Case No: A3/2001/1133; A3/2001/1255
Neutral Citation Number: [2002] EWCA Civ 612 
IN THE SUPREME COURT OF JUDICATURE
COURT OF APPEAL (CIVIL DIVISION)
ON APPEAL FROM CHANCERY DIVISION
MR JUSTICE PUMFREY
Royal Courts of Justice
Strand, 
London, WC2A 2LL

Friday 10th May 2002
Before :

LORD JUSTICE ALDOUS
LORD JUSTICE TUCKEY
and 
LORD JUSTICE RIX
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Between :

	(1)	HEWLETT PACKARD GMBH
(2)  AGILENT TECHNOLOGIES DEUTSCHLAND GMBH	Appellant	
	- and -		
	(1)	WATERS CORPORATION
(2)	WATERS LIMITED	Respondent	

AND BETWEEN:
Between :

	(1)	WATERS CORPORATION
(2)  WATERS LIMITED	Appellant	
	- and -		
	(1)	HEWLETT PACKARD GMBH
(2)  AGILENT TECHNOLOGIES DEUTSCHLAND GMBH	Respondent	
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(Transcript of the Handed Down Judgment of
Smith Bernal Reporting Limited, 190 Fleet Street
London EC4A 2AG
Tel No: 020 7421 4040,  Fax No:  020 7831 8838
Official Shorthand Writers to the Court)
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Roger Wyand QC and Daniel Alexander (instructed by Bird & Bird) for Hewlett Packard
Geoffrey Hobbs QC and Tom Mitcheson (instructed by Shoosmiths) for Waters Corporation
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Judgment
As Approved by the Court
Crown Copyright ©

Lord Justice Aldous:

1.	In his judgment of 24th April 2001 Pumfrey J held that EP (UK) 0309596 was valid but not infringed.  The patentees, Hewlett-Packard GmbH and Agilent Technologies Deutschland GmbH appeal against the decision of non-infringement.  As there is no need to distinguish between those two companies, I will refer to them as Agilent.  The respondents are Waters Corporation and their English subsidiary Waters Limited.  They cross-appeal contending that the patent is invalid as it lacks novelty and is obvious.  I will refer to them as Waters.  
The Background
2.	The patent was applied for on 26th September 1987.  It is for an invention entitled “Pumping apparatus for delivering liquid at high pressure”.  Essentially the patent describes a pumping apparatus intended to be used in “High Performance Liquid Chromatography” (HPLC).  
3.	HPLC is a chromatographic technique developed in the mid-1970s in which the sample to be analysed is either a liquid or converted into liquid form by dissolving it in a solvent.  Such analysis is widely used in industry for example for identification of compounds and quality control.  The liquid sample is injected into a stream of liquid which is pumped under high pressure into a “separation column”.  The column is commonly filled with very small silicon beads to which a compound called the stationary phase is bonded.  The liquid containing the sample (the mobile phase) passes through the silicon beads under high pressure.  The substances of the mobile phase to be analysed are retained by the silicon beads for different times, depending upon the affinities of such substances to the stationary phase.  As a result each substance will elute from the column at a different time.  Differences in elution times are recorded upon what is known as a chromatogram which shows the eluted substances graphically as peaks.  The time for which a substance is retained, from injection to elution, is referred to as the retention time.  For a given set of conditions the retention time is a characteristic of the substance and that can be used for identification with the area under the peak reflecting the amount of that substance in the mobile phase.  
4.	An important element of HPLC is smooth flow rate of the liquid through the column at high pressure.  Thus the pump which delivers the mobile phase to the column is one of the most important parts of an HPLC machine.  Piston pumps have been found to be particularly suitable to compel the mobile phase through the column.  
5.	Since the beginning of modern HPLC in the 1970s, suggestions have been made as to how to obtain flow rates at high pressure while ensuring that the flow is smooth.  A number of difficulties have been encountered.  A significant one is the effect of compressibility which is particularly noticeable with organic solvents which at high pressure (200 bar) can be reduced in volume by 1-3%.  
6.	At the priority date of the patent in 1987 there were four types of known HPLC pumps namely coil pumps, single-headed reciprocating system pumps, large volume syringe pumps operated by screw and stepper motor, and dual and triple-headed reciprocating pumps.  This case is concerned with dual-headed reciprocating pump systems.  
7.	In 1986 dual-headed reciprocating pumps could either be made so as to act in parallel or in series.  The patent in suit relates to a system with two pumps in series.  As of the priority date of the patent, such pumps were well-known.  Basically such pumps have the outlet of the first piston connected to the inlet of the second piston.  In general the two pistons pump in anti-phase to each other.  The first, or primary piston, sucks in liquid over a long period whilst the second or accumulator piston delivers liquid to the system.  The primary piston then delivers liquid to both the accumulator pump as well as the system.  In essence the accumulator piston in a series dual piston pump acts like an active pulse dampener.  
8.	It was also well-known that the flow rate was equal to the cross-sectional area of the piston delivering to the system multiplied by the velocity of that piston during the delivery stroke.  In the case of a series dual piston pump, the total flow from the pump to the system is determined by the volume of liquid which is drawn in by the primary piston in a complete pump cycle.  
