Not the least important feature of the work in hand is the preparation of a suitable explanatory lecture to accompany the experiments which are to be performed with the apparatus described. Upon the snap and vigor of the lecture depend in a large measure the successful presentation of the offering. It is safe to assume that the day of the electrical fakir is past-no longer can the smooth-tongued performer claim some supernatural power which enables him to take through his body enormous voltages which would prove fatal to the average mortal. The lecturer of this type is as much a thing of the past as is the old-time magician who makes claim to some occult power rather than to sleight-of-hand or mechanical ingenuity to accomplish his tricks. The electrical entertainer of to-day must bear in mind that in the past five years the education of the general public along the lines of electricity and science has advanced in an astonishing degree, and to offer his experiments under the guise of a wizard is not only to insult the intelligence of his audience, but to stamp himself as an absurd charlatan as well. Just as the modern prestidigitator credits his quickness of hand, so should the electrical entertainer give credit to modern science for his ability to perform the startling experiments he offers.

Class of Audience.-The class of audience catered to should also bear careful consideration. The style of talk favored by the intelligent and well-read Chautauqua assembly would be hopelesslyy out of place in even a high class vaudeville theatre. This is not due to the lesser degree of intelligence to be found in'the theatre audience so much as to the fact that such an audience demands to be shown rather than told. The experiments must speak for themselves and any lecture accompanying their presentation must be more in the nature of an explanatory "chatter" rather than a discourse on the theory and scientific reasons for the phenomena demonstrated. With the typical lecture audience, on the other hand, the explanatory remarks may be more comprehensive in nature, as such an audience comes to listen and be instructed, as well as to see and be entertained. At the same time the performer must not lose sight of the fact that many of the people in even a scholarly audience are totally unfamiliar with even the fundamentals of electricity except in a vague way, and his discourse should therefore be interspersed with frequent analogies in everyday life in order that the terms and phrases used may be clearly comprehended.

A clever touch of comedy is of almost inestimable value; for the theatre audience it should be of the "slapstick" variety, while for 'the lecture assembly it should be genteel or even subtle in nature. As an illustration of the former style of comedy, the writer has seen many a mediocre electrical act carried through to a riotous curtain simply because a handful of boys from the audience were knocked off their feet supposedly through contact with a wire. The same bit of comedy presented for the approval of a more cultured audience would have resulted in a few disdainful smiles.

Short Introduction Preferable.-The performer should beware of a lengthy introduction in either of the two cases. For the theatre, the opening remarks should be exceedingly brief and "straight from the shoulder," for an audience of this nature is ever impatient for something to happen ancl the quicker the action throughout the better the reception. If the lecturer is endowed with an unusually commanding presence, which invariably combines the gift of wit or humor, lie may carry the action with his own magnetic personality; but for the individual who is not gifted in this manner, the rapid-fire style is safer and less likely to subject him to the disconcerting ridicule of an unruly gallery crowd.

Impressive Opening Imperative.-The introductory remarks should be quickly followed up with an impressive experiment; this is to at once arrest the attention and whet the appetite for better things to come. After the successful completion of this one experiment, the performer has, in a large measure, gained the confidence of his people, and in consequence, they will be the more ready to listen to his further remarks. At this point may come the real introduction to the entertainment to follow. The experiments should be placed on the programme in logical order and every effort made to so arrange them that there shall be no wait whatever between the successive demonstrations.

The mediocre experiments should be interspersed with the spectacular and startling ones, and invariably the climax should consist of the one experiment that proves to be the masterpiece. It is not always possible to determine just which one from among the number may properly lay claim to this title and this is where the value of "trying it on the dog" comes in. As a matter of fact the final rehearsals of the performance should be before a real audience and a critical one at that, for only in this way can the production be whipped into shape.

Selection of Experiments.-The selection and preparation of the experiments to be used in his program must needs rest with the entertainer himself. The work must show the individuality of the entertainer, since he is to perform the experiments and is responsible for their reception by the audience. The hints offered in this book should, therefore, be considered in the light of suggestions only, and the most the writer can hope is that they will start the entertainer on the right track. Constant experiment day after day will serve to bring out the wonderful possibilities in the apparatus, and as the worker proceeds he should make note of the effects produced and strive in future attempts to make the manner of presentation more striking and interesting. The one big thing to be borne in mind, as outlined in the last article, is that the experiments must hold the interest of the audience without the necessity of discourse or explanation. In the first place, the high frequency discharge produces a deafening noise which in itself renders speech inaudible while the coil is in operation, and, secondly, the audience as a rule does not care

what the entertainer has to say and it must be shown. Simplicity should be the keynote throughout, for the average theatre audience may be treated as a more or less unruly crowd of children who want solely to be amused and entertained. With these facts in mind, the entertainer may plan his program. The number of experiments is seemingly limitless when one starts to operate the apparatus, and as the time allotted the average feature act in vaudeville is from twenty to thirty minutes, it is obvious that only the pick of the lot should be chosen. Some may be selected for their beauty, but the majority should he picked with a view to their sensational qualities.

