Eberhart's Manual of High Frequency Currents
Noble M. Eberhart
Chapter Four
Various Forms of Vacuum Tubes; Effects of Different Vacua;
Insulated Tubes; Fixed and Adjustable Socket Handles.
   Various forms of Tubes.  The vacuum tubes used in high frequency work have been made in almost every conceivable form to enable them to be applied to various parts of the body.  The vacuum of these tubes varies from one-five hundredth of an atmosphere up to that possessed by the X-ray, one one-millionth.  The color which appears in the tube varies according to the degree of vacuum; thus a low vacuum will produce a reddish color or glow in the tube; one of medium or slightly above medium vacuum, a blue color; and a high vacuum a white appearance.
   Strong says, “As the exhaustion proceeds from one-five hundredth to one-ten thousandth of an atmosphere, the disks become thicker and the striations fewer, and the color changes from a rose-pink to violet, blue (one one-thousandth), blue-white, and finally to a dense yellow-white.  A low X-ray vacuum would be about one one-hundred thousandth of an atmosphere.”
   Besides the degree of vacuum, the light is also supposed to be influenced by the kind of gas remaining in the tube, and some authorities claim that there is a direct analogy between the rapidity of the oscillations at the spark gap and the color of light in the tube.  As the lowest number of vibrations producing the color “red” is 450 billions per second and the highest violet 750 billions, this analogy seems improbable.
   The low vacuum tubes give off more heat, while the high ones give some chemical (ultra-violet) rays and if very high, X-rays.
   The red or red-pink vacuum, besides giving off more heat, is sedative and useful in painful conditions and in acute diseases and inflammation.
   The medium, blue, or blue-white vacuum gives off some chemical rays, and is more appropriate in chronic conditions.  It is often employed where the white vacuum would really be indicated, as this contains not only blue and violet, but also some ultra-violet rays.  All chronic ailments, where the vitality is impaired, skin diseases, indolent ulcers, etc., call for the employment of the white or blue-white tube.
Fig. 18 - Interrupterless Transformer, with Resonator Employed in Giving Auto-condensation.
Fig. 19 - Portable Outfits.
Fig. 20 - Tubes and Handles.[numbered]
Fig. 21 - Condenser electrode. Insulated Tubes.[numbered]

   Much of the foregoing is more theoretical than it is practical and I have finally come to the conclusion that a medium vacuum electrode (purple tinge) answers all practical purposes, and this is what I am now using.
   Vacuum tubes are ordinarily made in a single chamber, the tube fitting into the socket of a handle that is used for all the different forms.  Some tubes have a leading-in wire and others, instead of having a single chamber in the tube, have the vacuum divided into two chambers the size of the circumference of the tube, connected by a small tube, possibly the size of a small pencil, and surrounded by a chamber that is not a vacuum.  These latter are known as insulated tubes.
   The tubes used most frequently are shown in Fig. 20.  No. 1 is the body tube, which is used also in treating face and scalp.  No. 2 is the rectal tube; 3, vaginal; 4, nasal; 5, urethral or aural; 6, throat. In place of No. 1, No. 11, Fig. 21 will be found equally useful and in some instances superior on account of the ridges around the depression, enabling it to be used where it would be difficult to place the body tube.

Fig. 22 - Various types of Tubes.
Fig. 23 - Vacuum Tubes.

   Insulated Tubes. The advantage of the insulated tube which I have been in the habit of calling the Titus tube, because I believe it was first designed by Dr. Titus, is that with this tube the current may be introduced without loss into an orifice of the body.  Take a plain vacuum tube and attach to the current and when it is lighted up, surround it with the thumb and forefinger and it will be observed that there is no light beyond the point of contact.  It stands to reason, therefore, that if such a tube were introduced, for instance into the rectum, the point of contact with the body would draw off much of the current and the surface within the body would receive but little treatment.  For this reason with the insulated tube the opening of the orifice comes in contact with the non-vacuum part of the tube and the end of the tube where the vacuum exists thus conveys all of the current in at the desired point.
   I have been taken to task for my statement above, on the ground that contact with the encircling finger possesses no capacity.  It simulates, however, the conditions of certain orificial treatments and after trying the experiment referred to, I am sure the physician will resort to the use of insulated tubes for rectal and other orificial work.
   The principal forms of insulated tubes in use are shown in Fig. 21.  No. 7 is for the ear; 8, rectal, or prostatic; 9, post-nasal; 10, for vagina or uterus; 11, prostatic or for general surface use; 12. Urethral or aural; 13, nasal.
   The Adjustable Socket Handle.  The ordinary holder for high frequency tubes consists of a straight handle with a metal socket into which the tube is received as shown in Fig. 20.  This is suitable for holding electrodes that are applied to the surfaces of the body, but for most conditions I prefer a handle with a movable or adjustable socket.  Fig. 20.  This socket may be placed at any angle to the handle that may be desired and with a thumb screw made secure at this point necessary.  The advantage of this will be discussed in detail in Chapter VII., when considering the special technique for various portions of the body.
   The latest type of my adjustable handle is shown in Fig. 24.  It is of spring steel and accommodates tubes of varying diameters.
   Author’s Spatulate Tubes.  I have recently designed the tubes shown in Fig. 27.  They end in a flattened spatulate extremity.  In the body tube the end is at an angle with the main tube, thus making it much handier to use than the regulation type of body electrode.

Fig. 24 - Author’s Latest Adjustable Handle.

   The vaginal, prostatic and rectal tubes are similar in shape, but are straight.  They vary only in size and are made both plain and insulated.

Fig. 25 - A Neat Combination of High Frequency and X-Ray.

   The physician who has been using vaginal and prostatic tubes will readily perceive the advantages of the larger flat surface.  Either of these tubes will be found quite satisfactory for surface applications.

Fig. 26 - A Compact Portable Outfit.
Fig. 27 - Author’s New Spatulate Tubes.
Fig. 27a - Portable Outfit.