Bookend Manufacturer

Bookend

A bookend is an object that is designed to buttress, or support, an upright row of books. It is placed on either end to prevent books from falling over, such as in a half-filled bookshelf. Bookends are both utilitarian and, often, decorative. They are common in libraries and in homes. Heavy bookends have been used for centuries; the simple sheetmetal bookend was originally patented in the 1876 by William Stebbins Barnard,^[1] and uses the weight of the books themselves to make an anchor.

Bookends can be an important consideration in home decor. Some bookends are made of bronze, marble, wood and even large geodes. Elaborate and decorative bookends are not uncommon. In libraries, simple metal brackets are often used to support the end of a row of books.

 

 

Wooden Ship wheel

Ship's wheel

A ship's wheel is used to change its course. Together with the rest of the steering mechanism it forms part of the helm. It is typically connected to a mechanical, electric servo, or hydraulic system. In some modern ships the wheel is replaced with a simple toggle that remotely controls an electro-mechanical or electro-hydraulic drive for the rudder, with a rudder position indicator presenting feedback to the helmsman.

Helmsmen on older ships used a tiller (a horizontal bar fitted directly to the top of the rudder post) or a whipstaff (a vertical stick acting on a tiller).

Early ships' wheels (c. 1700) were operated to correspond to the motion                                          of The design of ships' wheels probably influenced that of the modern steering wheel.

the tiller, with a clockwise motion (corresponding to a right tiller motion) turning the rudder and thus the ship to the left. Eventually the control direction of the wheel was reversed to make it more consistent with the action of a motor vehicle's steering wheel.

A traditional ship's wheel is composed of eight cylindrical wooden spokes (though sometimes as few as six or as many as ten) shaped like balustersand all joined at a central wooden hub or nave (sometimes covered with a brass nave plate) which housed the axle. The square hole at the centre of the hub through which the axle ran is called a drive square and was often lined with a brass plate (and therefore called a brass boss, though this term was used more often to refer to a brass hub and nave plate) which was frequently etched with the name of the wheel's manufacturer. The outer rim is composed of four sections each made up of stacks of three felloes, the facing felloe, the middle felloe, and the after felloe. Because each group of three felloes at one time made up a quarter of the distance around the rim, the entire outer wooden wheel was sometimes called the quadrant. Each spoke ran through the middle felloe creating a series of handles on the outside of the wheel's rim. One of these handles/ spokes was frequently given extra grooves at its tip which could be felt by a helmsman steering in the dark and used by him to determine the exact position of the rudder—this was theking spoke and when it pointed straight upward the rudder was dead straight. The wood used in construction of this type of wheel was most often eitherteak or mahogany.

The steering gear of earlier ships sometimes consisted of a double wheel where each wheel was connected to the other with a wooden spindle that ran through a barrel or drum. The spindle was held up by two pedestals that rested on a wooden platform, often no more than a grate. A tiller rope or chain (sometimes called a steering rope or chain) ran around the barrel in five or six loops and then down through two tiller rope slots at the top of the platform before connecting to two sheaves just below deck (one on either side of the ship's wheel) and thence out to a pair of pulleys before coming back together at the tiller and therefore the ships rudder. Movement of the wheels (which were connected and moved simultaneously) caused the tiller rope to wind in one of two directions and shifted the tiller left or right. In a typical and intuitive arrangement, a helmsman turning the wheel counterclockwise would cause the tiller to move to starboard and therefore the rudder to swing to port causing the vessel to also turn to port.

Nautical Compass - Maximus International - www.replicartz.com

Compass

A compass is a navigational instrument that shows directions in a frame of reference that is stationary relative to the surface of the Earth. The frame of reference defines the four cardinal directions (or points) – north, south, east, and west. Intermediate directions are also defined. Usually, a diagram called a compass rose, which shows the directions (with their names usually abbreviated to initials), is marked on the compass. When the compass is in use, the rose is aligned with the real directions in the frame of reference, so, for example, the "N" mark on the rose really points to the north. Frequently, in addition to the rose or sometimes instead of it, angle markings in degrees are shown on

the compass. North corresponds to zero degrees, and the angles increase clockwise, so east is 90 degrees, south is 180, and west is 270. These numbers allow the compass to showazimuths or bearings, which are commonly stated in this notation.