Probably the most effective opening number is produced by the high frequency transformer in operation at full power with a dark stage. The streamers of fire leap out for so-veral feet in all directions from the ball atop the transformer. The discharge makes a tremendous crackling and crashing noise which impresses the audience through its weirdness even before the curtain rises. As the curtain ascends, the center of the stage appears to be filled with a twisting, darting mass of slender, purplish fingers of fire which snap at the entertainer as lie enters through the center door and walks down stage or toward the, footlights. The current may, at this time, be shut off and tae lights turned on full for the opening remarks which were discussed in a preceding paragraph.

After the short preliminary address the performer may briefly explain to the audience how modern science enables man to make electricity his servant, and a servant whose services are to be respected but not feared. For instance, he can say that if he were to place his hands across the terminals of the low frequency transformer (pointing out the instrument, but not explaining its principles) he would receive a shock that would positively be fatal, since its voltage is in excess of that used in the electric chair. He may then go on to say that through a simple process of conversion which changes the nature of the current but which does not in any way materially reduce its strength, and which, indeed, serves to increase its voltage to near or quite the millon mark, he is enabled to apply that erstwhile destructive force to the good of mankind, curing diseases, relieving pain and in countless other ways fulfilling the claim that electricity is man's greatest servant when intelligently handled. The performer may then show how the tremendous current can be taken through the body without danger, even though its voltage is hundreds of times that used for purposes of electrocution. A metal rod is grasped in the hands, and while standing on an insulated stool the performer approaches the ball discharger of the transformer with the lights out and the coil in operation. As the rod nears the ball, a beautiful halo or luminous vapor gathers at the point and increases in intensity as the distance is shortened. Finally, when the rod is within four or five feet of the ball, an enormous sheet of purplish white flame crashes across the intervening space and into the rod held in the hands. The spark leaps into the air and breaks as the heat causes it to rise, and the moment the discharge is broken another flame takes its place. If the distance is shortened to within six inches or a foot of the ball, a piece of stick or bit of paper held in the spark will be ignited immediately.

The performer may then withdraw and have the current turned off for a few words of explanation. The next experiment may be made to show that the current is actually going into the body of the entertainer. To this end, he approaches the ball with his rod held in one hand and in the other he grasps an electrode to which is connected a wire leading to one terminal of an incandescent lamp. The other terminal of the lamp is attached to a second electrode which is held by the assistant. When the current is turned on the spark leaps to the rod as before and the lamp is lighted to full incandescence or even burned out by the current passing between the bodies of the performer and his assistant standing nearby.

Some of the most startling and spectacular experiments of which the high frequency apparatus is capable are produced in connection with the insulated stool and the charged body of the performer. For most of these experiments, the frequency of the current should be increased by moving the primary clip of the oscillation transformer to a point where fewer turns are included in the circuit. This will reduce the spark length of the coil, but this loss can be tolerated in view of the fact that the current is smoother and the muscular contractive effects are totally missing. It is difficult for the performer to do justice to his experiments if he experiences any degree of shock, which, while not at all dangerous, is still disconcerting.

If the primary clip on the oscillation transformer is carefully adjusted after the performer has been connected with the discharge ball, a point will be found where his body seems literally to exude a luminescent halo of bluish white fire. When the free hand is raised directly over the head, little tongues of fire dart from the finger tips into the air. When a second person approaches to within a foot or so of the performer the space between their bodics is apparently filled with a luminous vapor, and a finger pointed at the performer instantly calls forth an intense, cone-shaped stream of light. A Geissler or other vacuum tube brought to within even six or eight feet of the charged body lights up with its characteristic glow, and, when it approaches to within a foot of the body, the glow is practically as bright as it would be if the current were passing into it through a wire instead of through space.

An entertaining experiment is to bring an incandescent lamp bulb, held by its base in the assistant's hand, close to a rod held in the hand of the performer. The current slowly strikes through the glass wall, and, as the fracture increases, the air is let into the bulb. As the vacuum lowers the - color of the glow in the bulb changes from bluish white to red, then to purple and finally it disappears as the spark punctures the wall and finds its way to the wires inside.

No further attempt will be made to describe "experiments" for to do so is futile at this point. The worker will find that every time he turns the current on, he finds some new wrinkle or stunt to do with the spark. Ardent experimentation with the apparatus itself is the very best teacher and a day spent merely in "playing" with the outfit will give the ingenious worker scores of fascinating experiments, some of which are suitable for the stage and others for the parlor or the laboratory.

Dr. Tesla prepared a series of intensely interesting lectures some years ago and his work, now in book form, offers a truly remarkable series of instructive experiments. While Dr. Tesla advocates, in his book, the use of a high frequency alternator or else an oil-immersed oscillation transformer, still many, if not all, of the performances he pictures can be shown with the apparatus described in this book.