Air Pumps.—The type of air pump varies with the depth of water to which the diver has to descend; it will be readily understood that the greater the depth the greater the quantity of air required by the diver. The pattern most generally in favour amongst divers of all classes is a three-cylinder single-acting pump, which is suitable for almost every description of work which the diver may be called upon to perform, either in deep or shallow water. Another most useful type is a two-cylinder double-acting pump (figs. 1 and 2), which is designed to supply two divers working simultaneously in moderate depths of water, or one diver only in deep water. An air-distributing arrangement is fitted, whereby, when it is desired to send two mendown together, each cylinder supplies air independently of the other; and when it is required to send one diver into deep water, the two cylinders are connected and the full volume of air from both is delivered to the one man. The same duty is also performed by a four-cylinder single-acting pump. Smaller pumps, having one double-acting or two single-acting cylinders, are also used for shallow water work.In most cases these air pumps are worked by manual power; this method of working is rendered necessary by the fact that the machines are usually placed in small boats from which the divers work and on which other motive power is not available. In cases, however, where steam or electric power is available the pumps are sometimes worked by their means—more particularly on harbour and dock works. In such instances the air is not delivered direct from the pump to the diver, but is delivered into an intermediate steel receiver to which the diver’s air pipe is connected, the object being to ensure a reserve supply of air in case of a breakdown of the pump. Some of these combinations of pumps and motors are so arranged that, in the event of an accident to the motor, the pump can be thrown out of gear with it, and be immediately worked by hand power. Each pump is fitted with a gauge (or gauges), indicating not only the pressure of air which the pump is supplying, but also the depth of water at which the diver is working. The cylinders are water-jacketed to ensure the air delivered to the diver being cool, the water being drawn in and circulated round the cylinders by means of a small metal pump worked from an eccentric on the main crank-shaft. Filters are sometimes attached to the suction and delivery sides of the pumps to ensure the inlet of air being free from dirt, and the discharge of air free from dirt and oil.Fig. 2.—Pump in chest, ready for work.Helmet.—The helmet and breastplate (fig. 3) are made from highly planished tinned copper, with gun-metal valves and other fittings. The helmet is provided with a non-return air inlet valve to which the diver’s air pipe is connected; the air when it lifts the inlet valve passes through three conduits—one having its outlet over the front glass, the others their outlets over the side glasses. In this way the diver gets the air fresh as it enters the helmet, and at the same time it prevents condensation of his breath on the glasses and keeps them clear. There is a regulating air outlet valve by which the diver adjusts his supply of air according to his requirements in different depths of water; the valve is usually made to be adjusted by hand, but sometimes it is so constructed as to be operated by the diver knocking his head against it, the spindle being extended through to the inside of the helmet and fitted at its inner extremity with a button or disk. By unscrewing the valve, the diver allows air to escape, and thus the dress is deflated; by screwing it up the air is retained and the dress inflated. Thus the diver can control his specific gravity and rise or sink at will. In case by any chance the diver should inflate the dress inadvertently, and wish to get rid of the superfluous air quickly, he can do so by opening an emergency cock, which is fitted on the helmet. Plate glasses in gun-metal frames are also fitted to the helmet, two, one on each side, being permanently fixed, while one in front is made either to screw in and out, or to work on a hinged joint like a ship’s scuttle; the side glasses are usually protected by metal cross-bars, as is also sometimes the front glass. Some divers prefer unprotected glasses at the side of the helmet, instead of protected oval ones.The breastplate is fitted on its outer edge with metal screws and bands. The disposition of the screws corresponds with that of the holes in the india-rubber collar of the diving dress described below. There are other methods of making a watertight joint between the diver’s breastplate and the diving dress, but, as these are only mechanical differences, it will suffice to describe the Siebe-Gorman apparatus, as exclusively adopted by the British government. Whatever the shape or design of the helmet or dress, Siebe’s principle is the one in universal use to-day.The metal tabs are for carrying the diver’s lead weights, which are fitted with suitable clips; the hooks—one on each side of the helmet—are for keeping the ropes attached to the back weight in position. The helmet and breastplate are fitted at their lower and upper parts respectively with gun-metal segmental neck rings, which make it possible to connect these two main parts together by one-eighth of a turn, a catch at the back of the helmet preventing any chance of unscrewing. The small eyes at the top of the helmet are for securing the diver’s air pipe and life line in position and preventing them from swaying.Front view of Helmet.Side sectional view of Helmet.A, Helmet.B, Breastplate.F, Emergency cock.G, Glasses in frames.H, Metal screws and bands.I, Metal tabs.J, Hooks for keeping weight ropes in position.L, Eyes to which air pipe and life line are secured.K, Segmental neck rings.D, Air conduits.M, Telephone receiver.N, Transmitter.O, Contact piece to ring bell.Back view of Helmet.Plan of Helmet.C, Air inlet valve.E, Regulating outlet valve.G, Glasses in frames.L, Eyes to which air pipe and life line are secured.P, Connexion for telephone cable.Fig. 3.TheDiving Dressis a combination suit which envelops the whole body from feet to neck. It is made of two layers of tanned twill with pure rubber between, and is fitted at the neck with a vulcanized india-rubber collar, or band, with holes punched in it corresponding to the screws in the breastplate. This collar, when clamped tightly between the bands and the breastplate by means of the nuts, ensures a watertight joint. The sleeves of the dress are fitted with vulcanized india-rubber cuffs, which, fitting tightly round the diver’s wrists, prevent the ingress of water at these parts also.Boots.—These are generally made with leather uppers, beechwood inner soles and leaden outer soles, the latter being secured to the others by copper rivets. Heavy leather straps with brass buckles secure the boot to the foot. Each boot weighs about 16 ℔. Sometimes the main part of the boot-golosh, toe and heel, are in one brass casting, with leather upper part, heavy straps and brass buckles.Lead Weights.—These weigh 40 ℔ each, and the diver wears one on his back, another on his chest. These weights and the heavy boots ensure the diver’s equilibrium when under water.Belt and Knife and Small Tools.—Every diver wears a heavy waist-belt in which he carries a strong knife in metal case, and sometimes other small tools.Air Pipe.—The diver’s air pipe is of a flexible, non-collapsible description, being made of alternate layers of strong canvas and vulcanized india-rubber, with steel or hard drawn metal wire embedded. At the ends are fitted gun-metal couplings, for connecting the pipe with the diver’s pump and helmet.Signal Line.—The diver’s signal line (sometimes called life line) consists of a length of reverse laid Manila rope. In cases where the telephone apparatus is not used, the diver gives his signals by means of a series of pulls on the signal line in accordance with a prearranged code.Telephonic Apparatus.—Without doubt one of the most useful adjuncts to the modern diving apparatus is the loud-sounding telephone (fig. 4), introduced by Siebe, Gorman & Co., which enables the diver to communicate viva voce with his attendant, and vice versa. In the British navy the type of submarine telephonic apparatus used is the Graham-Davis system. This is made on two plans, (1) a single set of instruments, for communication between one diver and his attendant direct, (2) an intercommunication set which is used where two divers are employed. With this type the attendant can speak to No. 1 or No. 2 diver separately, or with both at the same time, and vice versa; and No. 1 can be put in communication with No. 2 whilst they are under water, the attendant at the surface being able to hear what the men are saying. The advantages of such a system are obvious. It is more particularly useful where two divers are working one either side of a ship, or where the divers may be engaged upon the same piece of work, but out of sight of one another, or out of touch. It would prove its utility in a marked degree in cases where a diver got into difficulties; a second diver sent down to his assistance could receive and give verbal directions and thus greatly expedite the work of rescue.Fig. 4.