High Court of Australia Menzies J. Commonwealth Industrial Gases Ltd v MWA Holdings Pty Ltd [1970] HCA 38 ORDER 1. The defendants and each of them by their servants, workmen, agents or otherwise be restrained during the continuance of the rgistration of letters patent No. 205511 and any extensions and regrants thereof from infringing the said letters patent. 2. That the defendants and each of them deliver up to the plaintiff on oath or at the plaintiff's option to destroy all products infringing or made in infringement of any of the claims of the complete specification of the said letters patent and each of them. 3. An account to be taken of all gains and profits made by the defendants and each of them by reason of their infringement and that the defendants pay to the plaintiff the amount of such gains and profits when so ascertained. 4. Certify in accordance with s. 169, Patents Act 1952, that the validity of the claims of the complete specification of letters patent 205511 came in question. 5. The defendants and each of them by their servants, workmen, agents or otherwise be restrained during the continuance of the registration of letters patent No. 202348 and any extensions and regrants thereof from infringing the said letters patent. 6. That the defendants and each of them deliver up to the plaintiff on oath or at the plaintiff's option to destroy all products infringing or made in infringement of any of the claims of the complete specification of the said letters patent and each of them. 7. An account to be taken of all gains and profits made by the defendants and each of them by reason of their infringement and that the defendants pay to the plaintiff the amount of such gains and profits when so ascertained. 8. Certify in accordance with s. 169, Patents Act 1952, that the validity of the claims of the complete specification of letters patent 202348 came in question. 9. That the defendants pay to the plaintiff the plaintiff's costs of the suit. 10. Liberty to apply generally and in particular to the form of the order. Cur. adv. vult. J Menzies delivered the following written judgment:— Oct. 15 Menzies J This is an action to restrain infringement of letters patent Nos. 202348 and 205511, and for other relief. The defendants admit that if the patents are valid they have been infringed, with the reservation that it is contended that infringement of letters patent 202348 ceased in the middle of 1966 when a modification was made to the design of the articles which the defendants thereafter manufactured and sold. Letters patent 202348 are for an invention relating to mixer tubes for use in gas burners, such as oxy-acetylene blow pipes for welding, to reduce and extinguish "flashback" while the torch is in use. An expert witness, A. L. Clark, whose evidence I accept, described the phenomenon of flashback as follows: Normally, when a mixture of gases burns at a jet, the flame forms a narrow cone surrounded by an envelope of hot gas. The most intense combustion takes place at the surface of the cone where the flame is trying to travel at a fairly high velocity into the unburnt gases issuing from the jet. The competition between the oxygen from the jet and the flame which is trying to travel against it results in forming a stable flame with unburnt gas within the cone. The stability is maintained by balance between the velocity of the gas from the jet and the velocity of the flame trying to work back into the gas stream. The flame velocity, or burning velocity of acetylene is roughly thirty to thirty-five feet a second. It is normal, in an oxy-acetylene torch, to design it so that the gases issue at a speed of something over 300 feet a second from the jet of the torch. If something occurs to restrict the flow of gases from the torch, and so reduce their velocity, the flame then has an opportunity to work back through the narrow orifice of the jet into the mixer tube behind it. When that happens the combustion takes on a very different character. It is a well known phenomenon and has been photographed on many occasions; and the flame starts a pressure wave; the heat of the burning gases, in effect, compresses and increases the pressure locally; and this wave travels backwards from the point of combustion with rapidly increasing velocity until it reaches a certain speed, characteristic of the gas mixture and the size and dimensions of the tube or container, when it undergoes, suddenly, a further increase of velocity which thereafter remains constant. That is known as a detonation. The detonation wave continues to travel down the tube at an extremely high velocity, several thousand feet a second compared with the normal burning velocity of thirty-five feet a second, and this sets up an intense, but very minute, of course, in this case, pressure wave, immediately followed by a very high temperature zone where the combustion of the inflammable gas mixture takes place. This pressure wave can be reflected backwards and forwards from the sides or ends of the container in which the explosion or detonation occurs. If this container is an oxy-acetylene torch the detonation wave can carry back into the mixer where it might succeed in igniting the mixture of gases at their points of entry into the mixer. Once combustion is started there, it will continue until the gas flow is stopped and the flame extinguished. That is known usually as sustained flashback. The detonation wave may penetrate further through the gas inlet tubes of the torch and enter the acetylene hose or the oxygen hose. If it enters the acetylene hose, little harm is done, because acetylene is peculiar in the respect that it can undergo