Commencing with his embarkation at New York, our author succeeds, at once, in rivetting the attention of his readers by _a succession of minute details_. But there is this vast difference between the details of Mr. Slidell, and the details of many of his contemporaries. They--the many--impressed, apparently, with the belief that mere minuteness is sufficient to constitute force, and that to be accurate is, of necessity, to be verisimilar--have not hesitated in putting in upon their canvass all the _actual_ lines which might be discovered in their subject. This Mr. Slidell has known better than to do. He has felt that the apparent, not the real, is the province of a painter--and that _to give_ (speaking technically) _the idea of any desired object, the toning down, or the utter neglect of certain portions of that object is absolutely necessary to the proper bringing out of other portions--portions by whose sole instrumentality the idea of the object is afforded_. With a fine eye then for the picturesque, and with that strong sense of propriety which is inseparable from true genius, our American has crossed the water, dallied a week in London, and given us, as the result of his observations, a few masterly sketches, with all the spirit, vigor, raciness and illusion of a panorama. Very rarely have we seen any thing of the kind superior to the "American in England." The interest begins with the beginning of the book, and abides with us, unabated, to the end. From the scenes in the Yankee harbor, to the departure of the traveller from England, his arrival in France, and installment among the comforts of the Hotel Quillacq, all is terse, nervous, brilliant and original. The review of the ship's company, in the initial chapter of the book is exceedingly entertaining. The last character thus introduced is so peculiarly sketched that we must copy what the author says about him. It will serve to exemplify some of our own prior remarks.