. Then, when it is lowered, it opens the platysmatim of the small box. By this means, the box, Ν Π, becomes filled with air from the exterior, which the piston, raised anew, drives again into the damper.
It would be better to render the rod, Τ γ, immovable at Τ, around a pin, and fix at the bottom, Ρ, of the piston a ring through which this pin would pass, so that the piston would have no lateral motion, but would rise and descend with exact perpendicularity.
Porta, at the beginning of the seventeenth century, constructed at Naples a hydraulic organ according to the arrangement just described. A few years afterward, in 1645, Father Kircher constructed another at Rome for Pope Innocent X. These organs had the defect of not preserving the note, but of giving a series of harmonies. On the other hand, they produced an exceedingly agreeable tremolo. It was probably these unusual variations in sound that charmed the ears of the Greeks and Romans.
Heron afterwards describes a bellows organ, motion to which is communicated not by manual power, but by a windmill. Fig. 4 shows the arrangement with sufficient clearness to permit us to dispense with a description. It is interesting to reproduce, in that it carries the origin of windmills (which it is claimed were unknown to antiquity, because Vitruvius and Varro do not speak of them) back at least to the second century before our era.
CHAPTER III.
THE ORIGIN OF THE STEAM ENGINE.
All works that treat of the history of the steam engine speak of the eolipile of Heron as the most ancient manifestation known of that power which to-day fills the world. But very few persons know that we also find in the “Pneumatics” of the Greek engineer the germs of the tubular boiler and of the Papin cock which has been replaced in modern engines by the long D-valve. Here, in the first place, is a literal translation of the two passages that have reference to the apparatus, so often cited, of Heron:
“Balls may be held in the air by the following method:
“Fire is lighted under a boiler that contains water and is closed at its upper part. From the cover starts a tube which rises vertically, and at the extremity of which a hollow hemisphere is in communication with it. On placing a light ball in this hemisphere it will happen that the steam, on rising through the tube, will raise the ball in such a way that it will remain suspended.[9]
[9] Fig. 1 is borrowed from a MS. of the “Pneumatics” dating back to the Renaissance. The boiler should have been represented over a fireplace.
“To cause the revolution of a sphere on a pivot by means of a boiler placed over a fire.
“Let Α Β (Fig. 2[10]) be a boiler containing water and placed over a fire. It is closed by means of a cover, Γ Λ, which is traversed by a bent tube, Ε Ζ Η, whose extremity, Η, enters the hollow sphere, Θ Κ, in the direction of the latter’s diameter. At the other extremity is placed the pivot, Α Μ Ν, which is fixed upon the cover, Γ Λ. There are added to the sphere, at the two extremities of one of its diameters, two tubes bent at right angles and perpendicular to the line, Η Ν. When the boiler is heated, the steam will pass through the tube, Ε Ζ Η, into the small sphere, and, issuing through the bent tubes into the atmosphere, will cause it to revolve in situ.”
[10] This figure, likewise borrowed from a MS. of the Renaissance, is sufficiently clear to allow letters to be dispensed with.
The following apparatus, likewise described by Heron, but not so well known as those that preceded, shows that the ancients employed steam (mixed with hot air, it is true) for causing liquids to rise. According to Father Kircher, who reports it on the faith of an author named Bitho, there was at Saïs, Egypt, a temple dedicated to Minerva in which there was an altar upon which, when a fire was lighted, Dionysius and Artemis (Bacchus and Diana) poured, one of them wine, and the other milk.
The miracle was performed as follows:
“On lighting a fire upon an altar, figures make libations and serpents hiss (Fig. 3).[11]
[11] The letters on the engraving are again dispensed with.
