PRO AND CON At the period when these events took place, I had just returned from a scientific research in the disagreeable territory of Nebraska, in the United States. In virtue of my office as Assistant Professor in the Museum of Natural History in Paris, the French Government had attached me to that expedition. After six months in Nebraska, I arrived in New York towards the end of March, laden with a precious collection. My departure for France was fixed for the first days in May. Meanwhile, I was occupying myself in classifying my mineralogical, botanical, and zoological riches, when the accident happened to the Scotia. I was perfectly up in the subject which was the question of the day. How could I be otherwise? I had read and re-read all the American and European papers without being any nearer a conclusion. This mystery puzzled me. Under the impossibility of forming an opinion, I jumped from one extreme to the other. That there really was something could not be doubted, and the incredulous were invited to put their finger on the wound of the Scotia. On my arrival at New York the question was at its height. The hypothesis of the floating island, and the unapproachable sandbank, supported by minds little competent to form a judgment, was abandoned. And, indeed, unless this shoal had a machine in its stomach, how could it change its position with such astonishing rapidity?