—Diver’s Telephone Communication with the Surface.Q, Battery, with switch and bell in case.R, Attendant’s receiver and transmitter.The telephone instruments in the helmet consist of one or more loud-sounding receivers placed either in the crown of the helmet, or one on each side in close proximity to the diver’s ears. A transmitter of a special watertight pattern is placed between the front glass and one of the side glasses, and a contact piece, which, when the diver presses his chin against it, rings a bell at the surface, is fitted immediately below the front glass. A buzzer is sometimes fixed in the helmet to call the diver’s attention when the attendant wishes to speak, but as a rule the voice is transmitted so loudly that this device is unnecessary. A connexion, through which the insulated wires connecting the instruments pass, terminates in contact pieces, and the telephone cable, embedded in the diver’s signal line, is connected with it. The other end of the signal line is connected to a battery box at the surface. This box contains, besides the cells, a receiver and transmitter for the attendant, an electric bell, a terminal box, and a special switch, by means of which various communications between diver, or divers, and attendant are made. If, as is sometimes the case, the diver happens to be somewhat deaf, he can, whilst he is taking a message, stop the vibration of the outlet valve and the noise made by the escaping air, by merely pressing his finger on a spindle which passes through the disk of the valve, and thus momentarily ensure absolute silence.Speaking Tube.—The rubber speaking tube which was the forerunner of the telephonic apparatus is now practically obsolete, though it is still used in isolated cases.Submarine Electric Lamps.—Various forms of submarine lamps are used, from a powerful arc light to a self-contained hand lamp, the former giving about 2000 or 3000 candle-power, and requiring a steam-driven dynamo to supply the necessary current, the latter (fig. 5) giving a light of about 10 candle-power and having its own batteries, so that the diver carries both the light and its source in his hand. These submarine lamps are all constructed on the same principle, having the incandescent lamps, or carbons as the case may be, enclosed in a strong glass globe, the mechanism and connexions being fitted in a metal case above the globe, which is flanged and secured watertightly to the case.Self-contained Diving Dress.—The object of the self-contained diving dress is to make the diver independent of air supply from the surface. The dress, helmet, boots and weights are of the ordinary pattern already described, but instead of obtaining his air supply by means of pumps and pipes, the diver is equipped with a knapsack consisting of a steel cylinder containing oxygen compressed to a pressure of 120 atmospheres (= about 1800 ℔) to the square inch, and chambers containing caustic soda or caustic potash. The helmet is connected to the chambers by tubes, and the oxygen cylinder is similarly connected to the chambers. The breath exhaled by the diver passes through a valve into the caustic soda, which absorbs the carbonic acid, and it is then again inhaled through another valve. This process of regeneration goes on automatically, the requisite amount of oxygen being restored to the breathed air in its passage through the chambers. This type of apparatus has been used for shallow water work, but the great majority of divers prefer the apparatus using pumps as the source of the air supply.An emergency dress, using this self-contained system for breathing, has been designed by Messrs Fleuss and Davis, of the firm of Siebe, Gorman & Co., primarily as a life-saving apparatus, for enabling men to escape from disabled submarine boats.Fig. 5.—Submarine Electric Lamp, with and without Reflector.A, Metal case containing electrical fittings.B, Glass globe and incandescent lamp.C, Stand, which also protects the globe.D, Ring for suspending lamp.E, Reflector.The helmet diver is indispensable in connexion with harbour and dock construction, bridge-building, pearl and sponge fishing, wreck raising and the recovery of sunken cargo and treasure. Every ship in the British navy carries one set or more of diving apparatus, for use in ease of emergency, for clearing fouled propellers, cleaning valves or ship’s hull below the water line, repairing hulls if necessary, and recovering lost anchors, chains, torpedoes, &c.
Air Pumps.—The type of air pump varies with the depth of water to which the diver has to descend; it will be readily understood that the greater the depth the greater the quantity of air required by the diver. The pattern most generally in favour amongst divers of all classes is a three-cylinder single-acting pump, which is suitable for almost every description of work which the diver may be called upon to perform, either in deep or shallow water. Another most useful type is a two-cylinder double-acting pump (figs. 1 and 2), which is designed to supply two divers working simultaneously in moderate depths of water, or one diver only in deep water. An air-distributing arrangement is fitted, whereby, when it is desired to send two mendown together, each cylinder supplies air independently of the other; and when it is required to send one diver into deep water, the two cylinders are connected and the full volume of air from both is delivered to the one man. The same duty is also performed by a four-cylinder single-acting pump. Smaller pumps, having one double-acting or two single-acting cylinders, are also used for shallow water work.
In most cases these air pumps are worked by manual power; this method of working is rendered necessary by the fact that the machines are usually placed in small boats from which the divers work and on which other motive power is not available. In cases, however, where steam or electric power is available the pumps are sometimes worked by their means—more particularly on harbour and dock works. In such instances the air is not delivered direct from the pump to the diver, but is delivered into an intermediate steel receiver to which the diver’s air pipe is connected, the object being to ensure a reserve supply of air in case of a breakdown of the pump. Some of these combinations of pumps and motors are so arranged that, in the event of an accident to the motor, the pump can be thrown out of gear with it, and be immediately worked by hand power. Each pump is fitted with a gauge (or gauges), indicating not only the pressure of air which the pump is supplying, but also the depth of water at which the diver is working. The cylinders are water-jacketed to ensure the air delivered to the diver being cool, the water being drawn in and circulated round the cylinders by means of a small metal pump worked from an eccentric on the main crank-shaft. Filters are sometimes attached to the suction and delivery sides of the pumps to ensure the inlet of air being free from dirt, and the discharge of air free from dirt and oil.
Helmet.—The helmet and breastplate (fig. 3) are made from highly planished tinned copper, with gun-metal valves and other fittings. The helmet is provided with a non-return air inlet valve to which the diver’s air pipe is connected; the air when it lifts the inlet valve passes through three conduits—one having its outlet over the front glass, the others their outlets over the side glasses. In this way the diver gets the air fresh as it enters the helmet, and at the same time it prevents condensation of his breath on the glasses and keeps them clear. There is a regulating air outlet valve by which the diver adjusts his supply of air according to his requirements in different depths of water; the valve is usually made to be adjusted by hand, but sometimes it is so constructed as to be operated by the diver knocking his head against it, the spindle being extended through to the inside of the helmet and fitted at its inner extremity with a button or disk. By unscrewing the valve, the diver allows air to escape, and thus the dress is deflated; by screwing it up the air is retained and the dress inflated. Thus the diver can control his specific gravity and rise or sink at will. In case by any chance the diver should inflate the dress inadvertently, and wish to get rid of the superfluous air quickly, he can do so by opening an emergency cock, which is fitted on the helmet. Plate glasses in gun-metal frames are also fitted to the helmet, two, one on each side, being permanently fixed, while one in front is made either to screw in and out, or to work on a hinged joint like a ship’s scuttle; the side glasses are usually protected by metal cross-bars, as is also sometimes the front glass. Some divers prefer unprotected glasses at the side of the helmet, instead of protected oval ones.
