Sentence:  If you put foure Spleets in a Hiue, then cut their backes, where they must leane one against another, to square angles, such as be foure in a circle: if but three, cut them to <WSD>obtuse</WSD> angles, such as are three in a circle: (you may readily try them, before you put them in, by Moulds made iust to those formes) and so will they stand close and firme together. 
Meaning of the word marked with <WSD> tags:  Larger than one, and smaller than two right angles, or more than 90° and less than 180°.