Page:Euclid's Elements 1714 Barrow translation.djvu/532

 perpendiculars μν be erected equal to the Radii MN of parallel circles MOM paing thro' the correponding points M of that quadrantal Arc, the greatet of which βξ let be equal to the Radius BX of the bae of the Hemiphere: The figure αβξ will contain the Radii of all the circles of whoe Peripheries the uperficies of the Hemiphere conits. And if the perpendicular μν, βδ be erected equal to the Peripheries MOM, BDB, there will be made the figure αβδ equal to the uperficies of the Hemiphere. The dimenion of which figure if you can by any means find (as in this cae you are to find the Area of the figure αβξ) thence you will eaily deduce the content of the egment of the phere, agreeing to what you may gather by any lawful reaoning. Which Obervation, I think will not be unueful in Geometry.

FINIS.

T the Hand and Pen in Barbican are Taught, Writing, Common and Merchants Accounts, after that well approved Method of Mr. Normanel, Algeba, Geometry, Meauring, Surveying ,Gauging,Navigation and Dialing, with other parts of the Mathematicks, alo the Ue of the Globes, Maps and other Intruments, by me Robert Arnold.