The breastplate is fitted on its outer edge with metal screws and bands. The disposition of the screws corresponds with that of the holes in the india-rubber collar of the diving dress described below. There are other methods of making a watertight joint between the diver’s breastplate and the diving dress, but, as these are only mechanical differences, it will suffice to describe the Siebe-Gorman apparatus, as exclusively adopted by the British government. Whatever the shape or design of the helmet or dress, Siebe’s principle is the one in universal use to-day.
The metal tabs are for carrying the diver’s lead weights, which are fitted with suitable clips; the hooks—one on each side of the helmet—are for keeping the ropes attached to the back weight in position. The helmet and breastplate are fitted at their lower and upper parts respectively with gun-metal segmental neck rings, which make it possible to connect these two main parts together by one-eighth of a turn, a catch at the back of the helmet preventing any chance of unscrewing. The small eyes at the top of the helmet are for securing the diver’s air pipe and life line in position and preventing them from swaying.
A, Helmet.
B, Breastplate.
F, Emergency cock.
G, Glasses in frames.
H, Metal screws and bands.
I, Metal tabs.
J, Hooks for keeping weight ropes in position.
L, Eyes to which air pipe and life line are secured.
K, Segmental neck rings.
D, Air conduits.
M, Telephone receiver.
N, Transmitter.
O, Contact piece to ring bell.
C, Air inlet valve.
E, Regulating outlet valve.
G, Glasses in frames.
L, Eyes to which air pipe and life line are secured.
P, Connexion for telephone cable.
TheDiving Dressis a combination suit which envelops the whole body from feet to neck. It is made of two layers of tanned twill with pure rubber between, and is fitted at the neck with a vulcanized india-rubber collar, or band, with holes punched in it corresponding to the screws in the breastplate. This collar, when clamped tightly between the bands and the breastplate by means of the nuts, ensures a watertight joint. The sleeves of the dress are fitted with vulcanized india-rubber cuffs, which, fitting tightly round the diver’s wrists, prevent the ingress of water at these parts also.
Boots.—These are generally made with leather uppers, beechwood inner soles and leaden outer soles, the latter being secured to the others by copper rivets. Heavy leather straps with brass buckles secure the boot to the foot. Each boot weighs about 16 ℔. Sometimes the main part of the boot-golosh, toe and heel, are in one brass casting, with leather upper part, heavy straps and brass buckles.
Lead Weights.—These weigh 40 ℔ each, and the diver wears one on his back, another on his chest. These weights and the heavy boots ensure the diver’s equilibrium when under water.
Belt and Knife and Small Tools.—Every diver wears a heavy waist-belt in which he carries a strong knife in metal case, and sometimes other small tools.
Air Pipe.—The diver’s air pipe is of a flexible, non-collapsible description, being made of alternate layers of strong canvas and vulcanized india-rubber, with steel or hard drawn metal wire embedded. At the ends are fitted gun-metal couplings, for connecting the pipe with the diver’s pump and helmet.
Signal Line.—The diver’s signal line (sometimes called life line) consists of a length of reverse laid Manila rope. In cases where the telephone apparatus is not used, the diver gives his signals by means of a series of pulls on the signal line in accordance with a prearranged code.
Telephonic Apparatus.—Without doubt one of the most useful adjuncts to the modern diving apparatus is the loud-sounding telephone (fig. 4), introduced by Siebe, Gorman & Co., which enables the diver to communicate viva voce with his attendant, and vice versa. In the British navy the type of submarine telephonic apparatus used is the Graham-Davis system. This is made on two plans, (1) a single set of instruments, for communication between one diver and his attendant direct, (2) an intercommunication set which is used where two divers are employed. With this type the attendant can speak to No. 1 or No. 2 diver separately, or with both at the same time, and vice versa; and No. 1 can be put in communication with No. 2 whilst they are under water, the attendant at the surface being able to hear what the men are saying. The advantages of such a system are obvious. It is more particularly useful where two divers are working one either side of a ship, or where the divers may be engaged upon the same piece of work, but out of sight of one another, or out of touch. It would prove its utility in a marked degree in cases where a diver got into difficulties; a second diver sent down to his assistance could receive and give verbal directions and thus greatly expedite the work of rescue.
The telephone instruments in the helmet consist of one or more loud-sounding receivers placed either in the crown of the helmet, or one on each side in close proximity to the diver’s ears. A transmitter of a special watertight pattern is placed between the front glass and one of the side glasses, and a contact piece, which, when the diver presses his chin against it, rings a bell at the surface, is fitted immediately below the front glass. A buzzer is sometimes fixed in the helmet to call the diver’s attention when the attendant wishes to speak, but as a rule the voice is transmitted so loudly that this device is unnecessary. A connexion, through which the insulated wires connecting the instruments pass, terminates in contact pieces, and the telephone cable, embedded in the diver’s signal line, is connected with it. The other end of the signal line is connected to a battery box at the surface. This box contains, besides the cells, a receiver and transmitter for the attendant, an electric bell, a terminal box, and a special switch, by means of which various communications between diver, or divers, and attendant are made. If, as is sometimes the case, the diver happens to be somewhat deaf, he can, whilst he is taking a message, stop the vibration of the outlet valve and the noise made by the escaping air, by merely pressing his finger on a spindle which passes through the disk of the valve, and thus momentarily ensure absolute silence.
Speaking Tube.—The rubber speaking tube which was the forerunner of the telephonic apparatus is now practically obsolete, though it is still used in isolated cases.
Submarine Electric Lamps.—Various forms of submarine lamps are used, from a powerful arc light to a self-contained hand lamp, the former giving about 2000 or 3000 candle-power, and requiring a steam-driven dynamo to supply the necessary current, the latter (fig. 5) giving a light of about 10 candle-power and having its own batteries, so that the diver carries both the light and its source in his hand. These submarine lamps are all constructed on the same principle, having the incandescent lamps, or carbons as the case may be, enclosed in a strong glass globe, the mechanism and connexions being fitted in a metal case above the globe, which is flanged and secured watertightly to the case.
Self-contained Diving Dress.—The object of the self-contained diving dress is to make the diver independent of air supply from the surface. The dress, helmet, boots and weights are of the ordinary pattern already described, but instead of obtaining his air supply by means of pumps and pipes, the diver is equipped with a knapsack consisting of a steel cylinder containing oxygen compressed to a pressure of 120 atmospheres (= about 1800 ℔) to the square inch, and chambers containing caustic soda or caustic potash. The helmet is connected to the chambers by tubes, and the oxygen cylinder is similarly connected to the chambers. The breath exhaled by the diver passes through a valve into the caustic soda, which absorbs the carbonic acid, and it is then again inhaled through another valve. This process of regeneration goes on automatically, the requisite amount of oxygen being restored to the breathed air in its passage through the chambers. This type of apparatus has been used for shallow water work, but the great majority of divers prefer the apparatus using pumps as the source of the air supply.