The Patent
9.	The specification opens by stating that the invention relates to a pumping apparatus for delivering liquid at high pressure, in particular for HPLC applications.  It goes on to set out what the patentee thought was well-known at the time, namely that it was desirable that the flow rate of the liquid delivered to the column was adjustable over a wide range and that it was important that once adjusted it was kept constant as far as possible.  The specification then refers to some systems that were known at the time.  It states that to reduce pump pulsations it was known to use a dual piston pump having two interconnected pump heads, each with a reciprocating piston.  It refers to such a system described in United States Patent 4352636 in which the piston pumps are driven via cams and a common cam shaft and also to a dual piston pump with two interconnected pump heads described in USA Patent 4352636.  In that particular patent the pumps are connected in series with two check valves, one piston serving to accumulate some of the liquid delivered by the first piston and to deliver the accumulated liquid while the first piston is refilling.  The drive mechanism of the two pistons consists of a stepping motor, a gear and an intermediate shaft.  The rotation of the main shaft reciprocates crank arms to which the pistons are coupled.  The two pistons reciprocate 1800 out of phase in relation to each other and the first piston displaces twice the volume of the second piston.  The specification also draws attention to the fact that such an arrangement had a pulse dampener between the first pump chamber and the second pump chamber.  Such an arrangement was said to illustrate what was generally known at the priority date.  
10.	Mr Hobbs QC, who appeared with Mr Mitcheson for Waters, drew attention to evidence which showed that the acknowledgement of the prior art in the above passage was not complete.  However the claims have to be construed in the context of this specification not another document.  
11.	The specification goes on to explain why an increase of the frequency of pulsations is important:
“It is a further consequence of the variation of the stroke volume as a function of the flow rate that, particularly at low flow rates, the frequency of reciprocation of the pistons is higher than in a prior art pump having a fixed stroke for all flow rates. This increase in the frequency of reciprocation leads to a corresponding increase in the frequency of any remaining pulsations of the pump output which has advantageous effects on the reproducibility of quantitative chromatographic measurements. In contrast to low-frequency pulsations which may affect the retention times and areas of different peaks in the chromatogram in different ways, high-frequency pulsations are more like a uniform background signal which affects the whole chromatogram in substantially the same manner. The increase of the frequency of the pulsations is particularly advantageous when a detector is used which is very sensitive to flow pulsations, e.g., a refractive index detector.”
12.	The specification comes back to US Patent 4245963 in column 2 line 53.  It states that “it is known to reduce the pulsations caused by the compressibility of the liquids by using specially designed cams which are contoured such as to produce the same amount of outflow of pressurised liquid at all points in the cycle of rotation of the cam shaft, except for a short infill at the beginning of the expulsion stroke of the first piston.”  Thus a precompression phase is used.  
13.	There follows a statement of the object of the invention, which is “to provide a pumping apparatus, for delivering liquid at high pressure, … which has a simpler mechanical design and which substantially avoids over a wide range of flow rates, the problems caused by interferences of pulsations of the flow of the delivered liquid with the chromatographic measuring results.”  That is said to be solved by the characterising features of claim 1.  
14.	Claim 1, omitting the reference numerals, is as follows:
“A pumping apparatus for delivering liquid at a high pressure at which compressibility of the liquid becomes noticeable, and at a selectable flow rate, comprising 
a) a first piston for reciprocation in a first pump chamber, the first pump chamber having an inlet port and an outlet port, 
b) a second piston for reciprocation in a second pump chamber, the second pump chamber having an inlet port and an outlet port, 
c) a conduit connection between the outlet port of the first pump chamber and the inlet port of the second pump chamber, 
d) an inlet valve connected to the inlet port of the first pump chamber for allowing flow of liquid into the first pump chamber and for inhibiting flow in the opposite direction, 
e) an outlet valve connected to the outlet of the first chamber for allowing flow of liquid into the second pump chamber and inhibiting flow in the opposite direction, 
f) drive means for reciprocating the first and second piston, 
g) wherein the liquid in the first pump chamber is compressed to a high pressure before delivery of the compressed liquid into the second pump chamber, 
Characterised by
control means coupled to the drive means for adjusting the stroke lengths of the pistons between their top dead centre and their bottom dead centre, respectively, in response to the desired flow rate of the liquid delivered at the outlet of the pumping apparatus, with the stroke volume (i.e., the amount of liquid displaced during a pump cycle) being decreased when the flow rate is decreased and vice-versa, such that pulsations in the flow of the liquid delivered to the output of the pumping apparatus are reduced.”
15.	As appears from claim 1, the invention involves a series dual piston pump which seeks to overcome the difficulty of variation in flow rate and pressure pulsations in the outflow of the pump by reducing the stroke length of piston, hence the stroke volume with reducing flow rate.  That is emphasised at column 3 line 31 of the specification:
“In known solvent delivery systems, the flow rate is changed by changing the frequency of reciprocation of the pistons so that the pistons move at a higher frequency when a higher flow rate is selected, whereas the stroke volume remains the same when the flow rate is altered. According to the present invention, however, the flow rate is changed by changing both the frequency of reciprocation of the pistons and the stroke volume. In … the invention, the stroke volume is decreased with the flow rate. Thus, when the stroke volume becomes smaller, the volume which has to be compressed to the final pressure before delivery starts also becomes smaller. Since the volume to be compressed is smaller, the compression phase becomes shorter resulting in smaller pulsations of the outflow of the pump.”
