On the morning of the twenty-third of July there came a relapse. While the physicians were examining and dressing his wounds, the President experienced a slight rigor, followed by an increase of febrile symptoms. This was evidently owing to an interruption of the flow of pus, and, on the twenty-fourth, an operation was performed upon the cavity, by which the patient was relieved. The intense heat of those July days was very debilitating, and a variety of ingenious plans were tried to lower the temperature in the sufferer's room. The most successful experiment was that of Mr. Dorsay's, which was based on the system used in cooling the air in mines. It required considerable machinery, but by its means the temperature of the room was reduced to seventy-five degrees. The system is as follows: A stationary engine is first employed to compress the air which, when crowded into less space, gives out a large amount of heat. This is carried away by running water, and as soon as the air is again set free, it becomes as cool by expansion as it had before been heated by compression. On the 27th of July, a piece of the fractured rib was removed; the President was again able to take nourishing food, the fever subsided, and all the bulletins began to assume a cheerful tone. And so the long, long days passed by, with frequent alternations of hope and fear. On the 11th of August the President asked for pen and paper that he might write a letter. "Through all those weary weeks of pain, With death's dark angel nigh, But once to grasp the accustomed pen The trembling fingers try. "Those brave words from the strong man bowed, Courageously death meeting, To whom amid the courtly crowd Of great ones sending greeting? "The mother-bosom beat afar-- To her that tender letter; To her--through life his guiding star-- He writes he's 'getting better.'" By the middle of August it was evident that the President was suffering from pyæmia, or blood-poisoning. The swollen parotid gland occasioned fresh solicitude, and the stomach refused to perform its ordinary functions. Nourishing enemeta were then administered with excellent results, and the lancing of the parotid-swelling afforded temporary relief.