Twilight.-The Twilight is that duration of light which is apparent in the absence of the sun. It generally continues whilst he is traversing about 18 degrees below the horizon. It is caused by the column of atmosphere which surrounds the earth receiving the rays, or light, of the sun, and from which that light is transmitted to those parts of the surface of the globe opposite the sun at its rising and setting. Vertical Circles.-Vertical Circles are circles (supposed to be described in the heavens) perpendicular to the horizon, and meeting at the Zenith. They are sometimes called circles of altitudes, circles of azimuths, and prime vertical circles. Zenith and Nadir.-The Zenith is that point in the heavens which is directly over the observer's head; and the Nadir that which is opposite to it. Zenith Distance.-The Zenith Distance of a celestial object is equal to that portion of the vertical circle which is intercepted between the centre of the object and the observer's zenith. It is always equal to the complement of the altitude to a quadrant, or 90 degrees. EXPLANATION OF COMPASS TERMS. Variation of the Compass is the angle between the True North and the Magnetic North. This difference or error arises from the Magnetic Poles not coinciding with the Terrestrial ones, and is due entirely to the influence of the earth on Magnetic Needles, which is the same at few parts of the world. Deviation of the Compass is the angle included between the Magnetic North and the Compass North. This error is due to the disturbing influences of the iron of which the ship is built, as rudderposts, masts, chains, funnel, &c. ; her position when building, her cargo, or other causes within the ship. Local Attraction is the error caused by some disturbing force outside the ship, and belonging entirely to the locality at which a ship may be as mooring posts or chains, dock cranes, another iron vessel alongside, volcanic or magnetic influences, &c. Heeling Error is the effect produced on the Compass by the heeling of an iron or composite ship, the angle increasing with the amount of Heel. Leeway is the angle between the ship's course by Compass and the direction which she makes through the water, as shown by her wake. Compass Course is the course steered by ship's Compass. Magnetic Course is the Compass Course corrected for Deviation and Leeway. The True Course of a Ship is the Compass Course corrected for Deviation, Leeway, and Variation. EXPLANATION OF ASTRONOMICAL CHARACTERS. The Sun. The Moon. Mercury. ¿ Venus. The Earth. & Mars. 8 Ascending Node. ? Ceres. & Descending Node, SIGNS OF THE ZODIAC, &c. Aries (the Ram), 0° 8 Taurus (the Bull), 30° II Gemini (the Twins), 60° Cancer (the Crab), 90° Leo (the Lion), 120° my Virgo (the Virgin), 150° Libra (the Balance), 180° m Scorpio (the Scorpion), 210° Sagittarius (the Archer), 240° Capricornus (the Goat), 270° Aquarius (the Waterbearer), * Pisces (the Fishes), 330° [300° * Sextile, when two signs distant, or differing 60° in Longitude or Rt. Ascension. Quartile, when three signs distant, or differing 90° in Longitude or Rt. Ascension. Opposition, when six signs distant, or differing 180 in Longitude or Rt. Ascension. 8 N. North. O Mins. of Arc. " h. Secs. of Arc. m. Mins. of Time Degrees. S. Secs. of Time. 6 Conjunction, in the same degree or sign, or having the same Longitude or Rt. Ascn. TERMS AND ABBREVIATIONS USED IN SHIPPING. A/c.-Account. E. E.-Errors excepted. E.&O.E.-Errors and omissions excepted. F.O.B. Free on board. F.P.A.-Free of particular average. D/S.-Days after sight. %-Per cent. @-At, to. -Per. Ad valorem.-According to value. B/L.-Bill of Lading. Adjustment. The settlement of a loss incurred by the insured. Adventure.-Goods consigned to a party to be made the most of. Agio.-The Premium borne by a better sort of money above an inferior. Appraise. To value goods imported. Assets-A term for property and money in contradistinction to liabilities. Assurance.-See Insurance. Average.—A sacrifice made to prevent the total loss of a ship or cargo; an average of the loss insured for the benefit of all concerned, to be made good proportionately. Award.--The decision in arbitration. Banco.-A continental term for bank money at Hamburg and other places. Barratry.-A fraudulent act on the part of the master or crew of a vessel, against the interest of the owners. Insurances are effected against barratry. Bill of Health.-A certificate granted by Consuls and Customs Officers as to health of port. Bill of Lading.-A master's acknowledgment and undertaking as to receipt and delivery of goods or cargo. Bottomry.-Money borrowed on a ship's bottom or hull, to be repaid with interest if the ship return in safety, but if not to be lost or forfeited. Sometimes it is raised on the lading and master's personal security; see Respondentia. Brokerage.-The commission charged by merchants and brokers for securing and transacting business for ships. Charter Party.-A contract with the owner, agent, or master for the service of his vessel. Consul.-The commercial representative of one country residing officially in another, Credit, Letter of.