In presenting these lectures of mcandrew in book form, the author does so in the hope that they may be of benefit to some of that great class of hard workers whose life below the grating is but little understood by the public at large. These men are the backbone of modern seafarers, as they bear the heat and burden of the work of sea transportation. Inured from early youth to the hardest physical toil known to man, it is scarcely to be presumed that their early edu cation is such as to fit them for the higher positions in engineering; for example, those held by the licensed engineer officers under whom they serve.