In 1793 he was a member of the Committee of Health, appointed for the relief of the sick by yellow fever, and of the orphans made such by it. The duties of this position were faithfully and calmly fulfilled, “and his whole life,” says Prof. R. E. Thompson, “corresponded to the promise of that year.” He subsequently wrote a full account of this epidemic, of which four editions were published. Stephen Girard, who was one of the members of this committee, as Mr. Carey says, “to the inexpressible delight” of the members, volunteered his services, and became superintendent of the yellow fever hospital on Bush Hill. In 1792, or ’93, feeling for the sufferings and wretchedness of the numerous Irish immigrants who arrived in Philadelphia, he called a meeting, at the Coffee House, of a number of the most influential and prominent Irishmen, and submitted to the meeting a constitution, which he had prepared, and which was adopted, and thus was formed “The Hibernian Society for the Relief of Emigrants from Ireland.” This society exists at the present day in a highly flourishing condition. In 1796 he zealously engaged with a few other citizens in the formation of a Sunday-school Society, of which Bishop White became president. Between 1796 and ’98 he became involved in a very acrimonious controversy with William Cobbett, which was not of his seeking, but which he conducted with unflinching courage and ability. In addition to a considerable correspondence between them, the war became one of pamphlets and newspapers—Cobbett using his _Porcupine Gazette_. Mr. Carey issued a pamphlet entitled _A Plum Pudding for Peter Porcupine_, in which he says he “handled him with great severity.” He next published _The Porcupiniad, a Hudibrastic Poem_, in which he turned some of Cobbett’s own paragraphs into Hudibrastic verse, and “it is wonderful,” he says, “how smoothly they ran, in many instances, with the alteration of a single word or two.” Cobbett made no reply, and never after had Mr. Carey’s name in his paper but once or twice incidentally. This ended the controversy, and subsequently they became very good friends.