An emergency dress, using this self-contained system for breathing, has been designed by Messrs Fleuss and Davis, of the firm of Siebe, Gorman & Co., primarily as a life-saving apparatus, for enabling men to escape from disabled submarine boats.
A, Metal case containing electrical fittings.
B, Glass globe and incandescent lamp.
C, Stand, which also protects the globe.
D, Ring for suspending lamp.
E, Reflector.
The helmet diver is indispensable in connexion with harbour and dock construction, bridge-building, pearl and sponge fishing, wreck raising and the recovery of sunken cargo and treasure. Every ship in the British navy carries one set or more of diving apparatus, for use in ease of emergency, for clearing fouled propellers, cleaning valves or ship’s hull below the water line, repairing hulls if necessary, and recovering lost anchors, chains, torpedoes, &c.
Greatest Depths attained.—The greatest depth at which useful work has been performed by a diver is 182 ft. From this depth a Spanish diver, Angel Erostarbe, recovered £9000 in silver bars from the wreck of the steamer “Skyro,” sunk off Cape Finisterre; Alexander Lambert succeeded in salving £70,000 from the Spanish mail steamer “Alphonso XII,” sunk in 162 ft. of water off Las Palmas, Grand Canary; W. Ridyard recovered £50,000 in silver dollars from the “Hamilton Mitchell,” sunk off Leuconna Reef, China, in 150 ft. There are individual cases where much larger sums have been recovered, but those mentioned are particularly notable by reason of the great depth involved and stand out as the greatest depths at which good work has been done. The sponge fishers of the Mediterranean work at a maximum depth of about 150 ft., and the pearl divers of Australia at 120 ft. But submarine operations on the great majority of the harbour and dock works of the world are conducted at a depth of from 30 to 60 ft.
The weighted tools employed by divers differ very little from those used by the workmen onterra firma. Pneumatic tools, worked by compressed air conveyed from the surface through flexible tubes, are great aids, particularly in rock removal work. With the rock drill the diver bores a number of holes to a given depth, inserts in these the charges of dynamite or other explosive used, attaches one end of a wire to a detonator which is inserted in the charge, and then comes to the surface. The boat from which he works is then moved away from the scene of operations, paying out the wire attached to the detonators, and when at a safe distance the free end of the wire is connected to a magneto exploding machine, which is then set in motion.
A complete set of diving apparatus costs from £75 to £200, varying with the depth of water for which it is required.
The pay of a diver depends upon the nature of the work upon which he is engaged, and also upon the depth of the water. On harbour and dock work the average wage is 2s. to 2s. 6d. per hour; on wreck work from 3s. to 5s. an hour, according to depth; on treasure and cargo recovery so much per day, with a percentage on the value recovered, generally about 5%. The pearl fishers of Australia get so much per ton of shell, and the sponge fishers are also paid by results.
A problem which has been exercising the minds of those engaged in submarine work is the greatest depth at which it is possible to work, for, as is well known, many a fine vessel with valuable cargo and treasure is lying out of reach of the diver owing to the pressure which he would have to sustain were he to attempt to reach her. Mr Leonard Hill, and Drs Greenwood and J. J. R. Macleod conducted experiments in conjunction with Messrs Siebe, Gorman & Co., with a view to solving this problem, and their efforts have been attended with some considerable success. Dr J. S. Haldane has also carried out practical experiments for the British Admiralty, and under his supervision two naval officers have succeeded in reaching the unprecedented depth of 210 ft., at which depth the pressure is about 90 ℔ to the square inch.
Diving Bells.—Every one is familiar with the experiment of placing an inverted tumbler in a bowl of water, and seeing the water excluded from the tumbler by the air inside it. Perhaps it was to some such experiment as this that the conception of the diving bell was due. As is well known, the pressure of water increases with the depth, and for all practical purposes this pressure can be taken at 4¼ ℔ to every 10 ft. The following table shows the pressure at different depths below the surface of the water:—
If a diving bell be sunk to a depth of, say, 33 ft., the air inside it will be compressed to about half its original volume, and the bell itself will be about half filled with water. But if a supply of air be maintained at a pressure equal to the depth of water at which the bell is submerged, not only will the water be kept down to the cutting edge, but the bell will be ventilated and it will be possible for its occupants to work for hours at a stretch.
Tradition gives Roger Bacon, in 1250, the credit for being the originator of the diving bell, but actual records are lost in antiquity. Of the records preserved to us, probably one of the most trustworthy is an account given in Kaspar Schott’s work,Technica curiosa, published in the year 1664, which quoted from one John Taisnier, who was in the service of Charles V. This account describes an experiment which took place at Toledo, Spain, in the year 1538, before the emperor and some thousands of spectators, when two Greeks descended into the water in a large “kettle,” suspended by ropes, with its mouth downwards. The “kettle” was equipoised by lead fixed round its mouth. The men came up dry, and a lighted candle, which they had taken down with them, was still burning.
Francis Bacon, in theNovum Organum, lib. ii., makes the following reference to a machine, or reservoir, of air to which labourers upon wrecks might resort whenever they required to take breath:—
“A hollow vessel, made of metal, was let down equally to the surface of the water, and thus carried with it to the bottom of the sea the whole of the air which it contained. It stood upon three feet—like a tripod—which were in length something less than the height of a man, so that the diver, when he was no longer able to contain his breath, could put his head into the vessel, and having filled his lungs again, return to his work.”
“A hollow vessel, made of metal, was let down equally to the surface of the water, and thus carried with it to the bottom of the sea the whole of the air which it contained. It stood upon three feet—like a tripod—which were in length something less than the height of a man, so that the diver, when he was no longer able to contain his breath, could put his head into the vessel, and having filled his lungs again, return to his work.”
But it was to Dr Edmund Halley, secretary of the Royal Society, that undoubtedly the honour is due of having invented the first really practical diving bell. This is described in thePhilosophical Transactions, 1717, in a paper on “The Art of Living Under Water by means of furnishing air at the bottom of the sea in any ordinary depth.” Halley’s bell was constructed of wood, and was covered with lead, which gave it the necessary sinking weight, and was so distributed as to ensure that it kept a perpendicular position when in the water. It was in the form of a truncated cone, 3 ft. in diameter at the top, 5 ft. at the bottom and 8 ft. high. In the roof a lens was introduced for admitting light, and also a tap to let out the vitiated air. Fresh air was supplied to the bell by means of two lead-lined barrels, each having a bung-hole in the top and bottom. To the hole in the top was fixed a leathern tube, weighted in such a manner that it always fell below the level of the bottom of the barrel so that no air could escape. When, however, the tube was turned up by the attendant in the bell, the pressure of the water rising through the hole in the bottom of the barrel, forced the air through the tube at the top and into the diving bell. These barrels were raised and lowered alternately, with such success that Halley says that he, with four others, remained at the bottom of the sea, at a depth of 9 to 10 fathoms, for an hour and a half at a time without inconvenience of any sort.