16.	Figure 1 of the patent shows schematically a solvent delivery system for liquid chromatography incorporating the pumping apparatus of the invention.

Figure 1
17.	In outline capillary tubes 1a to d provide solvents to mixing valve 2, controlled by the gradient controller 45.  The pumping apparatus comprises two pumping units, 7 and 18, each having a piston 10 and 20 respectively arranged in bores 8 and 19.  A motor 36 which turns first in one direction and then in the other through a limited angular range drives two gears 33 and 34 by means of a gear 32.  That displaces the pistons 10 and 20 of the two pumping units by means of spindle drives 30 and 31.  The first pumping unit draws in the liquid controlled by the mixing valve from one or more of the containers A-D.  The liquid is then transferred to the second pumping unit by means of a connecting line 12-14 designed as a capillary tube.  Through a further connecting line 22 the liquid reaches the chromatogram column via the damping unit 23.  
18.	In use the rotary motion of the motor 36 causes piston 10 of the first pumping unit 7 to move downwards drawing in liquid out of the containers via the mixing valve.  A back flow of the liquid from pressure side of the pump is prevented by the non-return valve 13.  At the same time, the piston 20 of the second pump unit 18 moves upward at about half of the speed of the first piston and delivers the liquid to the columns.  After a defined rotational movement, the movement of the motor is reversed.  The piston 10 of the first pumping unit moves upwards.  At the same time the piston 20 of the second pumping unit moves downwards at about half the speed of the first piston 10.  Half the liquid delivered by the first pumping unit serves to fill up the bore 19 of the second pumping unit and the other half is pumped to the column.  Thus an approximately constant volume flow is delivered to the column without interruption.  Since liquid is intended to be delivered at high pressure, the influence of compressibility of the liquid becomes noticeable.  The liquid in bore 8 must first be brought up to the high final pressure of the pump before delivery by the first pumping unit commences.  Different volume flows can be delivered.  The decisive factor for the resulting flow rate in each case is the speed which the pistons 10 and 20 are moved in the bores 18 and 19.  In order to deliver a defined flow rate, each piston may move over a long stroke and with a long duration of stroke movement for a single pumping cycle, or over a short stroke in corresponding short duration of stroke movement.  The relationship is illustrated in figures 3 to 6 of the patent.  
19.	Figures 4, 5 and 6 illustrate the difference between this invention and the prior art devices where variation of flow rate is achieved by varying the frequency of the pumping.  That gives a constant percentage pulsation.  When using the invention namely to vary the stroke length with variation of flow rate, there is a substantial reduction of the percent pulsation.  The idea is to reduce the pressure pulsations that occur as a result of liquid being lost from the system or too much liquid being put into the system by altering the stroke length in response to flow rate.
Infringement
20.	The parties accepted that the correct approach to construction was that required by section 125 of the Patent Act 1977.  As I explained in Wheatley v Drillsafe [2001] RPC 133 at page 141:
“18.  …  Section 125 of that Act provides that an invention shall be that specified in the claim "as interpreted by the description and any drawings ... shall be determined accordingly."  The extent of protection is not only important when considering whether an alleged infringement falls within the claim, but also when considering validity.  A patent will be invalid if the extent of protection includes within it the prior art or something which was obvious having regard to the prior art.  
19. Section 125(3) requires the Protocol on Interpretation of Article 69 of the EPC to be applied.  It states:

"Article 69 should not be interpreted in the sense that the extent of the protection conferred by a European Patent is to be understood as that defined by the strict, literal meaning of the wording used in the claims, the description and drawings being employed only for the purpose of resolving an ambiguity found in the claims.  Neither should it be interpreted in the sense that the claims serve only as a guideline and that the actual protection conferred may extend to what, from a consideration of the description and drawings by a person skilled in the art, the patentee has contemplated.  On the contrary, it is to be interpreted as defining a position between these extremes which combines a fair protection for the patentee with a reasonable degree of certainty for third parties." 
The Protocol outlaws what can be termed strict literal and also liberal interpretation using the claims as a guideline.  The correct approach is to achieve a position between those extremes "which combines a fair protection for the patentee with a reasonable degree of certainty for third parties."”
21.	There was in the end no dispute of relevance as to the construction and method of operation of the Waters apparatus.  It has the basic construction of  the precharacterising part of claim 1.  The primary pump is in fluid communication with the accumulator pump in serial configuration.  The primary pump receives the mobile phase via an inlet valve which controls ingress and prevents fluid return during pumping.  It is driven by a stepper motor coupled to a ball screw assembly.  That motor is controlled by a CPU.  
22.	The accumulator pump is in fluid communication with the primary pump via a transducer and check valve.  It is driven separately but in the same way as the primary pump.  It delivers to the column via another transducer.  The check valve is controlled so that it will not allow the fluid from the primary pump to be transmitted until it is at substantially system pressure.  Having independent motor control and two pressure transducers measuring the pressure of each pump chamber independently enables the primary pump to precompress the primary fluid to that of the system pressure before delivery to the system.  That is said virtually to eliminate pressure pulsations at the outlet of the accumulator pump. 
