The Description of the Horological Ring-Dyall, which showeth the Hour of the Day in any part of the World.  
IT is projected our of two great Circles of the Sphere, An Axis, and a little Ring to hang it by. The greater Circle is the Meridian; one quadrant or quarter of it is divided into 90. degrees, to set it to the Latitude of the place wherein you are: On the other side of this Meridian, is a quadrant of Altitude, to take the height of the Sun, whereby you may find the Latitude.  
The lesser Circle, is the Aequinoctial, divided into 24. equal parts or hours. with their halfs and quarters; which are numbered but from III. in the morning, to IX. at night: the rest of the hours are left out, being seldom or never used.  
The Diameter, or broad Plate, hath a slit in the middle; and upon one side are the Months and Days of the year graduated to every fifty Day. On the other side is the Declination of the Sun, from the Aequinoctial to every fifth Day, which is to be used with the Quadrant of Altitude, to find the Latitude of the place. The little Ring is made to slide along the Quadrant, with a small tooth to set it to the Latitude; which if you know not, you may find it in this manner.  

1. EXAMPLE.  
Suppose the Latitude were unknown to you, and you would find it out yourself, admit on the 11th of June, you must by the former Rule find the Declination of the Sun for that day, which will be 23. degrees and a half, or 30. minutes Northwards; then take the height of the Sun at 12. a clock, which near about London, will be 62. degrees; subtract the Declination 23. degrees 30. minutes, out of 62. gr. and the remainder will be 38. degrees 30. minutes, the height of the Aequinoctial; take this 38. gr. 30. from 90. degrees, the remainder will be 51. deg. 30. min. the Latitude at London.  
Now if you observe in the Winter half-year, viz. from the 13th of September, to the 10th of March, than you must add your two sums together; and the sum taken out of 90. gr. will be the Latitude, as before.   

2. EXAMPLE.  
Admit the 10th of December, the Sun's Declination will be 23. gr. 30. Southward, the Meridian Altitude 15. gr. add these two sums together, which make 38. gr. 30. min. the height of the Aequinoctial; which being substracted from 90. gr. leaves 51. gr. 30. min. as before.  

How to find the Hour of the Day.  
You must set the tooth to the height of the Pole or Latitude, and the Hole in the Plate you must slide to the day of the Month; then draw out the Aequinoctial, or lesser Circle, and as near as you can, guess at the hour, and turn the hole to it; then hold the Instrument by the little Ring, and move it, till the Sun shine through the Hole upon the middle line in the Aequinoctial, that is the Hour of the Day: And the Meridian, as it hangeth, she weth the true South and North parts of the World.   

How to find the Elevation of the Pole, or Latitude of the Place.  
First set the Hole in the moving piece, to the day of the Month; then turn the other side, and against the hole you shall find the Sun's Decliration for that day. The same day you must take the Meridian Altitude of the Sun, which will be at twelve a clock every day, and may be performed by this Instrument thus: Put a Pin into the Hole, which you shall find in the Greatest Circle; then move the tooth to the beginning of the degrees in the lesser Quadrant, and turn the pin next to the Sun: and that degree which is cut by the shadow of the pin, is the height of the Sun.  
If the time of your observation be from the 10th of March, to the 13th of September, you must subtract the Declination out of the Altitude, and the remainder is the height of the Aequinoctial; which number being taken out of 93. degrees, showeth the Latitude of the place.    

Note that this Dyal, or any other Instrument for the Mathematics, are made by Walter Hayes, at the Cross-daggers in Moorfields, next door to the Popes-head Tavern, London.