This type of bell was used by John Smeaton in repairing the foundations of Hexham Bridge in 1778, but instead of weighted barrels, he introduced a force pump for supplying the necessary air. To Smeaton too we are indebted for the first diving bell plant in the form with which we are familiar to-day, that celebrated engineer having designed a square bell of iron, for use on the Ramsgate harbour works, in 1788. This bell, which measured 4½ ft. in length, 3 ft. in width and 4½ ft. in height, and weighed 2½ tons, was made sufficiently heavy to sink by its own weight. It afforded room enough for two men to work, and was supplied with air by a force pump worked from a boat at the surface.
Though the diving bell has been largely superseded by the modern diving apparatus, it is still used on certain classes of work the magnitude of which justifies the expense entailed, for it is not only a question of the cost of the bell, but of the powerful steam-driven crane which is needed to lower and raise it, and also of the gantry on which the crane travels. Sometimes a barge or other vessel is used for working the bell.
At the present day, two types of diving bell are employed—the ordinary bell, and the air-lock bell, which, however, is not so largely used.
On the new national harbour works at Dover, four large diving bells of the ordinary type (fig. 6) were employed. These bells, in each of which from four to six men descended at a time, consisted of steel chambers, open at the bottom, measuring 17 ft. long by 10½ ft. wide by 7 ft. high, and each weighed 35 tons. The ballast, which at once gives the necessary sinking weight to the bell and maintains its equilibrium, consisted of slabs of cast iron bolted to the walls of the bell, inside. Each bell was fitted with loud-sounding telephonic apparatus, by means of which the occupants could communicate either with the men attending the crane or the men looking after the air compressors at the surface. Electric lamps, supplied with current by a dynamo in the compressor room, gave the necessary light inside the bell. Seats and foot rails were provided for the men, and there were racks and hooks for the various tools. Suspended from the roof was an iron skip into which the men threw theexcavated material, which was emptied out when the bell was brought to the surface. Air was supplied to the bells by means of steam-driven compressors worked in a house erected on the gantry. The air was delivered into a steel air receiver, and thence it passed through a flexible tube connected to a gun-metal inlet valve in the roof of the diving bell; the pressure of air was regulated according to the depth at which the bell happened to be working. The maximum depth on the Dover works was between 60 and 70 ft., = about 25-30 ℔ to the square inch. A bell was lowered by means of powerful steam-driven cranes, travelling on a gantry, to within a few feet of the water, and the men entered it from a boat. The bell then continued its descent to the bottom, where the men, with pick and shovel, levelled the sea bed ready to receive the large concrete blocks, weighing from 30 to 42 tons apiece. Having completed one section, the bell was moved along to another. The concrete blocks were then lowered and placed in position by helmet divers. The bell divers, clad in thick woollen suits and watertight thigh boots, worked in shifts of about three hours each, and were paid at the rate of from 1s. to 15d. per hour.Fig. 7.—Air-lock Diving Bell.A, Working chamber.B, Air-lock.C, Pulleys and wire ropes for lowering and raising bell.D, Iron ladder.E, Tackles suspended from roof for raising and lowering objects.F, Air supply pipe.The cost of an ordinary diving bell, including air compressor, telephonic apparatus and electric light, is from £600 to £1500, according to size.TheAir-lock Diving Bell(fig. 7) comprises an iron or steel working chamber similar to the ordinary diving bell, but with the addition of a shaft attached to its roof. At the upper end of the shaft is an airtight door, and about 8 ft. below this is another similar door. When the bell divers wish to enter the bell, they pass through the first door and close it after them, and then open a cock or valve and gradually let into the space between the two doors compressed air from the working chamber in order to equalize the pressure; they then open the second door and pass down into the working chamber, closing the door after them. When returning to the surface they reverse the operation. It can readily be imagined that, owing to its unwieldy character, the employment of the air-lock bell is resorted to only in those cases where the nature of the sea bed necessitates its remaining on a given spot for some considerable time, as for instance in the excavation of hard rock to a given depth.An air-lock bell supplied to the British Admiralty, for use in connexion with the laying of moorings at Gibraltar, has a working chamber measuring 15 ft. long by 10½ ft. wide, by 7½ ft. high, and a shaft 37½ ft. high by 3 ft. in diameter. It is built of steel plates, with cast-iron ballast, and its total weight is about 46 tons. The bell is electrically lighted, and is fitted with telephonic apparatus communicating with the air-compressor room and lifting-winch room. It is worked through a well in the centre of a specially constructed steel barge 85 ft. long by 40 ft. beam, having a draught of 7 ft. 6 in. The wire ropes, for lowering and raising the bell, work over pulleys which are carried on a superstructure erected over the well. Two sets of air compressors are fitted on the barge—one set for supplying air to the bell, the other set for working a pneumatic rock drill inside the bell. The greatest depth at which this particular bell will work is 40 ft. The cost of the whole plant, including barge, was about £14,000.The diving dress has, however, to a great extent supplanted the diving bell. This is due not only to the heavier cost of the latter, but more particularly to the greater mobility of the helmet diver. Bell divers are naturally limited to the area which their bell for the time being covers, whereas helmet divers can be distributed over different parts of a contract and work entirely independently of one another. The use of the diving bell is, therefore, practically limited to the work of levelling the sea bed, and the removal of rock.See also the articleCaisson Diseaseas regards the physiological effects of compressed air.
On the new national harbour works at Dover, four large diving bells of the ordinary type (fig. 6) were employed. These bells, in each of which from four to six men descended at a time, consisted of steel chambers, open at the bottom, measuring 17 ft. long by 10½ ft. wide by 7 ft. high, and each weighed 35 tons. The ballast, which at once gives the necessary sinking weight to the bell and maintains its equilibrium, consisted of slabs of cast iron bolted to the walls of the bell, inside. Each bell was fitted with loud-sounding telephonic apparatus, by means of which the occupants could communicate either with the men attending the crane or the men looking after the air compressors at the surface. Electric lamps, supplied with current by a dynamo in the compressor room, gave the necessary light inside the bell. Seats and foot rails were provided for the men, and there were racks and hooks for the various tools. Suspended from the roof was an iron skip into which the men threw theexcavated material, which was emptied out when the bell was brought to the surface. Air was supplied to the bells by means of steam-driven compressors worked in a house erected on the gantry. The air was delivered into a steel air receiver, and thence it passed through a flexible tube connected to a gun-metal inlet valve in the roof of the diving bell; the pressure of air was regulated according to the depth at which the bell happened to be working. The maximum depth on the Dover works was between 60 and 70 ft., = about 25-30 ℔ to the square inch. A bell was lowered by means of powerful steam-driven cranes, travelling on a gantry, to within a few feet of the water, and the men entered it from a boat. The bell then continued its descent to the bottom, where the men, with pick and shovel, levelled the sea bed ready to receive the large concrete blocks, weighing from 30 to 42 tons apiece. Having completed one section, the bell was moved along to another. The concrete blocks were then lowered and placed in position by helmet divers. The bell divers, clad in thick woollen suits and watertight thigh boots, worked in shifts of about three hours each, and were paid at the rate of from 1s. to 15d. per hour.
