As noted in the previous chapter, mechanical vibration in its application was in the process of development when the Greeks wrapped one end of a saw in cotton and applied it to the part to be treated - while sawing a piece of wood with the uncovered portion for the production of vibration.  The improvements on primitive vibrating devices suggested for use with massage were various hand instruments - Klemm's muscle beater, Graham's elastic rods (See Fig. 1) with rubber balls, massage rollers (See Fig. 2) - and later the machines of Zander, Taylor, (See Fig. 3), Kellogg, Charcot, Phelan, Nebel, Herz, Funke and Krukenberg.

    There are two forms of Zander machines (See Figs. 4a and 4b), one for massage and the other for movements.  "Their operation depends upon various applications of the lever principle.  A manometer is so attached as to show or register the force used, the speed of each machine is governed by the number of teeth in its several cog-wheels, adjustable to obtain differing rates and extents of movements, and a special clutch-wheel or a governing handle is so fitted to each as to make it possible to throw the whole machine out of gear and stop it in an instant."

    Necessity is the mother of invention.  A demand for means of lessening the laborious task of the masseur and various other factors gave an impetus to an old subject.  French, Germans and Americans have accordingly invented and improved the wherewithal by means of which the work could be better and more easily accomplished by machinery, thereby saving the time, energy and patience of the operator, and enabling him to give treatment with greater precision as to stroke, and definite measurement as to speed.  The employment of the apparatus may or may not equal or excel that of manual massage, according to the touch, knowledge, skill and technique of the operator with each, and the adaptability of the apparatus to the particular work in question.  The vibrators now on the market are too numerous to mention, and many of them are not practical for therapeutic purposes.  The French have probably, contributed more to the literature of the subject of mechanical vibration than any other European nation, and a description of much of their apparatus can be found in the Transactions of the International Congress of Electro-Therapeutics for 1900.

    The most powerful vibrators are usually not portable as the motors are too heavy.  Only a few of the vibrators fulfill the requirements of a first class machine.  Some vibrators have a flexible shaft, others a rigid arm connected to the motor.  Compressed air vibrators use rubber tubing.  Most portable vibrators have merely a cord for conducting the current.  The device by means of which vibration may be administered is variously designated as applicator, attachment, and vibratode from vibration, vibro, to shake, and [nonscript] a way.

    Vigoreaux used to employ a tuning fork in connection with a sounding box, in the treatment of hemianaesthesia, contractures, pain, etc.  Among some of the devices are the vibratory fork of Boudet of Paris, used for anaesthesia and neuralgia, a hand vibrator, Charcot's vibratory helmet, the vibratory cap of Drs. Gilles de la Tourette, Larat and Gautier, the vibratory handle of Dr. Garnault, and the vibrating table of Drs. Charcot and Gilles de la Tourette, from which the patient received a treatment by sitting in a chair on the vibrating table.  Two well known vibrators in use today are German inventions.  One of the first vibrators introduced into this country from abroad came from Germany.  It resembled an oscillator.

    Among the small instruments noted is a vibrating urethral sound used by Lankowski, Berlin.  It [Journal of Advanced Therapeutics, June, 1902] is "a large metal sound fitted into the rolled end of a wide metal spring, wider and stronger than a watch spring.  The end of the spring holding the sound is screwed flat between the narrow metal plates, and fastened together with two thumb screws.  The sound is inserted in the urethra, and slight blows are struck on the projecting coil of the spring with a padded mallet."  The treatment was administered daily or on every second or third day.  The largest sound, able of being introduced without causing pain was found to produce the best results.  It was used in cases of relaxation, over-stimulation sexual neurasthenia, phosphaturia and prostatorrhea.

    For the administration of mechanical vibration by hand many devices sold in America are used, a few of which are a roller chain, consisting of a double roll of wooden balls, shown in Fig. 5, that revolve in a flexible, jointed, nickel-plated wire chain, having handles; a roller chain and exerciser combined, many massage rollers, a Preuss' elastic roller (Fig. 6) with 12 interchangeable balls - 4 smooth wooden balls, 4 corrugated wooden balls and 4 soft rubber balls - a neck roller, made of a piece of solid soft rubber corrugated into five prongs, wheel-shaped (Fig. 2), holding a nickel-plated roller of metal; a massage hammer (Fig. 7), with corrugated soft rubber cushions; muscle beaters; a combined roller, kneader and beater (Fig. 8); Graham's muscle beaters (Fig. 1), consisting of rubber balls attached to rods having a handle at one end; Klemm's beater (Fig. 9), with fingers made of "light springs," and Japanese massage rollers.

