Scottish Court of Session Decisions

William Murchland, plumber, Kilmarnock, sought to interdict Stewart Nicholson, farmer, Kirkcudbright, and John Gray, Stranraer, from infringing his patent granted 27th September 1889, for “improvements in apparatus for milking cows.”

The specification was in these terms—“My said invention has for its object the constructing and combining of apparatus for milking cows in an improved manner, and so as whilst operating more naturally and less roughly to be more economical than the ordinary milking process. In carrying out my invention suction is applied. to the cow's teats, but a special feature of my arrangements is that the milk is not drawn through a pump. According to another important feature of my invention the degree of suction or vacuum which is used is regulated by a column of liquid, which liquid may in some cases be the cow's milk itself; and although pumping or equivalent means is employed to produce the suction, being in some cases required only when starting the milking operation, any increase in the pumping action beyond what is necessary and corresponds to the column of liquid, merely draws air up through the column without materially affecting the degree of vacuum acting inside the apparatus. I believe that a column of liquid of a vertical length of about 12 feet is in most cases sufficient, but the length may be varied if found desirable in any case, and with stiff or dour cows a greater suction may be applied to make them yield their milk freely.”

The invention was thus described in the evidence of Edmund Hunt, the complainer's patent-agent—“The complainer's apparatus consists of a combination of parts suited for operating upon a large number of cows at a time. It operates by suction. There is a suction-producing apparatus, an apparatus producing a vacuum or partial vacuum, and that vacuum acts through main pipes and branch pipes, each of which branches is connected when required, to a receptacle or special milk pail for a particular cow. The vacuum is produced by a pump, which may be worked by hand or otherwise. For a small establishment it is moderate labour to work it by hand; for a large establishment you require power. In the ordinary action of a pump, if you go on pumping the vacuum goes on increasing until it approximates to a complete vacuum, which is equal to about 15 lbs. pressure to the square inch. I cannot say that I have actually personally ascertained it, but it is my belief that a suction of anything like 15 lbs. of atmosphere to the square inch is very injurious to a cow. That would be very much greater than the suction of a calf, and the complainer set himself to devise an apparatus by which the suction, that is, the vacuum, should not be allowed to get beyond a certain degree. After various trials and observations, and spending a great deal of time on the matter, he came to the conclusion that a vacuum, equal to about 12 feet of a column of liquid, or between 5 and 6 lbs. was about the best, all things considered, and was such as would not produce injury to the cows, however long continued. To illustrate what I mean, suppose this glass tube which I have in my hand is 12 feet long, and that it contains a column of liquid, that liquid column has a certain weight per inch of area. Now if the upper part of the column is connected with a closed vessel in which there is air and the air has been pumped, the atmosphere acting in the opposite direction is balanced by the weight of that column of liquid, plus the pressure of the air inside, consequently there will be a balance unless the air inside be reduced in proportion. The pressure of the air inside is just the difference between the weight of the column of liquid per inch of area as compared with the weight of the atmosphere per inch of area. If you have a complete vacuum the atmosphere will support a column of water 32 feet high. To come back to the complainer's apparatns, I have explained that the vacuum was produced by means of a pump. No. 26 of process, which I now produce, is a small model of the apparatus showing the different parts as arranged in a byre. The pump is connected with a closed upper tank at the top of the liquid column, and it is also connected by means of main pipes with branch pipes to the different stalls. The closed upper vessel is connected by means of a pipe about 12 feet long with an open vessel at the bottom. The bottom of that pipe is open and dips into water in the lower tank. Now, if you put into the lower tank the proper amount of water you just fill the pipe. From the