spontaneous decomposition, but that is not very likely to occur. There might be slight decomposition with acetylene causing a little soot inside the tube, but there would be no serious consequences. If, however, the detonation wave enters the oxygen supply tube — and these tubes are made of rubber — then it can very readily set fire to the rubber which, in the presence of pure oxygen, would burn extremely vigorously, and very quickly result in the bursting of the oxygen hose and, possibly, burning the operator, or doing other damage. The invention disclosed by letters patent 202348 has, as I see it, three features. First, gases, oxygen and acetylene, enter the tube radially, i.e., at right angles to the axis of the tube through a narrow annular space between a plug threaded into a counterbore; secondly, that the full circle radial directed entrance of oxygen is closely adjacent to the radial entrance of acetylene to secure immediate and thorough admixture; and thirdly, that the gas inlet end of the tube is wholly confronted by a flat reflecting surface by reason of that surface extending completely across the tube. Feature two is directed towards the reduction of the number of flashbacks; features one and three are directed to preventing flashbacks from penetrating the gas inlets and to their prompt extinguishment. The defendants contend that the invention lacked subject matter and was not novel by reason of the prior publication in Australia of earlier specifications, and by the earlier use in Australia of tubes embodying the invention. In the first place I have no doubt that, if the prior specifications and the earlier user relied upon were to be left out of account, what is claimed in the patent would have been genuinely inventive on 30 September 1954 — the priority date of the patent. To establish no inventive step, independently of earlier use and prior publication, would, I think, have been a hopeless undertaking. It is, no doubt, true that the introduction of gases into a mixing chamber by inlets at right angles to the axes of the chamber was not, by itself, inventive; nor was the introduction of two gases into a mixing chamber in close proximity to one another. Furthermore, to provide a mixing tube with a reflector which is flat, rather than convex or concave, would not, of itself, have been inventive. The invention claimed here, however, is the ingenious employment of these three features together — including the element that the reflector should extend completely across the tube at the inlet end — to achieve a result much sought after by earlier inventors, as the specifications examined in the course of the case demonstrate. The inventive step is of the character referred to by Lord Russell of Killowen in Non-Drip Measure Co. Ltd. v Stranger's Ltd. [1] , as follows: Whether there has or has not been an inventive step in constructing a device for giving effect to an idea which when given effect to seems a simple idea which ought to or might have occurred to anyone, is often [a] matter of dispute. More especially is this the case when many integers of the new device are already known. Nothing is easier than to say, after the event, that the thing was obvious and involved no invention. The words of Moulton L.J. [2] may well be called to mind in this connexion: — "I confess" (he said) "that I view with suspicion arguments to the effect that a new combination, bringing with it new and important consequences in the shape of practical machines, is not an invention, because, when it has once been established, it is easy to show how it might be arrived at by starting from something known, and taking a series of apparently easy steps. This ex post facto analysis of invention is unfair to the inventors, and in my opinion it is not countenanced by English patent law." My Lords, it is always pertinent to ask, as to the article which is alleged to have been a mere workshop improvement, and to have involved no inventive step, has it been a commercial success? Has it supplied a want? Some language used by Tomlin J. in the case of Samuel Parkes & Co. Ltd. v Cocker Bros. Ltd. [3] , may be cited as apposite: "Nobody, however, has told me, and I do not suppose that anybody ever will tell me, what is the precise characteristic or quality the presence of which distinguishes invention from workshop improvement The truth is that when once it has been found, as I find here, that the problem had waited solution for many years, and that the device is in fact novel and superior to what had gone before, and has been widely used, and used in preference to alternative devices, it is, I think, practically impossible to say that there is not present that scintilla of invention necessary to support the patent." No evidence is more cogent of the success of the invention than that the defendants simply copied it and made profits by making and selling the products. 1. (1943) 60 R.P.C. 135, at p. 142. 2. British Westinghouse Electric & Manufacturing Co. v Braulik (1910), 27 R.P.C. 209, at p. 230. 