CLARK, District Judge.
At the argument of this cause we reiterated our dismay at the continued impotence of our United States courts in the field of expert testimony. The necessity for the assistance of impartial experts in cases owing their existence, supposedly at any rate, to the promotion of science and the useful arts, seems plain. Yet even in patent cases the federal courts are given neither the authority nor the means for employing their own experts or “assessors in science.” Because of that this court was constrained to undertake'its own researches in an unfamiliar and highly technical field, and in doing so to begin at a time-consuming early point in the art.
That art is that of an electrical device known as a rectifier. The device has been thus defined in Principles of Mercury Arc Rectifiers and Their Circuits, Prince and Vogdes, at page 3: “A rectifier in the broadest sense is any device which presents a different resistance to the flow of current when the direction is reversed. To be of value, however, the conductivity in one direction must be quite good and the resistance to current flow in the other direction very high. Such a device will then act as an electrical check valve.”
They are of three types, kenotron, tun-gar, and mercury arc. The electrical principle of their operations seems to be this: An alternating current is applied to a hot cathode (filament). The cathode emits electrons, which are, of course, negative charges of electricity. They are drawn across a space by a positively charged anode (plate). This conducts the current in one direction. As the anode or plate emits no electrons, the movement of the charges in the opposite direction is impossible. The purpose of a rectifier is accordingly accomplished. Principles of Mercury Arc Rectifiers and Their Circuits, above cited, p. 4 et sequitur; Mercury Arc Power Rectifiers, Marti and Winograd, p. 11 et sequitur.
. Implicit in successful rectification is the delivery of the same amount of current that is received or, in more technical language, a low voltage drop. The principal factor in such a drop is the limitation of the current by the space charge. This space charge, a phenomenon governed by a fixed equation, is caused by the fact that the electrons when free in space represent a charge of negative electricity, and that ' therefore, for a fixed anode potential, there is a limit to the number of electrons which can be in the space at any time without making it impossible for other electrons to [609]*609enter from the filament region. Principles of Mercury Arc Rectifiers and Their Circuits, above cited, p. 7 et sequitur; Mercury Arc Power Rectifiers, above cited, p. 12.
In the kenotron rectifiers the anode and cathode are inclosed in an evacuated vessel and the space charge is accordingly not neutralized. Its field of usefulness is correspondingly confined to high voltages. In the mercury and tungar rectifiers the positive ions of the mercury vapor and of the argon gas in their respective bulbs reduce the space charge drop. These ions are caused by the collision of an electron and an argon atom and the consequent removal of an electron from an otherwise neutral atom. These argon ions are so heavy that the cathode’s electric field does not attract them all and they form a positive ion space charge. This space charge neutralizes the space chargq existing if only electrons are present. Principles of Mercury Arc Rectifiers and Their Circuits, above cited, pp. 17-20.
We find the usual skirmishing by expert witnesses and the usual delicate references to combinations. Apart from this, however, it is apparent from the testimony that most of the problems indicated by the preceding discussion had been solved independently of any teaching of the patents in suit. One problem, at least, remained, and is outlined in the following quotation from the interesting book of the plaintiff’s research engineers to which we have already referred. Speaking of tungar rectifiers, these learned gentlemen say at page 20: “The bombardment of the filament by the positive ions has another effect upon it. The material of the filament is slowly worn away. Some spot will usually suffer more erosion than the remainder of the filament and will become hotter, thus concentrating more load upon itself until it finally burns out. This is the factor determining the life of such rectifiers.” Principle of Mercury Arc Rectifiers and Their Circuits.
The plaintiff’s experts, Drs. Webb and Hull, attribute the solution of the problem, and therefore the touch of genius, to the prescription by the respective patentees of pressure for the included vapor or gases:
“The Meikle patent must also use sufficient pressure to prevent disintegration. If in the Meikle patent he had used pressure below say a millimeter he would have had serious disintegration. Now, the pressure there has to be chosen to suit a number of conditions. One is to still get the protection of the cathode from disintegration, and the other is to get low iosses ; consequently, he chooses pressures which were considerably lower than Friederich’s.” Dr. Webb, Record, pp. 90, 91.
“Our experiments up to that time were complete failures in their efforts to use low pressure gas, and the general belief was prevalent and well substantiated that hot cathode discharges using gas were necessarily accompanied by rapid disintegration of the cathode and resulting short life. It was a surprise to all those familiar with this field, and I was one of them, when Meikle discovered that by using a pressure of gas above a certain limiting value long life was obtained.” Dr. Hull, Record, pp. 196, 197.
