The newe attractiue Containyng a short discourse of the magnes or lodestone, and amongest other his vertues, of a newe discouered secret and subtill propertie, concerning the declinyng of the needle, touched therewith under the plaine of the horizon. Now first founde out by Robert Norman hydrographer. Heerevnto are annexed certaine necessarie rules for the art of nauigation by the same R.N.

¶ How to finde the variation of the Needle or Cumpas at any place, the eleuation of the Pole, and situation of the meridian vnknowne. (Book 3)

¶ The third Chapter. (Book 3)

WHen you would obserue the variation in any place, you must begin in y^e fornoone, the sooner, the better, and the more effec∣tuall maie your obseruatiōs be, do thus.

Take your Astrolabe and obserue du∣ly the height of the Sūne, for yourmore ease it shall bee best for you to note the same, when it agreeth to be iust vppon a degree, without any consideration of minuts or fractions, and at the instant of the same height, turne your Instrument to the Sunne, so as the shadowe of the lines maie fall iustly vppon the line of South and North in the fixed Flye.

Then, when the Needle doeth stande, looke directly ouer the North poinct of the Needle, what degree and fraction, if there be any, doth aunswere vnto the same in the fixed Flye, that is to saie, how many degrees it is from the North of the fixed Flye, which you shall note diligently, and may saie, that so many degrees &c. is the variation of the Sunnes shadowe from the North, as the North poinct of the Flye is from the North poinct of the Needle, either Eastwardes or West∣wardes as you shall finde the same. Thus maie you obserue diuers tymes, vpon seuerall degrees of the Sunnes eleuati∣on. And like as you doe in the fornoone, so must you also ob∣serue

the Sunnes eleuation in the afternoone, vpon the same degree of height, and with the same side of the Astrolabe and Index turned towards the Sunne, as it was in the fornoone, (for auoydyng of error that maie bee in the Instrument) no∣tyng at euery height what you finde the variation. And when the Sunne commeth to the meridian, it shall be good that you exactly obserue his eleuation vpon the same, for knowyng the true Latitude of the place: all whiche you shall set downe in forme followyng.

¶ Example.

¶ In Limehouse the sixteenth of October. Anno. 1580.

Fornoone.	Fornoone.	Afternoone.	Afternoone.	Afternoone.
Eleuation of the Sunne.	Variation of the shadow from the North of the Needle of the Needle to the Westwardes.	Eleuation of the Sunne.	Variation of the shadow from the North of the Needle to the Eastwards.	Variation of the Needle from the Pole or Axis.
Deg.	Degr. Min.	Deg.	D. M.	D. M.
17	52 35	17	30 0	11 17½
18	50 8	18	27 45	11 11 ½
19	47 30	19	24 30	11 30
20	45 0	20	22 15	11 22 ½
21	42 15	21	19 30	11 22 ½
22	38 0	22	15 30	11 15
23	34 40	23	12 0	11 20
24	29 35	24	7 0	11 17
25	22 20	25	Frō N. to w. 0. 8	11 14

The eleuation of the Sunne vppon the meridian 25. d. 58′. the declination 12. d. 30′. whiche I adde to the eleuation, be∣cause the Sunne hath South declination, and thereof amoun∣teth 38. d. 28′. the eleuation of the Equinoctiall, the whiche I subtract from 90. d. the rest is 51. d. 32′. the eleuation of the Pole Artik.

Now are you to consider, that out of the greater variaria∣tion of shadow vpon any degree of the Sunnes eleuation, is to be taken the lesser of the same degrees eleuation, whether it bee in the fornoone or afternoone, (except the same variati∣ons be bothe one waie from the North of the Needle, whiche then are to be added) the halfe of the remayner is the variation of the Needle or Cumpas from the Pole or true meridian.

In the former obseruations, I do finde the greatest varia∣tion in the fornoone, for, at 17. d. eleuation, the variation is 52. d. 35′. from North to West: And at the same eleuation in the afternoone. I finde the variation to be but 30. d. 0′. frō North to East. I take the lesser out of the greater and finde remay∣ning 22. d. 35′. the half thereof is 11. d. 17′. ½. So much I say is the Pole Artik, and true meridian line that passeth to the Pole by our Zenith at London, to the Westwardes of the North that the Needle sheweth. And therefore the Needle or Cumpas varieth from the true Northe 11. d. 17′. ½. to the Eastwardes.

Also at 25. d. eleuation in the fornoone the variation is 22. d. 20′. from North to West: at the same eleuation in the af∣ternoone the variation is 0. d. 8′. from North to West. Now because the variations are both one way, (that is to the West∣wardes) I adde them together (and so ought you to doe as of∣ten as you finde the variations so to agree) and I finde that they amount to 22. d. 28′. the half thereof is 11. d. 14′. which is the variation.

The variations of the Needle or Cumpas by the former obseruations, are set out towardes the right hand against eue∣ry degrees eleuation; and conferryng them all together, I do finde the true variation of the Needle or Cumpas at Lyme∣house

to be about 11. d. ¼. or 11. d. ⅓. whiche is a poinct of the Cumpas iust or little more. So that in a Cumpas whose wi∣ers are set directly vnder the flowre de Luce, the North and by West, and South and by East poincts doe shewe the true meridian.