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main pipes which go along the walls there are leaders or branch pipes going down to the stalls. The branches are connected to stop-cocks on the main pipe. In the model the branch is shown in connection with a milk receptacle. This receptacle has a top fitted with indiarubber, and when the apparatus is going to be used the rubber is wetted, and then when suction is applied and the air inside exhausted, the top is kept on by atmospheric pressure. The top is made of glass so that it can be seen whether the milk is flowing or not. Besides the branch pipe connecting the suction apparatus to the receptacle, there are four flexible tubes which come from the receptacle and terminate at the teat-cups, which are applied to the teats on the cow's udder. These teat-cups are of special construction, to a certain extent as described in complainer's specification, but with some little improvements which he has made since. The milk vessel is suspended over the back of the cow by means of a strap, so that if the cow moves about the receptacle moves with it. Assuming that the apparatus is all in situ ready for operating, if pumping is begun and continued so as to produce a greater degree of suction than corresponds to the liquid column the air just passes through, because the liquid in the lower tank gets depressed below the mouth of the pipe, and air enters and prevents the suction increasing beyond a predetermined amount. (Q) So that you can never get the chamber in the top to more than that amount of vacuum which you have said is the proper amount for drawing the milk from the cow?—(A) That is determined to a certain extent within a small range by the quantity of water you put in the lower tank—you may vary that a little, and there is an advantage in having a certain amount of water in the upper tank, because when you are fitting on the connecting receptacle, the air in the receptable combining with the air in the pipes, tends to reduce the amount of suction, and the water in the upper vessel just sinks to a corresponding extent, and closing the suction brings it back to its former amount. You can also see by the height of the water in the lower tank the exact state of your vacuum. If the pumping is being done by a worker he does not require to pump continuously, he may pump a short time, and then when he sees the water rising in the lower tank he sees that he must begin to pump again. That is a great convenience in practice. The lower tank acts practically as an automatic vacuum guage. When the milk is drawn from the teat-cups it falls into the receptacle, and does not enter the suction tubes at all. It does not pass through any part of the pump. By that means, besides the obvious advantage of cleanliness, you can also keep the milk of each particular cow separate from the milk of others, by the use of separate receptacles. The glass top to the receptacle enables the attendant to see when the milk ceases to flow from a particular cow, and then by turning a stop-cock he can stop the milking operation, so far as that particular cow is concerned. The teat-cup is a metal vessel with an internal rubber cup or tube with perforations in it, the upper rim of which bears round the neck of the teat. The thin lip or apparent washer on the teat-cup is a little improvement upon the teat-cup as described in the complainer's specification. Its advantage is softness, enabling the teat-cup to adapt itself more exactly to the teat.”

The specification by drawings illustrated the combination and process above explained, and proceeded—“The sucking action or exhaustion may be produced in any suitable known way, provided that the degree of vacuum is regulated by means of a column of liquid of suitable length, whereby the vacuum is prevented from becoming excessive. For example, the upper tank may be nearly filled with water by pumping, or by gravitation where a supply by gravitation is available, the column pipe being closed whilst filling the tank, and provision being made for the escape of air. Then when the apparatus is to operate, any openings by which air might re-enter being closed, the stopcock on the pipe is opened, and the water flowing down that pipe produces the required sucking action. In many cases it will be convenient to provide two upper tanks with connecting pipes and stopcocks arranged so that one may be filled whilst the other is in action and being emptied. Apparatus like a gasholder may be conveniently applied for exhausting, the interior of the bell being connected to the milking-pipes, whilst a weight attached to a rope passing over a pulley draws up the bell and produces the required vacuum, and will maintain it in the event of air leaking into the pipes. This arrangement may be used in combination with the regulating liquid column; or if the weight used to draw up the bell is carefully adjusted so as not to produce a degree of vacuum exceeding what is considered sufficient and best, the liquid column may be dispensed with. Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is—1. The combination of parts constituting the modification of my improved milking apparatus substantially as hereinbefore described with reference to figures 1 and 2 of the accompanying drawings. 2. The combination of parts constituting the modification of my improved milking apparatus substantially as hereinbefore described with reference to figure 7 of the accompanying drawings. 3. In milking apparatus, the connecting of a pipe from air-exhausting apparatus to a milk receptacle or collector which is separately connected to the teat cups, combined with the application of a liquid column to regulate the degree of exhaustion, substantially as hereinbefore described. 4. Combining with the other parts of the milking apparatus the employment of apparatus like a gas-holder, the bell of which is drawn up by a suitable weight for exhausting the air, substantially

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as hereinbefore described. 5. The construction of milk receptacle or collector substantially as hereinbefore described with reference to figures 5 and 6 of the accompanying drawings.”