23.	The characterising part of claim 1 is concerned with the control means and it is that part of the claim that Waters contend is not present in their apparatus.  The Waters pump can be operated in auto or manual modes.  When operating in the auto mode it has 5 analytical ranges.
Analytical Range	Flow Rate (ml/min)	Stroke volume	
Micro	0 – 0.53	25 μl	
Narrow	0.53 – 1.23	50 μl	
Normal	1.23 – 3.03 	100 μl	
Fast 	3.03 – 5.0 	120 μl	
Utility	5.0 – 10.0	130 μl	
24.	The utility range is used to purge solvent through the system, but the other 4 ranges reflect the sizes of columns typically used.  
25.	In operation below a flow rate of 5 ml/min the primary piston arrives at top dead centre and then waits for a short period to allow conditions to settle.  It then draws in sufficient fluid for the required stroke volume (25, 50, 100 or 120 μl) and precompression.  The primary piston then moves forward to precompress and to bring the pressure up to about system pressure.  The primary piston then waits for the accumulator piston to reach the end of its stroke.  At this point the transfer begins.  At the end of the transfer period the primary piston is at top dead centre again and the cycle is repeated.
26.	The transfer is controlled in the software.  The stroke length of the primary piston and the duration of the transfer period determine the stroke length for the accumulator piston.  
27.	For the purpose of infringement the parties accepted that the relationship between the flow rate and the stroke volume for the Waters pump was shown in Figure 7 of the witness statement of Mr James, the expert called by Agilent.  It is in this form.
28.	

The judge described Figure 7 as follows:
“17. …  Figure 7 annexed to Mr James’s report, which was not challenged on this point, shows the volume delivered during a pump cycle in the various operating ranges provided for automatically in the Waters pump and its controlling software. This diagram shows that in the three lowest ranges the accumulator piston stroke decreases with increasing flow rate. In the range between 3 and 5 ml per minute, it is more or less constant, falling again in the range between 5 and 7.5 ml per minute. It will be observed from this diagram that the substantial increases in stroke lengths in the accumulator piston take place only on range changes: within each range the length of the stroke of the accumulator piston either remains constant or decreases. …  Thus, between range changes, the Waters pump increases flow rate by increasing frequency of pumping and without also increasing the swept volume.”
29.	Mr James’s figure 7 shows that a change of flow rate from within one range to a flow rate within another range is achieved by a substantial change in stroke volume.  For example if any flow rate between 1.23 and 3.03 ml/min is being used and a change of flow rate is made below 1.23 ml/min the stroke volume will be decreased by at least 50 μl.  If the flow rate is increased above 3.03 ml/min then the stroke volume will be increased by at least 40 μl.  Figure 7 also shows that a change of flow rate within a range is accomplished by a change of frequency as the stroke volume of the pumps will not be changed.  The effect was referred to as step-wise in contrast to continuous stroke volume change where the stroke volume is changed with every change in flow rate.  
30.	The judge held that the Waters apparatus did not infringe.  He held that the characterising portion of the claim required reduction of stroke volume of both the pistons as the flow rate is reduced.  He said:
“22. On the face of it the claim is calling for a reduction in stroke volume of both pistons as the flow rate is reduced. I reject Agilent’s contention that there is no requirement in the claims as literally construed that the accumulator piston stroke length must increase with increasing flow rate. In my judgment, precisely the opposite is the case. The behaviour of the pistons of the Waters pump therefore represents a variant on the manner of operation called for by the claim in at least two respects: stepwise variation between ranges, constant volume (primary piston) and constant volume or volume reducing with increasing flow rate (accumulator piston) within each range.”
31.	The judge then considered whether the variations from the claim were material variations using the Protocol questions referred to in Wheatley v Drillsafe which were set out in the Improver case.  He said:
“26.  It seems to me that the omission of a continuously variable stroke volume within the flow ranges which might be selected for operation for a particular column is, in fact, a variant which does have a material effect upon the way the invention works. There is no suggestion in the specification that the dependence of stroke volume upon flow rate is in some way optional, quite the contrary. Thus, had I reached the third question in Improver, I would have come to the conclusion that had this variant had no effect upon the way the invention worked, nonetheless on a true construction of the specification it was excluded.”
32.	Mr Wyand QC, who appeared with Mr Alexander for Agilent, submitted that the judge had implied words into the characterising part of claim 1.  The claim  required there to be control means coupled to the drive means.  That was accepted to be present in the Waters apparatus.  The control means was for adjusting the stroke lengths of the pistons in the sense that it was configured to do so.  That was clear from Figure 7.  The adjustment was in response to the desired flow rate when a change was made from within one range to within another range.  Further when that happened, as Figure 7 showed, the stroke volume was decreased when the output was decreased and vice versa.  Further the result was that the pulsations in the flow of the liquid delivered to the output were reduced.  