A, Working chamber.
B, Air-lock.
C, Pulleys and wire ropes for lowering and raising bell.
D, Iron ladder.
E, Tackles suspended from roof for raising and lowering objects.
F, Air supply pipe.
The cost of an ordinary diving bell, including air compressor, telephonic apparatus and electric light, is from £600 to £1500, according to size.
TheAir-lock Diving Bell(fig. 7) comprises an iron or steel working chamber similar to the ordinary diving bell, but with the addition of a shaft attached to its roof. At the upper end of the shaft is an airtight door, and about 8 ft. below this is another similar door. When the bell divers wish to enter the bell, they pass through the first door and close it after them, and then open a cock or valve and gradually let into the space between the two doors compressed air from the working chamber in order to equalize the pressure; they then open the second door and pass down into the working chamber, closing the door after them. When returning to the surface they reverse the operation. It can readily be imagined that, owing to its unwieldy character, the employment of the air-lock bell is resorted to only in those cases where the nature of the sea bed necessitates its remaining on a given spot for some considerable time, as for instance in the excavation of hard rock to a given depth.
An air-lock bell supplied to the British Admiralty, for use in connexion with the laying of moorings at Gibraltar, has a working chamber measuring 15 ft. long by 10½ ft. wide, by 7½ ft. high, and a shaft 37½ ft. high by 3 ft. in diameter. It is built of steel plates, with cast-iron ballast, and its total weight is about 46 tons. The bell is electrically lighted, and is fitted with telephonic apparatus communicating with the air-compressor room and lifting-winch room. It is worked through a well in the centre of a specially constructed steel barge 85 ft. long by 40 ft. beam, having a draught of 7 ft. 6 in. The wire ropes, for lowering and raising the bell, work over pulleys which are carried on a superstructure erected over the well. Two sets of air compressors are fitted on the barge—one set for supplying air to the bell, the other set for working a pneumatic rock drill inside the bell. The greatest depth at which this particular bell will work is 40 ft. The cost of the whole plant, including barge, was about £14,000.
The diving dress has, however, to a great extent supplanted the diving bell. This is due not only to the heavier cost of the latter, but more particularly to the greater mobility of the helmet diver. Bell divers are naturally limited to the area which their bell for the time being covers, whereas helmet divers can be distributed over different parts of a contract and work entirely independently of one another. The use of the diving bell is, therefore, practically limited to the work of levelling the sea bed, and the removal of rock.
See also the articleCaisson Diseaseas regards the physiological effects of compressed air.
(R. H. D.*)
DIVES-SUR-MER,a small port and seaside resort of north-western France on the coast of the department of Calvados, on the Dives, 15 m. N.E. of Caen by road. Pop. (1906) 3286. Dives is celebrated as the harbour whence William the Conqueror sailed to England in 1066. In the porch of its church (14th and 15th centuries) a tablet records the names of some of his companions. The town has a picturesque inn, adapted from a building dating partly from the 16th century, and market buildings dating from the 14th to the 16th centuries. The coast in the vicinity of Dives is fringed with small watering-places, those of Cabourg (to the west) and of Beuzeval and Houlgate (to the east) being practically united with it. There are large metallurgical works with electric motive power close to the town.
DIVIDE,a word used technically as a noun in America and the British colonies for any high ridge between two valleys, forming a water-parting; a dividing range. For special senses of the verb “to divide” (Lat.di-videre, the latter part of the word coming from a root seen in Lat.vidua, Eng. “widow”), meaning generally to split up in two or more parts, seeDivision. In a parliamentary sense, to divide (involving a separation into two sides, Aye and No) is to take the sense of the House by voting on the subject before it.
DIVIDEND(Lat.dividendum, a thing to be divided), the net profit periodically divisible among the proprietors of a joint-stock company in proportion to their respective holdings of its capital. Dividend is not interest, although the word dividend is frequently applied to payments of interest; and a failure to pay dividends to shareholders does not, like a failure to pay interest on borrowed money, lay a company open to being declared bankrupt. In bankruptcy a dividend is the proportionate share of the proceeds of the debtor’s estate received by a creditor. In England, the Companies Act 1862 provided that no dividend should be payable except out of the profits arising from the business of the company, but, in the case of companies incorporated by special act of parliament for the construction of railways and other public works which cannot be completed for a considerable time, it is sometimes provided that interest may during construction be paid to the subscribers for shares out of capital. Dividends (excluding occasional distributions in the form of shares) are ordinarily payable in cash. Most companies divide their capital into at least two classes, called “preference” shares and “ordinary” shares, of which the former are entitled out of the profits of the company to a preferential dividend at a fixed rate, and the latter to whatever remains after payment of the preferential dividend and any fixed charges. Before, however, a dividend is paid, a part of the profits is often carried to a “reservefund.” The dividend on preference shares is either “cumulative” or contingent on the profits of each separate year or half year. When cumulative, if the profits of any one year are insufficient to pay it in full, the deficiency has to be made good out of subsequent profits. A cumulative preferential dividend is sometimes said to be “guaranteed,” and preferential dividends payable by all English companies registered under the Companies Acts 1862 to 1908 are cumulative unless stipulated to be otherwise. Certain public companies are forbidden by parliament to pay dividends in excess of a prescribed maximum rate, but this restriction has been happily modified in some instances, notably in the case of gas companies, by the institution of a sliding scale, under which a gas company may so regulate the price of gas to be charged to consumers that any reduction of an authorized standard price entitles the company to make a proportionate increase of the authorized dividend, and any increase above the standard price involves a proportionate decrease of dividend. Dividends are usually declared yearly or half-yearly; and before any dividend can be paid it is, as a rule, necessary for the directors to submit to the shareholders, at a general meeting called for the purpose, the accounts of the company, with a report by the directors on its position and their recommendation as to the rate of the proposed dividend. The articles of association of a company usually provide that the shareholders may accept the director’s recommendation as to dividend or may declare a lower one, but may not declare a higher one than the directors recommend. Directors frequently have power to pay on account of the dividend for the year, without consulting the shareholders, an “interim dividend,” which on ordinary shares is generally at a much lower rate than the final or regular dividend. An exceptionally high dividend is often distributed in the shape of a dividend at the usual rate supplemented by an additional dividend or “bonus.” Payment of dividends is made by means of cheques sent by post, called “dividend warrants.” All dividends are subject to income-tax, and by most companies dividends are paid “less income-tax,” in which case the tax is deducted from the amount of dividend payable to each proprietor. When paid without such deduction a dividend is said to be “free of income-tax.” In the latter case, however, the company has to make provision for payment of the tax before declaring the dividend, and the amount of its divisible profits and the rate of dividend which it is able to declare are consequently to that extent reduced. In respect of consols and certain other securities, holders of amounts of less than £1000 may instruct the Bank of England or Bank of Ireland to receive and invest their dividends. With few exceptions, the prices of securities dealt in on the London Stock Exchange include any accruing dividend not paid up to the date of purchase. At a certain day, after the dividend is declared, the stock or share is dealt in on the Stock Exchange, asex dividend(or “x. d.”), which means that the current dividend is paid not to the buyer but to the previous holder, and the price of the stock is lower to that extent. The expression “cum dividend” is used to signify that the price of the security dealt in includes a dividend which, in the absence of any stipulation, might be supposed to belong to the seller of the security. On the New York Stock Exchange the invariable practice is to sell stock with the “dividend on” until the company’s books are closed, after which it is usually sold “ex dividend.”
