Elementary Treatise on Quaternions

Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. Sometimes, indeed, this rule is most absurdly violated, for it is usual to take cos2a'' as equal to (cos a)2, while cos — 1x Is not equal to (cos No such incongruities appear in Quaternions; but what is true of oper...