Now this seems easy enough, and if every author prepared his copy carefully, so that there could be no possible mistake as to his meaning, nothing would be easier; but in practice a number of questions arise which would never be thought of by an outsider. On a new work being put in hand, some half-dozen compositors are given a few sheets of copy apiece, and if the proof-reader happens to be readily accessible he is bombarded within the first half-hour or so with, "How am I to spell centre?" "Has travelling one or two l's?" "Shall I capitalize the word State?" "Shall I spell out two hundred?" "Do you want ships' names in Italic?" and so on and so on. As to punctuation, every compositor thinks he knows better than proof-reader and author combined and follows his own sweet will. As every error on the first proof must be corrected by the compositor at his own expense, here arises the cause of war mentioned in our opening paragraph.
Much has been written about printers' errors and the mistakes of "the intelligent compositor." Aside from those caused by illegible manuscript, mistakes arise from faulty "distribution," that is to say, the type has been thrown into the wrong boxes. Thus we get _c_ for _e_, _h_ for _n_, _y_ for _p_, etc., these boxes being contiguous and the letters of the same thickness; if, for instance, the compositor picked up _u_ instead of _t_ the difference in thickness would at once be noticed by him and the mistake rectified. Then letters are sometimes set upside down and we find letters of a different "face" which have got into the case by mistake. In type set on machine, errors arise from striking adjacent keys, or some matrix will stick in the channel and make its appearance later, sometimes even in the next line. But the chief source of error is illegible or carelessly prepared manuscript, and to the author's slips of the pen must be added in these days the slips of the typewriter.
It is quite possible for a man to be an expert in astronomy, medicine, or natural history and yet have hazy ideas on spelling and punctuation. "When in doubt use a dash" is an old standing joke, but some authors use dashes all the time, making them do duty for commas, semicolons, and periods. They will write indifferently 4 or four and frequently their capital _a_'s _c_'s, _m_'s, and _n_'s cannot be distinguished from the small letters. They will commence a story telling that the "Captain" did so and so, and lo, on the next page the "captain" sinks into a common noun; and so with "Father," "mother," "Aunt," "uncle," etc. Just see what the story would look like if set according to copy!