33.	Mr Hobbs supported the conclusion reached by the judge.  He submitted that claim 1 when read in the context of the specification required both pistons to be adjusted.  The essence of the invention in the patent was to keep the frequency up by adjusting stroke length, thereby avoid damaging pulsations.  He drew attention to the word “respectively” in the characterising part of claim 1 and rightly submitted that meant that both of the pistons were being referred to.  The words “in response to the desired flow rate …” showed that the adjustment had to be as a function of the desired flow rate.  The phrase beginning with the words “such that” at the end of the claim provided the nature of the relationship envisaged by the earlier elements of the characterising portion of the claim.  It followed, he submitted, that in the context of the specification, the claim should be read as if the word “continuously” came before the words “in response”.  
34.	I prefer the submissions of Mr Wyand for Agilent.  No doubt the words of the claim have to be construed in the context of the whole specification having regard to what was the common general knowledge at the priority date: but it would not be right to imply a limitation into the words chosen by the patentee to define his monopoly.  The characterising part of the claim requires the control means to be coupled to both pistons for adjustment.  However there is no requirement that both pistons have to be adjusted at every increment of flow change.  In any case the argument as to whether the claim covers adjustment of one or both pistons is irrelevant as both pistons in the Waters apparatus have their stroke volumes adjusted when any adjustment of flow rate is made.  The crucial issue is whether the claim covers what was called step-wise operation.  
35.	In my view claim 1 does cover the Waters apparatus.  Its control means adjusts the stroke volumes of the pistons in response to the desired flow rate.  For example a change of flow rate from anywhere between 0.530 to 1.23 ml/min to below 0.530 or above 1.23 ml/min will result in a change of stroke volume.  The claim does not state that every change in flow rate has to be accompanied by a change in stroke volume and it would be wrong to imply such a limitation into the claim by importing a word such as “continuously”.  I therefore conclude that the claim covers what was referred to as step-wise adjustment.  That being so, the Waters apparatus infringes claim 1.  
Validity
36.	The principle item of prior art relied on before the judge was US patent No. 4681513 (Saito) which was applied for on 1st February 1985 and was published about a month before the priority date of the Agilent patent.  
37.	Saito discloses a two-stage pump assembly for use in a liquid chromatograph instalment.  The abstract is in this form:
“An accurately controllable two-stage pump assembly comprising two plunger pumps connected in series.  The suction port of the outlet pump A is connected to the discharge port of the inlet pump B so that the discharge port of the outlet pump A and the suction port of the inlet pump B act as the discharge port of the suction port, respectively, of the whole pump assembly.  While the inlet pump B is delivering fluid from the whole pump assembly, the outlet pump A completes the filling stroke of the whole pump assembly and fully increases the pressure inside the chamber of the outlet pump A.  While the inlet pump B is filling, the outlet pump A is in the stage of displacement stroke and delivers fluid from the whole pump assembly.  The plungers of the pumps are moved via cams by stepper motors which swing or rotate back and forth within a certain angular range.”	
38.	The judge said that it was apparent from the introductory passages of Saito that the inventor thought he had invented the series pump.  That, as the judge pointed out, was not important in the context of this case, which was concerned with the disclosure in the description of the preferred embodiment.  As can be seen from Figure 7 of Saito, reproduced below, the apparatus has all the precharacterising features of claim 1 of the Agilent patent.

39.	The pistons 43 and 53 in Saito are spring-loaded against cams 45 and 55.  The cams are mounted on a shaft.  The pistons move so as to follow the profile of the particular cam which oscillates.  Each cam is operated by a separate stepper motor which is driven from a control circuit.  The cams have three working regions as shown in Figure 10 of different slope called M, S and N.  
40.	As was the case before the judge, two passages in Saito were the subject of much discussion.  At column 6 line 36 Saito says:
“The operation of the novel pump assembly constructed as described above is now described. It is to be understood that the cams of the conventional system rotate in one direction. In contrast, in the novel assembly, the cams are rotated back and forth within the 360°. The novel assembly is similar to the conventional system shown in Figure 1 except in these respects. Data indicating a desired flow rate is first entered into the central control circuit 63. Then, the circuit 63 determines the rotational velocity of the cam 45 and the angular range within which the cam swings back and forth, according to the flow rate, the cam 45 acting on the pump 40. The central control circuit 63 then delivers a control signal to the driver circuit 44 to control the operation of the cam 45 in such a way that if the flow rate assumes a large value, the angular range within which  the cam 45 swings back and forth, hence the period Ta1 of the displacement stroke and the period Ta3 of the filling stroke, is extended or the rotational velocity is increased. In this way, the cam is swung right and left repeatedly within the selected angular range. 
… 
(column 7 line 3) The central control circuit 63 to which the output from the variation detector circuit 65 is applied monitors variations in the pressure inside the pipe 62 in synchronism with the output from the encoder 66. These variations are presented on the display means 67, for example, as shown in Figure 9. When the pressure characteristic is inclined upwardly to the right as shown in Figure 9(a), the pre-compression made by the pump 50 is [not sufficient]. When it is inclined downwardly to the right as shown in Figure 9(c), the precompression is [excessive]. When it is horizontal as shown in figure 9(b), the precompression is adequate. When the central control circuit 63 detects the condition shown in Figure 9 (a), it causes the motor driver circuit 54 to increase the velocity of the plunger 53 during the periods Tb1 and Tb2 for augmenting the precompression. In this way, velocities indicated by the broken lines in Figure 8 change to velocities indicated by dot and dashed lines 68 and 69. Inversely, when the condition shown in Figure 9(c) is detected, the control circuit 63 instructs the driver circuit 54 to decrease the velocity of the plunger 53 during the periods Tb1 and Tb2 for obtaining the condition shown in Figure 9(b). Although control operations are carried out in this way, the following conditions are invariably satisfied regarding Figure 8: 
(1) the area bounded by both the solid line and the time axis during the period Ta1 is equal to the area bounded by both the solid line and the time axis during the period Ta2. [Ta3]
(2) the area bounded by both the broken line and the time axis during the period Tb1 is equal to the sum of the area bounded by both the broken line and the time axis during the period Tb2 and the area bounded by both the broken line and the time axis during the period Tb3. 
