## Text-book on Navigation and Nautical Astronomy |

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### Common terms and phrases

altitude angle apparent August bearing bearing by compass causes centre chart chron circle coefficient comp compass correct correct magnetic cosec course declination deviation Diff difference direction dist distance draw Earth east effect equal equator error Example figure Find force given gives Greenwich heeling height of eye Hence horizon hour angle inch interval iron knots latitude longitude magnetic mean measured meridian method miles Moon Moon's needle noon object observed P.M. at ship parallel pass plane pole position represents right angles sailing scale September ship ship's head showed side slow standard star steering subtract Sun's Table taken tons triangle true variation vertical wind

### Popular passages

Page 299 - Northern hemisphere ; and what effect has it on the assumed position of the ship when she is steering on Northerly, and also on Southerly courses ? 17. The effect being as you state, on what courses would you keep away, and on what courses would you keep closer to the wind, in order to make good a given Compass course ? 18.

Page 371 - B sin 2A = 2 sin A cos A. cos 2A = cos2 A - sin2 A = 2 cos2 A - 1 = 1 - 2 sin2 A. 9 . 2 tan A ^T^tan^A' 2 tan A 1 - tan2 A sin 3 A = 3 sin A - 4 sin3 A.

Page 28 - The angle between the first and last directions of a ray which has suffered two reflections in one plane is equal to twice the inclination of the reflecting surfaces to each other. Let AB be the limb or graduated . arc, of a portion of a circle 60° in extent, but divided into 120 equal parts. On the radius CB let a silvered plane glass D be fixed, at right angles to the plane of the circle, and on the moveable radius CE let another such silvered glass, C, be fixed.

Page 44 - We have, then, that the sine of an angle is equal to the cosine of its complement, and conversely.

Page 297 - Certificate is to answer correctly at least eight of such of the following questions as are marked with a cross by the Examiner. The Examiner will not mark less than 12 : — . I 1.

Page 309 - If not, state the reason. 45. Given the heel, the direction of the ship's head by compass, and the heeling error observed, to find the approximate heeling error, with a greater or less given heel, and with the ship's head on some other named point of the compass, the ship's magnetic latitude being in both cases the same.

Page 211 - Supposing you have steered the following courses by the Standard Compass, find the correct magnetic courses made from the above deviation table.

Page 249 - ... distance, to obtain the approximate Greenwich mean time corresponding to the given distance. If the distance between the Moon and a Star increased or decreased uniformly, the Greenwich...

Page 27 - How is it to be applied ? 10 Place the index at error of minutes to be added, clamp it, and leave it. (NOTE. — The examiner will see that it is correct.) 11 The examiner will then place the zero of the vernier on the arc, not near any of the marked divisions, and the candidate will read it. NOTE. — In all cases the applicants will name or otherwise point out the screws used in the various adjustments.

Page 278 - This may be summed up by saying that like poles repel each other and unlike poles attract each other.