The magnetic compass was first invented as a device for divination as early as the Chinese Han Dynasty (since about 206 BC). The compass was used in Song Dynasty China by the military for navigational orienteering by 1040-1044, and was used for maritime navigation by 1111 to 1117.The use of a compass is,This was supplanted in the early 20th century by the liquid-filled magnetic compass.

recorded in Western Europe between 1187 and 1202, and in Persia in 1232.The dry compass was invented in Europe around 1300.

Types of compasses

There are two widely used and radically different types of compass. The magnetic compass contains a magnet earth's magnetic field and aligns itself to point to the magnetic poles.^[14] Simple compasses of this type show directions in a frame of reference in which the directions of the magnetic poles are due north and south. These directions are called magnetic north and magnetic south. The gyro compass (sometimes spelled with a hyphen, or as one word) contains a rapidly spinning wheel whose rotation interacts dynamically with the rotation of the earth so as to make the wheel precess, losing energy to friction until its axis of rotation is parallel with the earth's. The wheel's axis therefore points to the earth's rotational poles, and a frame of reference is used in which the directions of the rotational poles are due north and south. These directions are called true north andtrue south, respectively. The astrocompass works by observing the direction of stars and other celestial bodies.                                                                           

There are other devices which are not conventionally called compasses but which do allow the true cardinal directions to be determined. Some GPSreceivers have two or three antennas, fixed some distance apart to the structure of a vehicle, usually an aircraft or ship. The exact latitudes and longitudes of the antennas can be determined simultaneously, which allows the directions of the cardinal points to be calculated relative to the heading of the aircraft (the direction in which its nose is pointing), rather than to its direction of movement, which will be different if there is a crosswind. They are said to work "like a compass", or "as a compass".

Even a GPS device or similar can be used as compass, since if the receiver is being moved, even at walking pace, it can follow the change of its position, and hence determine the compass bearing of its direction of movement, and hence the directions of the cardinal points relative to its direction of movement. A much older example was the Chinese south-pointing chariot, which worked like a compass by directional dead reckoning. It was initialized by hand, possibly using astronomical observations e.g. of the Pole Star, and thenceforth counteracted every turn that was made to keep its pointer aiming in the desired direction, usually to the south. Watches and sundials can also be used to find compass directions. See their articles for details.

A recent development is the electronic compass which detects the direction without potentially fallible moving parts. This may use a fibre optic gyrocompass or a magnetometer. The magnetometer frequently appears as an optional subsystem built into hand-held GPS receivers and mobile phones. However, magnetic compasses remain popular, especially in remote areas, as they are relatively inexpensive, durable, and require no power supply.

Magnetic compass

The magnetic compass consists of a magnetized pointer (usually marked on the North end) free to align itself with Earth's magnetic field. A compass is any magnetically sensitive device capable of indicating the direction of the magnetic north of a planet's magnetosphere. The face of the compass generally highlights the cardinal points of north, south, east and west. Often, compasses are built as a stand alone sealed instrument with a magnetized bar or needle turning freely upon a pivot, or moving in a fluid, thus able to point in a northerly and southerly direction.

The compass greatly improved the safety and efficiency of travel,

especially ocean travel. A compass can be used to calculate heading, used with a sextant to calculate latitude, and with a marine chronometer to calculate longitude. It thus provides a much improved navigational capability that has only been recently supplanted by modern devices such as the Global Positioning System(GPS).

Porthole - Maximus International - www.replicartz.com - nautical gift manufacturer

Porthole

Maximus International - www.replicartz.com

A porthole is a generally circular window used on the hull of ships to admit light and air. Though the term is of obvious maritime origin, it is also used to describe round windows on armored vehicles, aircraft, automobiles (the Ford Thunderbird a notable example) and even spacecraft.

On a ship, the function of a porthole, when open, is to permit light and fresh air to enter the dark and often damp below-deck quarters of the vessel. It also affords below-deck occupants a limited, but often much needed view to the outside world. When closed, the porthole provides a strong water-tight, weather-tight and sometimes light-tight barrier.

A porthole on a ship may also be called a sidescuttle or side scuttle (side hole), as officially termed in the International ^[1] It is also used in related rules and regulations for the construction of ships.^[2] The use of the word "sidescuttle" instead of "porthole" is meant to be broad, including any covered or uncovered hole in the side of the vessel.

Convention for the Safety of Life at Sea. This term is used in the U.S. Code of Federal Regulations.