(3)  the delivery of the pump assembly during the period Ta3 is equal to the difference between the area bounded by both the broken line and the time axis during the period Tb3 and the area bounded by both the solid line and at the time axis during the periodTa3.”
41.	As the judge said, those passages are best understood by reference to Figure 8 of Saito:

42.	It is also necessary to refer to a short passage at column 8 line 17: 
‘The central control circuit 63 shown in Figure 7 selects one of three angular ranges according to the flow rate entered, and drives the pump within that angular range. The inlet pump 50 is required to deliver fluid at a larger flow rate than the outlet pump 40. Where the cam 55 is identical in profile with the cam 45, it is necessary to rotate the cam 55 over two or more of the angular ranges. In this manner, the novel pump assembly alone is capable of covering a very wide range of flow rates.”
43.	Before the judge it was submitted that claim 1 of the Agilent patent lacked novelty (section 1(1)(a) of the 1977 Act), alternatively it was obvious (section (1)(i)(b) of the 1977 Act) having regard to the disclosure in Saito.  He concluded that the teaching of Saito was far from simple to understand.  Having set out Mr Wyand’s submission he considered the evidence of Mr James and concluded:
“35. I understand Mr James’s evidence to be that in Saito the stroke length is indeed variable. This is true both of the primary piston and of the secondary piston and is because both primary and secondary piston stroke ranges are set to a value which depends upon the flow rate desired. Mr James is certainly of the view that in Saito the passage which I have quoted above which refers to the ‘angular range within which the cam 45 swings back and forth … or the rotational velocity is increased’ can be plausibly taken to mean that if for a set flow rate a particular angular range of the accumulator piston cam has been selected and the operator then wishes to increase the set flow rate, the higher set flow rate can be achieved by changing the angular range within which the cam 45 swings back and forth (by changing the cam region) or by increasing the angular velocity (the period of the swing remaining unaltered). In other words, the description is unclear as to what Saito is discussing: it may be stepwise variation or it may be a variation in angular velocity within a given range, resulting in increased swept volume if the cam region will accommodate the increased swing necessary for a fixed period. As I understand his evidence, Mr James prefers the first view because Saito lacks any explicit teaching that the period of the oscillation is to remain constant as the velocity increases, and this is, for the reasons I have given, essential if the swept volume is to increase with flow rate.
36.  Mr James identifies a further difficulty with Saito’s description of the movement of the primary piston. He points out that the cylinders of the inlet pump and the outlet pump are said to have the same diameter. Saito says that it is possible to make the maximum flow rate in the inlet pump larger than the maximum flow rate of the outlet pump. This means that the primary piston has to move at a higher speed than the accumulator piston, since they must have the same period. Accordingly, the angle of oscillation of the primary cam must be greater than that of the accumulator cam, and Saito clearly suggests, says Mr James, that the primary cam may oscillate so that it travels over more than one of the angular ranges S, M, and N. This would result in a very bumpy ride for the output of the pump, because of the sudden change in rate between the two ranges.”
44.	The judge then considered the evidence of Herr Riggenmann, the expert called by Waters. 
“37. Herr Riggenmann, on the other hand, did not find such difficulty in the disclosure of Saito. He concentrates upon the passage which refers to ‘… the following conditions [which] are invariably satisfied regarding Figure 8’. He says (in agreement with Mr James) that the first piston must be able to compress and then deliver a greater volume of fluid than the intake of the second piston. Since the cams are identical, and since the period of operation is the same, he draws the conclusion that the second piston must operate so that its chosen cam segment is not fully utilised when the first piston operates over the whole of a corresponding cam segment. He says this is clear from Figure 8. In coming to his conclusions, Herr Riggenmann performed certain calculations on the basis of Figure 8, and it, in particular, set up what he considered to be a plausible view of the speed of the accumulator piston during the period Ta1. He produced some of his working papers from the witness box, and it became clear that he had indeed carried out the calculations that he said he had carried out in checking the torque requirements of the motors. It is clear that preparations were being made to attack Herr Riggenmann’s bona fides, and I should say that Mr Wyand withdrew the suggestion as soon as Herr Riggenmann’s working papers had been analysed.”