The defendants’ expert, Commander Loftin, on the other hand, attributes the longer life of the plaintiff company’s tungar tubes to the use of a particular thoriated tungsten (Record, p. 177), and emphatically denies the pressure theory of his scientific confreres, using at page 178 of the record the following language: “The disintegration that he refers to means that which is supposed to come about by the ions which are created when the electrons bombard the molecules of gas and extract some electrons from those molecules, leaving the remaining part of the molecules positively ionized, so that it is attracted towards the cathode, and if it attains sufficient speed it will hit the cathode sufficiently hard to do some disintegration. And that is the reasoning around disintegration by bombardment. You cannot have that kind of bombardment, it cannot exist if you do not put some gas in the tube, so that the very thing that he says is the thing that makes possible the effect taking place, it is hard to see how he can reason the thing that causes the trouble is going to stop the trouble.”
In this disagreement between experts we are constrained to sit at the feet of scholarship which is not affected with an interest. In that scholarship we find confirmation of the defendants’ theory. The learned authors of the book, Mercury Arc Power Rectifiers, from which we have several times quoted, describe the function of gas or vapor pressure in the following language:
“The voltage required between electrodes for such a conduction of current [610]*610depends to a large extent on the gas or vapor pressure. The effect of the pressure is as follows: If the pressure is very low, considering, as an example, the limiting case of zero pressure, all the current must be carried by the electrons emitted from the negative electrode, since no gas molecules are then present for producing ionization by collision.
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CLARK, District Judge.
At the argument of this cause we reiterated our dismay at the continued impotence of our United States courts in the field of expert testimony. The necessity for the assistance of impartial experts in cases owing their existence, supposedly at any rate, to the promotion of science and the useful arts, seems plain. Yet even in patent cases the federal courts are given neither the authority nor the means for employing their own experts or “assessors in science.” Because of that this court was constrained to undertake'its own researches in an unfamiliar and highly technical field, and in doing so to begin at a time-consuming early point in the art.
That art is that of an electrical device known as a rectifier. The device has been thus defined in Principles of Mercury Arc Rectifiers and Their Circuits, Prince and Vogdes, at page 3: “A rectifier in the broadest sense is any device which presents a different resistance to the flow of current when the direction is reversed. To be of value, however, the conductivity in one direction must be quite good and the resistance to current flow in the other direction very high. Such a device will then act as an electrical check valve.”
They are of three types, kenotron, tun-gar, and mercury arc. The electrical principle of their operations seems to be this: An alternating current is applied to a hot cathode (filament). The cathode emits electrons, which are, of course, negative charges of electricity. They are drawn across a space by a positively charged anode (plate). This conducts the current in one direction. As the anode or plate emits no electrons, the movement of the charges in the opposite direction is impossible. The purpose of a rectifier is accordingly accomplished. Principles of Mercury Arc Rectifiers and Their Circuits, above cited, p. 4 et sequitur; Mercury Arc Power Rectifiers, Marti and Winograd, p. 11 et sequitur.
. Implicit in successful rectification is the delivery of the same amount of current that is received or, in more technical language, a low voltage drop. The principal factor in such a drop is the limitation of the current by the space charge. This space charge, a phenomenon governed by a fixed equation, is caused by the fact that the electrons when free in space represent a charge of negative electricity, and that ' therefore, for a fixed anode potential, there is a limit to the number of electrons which can be in the space at any time without making it impossible for other electrons to [609]*609enter from the filament region. Principles of Mercury Arc Rectifiers and Their Circuits, above cited, p. 7 et sequitur; Mercury Arc Power Rectifiers, above cited, p. 12.
In the kenotron rectifiers the anode and cathode are inclosed in an evacuated vessel and the space charge is accordingly not neutralized. Its field of usefulness is correspondingly confined to high voltages. In the mercury and tungar rectifiers the positive ions of the mercury vapor and of the argon gas in their respective bulbs reduce the space charge drop. These ions are caused by the collision of an electron and an argon atom and the consequent removal of an electron from an otherwise neutral atom. These argon ions are so heavy that the cathode’s electric field does not attract them all and they form a positive ion space charge. This space charge neutralizes the space chargq existing if only electrons are present. Principles of Mercury Arc Rectifiers and Their Circuits, above cited, pp. 17-20.
We find the usual skirmishing by expert witnesses and the usual delicate references to combinations. Apart from this, however, it is apparent from the testimony that most of the problems indicated by the preceding discussion had been solved independently of any teaching of the patents in suit. One problem, at least, remained, and is outlined in the following quotation from the interesting book of the plaintiff’s research engineers to which we have already referred. Speaking of tungar rectifiers, these learned gentlemen say at page 20: “The bombardment of the filament by the positive ions has another effect upon it. The material of the filament is slowly worn away. Some spot will usually suffer more erosion than the remainder of the filament and will become hotter, thus concentrating more load upon itself until it finally burns out. This is the factor determining the life of such rectifiers.” Principle of Mercury Arc Rectifiers and Their Circuits.
