About this time the celebrated doctor Cullen, of Scotland, made some curious discoveries in the art of producing cold by evaporation. Hoping that the genius of Franklin might throw some lights on this dawning science, a friend of doctor Cullen's wrote a statement of the facts to Franklin. The American philosopher, though now immersed in political pursuits, took a little leisure to repeat doctor Cullen's experiments on cold, which he so improved as easily to produce ICE in the _dog days_. But it was one of those discoveries, which, as he says, he _never valued, because it was too expensive to be of general utility_. About the autumn of 1761, he rendered himself prodigiously popular among the ladies in London, by completing that sweet toned little instrument of music, the HARMONICA. I have been told that his fame at court on this account, so awakened the recollection of George III. that he caused it to be signified to Dr. Franklin, that he felt a disposition to "_do something for him_." Our philosopher replied, that he wanted nothing for himself, but--that, _he had a son in America_. The king took the hint, and immediately made out a commission of "_Governor of his colony of New Jersey, for his beloved subject, Temple Franklin, Esq._" On such small things are the fortunes of men sometimes founded! Doctor Franklin was now become so great a favourite that the people of all classes seemed to take a pride in talking of him, and his sayings, insomuch that not a word of the brilliant sort could fall from his lips but it was sure to be caught up instantly and re-echoed through every circle, from proud St. James to humble St. Giles. The following impromptu made a great noise in London about this time. One evening in a large party at his friend Vaughan's he was, laughingly, challenged by a very beautiful girl, a Miss Gun, to make her a couplet of verses _extempore_. Well, madam, replied he, with great gallantry, since every body is offering a tribute to your graces, let me tender the following: "Cupid now to ensure his fun, Quits his _bow_ and takes to _gun_." This handsome play on her name instantly suffused the cheeks of Miss Gun with celestial roses, making her look much more like an angel than before. I mention this merely to show what an extraordinary mind that man must have possessed, who with such equal ease, could play the _Newton_ or the _Chesterfield_, and charm alike the lightnings and the ladies.