This section is from the book "Hill's Manual Of Social And Business Forms: A Guide To Correct Writing", by Thos. E. Hill. Also available from Amazon: Hill's Manual Of Social And Business Forms: The How-To-Do-Everything Book Of Victorian America.
Be particular to use a sheet appropriate in shape to the purpose for which it is employed. Paper is now manufactured of every size adapted to the wants of any article written. The names of the various kinds of paper in general use are Legal-cap, Bill-paper, Foolscap, Letter-paper, Commercial-note, Note-paper and Billet.
In the writing of all Legal Documents, such as wills, taking of testimony, articles of agreement, etc., legal cap is generally used, characterized by a red line running from top to bottom of the sheet.
For Bills, paper is commonly ruled expressly for the purpose, and generally bears the name and business advertisement of the person using the same, at the top.
When writing Notes, Orders, Receipts, Compositions, Petitions, Subscription Headings, etc., foolscap paper is used.
The common Business Letter should be so brief as generally to require but one page of commercial note, which is somewhat narrower and shorter than letter paper.