The plaintiff’s experts, Drs. Webb and Hull, attribute the solution of the problem, and therefore the touch of genius, to the prescription by the respective patentees of pressure for the included vapor or gases:
“The Meikle patent must also use sufficient pressure to prevent disintegration. If in the Meikle patent he had used pressure below say a millimeter he would have had serious disintegration. Now, the pressure there has to be chosen to suit a number of conditions. One is to still get the protection of the cathode from disintegration, and the other is to get low iosses ; consequently, he chooses pressures which were considerably lower than Friederich’s.” Dr. Webb, Record, pp. 90, 91.
“Our experiments up to that time were complete failures in their efforts to use low pressure gas, and the general belief was prevalent and well substantiated that hot cathode discharges using gas were necessarily accompanied by rapid disintegration of the cathode and resulting short life. It was a surprise to all those familiar with this field, and I was one of them, when Meikle discovered that by using a pressure of gas above a certain limiting value long life was obtained.” Dr. Hull, Record, pp. 196, 197.
The defendants’ expert, Commander Loftin, on the other hand, attributes the longer life of the plaintiff company’s tungar tubes to the use of a particular thoriated tungsten (Record, p. 177), and emphatically denies the pressure theory of his scientific confreres, using at page 178 of the record the following language: “The disintegration that he refers to means that which is supposed to come about by the ions which are created when the electrons bombard the molecules of gas and extract some electrons from those molecules, leaving the remaining part of the molecules positively ionized, so that it is attracted towards the cathode, and if it attains sufficient speed it will hit the cathode sufficiently hard to do some disintegration. And that is the reasoning around disintegration by bombardment. You cannot have that kind of bombardment, it cannot exist if you do not put some gas in the tube, so that the very thing that he says is the thing that makes possible the effect taking place, it is hard to see how he can reason the thing that causes the trouble is going to stop the trouble.”
In this disagreement between experts we are constrained to sit at the feet of scholarship which is not affected with an interest. In that scholarship we find confirmation of the defendants’ theory. The learned authors of the book, Mercury Arc Power Rectifiers, from which we have several times quoted, describe the function of gas or vapor pressure in the following language:
“The voltage required between electrodes for such a conduction of current [610]*610depends to a large extent on the gas or vapor pressure. The effect of the pressure is as follows: If the pressure is very low, considering, as an example, the limiting case of zero pressure, all the current must be carried by the electrons emitted from the negative electrode, since no gas molecules are then present for producing ionization by collision. In such a case, the negative space charge produced by the electrons is not compensated for, and a relatively high voltage is required between the electrodes to overcome this space charge and maintain conduction. If the pressure is high, the electrons encounter a high resistance in their path and a high voltage is necessary to overcome this resistance. At some intermediate pressure, which is generally quite low, the voltage between the electrodes is a minimum. This optimum pressure corresponds to the condition at which only enough gas molecules are present for producing, through ionization by collision, sufficient electrons for current conduction and sufficient positive ions to compensate for the negative space charge of the electrons.” Pages 12, 13.
We may say that a thorough reading of the book of the plaintiff’s research engineers affords at least an indirect contradiction of its present claim. Although, as we have seen, the authors state the problem of “loss of life through bombardment of the filament by positive ions,” they nowhere suggest a solution by pressure. In fact, the only reference to pressure that we can find therein is as follows: “The tungar anode is of graphite, and the cathode is of tungsten. The bulb is filled with argon gas, which has a pressure of about 5 centimeters of mercury when it is cold.” Pages 15, 16,
W.e are not sufficiently electrically minded to be dogmatic about the exact meaning of this reference. From it we have the impression that the pressure frequently claimed by plaintiff’s expert is a property of the gas rather than the result of some artificial application.
The scientific uncertainty of plaintiff’s theory also appears from the patents themselves. In the Friederich patent, No. 1,-393,520 (for a lighting device), the pressure of the mercury vapor was for the purpose of giving “an electric charge between the electrodes the characteristics of an electric arc.” Even for that purpose the inventor was extremely vague about the mathematical limits of his prescribed pressure. He used such language as, “at relatively considerable pressure,” “preferably approximating atmospheric pressure,” “a pressure with at least several millimeters of mercury,” “a gaseous pressure the order of one atmosphere” (76 centimeters, 760 millimeters)'.
Meikle (patent No. 1,266,517) admits the pressure voltage-drop theory indicated by our quotation from the book, Mercury Arc Power Rectifiers, but does add to it a function of suppressing electric disintegration. He is as vague as Friederich in his discussion of mathematical limits, referring in figures to “one millimeter,” “one centimeter,” and in words to “considerably,” “high enough,” “sufficiently high,” “permitting a discharge having a voltage drop of a few volts.”
We conclude that there is no touch of genius in the assertion of a theory so doubtful and so vague, and for that reason hold both patents void. It is unnecessary to consider, therefore, the 'defendants’ technical objections of double patenting, etc., and the question of whether or not a rectifier is analogous to a lighting arc device.