The respondents' patent dated 1891 was for “Improvements in and relating to milking machines and their fittings,” and they thus described their nature—“This invention has reference to and comprises a new or improved mode of and means or arrangement and combination of appliances or machines for the milking of cows, goats, or other animals, and which will be more simple, cleaner, convenient, efficient, and automatic than the appliances heretofore in use.” Their apparatus was of this kind—A large hollow tank or general milk receiving vessel, preferably of cylindrical shape, was placed upon a portable wheeled “trolly” or on the ground or in a recess below it, and formed the vacuum cylinder and general milk receiving vessel and reservoir combined, or it might only be the vacuum vessel with intermediate portable milk receiving vessels for each cow, or one vessel for every two cows. There was also, as in the complainer's apparatus, a vacuum effected by means of a pump; and also, as in the complainer's, a system of main leading pipes with branches taken off to each stall for the particular animal. The pump was preferably operated by a hand-wheel and crank arrangement, or a small motor was erected near the milk vessel and connected with it by an air suction pipe “to create a partial vacuum or suction within it preferably pulsating regulated by a valve with weighted lever or spring equivalent—opening inward.” The valve regulating the vacuum might be described as an inverted safety valve, that is, a small valve fitted to the air reservoir or upper tank, and constructed so as to open inwards. The valve was connected with a lever which was counterweighted and the weight was so adjusted as to allow the atmospheric pressure to open the valve whenever the degree of suction inside became less than the predetermined amount. The main pipe along the byre was underground but connected with the milk receptacles by branches and short flexible tubes. Teat-cups were fixed to the cow's teats and connected with the milk receptacles by flexible tubes. The process of milking was much the same as in the complainer's machine, but the milk was drawn from the smaller receptacles into the large receptacle first mentioned and drawn off from there by a tap. The specification then proceeded—“Having now particularly described and ascertained the nature of our said invention, and in what manner the same is to be performed, we declare that we are aware that it has been previously proposed to use in apparatus of the kind hereinbefore described vacuum pipes, a reservoir through which a vacuum is maintained by a suction pump, and having means for regulating the amount of vacuum, and we make no general claim to such arrangements, but what we claim is—1. The system or mode of and arrangement and combination of appliances or machines for the milking of cows or other like animals, comprising a main vacuum or milk and vacuum pipe or pipes and reservoir A through which a vacuum is maintained by a suction pump B, and with automatic acting vacuum shutting off main and teat branches, the milk being drawn off either into the main vacuum reservoir A or into intercepting suction isolating vessels or pails, all substantially as herein described in reference to and by way of application shown in drawings. 2. In a mechanical system of milking cows or other like animals, the fitting and use at the union joint connections to the main vacuum or vacuum and milk pipes, of vertical moving stem and stand tubes working fluid-tight and with a branch or branches leading therefrom, either to the udders of the cows or to intercepting milk isolating vacuum vessels for the purpose of placing these into or out of working connection with the main pipes and vacuum vessel and pump, substantially as herein described in reference to and by way of application shown in drawings. 3. In a mechanical system of milking cows or other like animals, the forming of the branch pipes leading from the T union couplings, or from the milk isolating intercepting vessels of an angular or curved shape for connecting an india-rubber branch pipe leading to the teat connections, so as to automatically shut off the vacuum when the teats are not in use, substantially as herein described in reference to and by way of application shown in drawings… 7. In a mechanical system of milking cows and other like animals, the construction and use of a portable vacuum or vacuum or milk main receiver or reservoir with safety relief valve, vacuum indicating gauge, and connecting fittings in combination with an air pump, and service pipe or pipes, substantially as herein described in reference to and shown in drawings.”

The complainer contended that the use by the respondents of a valve opening inwards with a weighted lever or spring equivalent, being a mechanical equivalent of the complainer's regulating apparatus of a column of water twelve feet high, was an infringement of his patent.

The respondents denied that their invention was anticipated by the complainer's patent, which they averred was invalid in respect of want of novelty. The patents which they averred had anticipated the complainer's patent were those of Gedge, 6th January 1864, Martins in the United States of America 13th June 1883, and a German patent by Steimann dated 3rd March 1887.

The respondents pleaded—“(1) The complainer's statements are irrelevant and insufficient to support the prayer of his note. (2) In respect that the respondents have not infringed the complainer's rights, interdict ought to be refused. (3) Interdict ought to be refused in respect that the complainer's alleged patent is void, 1st, for want of novelty, and 2nd, for want of utility.”

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Gedge's specification was for “improved apparatus for milking.” The following was the apparatus and mode of working—There was a large reservoir, on one side of which was a transparent plate bearing a graduated scale, so that the quantity of milk in the reservoir could be ascertained at any moment. Upon the top of the reservoir was fixed a pneumatic pump. The reservoir had not a lid, but a bung, which was unscrewed when it was desired to clean the vessel. A caoutchouc tube was attached to the reservoir and carried to the cow's teats, to which it was affixed by four short tubes of the same material, each fitted with a stop-cock. There was also a stop-cock close to the reservoir and another near to where the branches to the teats began to divide. When it was desired to work the machine all the stop-cocks were opened, the air exhausted by means of the pump, and a suction took place by which the milk ran into the reservoir. There was a large tap fixed in the reservoir in the opposite side to which the caoutchouc pipe was fixed, and when the required number of cows or other animals had been milked, the milk was run off by this tap into cans or other vessels. The pump required to be worked all the time of the milking, and there was no automatic regulating process.

