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Example.
SVppose a shippe on the sea C, whose distaunce I desire to knowe standing on the cliffe GFE, your glasse A equidistantly eleuate, AB the perpendicu∣lare lyne 72 inches, E your viewing station, DE the altitude of your eye 69 in∣ches, BE the distance betweene your two perpendiculare lines 20 foote, FG the heigth of the cliffe from the sea 96 pase. Now by deductings 69 inches the alti∣tude of your eye from 72 the lengthe of AB, the plumbe line from the glasse, there remayneth 3 your Diuisor; yf the grounde be leuell, otherwise ye muste adde or detracte the difference or vnequalitie according to the rules to fore gi∣uen, but here supposing your grounde leuell your diuisor remayneth 3. then re∣solue 20 foote into inches, and multiplye the same in the altitude of the cliffe vp to the glasse 98, so haue ye 23520, whiche diuided by 3 yeldeth in the quotient 7840, whiche is the exacte distaunce of that parte of the shippe whiche ye did es∣pye from the centre of your glasse.
YOu may on this manner from an highe hill or mountayne, hauing any playne or leuell grounde on the toppe, not onely measure the distance of any marke that ye can sée, but also set foorth the true platte and proportion of an whole Countrey, with all the Townes, Coastes, Harboronghes. &c.
For yf you mene circularely about your glasse, alway when you espy any marke, setting vp a staffe, writing thervppon the name of the place ye sée, whether it be village, porte, roade, or such lyke, ye shall in the end situate as it were the whole countrey in due proportion vpon your plat¦fourme, so that measuring the distaunce of euery staffe set vp from the middle lyne perpendiculare falling from the glasse, and the distaunce likewise of euery staffe from other, ye may (working by the golden rule) finde out the exacte distaunce of euery towne, village, porte, roade or suche lyke from your platfourme, and also how farre euery one is di∣stante off from other. Thus muche I thought good to open concerning the effects of a playne Glasse, very pleasant to practise, yea most exactlye seruing for the description of a playne champion countrey. But maruey∣louse are the conclusions that may be perfourmed by glasses concaue and conuex of circulare and parabolicall fourmes, vsing for multiplication of beames sometime the ayde of glasses transparent, whiche by fraction should vnite or dissipate the images or figures presented by the reflection