    Concussors for vibratory treatment are of many different shapes and sizes, including probe pointed ones (Fig. 10), for the pharnx; Ewer's disc, designed for the throat (Fig. 11); rounded knobbed, concave plate, slightly curved, and saddle shaped (Figs. 12, 13, 14 and 15), and Dapper's abdominal plate (Figs. 16 and 17); also concave wheels, cylindrical, corrugated roll and; rotation rollers of various designs.  There are also many designs of rotary, beaters (Figs. 18 and 19), employed for vibration therapy, some consisting of rubber bars, others of leather straps or hammers; others are for tapping massage, such as an instrument with a cylindrical end for vaginal and uterine use; a long leather covered fork for use in neck and throat treatment (Fig. 20), and a combination rotating and tapping concussor.

    A SMALL PORTABLE VIBRATORY APPARATUS, to be operated by hand, is used like forceps (Fig. 21).  "By opening and shutting two vibration exciters (hammers) are set in alternating motion. The operator can vary the speed "from 12 to 1500 vibrations per minute."

    Another example of a small portable apparatus is one provided with a vibrating fork, (Fig. 22), operated by dry cell batteries and said to give from 500 to 5000 strokes per minute.

    Among electrical vibratory instruments are an electric muscle beater, which consists of a carbon ball covered with chamois, and operated by a battery; an electric massage hammer, a galvanic massage roller, and larger instruments to be combined with the galvanic or faradic current, also special ear massage and electrical prostatic massage instruments.

    A small apparatus makes the hand the motor power.  It consists of a metal rod about two and one-half feet in length, to one end of which a hard rubber ball about two inches in diameter is attached; at the other end of the rod is a hook-like extremity covered with rubber tubing.  On this rod a sliding rod is placed at right angles to the long rod.  The sliding rod is shorter than the first one mentioned and has three rubber balls on it, the first being adjacent to the first rod, the second midway on the second rod, and the third and smallest at its distal end.  To operate it the covered end should be placed in contact with the part to be treated; the ball end being held with one hand and with the thumb and index finger of the other hand the sliding rod should be moved to and fro.  Fine, but not powerful, vibrations are thus produced.

    Zander of Stockholm, Taylor of New York and Kellogg of Michigan were among the noted pioneers in the induction of mechanical vibration with nonportable apparatus.  Among such apparatus was a vibrating chair, platform, bar and apparatus for mechanical beating, friction, kneading and trunk rolling.  These were the fore-runners of modern vibrators.  Many of the movements so produced were similar, but were not so easily applied as the more recent productions.  They operated by vibrating the patient en masse, not in part.

    Owing to the recognition of mechanical vibration by the profession, and the results obtained by its scientific application, many vibrators have appeared on the market.  Some of these are excellent and fill the requirements of a first class machine, whereas others are inferior.  It behooves the practitioner to acquaint himself with the essentials of a good machine, and to consider the therapeutic requirements before purchasing an apparatus.