“Let Α Β be a hollow pedestal upon which there is an altar, Γ, in whose interior there is a large tube, Δ Ε, that descends from the fireplace into the pedestal and divides into three small tubes. One of the latter, Ε Ζ, runs to the serpent’s mouth; another, Ε Ζ Η, to a vessel, Κ Δ, suitable for containing wine, and the bottom of which should be above the figure, Μ, as this tube has to be connected with the cover of the vessel, Κ Λ, by a grating; and the third tube, Ε Ν Ξ, rises likewise to a vessel, Ο, suitable for receiving wine, and is connected in the same way with its cover. The two latter tubes are soldered to the bottoms of the vessels, and in each of these vessels there is a siphon, Ρ Σ and Τ Υ. One extremity of each of these tubes dips into the wine, while the other, which ends in the hand of the figure that is to make the libation, traverses the side of the wine vessel. When you wish to light the fire, you will first put a little water into the tubes so that they shall not be burst by the dryness of the fire, and you will stop up all the apertures so that the air shall not escape. Then the blast from the fire, mixed with the water, will rise through the tubes up to the gratings, and, passing through these, will press upon the wine and cause it to flow through the siphons, Ρ Σ and Τ Υ. The wine issuing thus from the hands of the figures, the latter will appear to make libations as long as the altar is burning. As for the other tube, which leads the blast to the serpent’s mouth, it causes the latter to hiss.”
As regards the cock and the tubular boiler, we find these in a hot-water stove which Heron calls by the Græco-Latin name miliarion, because of its resemblance to a milestone.
Fig. 4 shows us, in the center, the fireplace in the shape of a vertical cylinder, which should have beneath it an air vent that is not shown in the cut. All around this there is a boiler, likewise cylindrical, filled with water. A certain number of tubes, such as Ο Κ and Μ Ν, put its different parts in communication by passing through the fireplace, and thus increase the heating surface.
The cock, Τ, serves to let off hot water, and the funnel, Σ, to introduce cold water into the boiler through a tube which runs to the bottom of the latter. The object of the bent tube is to allow of the escape of air when water is poured in, and to give exit to the steam that may be formed, and thus avoid the ejection of water through the funnel, Σ. Heron, in his text, says that this tube debouches in the interior of the funnel so that it shall not be perceived, and not as we have shown it for the sake of greater clearness. In the figure there may be seen a compartment formed by two vertical plates that make an angle into which water cannot enter. This is designed for actuating different figures through the play of the steam and of the several way cocks that I have mentioned. This latter consists of two concentric tubes capable of revolving with slight friction one within the other. The external tube, Γ Δ, is fixed to the upper side of the stove, and traverses it. It contains three apertures, φ, ψ, and χ, placed at different levels, and communicating, through small tubes, with the figures that are to be presently mentioned. The internal tube, Α Β, is open at its lower part, and thus communicates with the interior of the compartment, but is closed at its upper part, which latter debouches above the stove and may be manœuvered by the handle, Α. It contains three apertures at the same levels as apertures φ, ψ, and χ, but differently placed, so that when, through a rotary motion of the tube, Α Β, one of them is brought opposite an aperture of the same level in the tube, Γ Δ, the two others do not correspond. The positions that it is necessary to give them in order that such correspondences shall occur are denoted by marks engraved on the visible portions of the tubes. The tube, φ, terminates in a serpent’s head which bends toward the fireplace, and tube, ψ, terminates in a triton who holds a trumpet to his mouth. Finally the tube, χ, carries at its extremity a whistle that debouches in the body of a bird filled with water.
It will now be seen what will occur. The tube, Α Β, is removed and a little water is put into the compartment. This water flows into the tube, Λ Ξ (which passes under the fireplace and is closed at the side opposite its aperture, Ξ), and is converted into steam. When the tube, Α Β, has been replaced, the steam may at will be passed into the body of the bird, which will warble, or into that of the triton, who will blow his trumpet, or, finally, into that of the serpent, which will blow into the fire and quicken the flames.
CHAPTER IV.
GREEK LAMPS, TOYS, ETC.
PERPETUAL LAMPS.
The ancients utilized, in their prestiges, combustible gases, which, in many places, were disengaged naturally from the earth.
The Arab Schiangia, in a passage quoted by Father Kircher, expresses himself in this wise:
“In Egypt there was a field whose ditches were full of pitch and liquid bitumen. Philosophers, who understood the forces of nature, constructed canals which connected places like these with lamps hidden at the bottom of subterranean crypts. These lamps had wicks made of threads that could not burn. By this means the lamp, once lighted, burned eternally, because of the continuous influx of bitumen and the incombustibility of the wick.”
