As the outcome of a short but occasionally painful experience of mathematical papers, I would suggest that such a paper, if it is to be of any interest at all to the majority of those to whom it is addressed, must necessarily be boring to some of them. It is therefore with this explanation that I am trying to put before you results which are not in any sense new, which are, indeed, the stock-in-trade of the present-day analyst, and therefore well known to many here, but which may interest some whose studies have not lain in this particular direction.