-A letter written by one party to another, requesting the party addressed to advance the bearer or person named a certain sum of money. Days of Grace.-Days allowed by law or custom for payment of Bills of Exchange (except those payable at sight or on demand) after specified day of payment; thus, when three days are allowed, as usual in England, a bill due on the 5th of the month is payable on the 8th. Dead Freight. The damage payable by one who engages to load a ship fully, and fails so to do. Debenture.-An instrument of the nature of a bill or bond, by which a debt is claimable. May bear interest or confer some peculiar advantage. It is given at the Custom House to claim a drawback. Derelict.-Goods cast away or relinquished by wreck or otherwise. Reductions in duty are also made proportionate to the damage on them. Deviation is a divergence from the voyage insured which may release the underwriter from his risk. Drawback.-An allowance granted by Government to encourage exportation of an article, or a return of duties paid upon certain articles on exportation. Discount.-An allowance made for money paid before it is due. To discount a Bill is to buy from the holder the right to receive the money upon it when due. Dunnage.-Articles used in stowing a cargo or trimming a ship. Embargo.-An order issued by Government to prevent vessels sailing. Flotsam.-Goods floating after a wreck. Jetsam are those sunk. Lagan are those sunk but secured by a buoy. Groundage.-Money paid in some parts for permission to anchor. Insurance.-A contract whereby, for a stipulated consideration, called a premium, one party undertakes to indemnify the other against certain risks. Invoice.-A document enumerating goods sold from A to B. Where the goods are exported by A to be sold on his own account, the document is a specification, and not, strictly speaking, an invoice. Lay Days.-Days allowed by charter for loading or unloading ships. Lighterage. The expense of a lighter or barge. Manifest.-The specification of a cargo made out and signed by the master of a ship. Policy.-A document containing the contract of insurance. A Valued Policy is when the interest insured is valued. An Open Policy is one in which the amount is left for subsequent proof. In an open policy, where the value shipped does not equal the value insured, the difference is termed over insurance; and the proportionate amount of premium returnable to the insurer is called a return for short interest. Frimage.-A small allowance for the shipmaster's care of goods now generally included in the freight. Pro rata.-Payment in proportion to the interests concerned. Respondentia.-A contract of loan by which goods in a ship ar hypothecated to the lender, as in bottomry. Super Cargo. A person sent with a vessel to dispose of its cargo to the best advantage. EDUCATIONAL STANDARD REQUIRED BY VARIOUS MARITIME POWERS FOR MASTERS AND MATES. In its pure state air is composed as follows: Yes. No. The percentage of oxygen varies as follows:- Sea-shore Confined Houses.. 100 21 per cent. Each 20'50 do. 20'75 do. Air travels in England in healthy years at the rate of about 4 miles per hour, and in unhealthy years about 3 miles per hour. adult inhales a gallon of air per minute, and consumes daily 30 oz. of oxygen. For the conversion of this oxygen a certain amount of food is required-say 13 oz. of carbon for a male and 11 oz. for a female-equivalent to 3lb. and 24lb. of bread respectively. Figures to denote THE POWER OF THE WIND. FORMULA FOR RECORDING STATE OF THE WEATHER. B denotes Blue Sky, i.e. clear or u denotes Ugly, with a heavy hazy atmosphere. Lightning. Misty or Hazy-so as W appearance of the Visibility of distant . Dot under any letter, an extra- By the combination of these letters all the ordinary phenomena of the weather may be recorded with certainty and brevity. BCM-Blue sky, with detached opening clouds, but hazy round the horizon. Rain-continuous rain. GV-Gloomy dark weather, but Q Squally. Snow. Thunder. T distant objects remarkably visible. USE OF INSTRUMENTS IN FORETELLING In other Latitudes substitute South or Southward for North, &c. Much inequality of atmospheric pressure or temperature, great depression or elevation of the barometer, sudden or rapid alternations, great falls of rain or snow-indicate more or less change, more or less wind, with its usual accompaniments, either in some places only, or throughout an extensive area of hundreds of miles, if not thousands. Speaking generally, there is far less occasion to give warning of southerly storms by signal than of northerly, because those from the southward are preceded by notable signs in the atmosphere, by a falling barometer, and by a temperature higher than usual to the season; whereas, on the contrary, dangerous storms from a polar quarter (N. W. to N. E.) are sometimes sudden, and usually are preceded by a rising barometer, which is often misleading, especially when accompanied by a temporary lull, of perhaps a day or two, with an appearance of fine weather. |