3. (1929) 46 R.P.C. 241, at p. 248. The real question for decision here is whether the invention lacked subject matter or was not novel on 30 September 1954, by reason of prior use and prior publication. The prior publications principally relied upon were as follows: No. 2118447 available for inspection in Sydney since 23 August 1938; No. 1907604 available for inspection in Sydney since 5 September 1933, and British patent No. 604444 available for inspection in Sydney from 17 December 1948. Some of the specifications relied upon did show the entry of gases, or of a gas, into a mixer tube at right angles to its axis; i.e., radially. Some showed the gases entering a mixing tube at close proximity to one another. In one, 604441 — Volcan S.A. — oxygen is shown entering radially, and what can be regarded as a flat reflector plate is revealed. Unless what is revealed in these specifications, taken with the knowledge that not only one gas, but two, can be introduced into a mixer chamber at right angles, and that gases can be introduced into such a chamber in close proximity to one another, is sufficient to deprive the patent in suit of validity, none of the other specifications put in evidence, taken separately or together, could do so. I propose to examine 604444 as the earlier specification closest to the invention in suit, and to deal with the others more generally. In 604444 there is revealed oxygen entering a mixer tube radially in front of a flat surface, part of which faces a drilling (11) which is extended at a point where acetylene enters through drillings at an angle to the axis of the upper part of the mixer tube (3). There are significant differences between what appears from 604444 and the patent in suit. First, assuming that (11) and (3) together constitute the mixer tube, it is apparent that the gases do not enter in close proximity to one another; secondly, the acetylene does not enter radially; and thirdly, the surface of the plug (10) — around which the oxygen enters — although constituting a flat reflector, is not a reflector which extends completely across the mixer tube at the inlet end because, as I have indicated, that part of the tube marked (3) is of greater diameter than that part of the tube marked (11). It seems that 604444 could not lead anyone to, or even towards, the invention shown in 202348. The differences are fundamental and in a construction such as that shown in 604444 flashback would, at the point of entry of the acetylene, be likely to be dispersed so that part followed the path of the acetylene entries and part only reached the flat reflector to be reflected back along the axis of the tube. At this point I should say that all the specifications relied upon by the defendants, including 604444, were critically examined by Mr. Clark who was indeed a highly qualified expert witness. As to each of them Mr. Clark expressed the opinion that a skilled craftsman, having the advantage of what was disclosed, would not be led to the invention in 202348. This evidence I accept. The contention that there had been prior user — apart from the production of Ex. 8, which was a mixer tube satisfactorily identified as similar to what was being manufactured in Australia in 1953 and 1954 — depended upon oral evidence. First there was the evidence of two of the directors of the defendant companies, Mr. Graham and Mr. Yates, that from time to time in the period between 1942 and 1954 they had seen welding and cutting equipment comprising inter alia a mixing tube with the features, or some of the features, described in the plaintiff's letters patent 202348. I cannot rely upon this evidence. It is not that I dismiss the evidence as deliberately untruthful — although I am disposed to think that the evidence relating to Ex. 8 and Ex. 9 — which was a less than accurate representation of Ex. 8 — was not wholly frank — it is rather that I cannot accept as reliable, oral evidence relating to particular pieces of equipment to which some reference has been found in the records of the defendant company, and then, as if by unaided recollection of observations made up to twenty-eight years ago, that equipment has been identified and described by the witnesses. It is apparent that during the long period since the equipment was seen, the witnesses must have looked at hundreds, if not thousands, of unremarkable pieces of similar equipment, and I have no confidence in their stated recollections of particular pieces of equipment among those numbers. One instance will serve to illustrate the difficulty that I feel about evidence of this sort. Mr. Yates described in detail the mixing chamber of a cutter which he saw in 1953 and about which the defendants had a job card from which it was inferred that it was an American piece of apparatus made by a company called National. No particulars were given about this mixing chamber and there was no description of it in the records, but Mr. Yates — his memory no doubt stimulated by later examination of apparatus made by the National company, and photographs of such apparatus which may, or may not, have been the same as the apparatus examined in 1953 — gave an elaborate description of the particular mixing chamber seen by him seventeen years ago. It is apparent to me that although Mr. Yates said he was relying entirely upon his memory — and perhaps he believed he was — nevertheless what he was doing was describing what he now thought he would have found in the particular mixing chamber which he had seen so long ago. I have no doubt he was reconstructing on the basis of later observations; he was not remembering what he actually saw. The next evidence relating to prior use was given by Mr. Bulgin, who was, I think, both a truthful and a reliable witness. He is a welding or combustion engineer and had been in the business of the defendants in 1952-1953. Upon leaving the business he set up on his own account and manufactured blow pipes with mixer tubes. In the witness box he drew a sketch of the mixer tubes which he had made and sold in 1953-1954 (Ex. 32) and identified Ex. 8 as a tube of later construction, but as being the same as those which he had made in 1953-1954. In this time some eighty oxy-acetylene blow pipes, containing such mixer tubes, were sold. The safest