45.	The judge concluded:
“38. In my judgment it cannot be fairly said that Saito contains clear directions to vary the size of the sector of the cam segments traversed. As Mr Wyand points out, even if there were such a direction, it does not necessarily follow that the flow rate is increased by increasing stroke length. Everything would depend upon the effect of the control system, and in particular how it regulated the speed of rotation of the cam within a single cam segment. It has to be borne in mind that part of the cam segment (so far as the primary pistons concerned) must be used to compensate for the compressibility of the fluid. Herr Riggenmann accepted that so far as range M was concerned, there was insufficient capacity to compensate for compression if the fluid had a compressibility greater than 0.5 per cent, which is a very low figure for the solvents in use in this analytical technique.
 39.  There is plainly no express teaching in Saito to arrange the control means 63 so that the stroke volume alters with the flow rate, other than by way of selecting the different cam ranges. For the reasons which I have already expressed in considering infringement of this claim, I do not consider that a stepwise variation unaccompanied by variation within each step falls within the claim. However, there this, in my view, a dilemma facing the patentee. However that may be, I do not consider that this claim is anticipated by Saito.”
46.	Mr Hobbs submitted that the judge had failed to take into account the whole of the teaching of Saito: in particular the terms of claims 1 to 5.  He also drew to our attention passages in the cross-examination of Mr James, which he submitted led to the inevitable conclusion that Saito disclosed all the features of claim 1 of the Agilent.  
47.	I believe that Mr Hobbs’s reliance on the Saito claims was misplaced.  They set out the monopoly claimed by Saito. They emphasise what the inventor thought was his invention but do not add to or modify the disclosure.  However there is no need for me to consider those submissions in depth, due to a concession made by Mr Wyand and the conclusion I have reached as to the ambit of claim 1 of the Agilent patent.  For my part I believe the judge was entitled to come to the conclusion he did upon his view that claim 1 did not include an apparatus arranged for step-wise use, but his conclusion is not directly relevant to a decision as to whether claim 1 of the Agilent patent which did  encompass what was called step-wise operation was novel.  Inevitably the argument is different once it is realised that claim 1 is of wider ambit than that considered by the judge.  
48.	Saito is in part concerned with the same problem as the Agilent patent, namely “to provide a pump assembly producing only a small amount of flow rate pulsations” (see column 4 lines 22 to 24).  The solution that is explained is use of a two-stage series pump with means for producing pre-compression as is illustrated in Figure 8.  This requires a detector (64, 65) for detecting variations in pressure at the discharge conduit of the accumulator pump.  The signals from the detector are used to control the angular velocity of the primary pump.  It does not detect the pulsations and then vary the angular velocity of the primary pump to compensate.  There is a real difference of idea between the teaching of Saito and the Agilent patent.  In Saito any pressure variation is detected and the control unit then tells the primary pump to speed up or slow down according to what the variation is.  In contrast, the characterising part of claim 1 of the Agilent patent requires alteration in response to a flow rate to the column.  
49.	Mr Wyand accepted that in column 6 of Saito there was a description of the operation of the accumulator piston.  Each time a flow rate was selected it was to be inferred that a different segment of cam would be used with the result that there would be a possible three step-wise adjustment dependent on flow rate.  Thus on the construction of claim 1 most of the requirements of its characterising part were met.  His submission was that claim 1 was novel because it had not been established that Saito disclosed the last features of claim 1, namely “such that  pulsations in the flow of the liquid delivered to the output of the pump apparatus are reduced.”  I will come to the rival submission on this issue after setting out the principles to be applied to decide whether Mr Wyand’s submission is correct.  
50.	Claim 1 of the Agilent patent will lack novelty if Saito made available an apparatus within that claim.  The test is strict in that the claimed subject matter must be disclosed directly or unambiguously from the prior art.  In my view no better explanation of the test has been given than that of the Court of Appeal in General Tire & Rubber Co. Ltd v Firestone Tyre & Rubber Co. Ltd [1972] RPC 457 though that judgment was concerned with novelty under the 1949 Act.  At 458 the Court said:
“When the prior inventor’s publication and the patentee’s claim have respectively been construed by the court in the light of all properly admissible evidence as to technical matters, the meaning of words and expressions used in the art and so forth, the question whether the patentee’s claim is new for the purposes of section 32(1)(e) falls to be decided as a question of fact.  If the prior inventor’s publication contains a clear description of, or clear instructions to do or make, something that would infringe the patentee’s claim if carried out after the grant of the patentee’s patent, the patentee’s claim will have been shown to lack the necessary novelty, that is to say, it will have been anticipated.  The prior inventor, however, and the patentee may have approached the same device from different starting points and may for this reason, or it may be for other reasons, have so described their devices that it cannot be immediately discerned from a reading of the language which they have respectively used that they have discovered in truth the same device; but if carrying out the directions contained in the prior inventor’s publication will inevitably result in something being made or done which, if the patentee’s patent were valid, would constitute an infringement of the patentee’s claim, this circumstance demonstrates that the patentee’s claim has in fact been anticipated. 
If on the other hand, the prior publication contains a direction which is capable of being carried out in a manner which would infringe the patentee’s claim, but would be at least as likely to be carried out in a way which would not do so, the patentee’s claim will not have been anticipated, although it may fail on the ground of obviousness.  To anticipate the patentee’s claim the prior publication must contain clear and unmistakable directions to do what the patentee claims to have invented: Flour Oxidizing Co. Ltd v. Carr & Co Ltd. ((1908) 25 RPC 428 at 457 line 34, approved in B.T.H. Co. Ltd v Metropolitan Vickers Electrical Co. Ltd (1928) 45 RPC 1 at 24, line 1).  A signpost, however clear, upon the road to the patentee’s invention will not suffice.  The prior inventor must be clearly shown to have planted his flag at the precise destination before the patentee.”
