The Appellants were the registered joint proprietors of a patent in respect of an invention entitled "PressureResistant Bag", used in support systems in mines. The Respondent manufactured and sold a competing product. The Appellants alleged that their patent had been infringed and applied for a permanent interdict restraining the respondent from selling or offering its product for sale and for an order for the delivery­up of any infringing bags. The court a quo dismissed the application. On appeal, the Court was required to decide whether the Respondent's product infringed the Appellant's patent. Held ­ The Court stated that infringement proceedings are concerned only with the invention claimed. In case there was no evidence to show that the patent should be read in a manner that would give the words of the claim meaning other than their primary meaning. The Court held that the Appellants had to show that all of the features or limitations of the claim were present. It noted that it was a common cause that the Respondent's product was very similar to the patented product. The Court only had to decide whether or not Respondent's product included a second bag, ie whether the sleeve of its bag was a second bag. The Court found that there was no room for the application of the concept of purposive construction in interpreting the patent specification. Whether the particular features of the claimed invention taken by the alleged infringer represent all the essential features of the claim remains a question of construction. A test which necessitates extrinsic evidence will be inappropriate in most cases. The Court noted that the patent in the case did not involve technical complexities. The words of the claim were ordinary English words clearly used in their ordinary connotation and the claim was unambiguous. There was nothing that would justify a reference either to phraseology in the body of the specification or to extrinsic evidence relating to the art. The claim in issue should be read in its own terms. The Court held that the patentee should be understood to have intended that effect should be given to the limitation to the claim which followed from the use of the words "second bag". The Respondent's product did not have a second bag and therefore did not infringe the claim. The appeal was dismissed with costs including the costs of two counsel