Grammelogia, or, The mathematicall ring extracted from the logarythmes, and projected circular : now published in th[e] inlargement thereof unto any magnitude fit for use, shewing any reasonable capacity that hath not arithmeticke, how to resolve and worke, all ordinary operations of arithmeticke : and those that are most difficult with greatest facilitie, the extract on of rootes, the valuation of leases, &c. the measuring of plaines and solids, with the resolution of plaine and sphericall triangles applied to the practicall parts of geometrie, horo[l]ogographic, geographie, fortification, navigation, astronomie, &c, and that onely by an ocular inspection, and a circular motion / invented an[d] first published, by R. Delamain, teacher, and student of the mathematicks.

Courteous Reader

HItherto the world hath beene abused as well as my selfe, with a false Rumor (raised by some rude ignorant tongue) that my Invention both of Ring and Qua∣drant was got, or borrowed, or stollen (even as they please to miscall it) from another Man, by the sight of a Letter, by some private Conference by — J know not what meanes (nor they neither) but onely by their malicious phancy: which how true, how just it is, that the world and my selfe may have our right, and they the shame, by this following just defence and future event, J hope thou mayest fully be enformed. I did not in∣tend to take this course, but sought peace and my right by a private and friendly way; but failing of it my good intentions scorned and slighted; J desire all may now Iudge who is in fault; and let this ensuing discourse be my Plea.