since, and I presume he is well, or I should have heard from him. I have treated two or three other cases similar to this, with the same result.

Dr. Wheatland: I am reminded of an electrode which was presented to the American Electro-Therapeutic Association at Buffalo. It was a syringe electrode with the end covered with cotton. The fluid is carried to the end with a separate part for the current. When the electrode has reached the desired point the fluid is forced up by a syringe.

Dr. Gray: Every man for the tools he is used to. I want to say a word in regard to the electrode which has just been mentioned. It is a good thing, especially in the line of intra-uterine troubles, but I think a word of caution should be given to anyone who is going to try it for the first time. If a person has not thought about it he does not realize how much force he uses in pushing down the piston of the syringe. I had two cases of shock and collapse from attempting to do that sort of thing which I should not care to repeat. It is for that reason that I speak of this. The use of this electrode in the male urethra would probably not produce such symptoms, but in a case of endometritis great care must be given to the amount of fluid used. There is no way to tell actually the amount of fluid the uterus will hold. I think it would also be wise to experiment a little with it, and see just how much pressure it takes to saturate the cotton. I should do this if I were going to use it for the first time.

Dr. Reeves, of Boston: One might have a check on the syringe of 5 ma., or 2 ma., or any number you wish.

Dr. White, of Boston: I got this word only this afternoon, and so have not much of a paper. I was asked to speak a little on high frequency. I have not used the static machine so much. in giving high frequency, as with the various coils. I understand from experts that the so-called high-frequency machine. is not a strictly high-frequency machine. Just what the difference is I cannot exactly explain. My work with high frequency has been perhaps more especially in cases of nervous diseases than in prostatitis and the other cases spoken of here to-night. I lately had a discussion with a prominent New York doctor who had sent me some literature. He took exception to a letter I wrote to a physician who had written an article telling about giving from a static machine some 250 ma. The doctor did not like my calling attention to the amount of current. You can't get more out of a machine than you can put into it. Most vacuum tubes run from 50 to 55 or possibly 60 ma. My treatment has been largely in cases of insomnia, nervous debility, and sciatic neuritis. I used to treat sciatica with the static machine, using a heavy spark and giving all the machine would carry. It was pretty hot work for the patient. Instead of that I have lately been using the vacuum tube and giving it through

the trousers. It is pretty hot, but not quite so bad as that from the static machine. So far I have had good results.

Insomnia I have treated through the cervical region, running down the spine, giving a good deal of treatment to the spine. The other cases I mentioned would, of course, come in under the various paralyses.

Dr. Morse: In using high frequency do you, as a rule, use it through the clothing or on the flesh? For instance, in a case of sciatica?

Ans. I get down to as thin clothing as I can, the thinner the better.

Dr. McFee: Is there any particular advantage in using the spark through the clothing?

Ans. I prefer treating near the skin.

Dr. Davis: I have been much interested in what Dr. White has said on this subject. I am using this method with a great deal of satisfaction. The more I use it the better I like it, and I am thoroughly convinced that the field of high frequency has hardly yet been touched. It reaches such a large range of diseases that it is easier to mention those it does not reach than those it does.

NEW AND IMPROVED APPARATUS.

This department is devoted to publishing, with illustrations, drawings, and descriptions, new apparatus, electrodes, etc., for the benefit of those interested in the progressive improvements in armamentaria. A NEW STATIC CURRENT CONTROLLER.

The importance of regulating the current from the larger static machines which are coming rapidly into general use has created a demand for a means of controlling the output, thereby adjusting them to a wider range of therapeutic application. The device shown here is a simple resistance rheostat with

adjustable screw, to be placed by an attachment in the circuit between the grounded side of the static machine and the earth. The solution has been adapted to the scale whereby the measurement of correct strength is indicated, not in milliamperes or volts, but in the relative capacity of machines having different numbers of revolving plates. By this means the effects of an eight-plate, twelve-plate, sixteen- or twenty-plate machine may be employed according to the indication, when the largest type of machine is employed. The device is not patented, and may be procured by Van Houten & Ten Broeck Co., 300 Fourth Avenue, New York.

Director of the Roentgen Ray Laboratory of Philadelphia, General Hospital.

Mr. President and Members:-One of the disadvantages in the use of the Röntgen rays in therapeutics lies in the want of a practical and accurate unit of dosage. Manifold have been the labors put forth for obtaining such a standard, but thus far, these labors have been unavailing; principally because idiosyncrasy plays so largely the rôle, and the difficulty in asserting what number of irradiations any special case may demand-the personal equation being a very large and determining factor.

