The Princess Anne and the queen were on exceedingly bad terms, the chief reason of their disagreement being Anne's passionate devotion to the famous Sarah Jennings, wife of the yet more famous Duke of Marlborough. The Marlboroughs, a clever, able, ambitious, unscrupulous pair, encouraged the jealousy between the sisters to secure their own ends, and at length formed a "Princess's party," which gave William the Third considerable trouble during his reign. The Queen insisted that Lady Marlborough, as she then was, should be dismissed from the Princess's service. Anne was equally determined to keep her beloved friend about her at all risks. This led to endless disputes and quarrels between the royal ladies; and the little Duke of Gloucester became a fresh subject of contention. When she was in town, the Princess, who was a tender mother, passed much of her time in the nursery of her heir.... Whenever the Queen heard her sister was there she forebore to enter the room, but would send an inquiry or a message to her royal nephew--"a compliment," as it was called in the phraseology of the day. The set speech used to be delivered by the queen's official in formal terms to the unconscious infant, as he sat on his nurse's knee; and then the courtly messenger would depart, without taking the slightest notice of the Princess Anne, although she was in the room with her child. Sometimes Queen Mary sent her nephew rattles or balls, or other toys, all which were chronicled in the _Gazette_ with great solemnity; but every attention to the little Gloucester was attended with some signal impertinence to his mother.[109] For two years the little boy throve well in the good air of Kensington, without any illness. But in the third year he was attacked by ague. Fifty years before he would probably have been bled and reduced in every way, and would speedily have died. But medical science was improving; and a wonderful discovery had been made in far-off Peru. The ague was cured by Doctor Radcliffe and Sir Charles Scarborough, "who prescribed the Jesuit's Powder, of which the Duke took large quantities early in the spring of 1694, for the same complaint most manfully."[110] This Jesuit's Powder was none other than the famous Peruvian Bark, made as we all know from the bark of the Chinchona trees, so-called by Linnæus after the Countess of Chincon, wife of the Viceroy of Peru. This lady's cure in 1638 from a desperate fever, brought the quinine--the "bark-of-barks" as its Indian name signifies--into notice, and gave the world one of the most precious remedies we possess against disease. This ague was the first, but by no means the last illness our poor little boy had to endure; for all through his short life he was delicate.