(S. D. H.)
DIVIDIVI,the native and commercial name for the astringent pods ofCaesalpinia coriaria, a leguminous shrub of the suborderCaesalpinieae, which grows in low marshy tracts in the West Indies and the north of South America. The plant is between 20 and 30 ft. in height, and bears white flowers. The pods are flattened, and curl up in drying; they are about ¾ in. broad, from 2 to 3 in. long and of a rich brown colour. Dividivi was first brought to Europe from Caracas in 1768. It contains about 30% of ellagitannic acid, whence its value in leather manufacture.
DIVINATION, the process of obtaining knowledge of secret or future things by means of oracles, omens or astrology. The root of the word,deus(god) ordivus, indicates the supposed source of the soothsayer’s information, just as the equivalent Greek term,μαντική, indicates the spiritual source of the utterances of the seer,μάντις. In classical times the view was, in fact, general, as may be seen by Cicero’sDe divinatione, that not only oracles but also omens were signs sent by the gods; even the astrologer held that he gained his information, in the last resort, from the same source. On the side of the Stoics it was argued that if divination was a real art, there must be gods who gave it to mankind; against this it was argued that signs of future events may be given without any god.
Divination is practised in all grades of culture; its votaries range from the Australian black to the American medium. There is no general agreement as to the source of the information; commonly it is held that it comes from the gods directly or indirectly. In the Bornean cult of the hawk it seems that the divine bird itself was regarded as having a foreknowledge of the future. Later it is regarded as no more than a messenger. Among the Australian blacks, divination is largely employed to discover the cause of death, where it is assumed to be due to magic; in some cases the spirit of the dead man is held to give the information, in others the living magician is the source of the knowledge. We find moreover a semi-scientific conception of the basis of divination; the whole of nature is linked together; just as the variations in the height of a column of mercury serve to foretell the weather, so the flight of birds or behaviour of cattle may help to prognosticate its changes; for the uncultured it is merely a step to the assumption that animals know things which are hidden from man. Haruspication, or the inspection of entrails, was justified on similar grounds, and in the case of omens from birds or animals, no less than in astrology, it was held that the facts from which inferences were drawn were themselves in part the causes of the events which they foretold, thus fortifying the belief in the possibility of divination.
From a psychological point of view divinatory methods may be classified under two main heads: (A) autoscopic, which depend simply on some change in the consciousness of the soothsayer; (B) heteroscopic, in which he looks outside himself for guidance and perhaps infers rather than divines in the proper sense.
(A) Autoscopic methods depend on (i.) sensory or (ii.) motor automatisms, or (iii.) mental impressions, for their results. (i.) Crystal-gazing (q.v.) is a world-wide method of divining, which is analogous to dreams, save that the vision is voluntarily initiated, though little, if at all, under the control of the scryer. Corresponding to crystal-gazing we haveshell-hearingand similar methods, which are, however, less common; in these the information is gained by hearing a voice. (ii.) The divining rod (q.v.) is the best-known example of this class; divination depending on automatic movements of this sort is found at all stages of culture; in Australia it is used to detect the magician who has caused the death of a native; in medieval and modern times water-divining ordowsinghas been largely and successfully used. Similar in principle iscoscinomancy, or divining by a sieve held suspended, which gives indications by turning; and the equally common divination by a suspended ring, both of which are found from Europe in the west to China and Japan in the east. The ordeal by the Bible and key is equally popular; the book is suspended by a key tied in with its wards between the leaves and supported on two persons’ fingers, and the whole turns round when the name of the guilty person is mentioned. Confined to higher cultures on the other hand, for obvious reasons, is divination by automatic writing, which is practised in China more especially. The sand divination so widely spread in Africa seems to be of a different nature.Trance speaking, on the other hand, may be found in any stage of culture and there is no doubt that in many cases the procedure of the magician or shaman induces a state of auto-hypnotism; at a higher stage these utterances are termed oracles and are believed to be the result of inspiration (q.v.). (iii.) Another method of divination is by the aid of mental impressions; observation seems to show that by some process of this sort, akin to clairvoyance (q.v.), fortunes are told successfully by means of palmistry or by laying the cards; for the same “lie” of the cards may be diversely interpreted to meet different cases. In other cases the impression is involuntary or less consciously sought, as in dreams (q.v.), which, however, are sometimes induced, forpurposes of divination, by the process known as incubation or temple sleep. Dreams are sometimes regarded as visits to or from gods or the souls of the dead, sometimes as signs to be interpreted symbolically by means of dream-books, which are found not only in Europe but in less cultured countries like Siam.
(B) In heteroscopic divination the process is rather one of inference from external facts. The methods are very various. (i.) The casting of lots,sortilege, was common in classical antiquity; the Homeric heroes prayed to the gods when they cast lots in Agamemnon’s leather cap, and Mopsus divined with sacred lots when the Argonauts embarked. Similarly dice are thrown for purposes of sortilege; theastragalior knucklebones, used in children’s games at the present day, were implements of divination in the first instance. In Polynesia the coco-nut is spun like a teetotum to discover a thief. Somewhat different are the omens drawn from books; in ancient times the poets were often consulted, more especially Virgil, whence the namesortes virgilianae, just as the Bible is used for drawing texts in our own day, especially in Germany. (ii.) Inharuspication, or the inspection of entrails, inscapulomancyor divination by the speal-bone or shoulder-blade, in divination by footprints in ashes, found in Australia, Peru and Scotland, the voluntary element is prominent, for the diviner must take active steps to secure the conditions necessary to divination. (iii.) In the case ofauguryandomens, on the other hand, that is not necessary. The behaviour and cries of birds, andangangor meeting with ominous animals, &c., may be voluntarily observed, and opportunities for observation made; but this is not necessary for success. (iv.) Inastrologywe have a method which still finds believers among people of good education. The stars are held, not only to prognosticate the future but also to influence it; the child born when Mars is in the ascendant will be war-like; Venus has to do with love; the sign of the Lion presides over places where wild beasts are found. (v.) In other cases the tie that binds the subject of divination with the omen-giving object is sympathy. The name of the life-index is given to a tree, animal or other object believed to be so closely united by sympathetic ties to a human being that the fate of the latter is reflected in the condition of the former. The Polynesians set up sticks to see if the warriors they stood for were to fall in battle; on Hallowe’en in our own country the behaviour of nuts and other objects thrown into the fire is held to prognosticate the lot of the person to whom they have been assigned. Where, as in the last two cases, the sympathetic bond is less strong, we find symbolical interpretation playing an important part.
