This most curious narrative suggests that in some way Drebel, who died in London in 1634, had discovered the art of compressing oxygen and conceived the idea of making it serviceable for freshening the air in a boat, or other place, contaminated by the respiration of a number of men for a long time. Indeed the reference made to the substance by which Drebel purified the atmosphere in his submarine as "a liquor" suggests that he may possibly have hit upon the secret of liquid air which late in the nineteenth century caused such a stir in the United States. Of his possession of some such secret there can be no doubt whatsoever, for Samuel Pepys refers in his famous diary to a lawsuit, brought in the King's Courts by the heirs of Drebel, to secure the secret for their own use. What was the outcome of the suit or the subsequent history of Drebel's invention history does not record.
Throughout the next 150 years a large number of inventors and near-inventors occupied themselves with the problem of the submarine. Some of these men went no further than to draw plans and to write out descriptions of what appeared to them to be feasible submarine boats. Others took one step further, by taking out patents, but only very few of the submarine engineers of this period had either the means or the courage to test their inventions in the only practicable way, by building an experimental boat and using it.
In spite of this apparent lack of faith on the part of the men who worked on the submarine problem, it would not be fair to condemn them as fakirs. Experimental workers, in those times, had to face many difficulties which were removed in later times. The study of science and the examination of the forces of nature were not only not as popular as they became later, but frequently were looked upon as blasphemous, savouring of sorcery, or as a sign of an unbalanced mind.
_A Gas Attack Photographed from an Airplane._]
England and France supplied most of the men who occupied themselves with the submarine problem between 1610 and 1760. Of the Englishmen, the following left records of one kind or another concerning their labours in this direction. Richard Norwood, in 1632, was granted a patent for a contrivance which was apparently little more than a diving apparatus. In 1648, Bishop Wilkins published a book, _Mathematical Magick_, which was full of rather grotesque projects and which contained one chapter on the possibility "of framing an ark for submarine navigation." In 1691, patents were granted on engines connected with submarine navigation to John Holland--curious forerunner of a name destined to be famous two hundred years later--and on a submarine boat to Sir Stephen Evance.