The best way of ascertaining if the bureaus are able to do them is to mobilize--to put into commission and send out to sea all the craft that will be needed, fully equipped with a trained personnel and with a well-conditioned material; and then direct the commander-in-chief to solve a definite strategic problem--say to defend the coast against a hypothetical enemy fleet--the solution including tactical games by day and night. Before attempting the solution of a strategic problem by an entire naval force, however, it is usual to hold mobilization exercises of a character less complete, in the same way that any course of training begins with drills that are easy and progresses to drills that are difficult. The simplest of all the preparative drills--if drills they correctly can be called--is the periodical reporting, once a month, or once a quarter, by each bureau and office, of its state of readiness; the report to be in such detail as experience shows to be the best. In the days when each bureau's preparation consisted of comparatively few things to do, the chief of that bureau could be relied on to do the things required to be done by his bureau; and his oral assurance to the secretary that--say all the ships had enough ammunition, or that adequate provision had been made for coal, or that there were enough enlisted men--would fulfil all requirements. But in the past fifty years, the requirements have increased a hundredfold, while the human mind has remained just as it was. So it has seemed necessary to institute a system of periodical preparation reports, to examine them carefully, and to use all possible vigilance, lest any item be forgotten or any work done by two bureaus that ought to be done by only one. Who should examine the reports? Naturally the same persons as decide what should be done. The same studies and deliberations that fit a person to decide what is needed, fit him to inspect the product that is offered to supply the need; not only to see if it comes up to the specifications, but also to decide whether or not any observed omission is really important; to decide whether, in view of certain practical difficulties, the specifications may be modified; and also to decide whether certain improvements suggested by any bureau should or should not be adopted.