Sympathy and symbolism, association of ideas and analogy, together with a certain amount of observation, are the explanation of the great mass of heteroscopic divinatory formulae. But where autoscopic phenomena play the chief part the question of the origin of divination is less simple. The investigations of the Society for Psychical Research show that premonitions, though rare in our own day, are not absolutely unknown. Pseudo-premonitions, due to hallucinatory memory, are not unknown; there is also some ground for holding that crystal-gazers are able to perceive incidents which are happening at a distance from them. Divination of this sort, therefore, may be due to observation and experiment of a rude sort, rather than to the unchecked play of fancy which resulted in heteroscopic divination.
See also the articlesAugurs,Oracle,Astrology,Omen, &c.Authorities.—Bouché Leclercq,Histoire de la divination dans l’antiquité; Tylor,Primitive Culture, passim; Maury, “La Magie et l’astrologie,”Journ. Anth. Inst.i. 163, v. 436;Folklore, iii. 193; Ellis,Tshi-speaking Peoples, p. 202;Dictionnaire encyclopédique des sciences médicales, xxx. 24-96;Journ. of Philology, xiii. 273, xiv. 113; Deubner,De incubatione; Lenormant,La Divination, et la science de présages chez les Chaldéens; Skeat,Malay Magic; J. Johnson,Yoruba Heathenism(1899).
See also the articlesAugurs,Oracle,Astrology,Omen, &c.
Authorities.—Bouché Leclercq,Histoire de la divination dans l’antiquité; Tylor,Primitive Culture, passim; Maury, “La Magie et l’astrologie,”Journ. Anth. Inst.i. 163, v. 436;Folklore, iii. 193; Ellis,Tshi-speaking Peoples, p. 202;Dictionnaire encyclopédique des sciences médicales, xxx. 24-96;Journ. of Philology, xiii. 273, xiv. 113; Deubner,De incubatione; Lenormant,La Divination, et la science de présages chez les Chaldéens; Skeat,Malay Magic; J. Johnson,Yoruba Heathenism(1899).
(N. W. T.)
DIVINING-ROD.As indicated in the articleMagic,Rhabdomancy, or the art of using a divining-rod for discovering something hidden, is apparently of immemorial antiquity, and the Romanvirgula divina, as used in taking auguries by means of casting bits of stick, is described by Cicero and Tacitus (see alsoDivination); but the special form ofvirgula furcata, or forked twig of hazel or willow (see alsoHazel), described by G. Agricola (De re metallica, 1546), and in Sebastian Munster’sCosmographyin the early part of the 16th century, used specially for discovering metallic lodes or water beneath the earth, must be distinguished from the general superstition. The “dowsing” or divining-rod, in this sense, has a modern interest, dating from its use by prospectors for minerals in the German (Harz Mountains) mining districts; the French chemist M.E. Chevreul1assigns its first mention to Basil Valentine, the alchemist of the late 15th century. On account of its supposed magical powers, it may be taken perhaps as an historical analogue to such fairy wands as thecaduceusof Mercury, the golden arrow of Herodotus’s “Abaris the Hyperborean,” or the medieval witch’s broomstick. But the existence of the modern water-finder or dowser makes the divining-rod a matter of more than mythological or superstitious interest. TheSchlagruthe(striking-rod), or forked twig of the German miners, was brought to England by those engaged in the Cornish mines by the merchant venturers of Queen Elizabeth’s day. Professor W. F. Barrett, F.R.S., the chief modern investigator of this subject, regards its employment, dating as it does from the revival of learning, as based on the medieval doctrine of “sympathy,” the drooping of trees and character of the vegetation being considered to give indications of mineral lodes beneath the earth’s surface, by means of a sort of attraction; and such critical works as Robert Boyle’s (1663), or theMineralogia Cornubiensisof Pryce (1778), admitted its value in discovering metals. But as mining declined in Cornwall, the use of the dowser for searching for lodes almost disappeared, and was transferred to water-finding. The divining-rod has, however, also been used for searching for any buried objects. In the south of France, in the 17th century, it was employed in tracking criminals and heretics. Its abuse led to a decree of the Inquisition in 1701, forbidding its employment for purposes of justice.
In modern times the professional dowser is a “water-finder,” and there has been a good deal of investigation into the possibility of a scientific explanation of his claims to be able to locate underground water, where it is not known to exist, by the use of a forked hazel-twig which, twisting in his hands, leads him by its directing-power to the place where a boring should be made. Whether justified or not, a widespread faith exists, based no doubt on frequent success, in the dowser’s power; and Professor Barrett (The Times, January 21, 1905) states that “making a liberal allowance for failures of which I have not heard, I have no hesitation in saying that where fissure water exists and the discovery of underground water sufficient for a domestic supply is a matter of the utmost difficulty, the chances of success with a good dowser far exceed mere lucky hits, or the success obtained by the most skilful observer, even with full knowledge of the local geology.” Is this due to any special faculty in the dowser, or has the twig itself anything to do with it? Held in balanced equilibrium, the forked twig, in the dowser’s hands, moves with a sudden and often violent motion, and the appearance of actual life in the twig itself, though regarded as mere stage-play by some, is popularly associated with the cause of the water-finder’s success. The theory that there is any direct connexion (“sympathy” or electrical influence) between the divining-rod and the water or metal, is however repudiated by modern science. Professor Barrett, who with Professor Janet and others is satisfied that the rod twists without any intention or voluntary deception on the part of the dowser, ascribes the phenomenon to “motor-automatism” on the part of the dowser (seeAutomatism), a reflex action excited by some stimulus upon his mind, which may be either a subconscious suggestion or an actual impression (obscure in its nature) from an external object or an external mind; both sorts of stimulus are possible, so that the dowser himself may make false inferences (and fail) by supposing that the stimulus is an external object (like water). The divining-rod being thus “an indicator of any sub-conscious suggestion or impression,” its indications, no doubt, may be fallacious; but Professor Barrett, basing his conclusions upon observed successes and their greater proportion to failures than anything thatchance could produce, advances the hypothesis that some persons (like the professional dowsers) possess “a genuine super-normal perceptive faculty,” and that the mind of a good dowser, possessing the idiosyncrasy of motor-automatism, becomes a blank ortabula rasa, so that “the faintest impression made by the object searched for creates an involuntary or automatic motion of the indicator, whatever it may be.” Like the “homing instinct” of certain birds and animals, the dowser’s power lies beneath the level of any conscious perception; and the function of the forked twig is to act as an index of some material or other mental disturbance within him, which otherwise he could not interpret.
It should be added that dowsers do not always use any rod. Some again use a willow rod, or withy, others a hazel-twig (the traditional material), others a beech or holly twig, or one from any other tree; others even a piece of wire or watch-spring. The best dowsers are said to have been generally more or less illiterate men, usually engaged in some humble vocation.
Sir W. H. Preece (The Times, January 16, 1905), repudiating as an electrician the theory that any electric force is involved, has recorded his opinion that water-finding by a dowser is due to “mechanical vibration, set up by the friction of moving water, acting upon the sensitive ventral diaphragm of certain exceptionally delicately framed persons.” Another theory is that water-finders are “exceptionally sensitive to hygrometric influences.” In any case, modern science approaches the problem as one concerning which the facts have to be accepted, and explained by some natural, though obscure, cause.