A short treatise of dialling shewing, the making of all sorts of sun-dials, horizontal, erect, direct, declining, inclining, reclining; vpon any flat or plaine superficies, howsoeuer placed, with ruler and compasse onely, without any arithmeticall calculation. By Edvvard Wright.

CHAP. IV. The third diuision of Dials, either agreeing with the plaine of the Meridian, or disagreeing from the same. (Book 4)

ALl flats doe either agree with the plaine of the Meridian circle (which may therefore bee called meridian flats) or else they disa∣gree from the same.

2 They are knowne thus: If the flat bee erect and declining 90. degrees, it is a Meridian flat, o∣therwise it is no Meridian flat; and then you must first draw therin the meridian line, after this maner.

3 If the flat be Horizontal, take the clinatory* 1.1 and lay it flat downe thereupon; and turning it a∣bout till the needle hang precisely ouer the Magne∣ticall meridian, by that side thereof that is parallel to the true Meridian line of the Clinatory, drawe a right line, for that shal be the Meridian line desired.

4 In erect flats the Meridian line is perpendicu∣lar, and therefore laying the Clinatory close to

such a flat in such sort that the plumbline hang pre∣cisely* 1.2 on either side of the quadrant, a line drawne by the side of the clinatory, parallel to that side of the quadrant, shall be the meridian line.

5 In direct flats, a line perpendicular to the line* 1.3 aequidistant from the Horizon, is the Meridian line we seeke for.

6 In flats reclining or inclining, declining also* 1.4 90. degrees (which are commonly called, East, or West reclining or inclining) the meridian line is parallel to the horizon.

[illustration]

7 For alother* 1.5 inclining or reclining, & withall de∣clining flats, drawe a line vpon some pastbord or paper which shall bee cal∣led the hori∣zontal me∣ridian AB. wherein set∣tingone foot of your cō∣passes, with the other draw an arch of a circle; & therin reckon the complement of the

declination FC. drawing a right line BC. by the end thereof out of the center B. This right line you shall crosse squire-wise with another as AC. which may be called the base of inclination or re∣clination, and must also meet with the horizontall meridian at A. and setting one foot of your com∣passes in the crossing at C. with the other foote draw an arke, counting therein the complement of the reclination or inclination AG. drawing a right line by the end therof, out of the center of the fore∣said ark CGD. & from A erect AD. perpendicular to AC. which may meet with CGD. the line of re∣clination or inclination at D. Also from A. draw the line AF. perpendicular to the horozontal meridian, AB. in the point A. and equal to the former perpen∣dicular AD. and from the end therof draw a line to (the center of the arke of declination) B. Then con∣tinuing foorth AC. to N. (that CN. be equall to CD) from N. you shall draw a line to B. which (if you haue wrought truely) must be equall to BE. Now the angle contained betweene the lines NB. and BC. sheweth how much the Meridian line in your Diall ground should be distant from the line which you drew aequidistant to the Horizon heere represented by BC. In this line therefore (in the Dial ground) set one foote of your compasses, and extending the other that way which the Diall de∣clineth, drawe an arke of a circle, vpwards in recli∣ners, but downewards in incliners: and therein count the said angle from the line parallel to the Horizon, and drawe by the end thereof a line,

which shall bee the true Meridian in the Dial ground.

[illustration]

8 From* 1.6 A draw AH perpendicu∣lar to EB. make BI. e∣qual to BH. from I. let IK be drawn perpendicu∣lar to BN. make CL. equal to CK and drawe a line from L to A. of these three lines AH. IK. and LA. make the triangle AHM. for then the angle AHM. is the angle which the dial ground maketh with the plain of the meridian.

Notes

• * 1.1

  How to drawe the Meridian line, in Hori∣zontall flats.
• * 1.2

  In erect flats.
• * 1.3

  In direct flats.
• * 1.4

  In reclining or inclining flats, declining 90. degrees.
• * 1.5

  In incl••ning or reclining flats declining lesse then 90. de∣grees.
• * 1.6

  To finde the angle which the dial ground (or flat) maketh with the plaine of the meridi∣an.