"It may not be fit, in point of discipline, that a subordinate officer should dispute the commands of his superior, if he were ordered to go to the mast head: but if the superior were to order him thither, knowing that, for some bodily infirmity, it was impossible he should execute the order, and that he must infallibly break his neck in the attempt, and it were so to happen, the discipline of the navy would not protect that superior from being guilty of the crime of murder."