It is possible that it was to an artifice of this same nature that were due some of the numerous perpetual lamps that history has preserved a reminiscence of, such as that which Plutarch saw in the temple of Jupiter Ammon, in Egypt, and that in the temple of Venus, which Saint Augustine could only explain as due to the intervention of demons. But the majority of them owed their peculiarity only to the precautions taken by the priests to feed them without being seen. It was only necessary, in fact, that the wick, which was made of asbestos threads or gold wire, should be kept intact, and that the body of the lamp should communicate with a reservoir placed in a neighboring apartment in such a way that the level of the oil should remain constant. Heron and Philo have left us descriptions of a certain number of arrangements that permitted of accomplishing such an object.
The same authors likewise point out different processes for manufacturing portable lamps in which the oil rises automatically. The most ingenious one is that which is at the present day known under the name of “Heron’s Fountain.”[12]
[12] In 1801, Carcel and Carreau applied Heron’s system to lamps without, perhaps, knowing that they were thus returning to the primitive apparatus.
The following is the Alexandrine engineer’s text:
“Construction of a candelabrum such that upon placing a lamp thereon, there comes up through the handle, when the oil is consumed, any quantity that may be wished, and that, too, without there being any need of placing above it any vessel serving as a reservoir for the oil.
“A hollow candelabra must be made, with a base in the shape of a pyramid. Let Α Β Γ Δ be such pyramidal base, and in this let there be a partition, Ε Ζ. Again, let Η Θ be the stem of the candelabrum, which should also be hollow. Above, let there be placed a vessel, Κ Λ, capable of containing a large quantity of oil. From the partition, Ε Ζ, there starts a tube, Μ Ν, which traverses it and reaches almost to the cover of the vessel, Κ Λ, upon which latter is placed the lamp in such a way as to allow only a passage for the air. Another tube, Ξ Ο, passes through the cover and runs down, on the one hand, to the bottom of the vessel, Κ Λ, in such a way that the liquid may be capable of flowing, and on the other, forms a slight projection on the cover. To this projection there is carefully adjusted another tube, Π, which is provided with a stopper at its upper part, and, traversing the bottom of the lamp and united with it, is wholly inclosed within the interior of the lamp. To the tube, Π, there is soldered another and very fine one which communicates with it and reaches the extremity of the lamp handle. This tube debouches in the latter in such a way that its contents may empty into the lamp, the orifice of which is of the usual size. Under the partition, Ε Ζ, there is soldered a cock that enters the compartment, Γ Δ Ε Ζ, in such a way that when it is open the water from the chamber, Α Β Ε Ζ, may pass into the compartment, Γ Δ Ε Ζ. Through the upper plate, Α Β, there is pierced a small hole, through which the compartment, Α Β Ε Ζ, may be filled with water, the air within escaping through the same aperture.
“Let us now remove the lamp and fill the vessel with oil by the aid of the tube, Ξ Ο. The air will escape through the tube, Μ Ν, and afterward through a cock which is open near the bottom, Γ Δ, when the water has flowed out from the compartment, Γ Δ Ε Ζ. Let us place the lamp upon its base, connecting it at the same time with the tube, Π. When it becomes necessary to pour oil into it, we will open the cock near the partition, Ε Ζ. The water that is in the compartment, Γ Δ Ε Ζ, as well as the air therein, being forced through the tube, Μ Ν, into the vessel, will cause the oil to rise and pass into the lamp through the tube, Ξ Ο, and the one that forms a continuation of it. When it is desired to cause the oil to stop coming over, the cock is closed, when the flow will cease. This may be repeated as often as may be necessary.”
Such was, perhaps, Plato’s lamp, of which Athenæus speaks in the “Banquet of the Sophists,” and by means of which the illustrious philosopher was enabled to have a light for himself during the longest nights in the year.
AN ANCIENT AUTOMATON.
In his “Spiritalia” (written about 150 B.C.) Heron describes several automata of which figures of birds form a part; but perhaps the most remarkable for its ingenious simplicity is No. 44, the illustration of which we reproduce.