course, in dealing with Mr. Bulgin's evidence, is probably to concentrate attention on Ex. 8 itself, for I am satisfied that if the plaintiff's invention is to be found in that piece of apparatus, then the plaintiff's patent is invalid. In my opinion, however, Ex. 8 does not lead to, nor does it even lead towards, the plaintiff's invention. Exhibit 8 is the end of a mixing chamber where the oxygen entrances are situated. Acetylene, it appears, entered the chamber at a higher point — see Ex. 32. Exhibit 8 shows a cavity which is almost a cone. In it there are drilled holes for the entry of the oxygen. I cannot be sure that the entry is at right angles, but, if it is not, the angle of entry is not much less than ninety degrees. However that may be, the cone could not reflect flashback along the axis of the mixer tube. Any flashback that was reflected would be reflected at various angles and would cause a good deal of turbulence. Moreover, the reflecting surface could not be regarded as extending completely across the mixer tube and it seems that oxygen does enter through the reflecting surface. Furthermore, the gases do not enter the tube closely adjacent to one another. Mr. Bulgin's sketch (Ex. 32) shows that. Again I have had the advantage of Mr. Clark's examination of Ex. 8 and I accept his view that there is nothing in that exhibit which would lead a skilled craftsman to the invention disclosed in the plaintiff's patent. I do not regard Mr. Bulgin's manufactures and sales in 1953 and 1954 as affecting the validity of the plaintiff's patent. Accordingly, I am satisfied that neither the specifications published nor the devices proved to have been in use before 30 September 1954, either separately or together, would lead a skilled craftsman to the invention described in letters patent 202348. I find that the defendants have not made out their objections to the plaintiff's invention that it lacked subject matter or was not novel. The other objection to validity being groundless, I find that letters patent 202348 are valid. As I have already indicated, the defendants admitted infringement of letters patent 202348 up to the middle of 1966, but deny it thereafter. What I find happened is that the defendants, having simply copied articles of the plaintiff's manufacture, upon receipt in the middle of 1966 of a letter from the plaintiff's patent attorneys alleging infringement of letters patent 202348, consulted their own patent attorneys and thereafter modified their own manufacture by drilling the mixer tube to a very slightly concave, rather than a perfectly flat, base. In my judgment the modification so made did not prevent equipment manufactured and sold thereafter from constituting an infringement of the letters patent. Patent rights are not to be set at nought by such a subterfuge which I am satisfied added nothing to the equipment and was made merely in an attempt to take full advantage of the invention while avoiding infringement of the plaintiff's letters patent by a modification so small as to be insignificant. I find that the base of the mixer chambers, which the defendants manufactured and sold after the middle of 1966, was so close to the plaintiff's specification in that the degree of concavity was so slight that such manufacture and sale continued to amount to infringement. The cases do establish that, if the alleged infringement differs materially from an essential feature of the plaintiff's claim, there can be no infringement. This principle emerges from the recent case of Rodi & Wienenberger A.G. v Henry Showell Ltd. [4] , and the High Court decision in Shave v H. v McKay Massey Harris Pty Ltd [5] . In the present case normality of the reflector is made an essential feature of the plaintiff's patent. As I have said, however, the modified manufacture since 1966 does not avoid that essential feature because the reflector as made thereafter is so close to being flat that the defendant's manufacture and sale still takes the plaintiff's invention. 1. [1969] R.P.C. 367. 2. (1935) 52 C.L.R. 701. I find, therefore, letters patent 202348 valid and infringed, and that the infringement by all the defendants still continues. Letters patent 205511 relates to a means for effecting a union between the mixer tube and the hand-piece of oxy-acetylene welding equipment whereby the former is readily adjustable in relation to the latter, so that the flame may be easily directed by the operator in a full circle of directions. Such union is achieved by the invention in either of two ways — (1) by means of the engagement of a plug and counter bore — both frustro-conical — see claim 2 and figure 1, or (2) by means of the engagement of a plug and counter bore which are both cylindrical — see claim 3 and figure 2. The problem which the invention was designed to meet is stated as follows: It is a matter of convenience, amounting to necessity, for the union whereby the tip carrying mixer tube is joined to the handpiece, to be such as will allow the tip to be readily adjustable relative to the handpiece so that the flame may be directed in accordance with the requirements of the work. It will also be appreciated that as two different gases have to be separately fed to the mixer tube, it is necessary to provide two distinctly separate seatings or sealing surfaces between the handpiece and the mixer tube required to be rotationally adjustable relative thereto. Earlier solutions are described as follows: Hitherto the mentioned adjustability has been achieved by providing the rearward or inlet end of the mixer tube with two seatings relative to the handpiece, one of these being made of fibre or other soft material