The methods in vogue all depend on either thermal, chemical, physical, or electrical changes induced in a special reagent employed; they are therefore mechanical indices for a study of the intensity of the rays, and while practical, they afford no insight into the amount of biological action occurring in the tissues.

The following are the methods that have won most approval: A. THE MEASUREMENT OF THE ELECTRIC CURRENTS.

1. The Current Going to the Primary Coil.-The voltage and amperage of a current that goes to a coil depends upon the varieties of the interrupters and the construction of the primary coil. The secondary or induced current depends upon the variety of the current or winding of the coil, because the same coil and interrupter may give different qualities of the rays. depending upon the make and the vacuum of the tube.

* Read at the Sixteenth Annual Meeting of the American Electro-Therapeutic Association at Philadelphia, September 21, 1906.

2. Milliamperage of the Secondary Induced Current.-The milliamperemeter was first advocated by d'Arsonval who used it with a Villard tube, and proved that the production of X-rays is proportionate to the intensity of the current, and has shown photographs in support of this assertion. The milliamperemeter measures the current passing through a tube; but does not tell us how much energy is expended in the production of the rays.

The milliamperemeter measures the resistance of the tube. There are degrees of vacuum where no X-rays are produced, yet the milliamperemeter indicates a passing current. The resistance of a tube often depends upon the shape and angle of the anode (platinum), upon the surface of the cathode and upon the focal distance of the cathode. A valve tube makes the current unidirectional as is shown by the ossilograph, the latter also shows absence of constant movement in the needle, whilst the milliamperemeter shows the slight changes in the vacuum by the deflection of the needle. It should never be forgotten that the reading of the milliamperemeter is not necessarily an absolute index of the amount of X-ray production in the tube. Thus we read the milliamperage and we know that the current is passing from the secondary into the tube; but how much of the current going through the tube is expended in the production of the X-rays? So much depends upon the make, shape, size, etc., of the tube and upon the relation existing between the cathode and anode that the answer is difficult, if not impossible. However Wertheim Salomonson* described and exhibited a new instrument for measuring the energy of a variable current of high potential. The milliamperemeter usually used for measuring the current in the secondary circuit indicates the mean current, whereas what we really require is the mean square value, and with an oscillating current these two values are not proportional.

The dilatometer devised by Professor Salomonson measures the energy expended in the secondary circuit directly. It consists of a paraffin oil thermometer, which is heated by the current passing through a slate resistance. Slate has a high and fairly constant electric resistance. The heating effect of even a small current is therefore readily appreciable. The heat is communicated to the surrounding paraffin, and the consequent ex* Archives of the Röntgen Ray, April, 1906.

pansion in the paraffin is shown in a capillary tube attached to the vessel. The rise of the meniscus in this tube will therefore be a measure of the total energy expanded in the circuit during the time the current has passed through the resistance. The dilatometer sums up the values of the energy for each instant since the current was started; its readings will therefore be proportional to the mean square of the current, and the rise of the meniscus per unit time will give the mean square intensity of the current. The dilatometers are standarized by means of an electrodynamometer and a stop-watch, a small steady current being passed through the two instruments.

Experiments with these instruments showed that the efficiency of a Ruhmkorff coil is the same for all intensities of current in the primary, provided that the resistance in the secondary circuit remains unaltered.

3. Spintermeter.-The length of the spark-gap (parallel) on the secondary coil or induced current was the earliest method employed. The length indicates the internal resistance of a tube to the passage of the current; the longer the spark-gap the higher will be the vacuum. But it is a fact that the variation in the supply of current in the primary coil or interrupter will change the length of the spark-gap, with the same tube in circuit. The pointed rods of the electrodes, the composition of the rods, the atmospheric conditions, such as moisture, etc., the construction of the coil, interrupter, etc., the source of current, and also the amount of the current, will alter the length of the spark-gap. Two different tubes with the same current and same spark-gap may give different degrees of radiation because the size of the electrodes may be different and different metal may be used, etc. Béclére, of Paris, employed a graduated rod capable of sliding to and fro. On this scaled bar he observes the number of inches or centimeters. This is a convenient form of measurement and every coil is thus supplied and is universally employed. This method is often misleading, as I have seen a tube with 3 or 4 inches (7.5 or 10 cm.) of sparkgap where the rays were far less penetrating and in some instances cathodic rays were produced.

The data given by the spintermeter hold good only for the special apparatus that the operator employs and not necessarily for other forms of this apparatus.