From Mechanics in Guide part of ABC of Plain Words by Sir E Gowers (1951)

In Modern English Usage Fowler makes an elaborate study of the hyphen. He begins engagingly by pointing out that "superfluous hair-remover" can only mean a hair-remover that nobody wants, and he proceeds to work out a code of rules for the proper use of the hyphen. He admits that the result of following his rules

"will often differ from current usage". But, he adds, "that usage is so variable as to be better named caprice".

The author of the style-book of the Oxford University Press of New York (quoted in Perrin's Writer's Guide) strikes the same note when he says "If you take hyphens seriously you will surely go mad".

I have no intention of taking hyphens seriously. Those who wish to do so I leave to Fowler's eleven columns. If I attempted to lay down any rules I should certainly go astray, and give advice not seemly to be followed. For instance, the general practice of hyphening co when it is attached as a prefix to a word beginning with a vowel has always seemed to me absurd, especially as it leads to such possibilities of misunderstanding as unco-ordinated must present to a Scotsman. If it is objected that ambiguity may result, and readers may be puzzled whether coop is something to put a hen in or a profit-sharing association, this should be removed by a diaeresis (coöp) not a hyphen (co-op). That is what a diaeresis is for.

I will attempt no more than to give a few elementary warnings.

1. Do not use hyphens unnecessarily. Write, for instance, today, not to-day, halfpenny not half-penny, motor car, not motor-car. If you must use overall as an adjective (though this is not recommended) write it like that, and not over-all.

2. If you do split a word with a hyphen, make sure you split it at the main break. Though you may write self-conscious, if you wish to have a hyphen in the word, you must not write unself-conscious but un-selfconscious.

3. To prevent ambiguity a hyphen should always be used in a compound adjective (e.g. well-written, first-class, six-inch, copper-coloured). The omission of a hyphen between government and financed in the following sentence throws the reader, on to a false scent:

When Government financed projects in the development areas have been grouped. . .

4. Do not be guilty of the slovenly habit of putting extraneous words inside a hyphenated pair of words. Not even scarcity of paper can excuse writing:

Where chaplains (whole- or part-time) have been appointed.

instead of

"where chaplains have been appointed, whole-time or part-time".