Astronomia Britannica exhibiting the doctrine of the sphere, and theory of the planets decimally by trigonometry, and by tables : fitted for the meridian of London ... / by John Newton ...

CHAP. 29. To find the Parallaxes of Longitude and Latitude.

BY the rules delivered in the former part, find at the true Conjucti∣on the Midheaven, with its altitude and the Meridian angle.

Example.

The Suns place

♈ 19. 246

The Suns Right Ascension

17. 749

Time in Degrees

329. 391

Right Ascension of Midheaven

347. 140

Midheaven

♓ 16. 022

Meridian angle

67, 078

Declination of Midheaven

5. 533

Altitude of the Equator at London

38. 467

Altitude of Midheaven

32. 834

2 The angle of the Ecliptique and Horizon, or altitude of the Nona∣gesime degree, and his distance from the Midheaven is thus found, by the 17 Chapter of the first part.

As the Radius

To the sine of the Meridian angle	67. 07	9. 9642509
So is Cosine of the Altitude of M C	32. 83	9. 9244255
To the Cosine of the Angle, &c.	39. 30	9. 8886764

Then as Radius

To the Cosine of the Meridian angle	67. 07	9. 5906259
So is cotang. of the altitude of the M. C.	32. 83	10. 1903074
To the tang. of the distance of the M. C. from the Nonagesime degree	16. 02	9. 7809333
This M C falling betweene Capricorn and Cancer this distance is to be added to the Midheaven		♓ 16. 02
And the Nonagesime degree will be in		♈ 17. 14

3 Find the Node Ascendent and Subtract it from the Nonagesime de∣gree, with the remainder enter the Table of the Moones latitude, which if North adde to the angle of the Ecliptique and Horizon; if South sub∣tract it from it, so have you the altitude of the Nonagesime degree of the Moones orbe.

Example.

The Node Ascendent Subt.

10. 439

The Nonagesime degree

17. 140

There rests

6. 701

Which gives the Moones Latitude Adde

. 570

The angle of the Ecliptick and Horizon

39. 300

Altitude of the Nonagesime degree of the Moones orbe

39. 870

4 Take the distance of the S••n from the Nonagesime degree, which in our Example of the true Conj••ction is •• d. 10.

5 Out of the table of Horizontall parallaxes, take the Horizontall Pa∣rallax of the Sun and Moon, the difference of them is the Horizantall pa∣rallax of the Moon from the Sun.

Example.

The Horizontall parallax of the Sun is

. 03912

The Horizontall parallax of the Moon

. 99396

Horizontall parallax of the Moon from the Sun

. 95484

6 Adde the Logarithme of the Horizontall parallax of the Moon from the Sun, the sine of the Altitude of the Moones orbe, and the sine of the distance of the Sun from the Nonagesime, their summe subtracting twice Radius, is the Logarithme of the parallax of longitude.

Example.

Horizontall parallax of the Moon from the Sun	95484	1. 9799306
Altitude of Nonagesime in the Moones orbe, sine	39. 87	9. 8068904
Distance of the Sun from the Nonagesime, sine	2. 10	8. 5639994
Parallax of longitude 02243		2. 3508204

Here note that whensoever the Suns place is lesse then the Nonage∣sime degree, the Parallax of Longitude, makes the luminaries appeare more west than the truth, and in the occidentall Quadrant, when more then in the orientall.

7 Adde the Logarithme of the Horizontall parallax of the Moon from the Sun to the Cosine of the Nonagesime in the Moones orb; the summe rejecting Radius is the Logarithme of the parallax of Latitude.

Example.

Horizontall parrallax of the Moon from the Sun	95484	1. 979930••
Altitude of Nonag. in the Moones orb, Cos••ne	39. 87	9. 8850789
Parallax of latitude	0. 73284	1. 8650095