5. A period should always be put after roman numerals, except when used in the paging of prefaces, etc.
George III. came to the throne in 1760.
OBSERVATION 1. In many modern works the period is omitted; as,—
William I made a mistake.
There being no comma after “William,” it is supposed to be obvious that the mistake was made by William the First. The insertion or omission of the period is becoming wholly a matter of printing-office style.
II. COLON.
6. A colon is put at the end of a clause complete in sense, when something follows which tends to make the sense fuller or clearer. (See Rules 9 and 13.)
There is yet another sphere for the electric motor to fill: that of street railway propulsion.—N. A. Review; April, 1888.
In free states no man should take up arms, but with a view to defend his country and its laws: he puts off the citizen when he enters the camp; but it is because he is a citizen, and would continue to be so, that he makes himself for a while a soldier.—Blackstone’s Commentaries, Book I., Ch. 13.
7. The last of several clauses that introduce a concluding remark or sentiment should be followed by a colon, if the preceding clauses have been punctuated with semicolons.