Brief contents of the course

Clauses of Purpose
Clauses expressing purpose may, as is well known, be introduced either by the conjunction that or by the phrase in order that. There is a basic difference between the two variants. A clause introduced by in order that is sufficiently characterised as a clause of purpose, and nothing else is needed to identify it as such. A clause introduced by that, on the other hand, need not necessarily be a clause of purpose: it can also belong to one of several other types. To identify it as a clause of purpose other indications are needed, and the most usual of these is the verb may (might) or should as part of its predicate.
A clause of purpose can also be introduced by the phrase so that, and some special signs are needed to distinguish it from a clause of result.
Let us take as an example the following sentence with two clauses introduced by the phrase so that. Although slightly nearsighted, Elisabeth, so that nothing might damage the charm of her dark brown eyes, tragic and wide apart under straight brows, wore no glasses but carried instead a miniature lorgnette, for which she now searched in her purse, unobtrusively and on her lap so that Steitler, who was speaking to her son, would not notice.
Both clauses here are clauses of purpose, not result, and this is seen from the following facts: as to the first clause, its position between the subject of the main clause (Elizabeth), and its predicate (wore), shows beyond doubt that it cannot express result: the result could not possibly be mentioned before the action bringing it about was stated. Another point speaking in favour of the clause being one of purpose is its predicate (might damage). As to the second clause introduced by so that, its position at the end of the sentence does not tell anything about its being a clause of purpose or of result. That it is a clause of purpose is seen from the predicate (would not notice), which would have no reasonable sense in a clause of result. If we make a slight change and replace the predicate would not notice by did not notice, the clause will decidedly be a clause of result. So the meaning of the clause appears to depend entirely on the verb would.
Compare also the following sentence: Mrs Cox did not object to this so long as they talked English, so that she could keep a line on the conversation; if it was French, she did not know what they were up to. Here the words talked English and could keep a line point to the meaning of purpose, rather than result.