The Lord Ordinary ( Low) allowed a proof, and upon 29th November 1892 pronounced this interlocutor:—“Sustains the respondents' pleas; recals the reasons of suspension; refuses the prayer of the note, and decerns, &c.

“ Opinion.—-The complainer's patent is for ‘Improvements in Apparatus for Milking Cows.’ He says in the specification that his invention has for its object the constructing and combining of apparatus for milking cows in an improved manner, and so as, while operating more naturally and less roughly, to be more economical than the ordinary milking process. The patent is thus for a combination, and the first question is, whether the invention is a proper subject-matter for a patent.

I am of opinion that that question, so far as the combination claimed is concerned, must be answered in the affirmative. No doubt a machine for milking cows by suction is not a new thing, and it may be that the various parts constituting the complainer's machine are old, but in my opinion the combination produces the desired result in a more useful and beneficial way than that in which it has ever before been accomplished. Therefore, in so far as the complainer's patent is for a combination, I do not think that it can be challenged either on the ground of want of novelty or of want of utility.

The next question is, whether the respondents' machine is an infringement of the complainer's patent.

I think that the most important feature in the complainer's invention is the automatic regulation of the force of the suction which is applied to the cow's teats. In milking machines prior to the complainer's there was no automatic means of regulating the vacuum or degree of suction, and the consequence was that injury to the cow, from excessive suction being exerted upon the teats, was apt to result. The complainer's method of regulating the vacuum or degree of suction is by means of a column of liquid of a suitable length. The respondents attain the same end by means of an inverted safety valve. Except for that difference it appears to me that the respondents' machine is substantially the same as that of the complainer; and the question is, whether the substitution of the safety valve for the liquid column so differentiates the respondents' machine from that of the complainer that it cannot be said to constitute an infringement of the complainer's patent.

The complainer contended that the safety valve is a mechanical equivalent for the liquid column, and that as the substance of the complainer's invention has been taken by the respondents, they cannot plead that they have not infringed his patent merely because they have, as regards one of the parts of the machine, adopted a well-known mechanical equivalent.

The respondents, on the other hand, argued that the complainer in his specification confines himself to the liquid column as the mode of regulating the vacuum—or, at all events, confines himself to that mode, with a somewhat vague suggestion of one other possible method—and therefore cannot object to a machine which has not the liquid column, although it has a safety valve which effects the same object.

It is therefore necessary to turn to the complainer's specification and to see how he describes his invention and what he claims.

In the specification he says—‘In carrying out my invention suction is applied to the cows' teats; but a special feature of my arrangements is that the milk is not drawn through the pump. According to another important feature of my invention the degree of suction or vacuum which is used is regulated by a column of liquid, which may in some cases be the cows' milk itself; and although pumping or equivalent means is employed to produce the suction, being in some cases required only when starting the milking operation, any increase in the pumping action beyond what is necessary, and corresponds to the column of liquid, merely draws air up through the column without materially affecting the degree of vacuum acting inside the apparatus. I believe that a column of liquid of a vertical length of about 12 feet is in most cases sufficient, but the length may be varied if found desirable in any case, and with stiff or dour cows a greater suction may be applied to make them yield their milk freely.’

The specification then goes on to refer to the drawings appended to the specification, which, inter alia, show two tanks, the one 12 feet above the other, connected by a pipe which contains the regulating liquid column.

“Then, after explaining the various drawings, the specification proceeds—‘The sucking action or exhaustion may be pro

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duced in any suitable known way, provided that the decree of vacuum is regulated by means of a column of liquid of suitable length whereby the vacuum is prevented from becoming excessive.’

Finally, the specification says that an apparatus like a gasholder may be conveniently applied for exhausting; and then after describing the way in which the gasholder is to be worked, it is added—‘If the weight used to draw up the bell’ ( i.e., the gasholder) ‘is carefully adjusted so as not to produce a degree of vacuum exceeding what is considered sufficient and best, the liquid column may be dispensed with.’

The first two claims are for the combinations as described with reference to the drawings.