    A serviceable type of flexible shaft machine (Figs. 23 and 24) comprises an electric "motor specially wound to give proper speed for the work and is provided with a speed controller in base "for use with the direct current.  The pedestal is adjustable and provided with a rotating top.  The stroke is obtained by the revolving of an eccentric, which is readily adjusted for the regulation of the stroke.  The machine is operated by a 220-volt, or 110-volt, direct current, or by an alternating current.  The outfit in the latter case has "an alternating current motor so connected that the speed is regulated perfectly by mechanical means, thus obviating the constant destructive sparking that is inevitable when commutators are used on alternating current motors." It can be used with a 60, 125 or 133 cycle current.  Another form or type of machine has a peculiar handle which imparts a lateral rubbing movement to the applicator.  Another form (Fig. 25) of the same machine is a combination pneumatic and mechanical vibratory massage outfit, which consists of a special motor that can be operated at any speed from 200 revolutions per minute to 6000 revolutions per minute, two speed controllers, one for the pump and one for the vibrator handle, a pneumatic pump that gives a stroke from 0 to 11/4 inches, and a vibratory massage handle.  The pump gives four air movements, straight exhaust or suction, suction with release, alternate suction and compression, and a succession of forward impulses or compression.  An otoscope, which is also necessary in ear massage, and glass cups for eye treatment are provided.  In the handle is an air port hole, which is covered by the thumb of the operator during an administration, allowing him to control the escape of air.  The cable is provided with six attachments and the handle has a removable cap and a device for regulating the strength of the vibrations.  By means of a two-speed countershaft it is possible to use any size motor, water or
electric.  Of the numerous vibratodes (Fig. 26) made for use with the apparatus are: a small rubber cone, a medium sized soft rubber cone, an extra large one and two soft rubber cones for special work, a straight probe, a straight rectal applicator for internal use, an internal rectal applicator with spring to lessen severity of vibrations, a rectal for external use, a curved applicator for the throat, one cone of hard rubber, a large and small corrugated rubber disc, a cushioned applicator, a probe with springs, a probe with twisted silver wire with eyelet to carry medicated ribbon, a convex hard rubber vibratode, a large convex hard rubber muscle roller, a large concave heart applicator and a spinal applicator, fingers separated sufficiently, to span the
spine.  Special vibratodes include a 12-inch rectal vibratode with flushing attachment.  The vibratodes may be attached in a straight line with the handle, or at right angles to it. The weight in the cap-shield has a rotary motion which imparts a tapping motion to the vibratode.

    Another form of machine comprises a transformer motor which is operated by a switch giving perfect control of speed; on one end a massage handle or a nasal drill can be attached, and on the other end a small pump is attached which is used for aural and other forms of pneumo-massage.

    This motor also transforms the direct current into the alternating, which is again passed into another transformer, which delivers a cautery current sufficient to heat any knife, and also a current for lighting diagnostic lights.

    Another flexible shaft vibrator consists of a ball bearing oscillating lever revolving on its own axis, with a ball bearing sliding fulcrum provided with a take-up for perfect adjustment.  This construction, with the ball bearings running in a heavy grease, ensures operation with a minimum of friction, no lost motion, noiseless running and a remarkable smoothness of stroke, which remains constant irrespective of the pressure exercised.  The stroke is instantly adjustable and the vibrator is interchangeable throughout, no moving parts are exposed and vibratodes are easily and quickly adjusted.

    The most widely known rigid arm machine (Fig. 27) consists of a perpendicular bar mounted on a metal base at right angles to it.  To the perpendicular bar is attached one end of a jointed arm supporting a weight, the other arm being supported by a short perpendicular bar to the base.  On the upper part of the long perpendicular bar is a rigid jointed arm supporting a motor, to one side of which is a attached the metal handle bar with its perpendicular attachment, on the end of which are screwed the vibratodes.  The rigidity of the arm is a particular feature of this apparatus.  It can be operated by the direct or alternating electric current.

    By means of two adjusting devices the vibratodes as a whole can be swung backwards and forwards, or from side to side.  The motor is connected by insulated cords, to a plug screwed into an incandescent lamp socket.  The holder of the vibratode has a short shaft clamped by a nut on each side, which can be shifted in such a manner as to lengthen or shorten the stroke.  The motion of the vibratode itself is to and fro in one plane.  The attachments employed with this instrument are a hard rubber rectal, a throat attachment, a hard rubber ball for spinal work, a soft rubber brush, or multiple point vibratode, and a rubber cup.                    I