51.	As I have said Mr Wyand accepted that the three parts of the cam surfaces of Saito would produce three different stroke lengths.  His submission was that claim 1 had novelty as there was no disclosure that the control means of Saito would operate “such that pulsations in the flow of the liquid delivered to the output of the pumping apparatus are reduced.”  He submitted that the basic teaching of Saito was to reduce the pulsations by what Mr James called the “global” feedback compensation mechanism comprising the pressure sensor 64 and variation detector circuit 65.  According to Mr James:
“… the “global” feed-back compensation mechanism used by Saito is such that the level or threshold of pressure pulsations in the outflow of the pump is predetermined by the variation detector circuit.  This means that, in such circumstances any reduction in stroke volume at lower flow rates would not in any event result in a reduction in the pressure pulsations on the outflow of the pump.”
52.	According to Mr Wyand and it seems Mr James there is no teaching in Saito to reduce the stroke length such that pulsations in the flow delivered are reduced and it is by no means certain that any reduction in the stroke length obtained in Saito would have that effect having regard to the global compensation system which was at the heart of the Saito patent.  The “flag”, referred to in General Tire, had not, according to Mr Wyand, been clearly and unambiguously placed within claim 1 of the Agilent patent.  That, he submitted, was supported by what had happened in this case.  Waters denied that their apparatus operated in the way required by the last few words of the claim.  They were entitled to make that denial as it was not inevitable that that feature of claim 1 was present due to the presence of the transducers at the outlet of the accumulator pump.  For that reason Agilent had to do experiments to show that the last feature was used.  It is, Mr Wyand submitted, by no means clear that the result would be the same with a Saito device, even if one could be built from the description in the patent.  
53.	Mr Hobbs submitted that if the presence of the global compensation system of Saito meant that claim 1 had novelty, then it followed that the Waters’s apparatus did not infringe for the same reason.  That submission cannot be right.  The system used in the Waters apparatus has been established to have the feature of the last words of the claim.  But the evidence does not establish that the Saito system is identical.  It could be similar, but that is not sufficient to take away the novelty of a claim unless it be established that any difference was not material to the feature of claim 1.
54.	Next, Mr Hobbs submitted that the last lines of claim 1 were a statement of the inevitable consequence of using the claimed apparatus.  He relied in support on statements made by Mr James in cross-examination (see Evidence 1 pages 126 to 133).  At first sight that submission appears to have force, but I have not felt it right to accept it without evidence to that effect directed to the Saito disclosure.  In any case the evidence of Mr James, to which I have referred in paragraph 51 above, suggests to the contrary.  As the onus is upon Waters, I have come to the conclusion that they have not established that the last feature of claim 1 is the inevitable result of the other features being present in Saito.  I conclude that Waters have not established that Saito contains clear and unmistakable directions to do that claimed in claim 1 of the Agilent patent.
55.	Waters also attacked claim 1 as being obvious.  They accepted, as did Agilent, that the structured approach in Windsurfing International v Tabur Marine (Great Britain) Ltd [1985] RP 59 was appropriate.  
56.	In the circumstances of the case I can go straight to question 3 of Windsurfing.  I have already decided that the only difference between the prior art and the invention is contained in the last feature of claim 1.  It therefore remains to decide whether the addition of that feature was obvious.  In my view it was not.  According to Mr James, Saito proposes that the pulsations were dealt with by the global feed-back compensation.  I can see no reason why it would be obvious to depart from that teaching at the priority date of the patent.  Certainly we were not shown any evidence that such would have been obvious.  There is a real difference in the idea behind Saito and that of the Agilent patent and it is difficult to see that anything in Saito when considered together with the common general knowledge would lead to the Agilent invention if it is not disclosed.
Conclusion
57.	For the reasons given I would allow the appeal and hear counsel as to the order to be made.  
Lord Justice Tuckey:
58.	I agree.
Lord Justice Rix:
59.	I also agree.  
Order: The Claimants’ appeal be allowed and the defendants’ appeal be dismissed; the defendants to pay the claimants their costs of (i) the petition for revocation dated 17th December 1997, (ii) the action for infringement commenced by writ of summons sated 4th August 1998 and of the counterclaim for invalidity raised therein, (iii) the appeals of the claimants and the defendants pursuant to the appeal notices dated 23rd May 2001 and 6th June 2001; permission to appeal to the House of Lords refused; the order for delivery up to be stayed pending resolution of the House of Lords’ procedure; the question relating to the inquiry and account and the assessment of costs to go ahead; interim order on account of costs in the sum of £300,000; stay of the injunction ordered pending resolution of the House of Lords’ procedure; undertaking given by Mr Hobbs QC on behalf of his clients to put in the petition within 14 days; an undertaking by Mr Hobbs QC on behalf of his clients to ensure that they keep appropriate accounts to enable the damages to be calculated; counsel to lodge a draft minute of order.

(Order does not form part of the approved judgment)