Structure

A porthole consists of at least two structural components and is, in its simplest form, similar to any other type of

window in design and purpose. The porthole is primarily a circular glass disk encased in a metal frame that is bolted securely into the side of a ship's hull. Sometimes the glass disk of a porthole is encased in a separate frame which is hinged onto the base frame so that it can be opened and closed. In addition, many portholes also have metal storm covers that can be securely fastened against the window when necessary. The main purpose of the storm cover is, as its name implies, to protect the window from heavy seas. It is also used to block light from entering lower berths when darkness is preferred. Storm covers are also used on Navy and merchant marine ships

to prevent interior light from escaping the ship's lower berths, and to provide protection from hostile fire. Hinged porthole windows and storm covers are accessible from inside the ship's hull, and are typically fastened to their closed positions by hand tightening several pivoting, threaded devices, commonly referred to as "dogs." Older portholes can be identified by the protruding collar of their base plate which may be up to several inches deep, thus accommodating the thickness of a wooden hull.

Portholes range in diameter from several inches to more than two feet, and weigh from several pounds to over one hundred pounds.

Much of the porthole's weight comes from its glass, which, on ships, can be as much as two inches thick. Metal components of a porthole are also typically very heavy; they are usually sand-cast and made of bronze, brass, steel, iron, or aluminium. Bronze and brass are most commonly used, favoured for their resistance to saltwater corrosion. The design of the porthole is such that it achieves its humble purposes without sacrificing the integrity of the ship's hull. The porthole's thick glass and rugged construction, tightly spaced fasteners, indeed even its round shape, all contribute to its purpose of maintaining hull strength and pressure of storm waves crashing against it.

Sextant history & use - Nautical sextant manufacturer

Sextant

Nautical Sextant Manufacturer

Nautical sextant manufacturer

A sextant is an instrument used to measure the angle between any two visible objects. Its primary use is to determine the angle between a celestial object and the horizon which is known as the object's altitude. Using this measurement is known as sighting the object, shooting the object, or taking a sight and it is an essential part of celestial navigation. The angle, and the time when it was measured, can be used to calculate a position line on a nautical or aeronautical chart. Common uses of the sextant include sighting the sun at solar noon and sighting Polaris at night (in the Northern Hemisphere), to find one's latitude. Sighting the height of a landmark can give a measure of distance off and, held horizontally, a sextant can measure angles between objects for a position ^[1] A sextant can also be used to measure the lunar distance between the moon and another celestial object (e.g., star, planet) in order to determine Greenwich time which is important because it can then be used to determine the longitude on a chart.The scale of a sextant has a length of ⅙ of a turn (60°); hence the sextant's name (sextāns, -antis is the Latin word for "one sixth"). An octant is a similar device with a shorter scale (⅛ turn, or 45°), where as a quintant (⅕ turn, or 72°) and a quadrant (¼ turn, or 90°) have longer scales.

Sir Isaac Newton (1643–1727) invented the principle of the doubly reflecting navigation instrument (a reflecting quadrant—see Octant (instrument)), but never published it. Two men independently developed the octant around 1730: John Hadley (1682–1744), an English mathematician, and Thomas Godfrey (1704–1749), a glazier in Philadelphia. John Bird made the first sextant in 1757. The octant and later the sextant, replaced the Davis quadrantas the main instrument for navigation.

Advantages

Nautical sextant manufacturer

Like the Davis quadrant (also called backstaff), the sextant allows celestial objects to be measured relative to the horizon, rather than relative to the instrument. This allows excellent precision. However, unlike the backstaff, the sextant allows direct observations of stars. This permits the use of the sextant at night when a backstaff is difficult to use. For solar observations, filters allow direct observation of the sun.

Since the measurement is relative to the horizon, the measuring pointer is a beam of light that reaches to the horizon. The measurement is thus limited by the angular accuracy of the instrument and not the sine error of the

length of an alidade, as it is in a mariner's astrolabe or similar older instrument.

A sextant does not require a completely steady aim, because it measures a relative angle. For example, when a sextant is used on a moving ship, the image of both horizon and celestial object will move around in the field of view. However, the relative position of the two images will remain steady, and as long as the user can determine when the celestial object touches the horizon the accuracy of the measurement will remain high compared to the magnitude of the movement.

Nautical sextant manufacturer

The sextant is not dependent upon electricity (unlike many forms of modern navigation) or anything human-controlled (like GPS satellites). For these reasons, it is considered an eminently practical back-up navigation tool for ships.