    A mechanical vibration apparatus which employs compressed air or liquid carbonic acid gas as power consists of a handle which is surmounted by a horizontal tube, the upper part of which is surmounted by a small metal chamber containing four air chambers.  The horizontal tube contains the piston, with three airspaces into which three of the four air chambers open, the fourth air chamber opening into the space not occupied by the piston, the rush of air from which causes the piston to move forwards and backwards in the horizontal tube which imparts an up and down motion to the vibratode, which is introduced into this holder, the opposite, end of which makes one end of the horizontal tube.  The handle is connected with the atomizer valve or shut-off of any air tank or nebulizer outfit by a flexible rubber tube.  The motion imparted is an up and down stroke.  The following vibratodes are provided with the apparatus; one for the uterus, one straight and one curved probe for mucous cavities, a roller vibratode, a multiple knobbed one for applications over the abdominal viscera, a soft-cushioned disc, vibratode and a small hard one for body vibration, a small soft cone for the face and arms, a large soft rubber cone for aural massage, a soft rubber rectal-uterine, and an extremely long soft rubber rectal probe (Fig. 28).  It is claimed that only five pounds of air pressure are necessary to operate it, though oftener 15 to 25 pounds pressure are desired.  It will produce over 7000 impulses per minute of a quality ranging from a most delicate touch to energetic vibratory impulse.  The air pressure should be varied to the requirements treated.  Twelve pounds is sufficient for application to the throat and neck; ten pounds for the liver, and twenty pounds for the treatment of hemorrhoids.

    Dr.  Abrams, author of "Spondylotherapy," employs an apparatus which is essentially a pneumatic hammer, giving a stroke of 11/4 inches and operated by compressed air.  The force of the concussion blow may "be regulated by a stop-cock or by the pressure of the concussor on the spinous processes." The concussors vary in size "to include one, two, three or more spinous processes."

    If a compressed air outfit be employed for power, a power pump is to be preferred to a hand pump.  No hydraulic air compressor is satisfactory unless at least "30 pounds faucet water pressure" can be furnished.

    AN OSCILLATOR (Fig. 29) is a combined type of apparatus; an oscillatory as well as a vibratory treatment can be administered with it.  It is operated by an electric motor and consists of a standard, the head of which is a short, horizontal shaft, on each end of which is a wheel, provided on each outer surface with an eccentric.  The motor power may be either gas, water or electricity.  The motor is, connected to the pulleys on the head of the vibrator by a belt. The applicators for oscillation consist of a broad belt, a narrow belt, a hand piece and a foot rest.

    A millimeter scale is marked on the side of each eccentric, which, when employing oscillation should be adjusted the same distance from the center of each axis.  After loosening each set screw, shift each eccentric the indicated distance from the center, the distance being regulated to the fineness of oscillatory movement desired, one millimeter or one and one-half millimeters being very fine and suitable to use with the smaller belt for the treatment of headaches or in ear or throat cases; two and one-half millimeters or so for cases where the hand-piece is used.  Two to eight or nine millimeters are usually used with the large belt applied to the body unless very powerful work is required, when ten or eleven millimeters may be used, the limit being sixteen millimeters.  After adjustment tighten the set screws.  The motor for good work should make at least 2000 revolutions per minute, the speed being regulated by a system of pulleys for use with the alternating current, or pulleys and rheostat when the direct current is employed.  When the hand-piece is used, only one eccentric is employed, the other having been put on center, but with the other applications both eccentrics are used.  The belts should be non-elastic and firm.  The hand applicator may he used in combination with the faradic or galvanic battery.  The belt applicator may also be used with electricity.

    The action of the tissue oscillator differs from a percussion stroke - it produces oscillation, having a two-fold vibratory effect; the motion being governed by both eccentrics.  When the motion is governed by one eccentric, vibration in its limited sense is produced.  A revolving stool, and one or two high-backed chairs, one with and one without arms, are useful in giving treatment, but when the hand applicator is applied administration may be given lying down.  Two hand-applicators may be used together in such a manner that they may be applied as in heart massage.

    To use the belt, adjust the eccentrics, direct the patient, if a body treatment is desired, to remove the corsets or coat and vest, and facing the machine adjust the belt.  He must make a pull of about twenty-five pounds on it in order to keep it taut.  At the same time the hands should be kept upon the handles to keep them in line.

    An improvement in the above apparatus is the addition of a flexible shaft for the administration of forms of vibration other than the oscillatory.  The end of the flexible shaft is inserted into the open screw end at the side of the oscillator; a set screw is provided which enables the operator to tighten it down firmly.  Both eccentrics must be adjusted on the center before using the vibrator attachment.  It is preferable to insert the vibration shaft on the heavy or pulley side of the oscillator.  Any possible speed may be used and regulated by the pulleys or rheostat when the direct current is used.  If the greatest speed is desired, place the pulley belt on the inside cone or steps of pulleys.  Any flexible shaft can be used.