The description of this, as given by Heron, is somewhat meager and unsatisfactory, but the drawing is so very plain that, taken in connection with other mechanism in his work, operated in a similar way, it is easy to understand how the desired result was accomplished.
An air-tight box of metal was provided, which was divided into four compartments, 1, 2, 3, 4, by horizontal diaphragm plates. On the top of this box was a basin, O, for receiving the water of a fountain. Around this basin were four birds, A, B, C, D, perched upon branches or shrubs, which apparently grew out of the top of the box. Each of these branches was hollow, and communicated with one of the compartments already named, by one of the pipes, 9, 10, 12, and 13, which passed but a very short distance through the tops of the several compartments. The bodies of the birds were also hollow, and were connected with the hollow branches by tubes in their legs. In the hollow body of each bird were two musical reeds or whistles of different note. One of these would sound when air was forced outward through the beak of the bird, and the other would only respond to air drawn inward. This alternate action of the air, and consequent variation of note, was produced by the peculiar way in which the water supplied by the fountain was made to pass through the several compartments.
The water from the basin, O, entered compartment 1 near its bottom by the pipe 11, and as it rose in the compartment, it compressed the air above it, which escaped through the beak of the bird, A, and caused its first note to sound; but when the water reached the top of the bend of the siphon 5, it at once began to discharge by that siphon into compartment 2; but as the siphon 5 was so proportioned that it discharged the water much faster than it was supplied by pipe 11, the level of the water in compartment 1 gradually fell, and the air in passing into this compartment through the beak of the bird, A, caused its second note to sound. As the water rose in compartment 2, it compressed the air above it, which passed by the pipe 10, to the bird, B, which then sounded its first note, while the bird, A, was sounding its second, and this state of affairs continued until all of the water was discharged from the compartment 1, and compartment 2 was filled to the top of the bend of siphon 6, which then began to discharge into compartment 3; and as siphon 5 had ceased to operate, the water gradually fell in compartment 2, and the air entering by the beak of the bird, B, sounded its second note. While this was taking place, compartment 1 was again filling, and the first note of bird, A, sounding; and compartment 3 was also filling, and the air above the water therein was being forced by the pipe 12 into the bird, C, and causing its first note to sound.
By following out the operations described, and tracing the action of the flux and reflux of the water in the compartments 3 and 4, it will readily be seen that the bird, C, will sound its second note when the compartment 3 is being discharged by siphon 7 into compartment 4, and at the same time the bird, D, will sound its first note, and that eventually the water will escape from the automaton by the siphon 8, causing the second note of the bird, D, to be heard.
It is evident that by simple and well-known means any or all of the bird notes can be made to trill, and that it is only necessary to properly proportion the discharging capacity of the siphons to insure the repetition and admixture of the notes in a bird-like manner; and it is further evident that the employment of the ideas involved is not of necessity confined to but four birds, as several birds, each having different notes, might be operated from the same compartment, and of course as many compartments as may be wished can be used. Furthermore, the wings of the birds could be made to move, and their beaks to open and shut, by the movement of the same air which acted upon the musical reeds or whistles.
Each of the siphons in the automaton was intermittent in its action, ceasing to flow when its compartment was emptied, and beginning again spontaneously when the water reached the level of the top of its bend. The antiquity of intermittent siphons is of special interest from the fact of their comparatively recent application in sanitary plumbing.
Chaucer was not much in error as regards his own time (1328-1400), and his words are only somewhat less true to-day:
Cometh al this new corne fro yere to yere;
And out of old bookes, in good faithe,
Cometh all this new science that men lere.”
A GREEK TOY.
Upon a pedestal there is fixed a small tree around which is coiled a dragon. A figure of Hercules stands near by, shooting with a bow, and there is an apple lying upon the pedestal. If this apple be lifted from the latter, Hercules will shoot his arrow at the dragon, and the latter will hiss.