The third and fourth claims are as follows:—‘3. In milking apparatus, the connecting of a pipe from air-exhausting apparatus to a milk receptacle or collector which is separately connected to the teat cups, combined with the application of a liquid column to regulate the degree of exhaustion, substantially as hereinbefore described. 4. Combining with the other part of the milking apparatus the employment of apparatus like a gasholder, the bell of which is drawn up by a suitable weight for exhausting the air, substantially as hereinbefore described.’

Now, it is clear that the complainer regarded the regulation of the vacuum by means of the liquid column as a matter of first importance in his invention, and although he says that the column may be dispensed with if the gasholder is used to create the vacuum, it is only in that case that it can be dispensed with. Further, when the complainer claims for the gasholder, he does so only as a method of exhausting the air, and not as a mode of regulating the vacuum.

The respondent has therefore not taken the most important part of the complainer's invention, but it is said that he has adopted a mechanical equivalent, and is therefore guilty of infringement.

There is no doubt that the respondent's safety valve serves the same purpose as the complainer's liquid column, but it seems to me that that fact does not solve the question. I do not give any weight to the respondent's contention that as the complainer specifies the liquid column, without adding such words as ‘or any other suitable means of regulating the vacuum,’ he is therefore to be strictly held to the method which he specifies. The want of such general words would not justify a subsequent inventor making an apparatus in which the method of regulating the vacuum was only colourably different from that of the complainer, nor would the addition of such words strike at an apparatus in which a totally different method was used. At the same time, I think that an inventor must be held more strictly to his specification when his invention is for an improvement in the method of producing a known result than in the case when the thing produced is a novelty— Curtis v. Blatt, 3 Ch. Div. 135.

Now, the idea of the regulation of the vacuum in a milking machine was not a novelty. Martin, in his patent of 1883, recognised the importance of regulating the vacuum, and attempted to provide means to effect that object, although the description which he gave of the means is not very intelligible, and his method does not seem to have been successful. Nevertheless, the fact is that Martin devised one way of regulating the vacuum; the complainer invented a second way (and it seems to me to be a very simple and ingenious way); and the respondent has hit upon a third means of accomplishing the same end.

In these circumstances the question seems to me to be, whether the respondents' method is just the complainer's method with a colourable difference. I do not think that it is. It is true that an inverted safety valve was a known contrivance for relieving the pressure of the outward air upon a vessel within which the air had become too much exhausted. But it had never been applied to an apparatus for milking cows. When the idea is suggested it appears obvious enough, but no one had hit upon it before. Martin did not think of it, and I do not believe that the complainer thought of it. The former resorted to a complicated device which I cannot attempt to explain, and the latter applied the liquid column and the gasholder. I do not see why the respondent should be prevented from using the safety valve. It is a mechanical equivalent for the liquid column in the sense that it accomplishes the same object, but in no other sense. I cannot find from the evidence that a liquid column and a safety valve have ever been recognised or used as interchangeable mechanical equivalents in any process. I recognise the ingenuity on the complainer's part in adopting the liquid column to procure the desired effect, but I think that ingenuity must also be credited to the respondents in putting the well-known safety valve to that particular use.

I am therefore of opinion that the respondents have not infringed the complainer's patent.

There is one other point with which I must deal. The respondents argue that the fifth claim in the complainer's patent is bad, and that therefore the whole patent is invalid.

The fifth claim is as follows—‘5. The construction of milk receptacle or collector substantially as hereinbefore described, with reference to figures 5 and 6 of the accompanying drawings.’

Now, the milk collector described in the specification and shown in the drawings is just a milk can with nozzles, to which the indiarubber tubes from the cow and from the exhaust pump can be fixed, having a pane of glass let into the lid, through which the inside of the vessel can be seen, and having, I rather think, a tap by means of which the milk can be drawn off.

I greatly doubt if such a vessel could in

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any case be made the subject of a patent, because I do not think that it required any invention at all. But however that may be, it was clearly anticipated, in my opinion, by Gedge's patent in 1863. Gedge has a reservoir to receive the milk, practically the same as the complainer's collector. The only differences are that Gedge's pane of glass is in the side instead of on the lid, and that it has not a moveable lid but a bung, which may be unscrewed when it is necessary to clean out the vessel. It is true that the pump in Gedge's patent is attached to the reservoir. Gedge apparently thought that it was convenient to have the whole apparatus in one piece, but although the pump was joined to the reservoir, the two were not the less separate pieces of mechanism, and it required no effort of invention to disconnect the two.