    A vibrator has been perfected to be ran with dry cells.  It is claimed that the cost of a machine operated in this way giving full power of a stationary machine is about fifteen cents per hour.

    A "counterweight" vibrator (Fig. 30) is a machine without a rigid arm or a flexible shaft, "the hand piece being attached to the motor in such a way that it can be adapted to any part of the body.  The motor is suspended from an arm that is supported by a spring.  The hand piece is so attached to the motor that the direction of the stroke can be changed without changing the position of the motor.  This is attached to the wall." It has a wide range of action.  It is claimed that its vibrations are not transmitted.

    For the general practitioner a portable apparatus is valuable.  Portable machines are all made on about the same principle.  A favorite type (Fig. 32) consists of a motor to which is attached a handle connected by a cord to a suitable plug which can be connected to a lamp socket.  The vibratode is connected to one end of the motor.  It gives a "percussion and a synchronous oscillatory stroke" which has a wide range made by "the manipulation of the knurled regulating thumb wheel."  A visible scale shows the strength of vibration being used.  Vibratodes and a suitable case complete the outfit, which weighs three pounds.  A transforming connection can be used so the vibrator may be used where there is an alternating current as well as where a direct current only is at hand.

    As early as 1808 Dr. Thomas S. Dowse [Lectures on Massage and Electricity in the Treatment of Disease], Fellow of the College of Physicians of Edinburgh, used the faradic current with two damp chamois-covered metal electrodes, or sponge electrodes, and the galvanic with sponge electrodes as well as a unipolar current from the static machine for administering vibra-massage.

    Dr. Morris W. Brinkmann, of New York, for the application of selective, harmonic, electric vibration uses "an apparatus [Journal of Advanced Therapeutics], having three ribbon vibrators of different thicknesses, each being adjustable for tension by its own lever and thumbscrew; each also having its own contact point and individual adjustment.  The primary current, instead of passing through the ordinary spring or ribbon vibrator, was split into two or three divisions according to the number of ribbons in use.  We therefore get induced currents in the secondary of desired speeds, as determined by the tension or attunement adjustments.  The current tension is regulated by the amount of current allowed to pass through the primary, the amount of secondary embracing the primary, and the particular winding of the secondary used."

    Considerable discussion has arisen from time to time as to whether this or that-machine was properly a mechanical vibrator.  Some claim that a "vibrator must have a to-and-fro motion and others that one apparatus rotates, another percusses, another pounds, and still another shakes.  The subject of vibration must be considered in a broader sense, as correctly considered, a vibration is "a recurrent change of position."

    Modern mechanical vibrators classified according to the manner of stroke are:

1. Those which have a to and fro motion in one direction or plane.

2. Those characterized by an up and down motion.

3. Those which have distinct oscillations.

4. Those which have a lateral motion in all planes of a rotary motion.

    The essential elements of a good machine are as follows, when considered not therapeutically but with reference to mechanism.  It should be constructed so as not to injure, by soiling or tearing, the patient's clothing; the vibrations of uniform quality should be capable of a range from weak to strong, and the force of impulse and rate, or speed, should be under control (the rate ranging as high as 6500 per minute), and the stroke should be adjustable.  It should be easily moved about, easily operated, and readily adapted to the part to be treated.  It should have the least possible frictional wear, and the vibratodes should be easily adjusted.  The apparatus should be so constructed as not to be easily broken or put out of repair.  Weight and transmitted vibrations to the operator are objectionable features.  A purchaser should always remember that an apparatus is "no more durable than its weakest part."

    The numerous mechanical vibrators of the present day differ in size, in form, in the supporting arm - flexible or rigid - in the motor power, - hand, electric, gas, water, etc.; in the form of vibratodes; in the composition of vibratodes, as metal, hard rubber, soft rubber, spongy rubber, and compressible containing air; the kind of stroke, - lateral or to and fro, tapping or rotary; and in the range of speed and applicability.  Some are much more meritorious than others.  The selection of a machine should depend upon the work to be done.  None of them are perfect, but all have merit.  As Dr. George H. Taylor [Massage] so aptly states, "Mechanical impulse may be so applied as to oppose the end sought, and actually to operate in the direction of morbid activity, it may obstruct physiological endeavor."  There must be such an adaptation of mechanical processes as will successfully blend with the various physiological processes.