A tolerably close estimate of the words contained in even bad manuscript may be made by counting the lines of say twelve of its varying pages, then getting an average per line of the words in several lines taken from each page, and multiplying the number of the former by that of the latter. Next add the average allowance for chapter-lines, sub-heads, and other break-lines, counting them as full lines. Reduce the break-lines to full lines, adding them to the whole, and you have the contents of twelve pages. Divide by twelve to find the contents of a single (average) page.
For example, a work of 400 pages in manuscript is submitted. Twelve average pages, taken at intervals, give an average of 30 lines to a folio. Three lines taken at various places from each of these twelve pages indicate an average of eleven words to a line. This will give about 330 words to a page, exclusive of breaks, chapter and other lines, for which an allowance is made of four lines, or 44 words, for each page of manuscript, which, added to 330, makes 374. Multiply the 374 words per page by the 400 pages in the manuscript, and you have a result of 149,600 words in all.
To know how many pages of printed matter this will make, it is now necessary to have the size of type and page to be used. An exact printed page, containing the one and representing the other, is always a good guide in completing the calculation, which is done by dividing the number of words contained in the manuscript by that of the printed page. This will give the desired cast-off for the work in printed pages.
Thus, the estimate of the manuscript gives 149,600 words; that of the printed page of the size required - set up in leaded long primer, we will say for example - gives 480 words; consequently 149,600 divided by 480 gives 312 pages, or 20 sheets, if printed in octavo.
When extra or more than single "leading" of matter is required, count the extra leads (six-to-pica being the size most used in book-composition) iu the following proportions: three for a nonpareil line; four for brevier and bourgeois; five for long primer and small pica; six for pica; and so on, increasing or diminishing in the necessary ratio for larger or lesser sizes.
For works under 144 pages, the cast-off of which does not reach a number of folios divisible by 4, there should be added the number that will make it so. Thus, 110 will be counted as 112; 134 as 13G; and so on. A sufficient allowance of pages, added in the same way, should be made in cast-offs for larger works, adopting 8 or 12 as the even dividing number. This rule applies more particularly to works where the copy is very irregular or much crowded with abbreviations and closely written notes, alterations, interlines, etc.