which is able to deform under pressure and thereby enable gas-tight sealing on both seatings, but such arrangement as used heretofore have been generally unsatisfactory and have necessitated the use of spanners in order to ensure tightness of fit and thus increase the inconvenience of adjusting the mixer tube relative to the handpiece or removing it therefrom. The object of the plaintiff's invention as stated was as follows: The object of this invention is to overcome the stated disabilities in a simple manner by the provision of a union between the mixer tube and the handpiece, in which hand pressure alone is sufficient for gas-tight seating of the two sealing surfaces or for removal or adjustment of the mixer tube relative to the handpiece, and for retaining the mixer tube securely in selected adjustment, thus enabling, to the great convenience of the user, the welding tip to be turned to any convenient angle while the gases are flowing and even while the gases are ignited, without involving gas leakage, necessity for spanners, or other inconvenience. The invention consisted: in a mixer tube and handpiece union for a welding blowpipe; comprising, a spigot on the outlet end of the handpiece having a bore and a counterbore therein to the floors of which two gas passages respectively open, coaxial minor and major plugs on the inlet end of the mixer tube which are rotatable and axially movable within said bore and counterbore respectively, passages in said inlet end whereby the interior of said mixer tube is in communication with the interiors of both said bore and said counterbore, circumferential sealing means between said minor plug and said bore and between said major plug and said counterbore, and manually operable clamping means for holding said outlet and inlet ends tightly together in selected rotational adjustment of one relative to the other. To establish the invalidity of this patent, the defendants relied upon prior publication by reason of a number of specifications previously published, and upon earlier user. I am satisfied that the invention was not disclosed or used before its priority date; i.e. 20 April 1955; and that the invention does not lack subject matter. I can deal with the matter generally. It did appear clearly enough that the mixer tube and handpiece for welding blow pipes had, in the past, been held together by clamping means consisting of a nut, or similar device, usually adjustable by a spanner and, perhaps, rarely by manual pressure. In such apparatus the tip could be rotated relatively to the handpiece by loosening the nut, but this could not be done with safety while the torch was alight. Furthermore, it could not be done with safety while the gases were flowing because there would be leakage once the union was loosened by unscrewing the nut. In the earlier equipment, therefore, the adjustment of the tip to the handle could only be made by extinguishing the torch, unscrewing the nut, turning the tip, and then tightening the nut so that, in use, the tip was held rigidly in one position. The whole point of the invention is that the tip of the blow pipe can be rotated by loosening the nut while the gas is flowing, and even while the flame is burning. Not only can it be readily rotated in these circumstances, but it can be held in a new position simply by tightening the union nut by hand. The movement of the union nut does not merely loosen the connexion without the escape of gas, it carries the tip end to a point where it can be rotated in relation to the handle while the gases remain sealed off so that they will neither mix nor escape. The tip can, therefore, be rotated without shutting down the supply of gases, and even without extinguishing the flame. This seems to me both inventive and novel. As to the prior publications and earlier use relied upon by the defendant, I have the evidence of an undeniable expert, namely Mr. Osman, that a study of all the examples of prior art which were in evidence and of all the specifications relied upon as anticipations would not lead a man skilled in the trade to the form of construction described in letters patent 205511. This evidence I accept. The only specification to which I ought to refer specifically is Ex. 25, Jacobsson No. 2518895, for in the apparatus there described it was possible to turn the tip in rotation to the handle without shutting off the supply of gas and without allowing the escape or mixing of the gases, although it would not have been possible to have done this while the flame was burning. However, the result of rotational movement without the necessary escape of gas was achieved in a way entirely different from that disclosed by letters patent 205511. In Jacobsson the handle and the tip section are held together by a frictional force of rings composed of resilient plastic material to form gas-tight seals but not held sufficiently tightly to prevent rotational movement. What is disclosed, even if it were effective to enable rotation while the torch was burning, is something quite different from the invention disclosed in 205511, and does not constitute an anticipation of that invention. Moreover, I accept the evidence of Mr. Osman that the rotation of the tip while the torch was burning in apparatus such as that described in Jacobsson would be hazardous. On the other hand, I accept the evidence that apparatus made in accordance with the invention does safely permit the rotation of the tip while the torch is burning. Accordingly, I think the objections to the validity of letters patent 205511 have not been made out and that the patent is valid and infringed by the defendants and each of them.