Mechanism of the Toy.—Let Α Β be the water-tight pedestal under consideration, provided with a diaphragm, Γ Δ. To this latter there is fixed a small, hollow, truncated cone whose apex points toward the bottom of the vessel, and from which it is just sufficiently distant to permit the water to pass. To this cone there is adjusted with care another one, Θ, which is fixed to a chain that, passing through an aperture, connects it with the apple. Hercules holds a small horn bow, whose string is stretched and laced at a proper distance from the right hand. The left hand is provided with a detent. To the extremity of this latter there is fixed a small chain or a cord that traverses the top of the pedestal, passes over a pulley fixed to the diaphragm, and connects with the small chain that joins the cone with the apple. This cord passes through the hand and body into the interior of Hercules. A small tube, one of those used for whistling with, starts from the diaphragm, rises through the top of the pedestal, and passes into the interior of the tree or around it.
Now, if the apple, Κ, be raised, the cone, Θ, will be raised at the same time, the cord, Χ Φ, will be tightened, the catch will be freed, and this will cause the arrow to shoot. The water in the compartment Α Γ, running into the compartment Β Γ, will drive out the air contained in the latter, through the tube, and produce a hissing. The apple being replaced, the cone, Θ, will adjust itself against the other, stop the flow, and thus cause the hissing to cease. The arrow and its accessories will then be adjusted anew.
When the compartment Β Γ is full, it is emptied by means of a spout provided with a key, and Α Δ is again filled as we have indicated.
THE DECAPITATED DRINKING HORSE.
The optical delusion known as the talking decapitated person has already been described in Book I., Chapter I., of the present work. The ancients invented an analogous trick, but one that was founded upon a very ingenious mechanical combination. This is found described at the end of Heron’s “Pneumatics,” under the title, “To cut an animal in two and make him drink.” It is as follows:
“Let us suppose a hollow pedestal, A B C D, divided in its center by a diaphragm, E F. Above the pedestal there is fixed a statuette representing a horse and traversed by a tube, M N, which terminates on the one hand in the horse’s mouth, and in the other in the upper part of the compartment, A B E F, after following one of the legs. It will be conceived, in the first place, that if the said compartment be filled with water through an aperture, T, which is afterwards stopped up, and that then a cock be opened, so as to form a communication between the upper compartment and the lower (which latter is itself provided with an open air-hole), the water will flow, and, in doing so, tend to cause a vacuum in the tube, M N, so that when a vessel of water is brought near the animal’s mouth the water will be sucked up.
“If the cock be so arranged as to present its key upon the top of the pedestal, and if to the key there be adapted a statuette representing a man armed with a club, things may be so arranged that the animal shall drink when the man has his back turned, for example, and that he shall stop drinking when the man threatens him with the club.
“The following is the way in which a knife may be passed through the animal’s neck without causing the head to fall or interrupting communication between the mouth and pedestal. The head and body form two distinct pieces, which are adjusted according to the plane, O P (Figs. 1, 2, and 3). The tube, M N, is interrupted to the right of this slit, and the two parts of it are connected by a smaller tube, α β, which enters by slight friction into the interior of each of them; and to this small tube, α β, there are fixed two racks, δ and ε. Above δ and under ε are placed two segments of toothed wheels, π and ρ, which are movable around axles fixed in the body of the animal. Over the whole there is a third wheel, which is likewise movable around an axle fixed in the animal’s body, and the thickness of which keeps increasing from the centre to the circumference. This wheel is cut out into three parts of circles, μ, ν, and ξ, which have for diameters three of the sides of the inscribed hexagon. It is inclosed in the neck in such a way that the circular cavity containing it embraces just four of the sides of the inscribed hexagon, the two other sides projecting outside of the plane, O P. In the piece that forms the head a circular cavity is formed capable of containing this projecting portion of the wheel, and a wedge-shaped profile is given it, so that when one tooth of the wheel, σ, is engaged therein by the edge, it can also only leave it by the edge. Let us now suppose the wheel, σ, free; let us engage one of its teeth in the cavity, χ ψ; let us cause the head and body to approach; let us fix the wheel, σ, in the body by means of the movable axle traversing it; and let us introduce a knife into the slit, O P, and see what will happen.