I am therefore of opinion that the fifth claim is bad, and if that is the case, it is not disputed that the whole patent is also bad.

The last point is sufficient to dispose of the case, but as the question of infringement apart from the fifth claim was fully argued, and the parties desired me to give my judgment upon that question, I have thought it right to do so.”

The complainers reclaimed, and argued—(1) The respondents had infringed the complainer's patent. The Lord Ordinary had apparently only two categories of patents in his mind. First, the case where a person invents a new thing introducing a totally new principle, and gets what is truly a master patent which enables him to check all modifications of the patent as infringements. The most notable case of that kind in recent years was the hot-blast, Secondly, at quite the other end of inventions was the combination patent of an old machine, upon which improvements were made so as to obtain the old result in an improved manner, and the Lord Ordinary had put the complainer's patent into this category, but there was a third category which he had overlooked, that, viz., where there was a combination of well-known mechanical appliances, but where the purpose to which the combination was applied had never been attained in that manner before. To that third category the complainer's combination belonged, and the question was whether in the construction of the respondent's machine he had not taken the pith and marrow of the complainer's combination, by the use of a mechanical process equivalent to the means used by the pursuer for regulating the suction. The complainer's combination was for a multiple milking machine by suction with an automatic regulating process, and the whole combination made a new machine. The process used by the complainer for regulating the force of suction in the cows' teats was a column of liquid twelve feet in height; that was a known method of regulating the withdrawal of air from vessels, but had never been applied to such a combination as this before. The respondents took a perfectly well-known mechanical equivalent, viz., an inverted valve, and used it for the same purpose as the complainer had used the liquid column, and that constituted an infringement— Curtis v. Platt, November 6, 1863, L.R., 3 Ch. Div. 135, Note; Proctor v. Bennis, August 4, 1887, L.R., 36 Ch. Div. 740; Miller & Company v. The Clyde Bridge Steel Company, Limited, July 25, 1892, 9 R.P.C. 470; Automatic Weighing Machine Company v. National Exhibitions Association, Limited, November 18, 1891, 9 R.P.C. 41; Wenham Gas Company Limited v. Champion Gas Light Company, 9 R.P.C. 49. (2) Prior Knowledge—The complainer's invention had not been anticipated by any of the inventions alleged in this case. Gedge's claim was only for application to single cows, and had no automatic regulating machinery. Martin's system was admitted by the Lord Ordinary to be unsuccessful, and it was a well-known principle of patent law that it was only machines that could be successfully worked that could be founded on as fair inventions, while Steinman's system was for the use of catheters, and not for suction pipes to the cows' teats at all. With regard to the complainer's fifth claim, there were several important points about the receptacle which had not been previously the subject of patents. There was the glass top which could be easily removed at ordinary times, but when the air was exhausted could not be moved. There was the fact that for the first time, the milk of each cow was contained in one receptacle, and that it could be seen when one teat was milked out and the pressure could be removed, and finally the fact that such a receptacle had never been used in connection with a multiple cow-milking machine before.

The respondents argued—Gedge had obtained a patent for milking cows by means of suction regulated by means of a pump. All that could be patented afterwards was a combination for improvements upon the method. The complainer had found out one method of improvement and the respondent another, but the one did not infringe the other, as the one previous in date could be infringed only by a colourable imitation of its own method— Stewart & Briggs v. Bell's Trustee, December 5, 1883, 11 R. 236; Automatic Machine Company v. Knight, March 20, 1889, 6 R.P.C. 297. If a patent is for a combination only, all the essential and characteristic features of the combination must be used or there is no infringement. In the complainer's case it was expressly stated that the principal feature in the combination was the column of liquid 12 feet high to regulate the action. The respondents' method of arriving at the same result was by means of an inverted valve which was also an old means for preventing collapse when the air was withdrawn from a vessel. Even if it was a mechanical equivalent of the liquid column, it was not an infringement of it— Gwynne v. Drysdale & Company, March 5, 1886, 11 R. 684; Nettlefolds, Limited v. Reynolds, April 11, 1892, 9 R.P.C. 270; Tweedale v. Ashworth, February

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12, 1892, 9 R.P.C. 121; Miller & Company v. The Clyde Bridge Steel Company, Limited, July 25, 1892, 9 R.P.C. 470; Seed v. Higgins & Others, July 19, 1860, L.R. 8 H. of L. Cases, 550. As regarded the fifth claim for an invention in the receptacle, the Lord Ordinary was right in holding that it was anticipated by Gedge's patent.

At advising—