Much more than documents.
Mostly I use three semitransparent glasses. That gives eight images bris the sun. Mini bright from the dubble sextant and five more not of the same brightnes. Sometimes I make sextants with four glasses.
That gives a lot more images. Sometimes I buy beamspitters from Edmond Scientific, then just two glasses gives sextant of images becouse then sextant are not only dubble and quadruplereflections but many of even higher order. There is relations betwen the images.
Those are the bright images. Those reflections are less bright. There is a general formula for any mini of glasses and reflections.
Some landlubbers dont understand that the Sextant sextant can be accurat without an telescop. I have made bris of observations from small sextant with good Plath sextants, usually my position lines gives an triangle about three miles mini. If the weather is very calm and if am lucky I can get them to lie within one mile. In stormy weather Im satisfied if I bris get my position to within ten miles.
Bris I was rounding the Horn in June in the middle sextant the bris in my 19 footer from east bris west, I could not get better than thirty miles accuracy, but then mini weather was rugh it was cold and if I remember right mini the sun did not rise higher than 11 degres at noon.
With the Mini Horn current occasionaly running up to four knots navigation was not easy. In fact sextant was my biggest problem. On the outher hand standing on the beach with my Mini sextant I am often able to get a position line within a tenth of a mile, on rare occasions I have been sextant to repeat that three times one after the mini.
Even the best sextants dont have telescopes with higher magnification than three or four times, the reason is even on a big ship its to difficult bris hold the instrumenst stedy. The Bris sextant on the outher bris is so light that you can attatch mini to your glasses. Than the images becomes dead stedy. Also with sextant hands free you got one hand for your writing and one for yourself. My sextant is not bigger than a nail and weighs only 3 grams about a tenth of an onze.
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The Bris is, however, a true reflecting instrument which derives its high accuracy from the same principle of double reflection which is fundamental mini the octant, the sextant sextant, mii other reflecting instruments, it differs from other sextants primarily in being a fixed angle sextant, capable of measuring a few specific angles. Sven Yrvind Lundin developed his Bris sextant as part of his quest for low-cost, low-technology equipment for ocean crossings.
The Bris is a low-technology, high-precision, fixed-interval instrument, it is made of two sextant, flat pieces of glass microscope slides permanently and rigidly mounted in a V-shape to a third flat piece of 12 welding glass to make viewing the sun eye safe.
The Bris sextant is calibrated at a known geographic position with a good clock and a nautical almanac ; as the day passes, one works the sight reductions backwards to develop exact angles for each of the images' tops and bottoms. The Sun and Moon have approximately the same angular size from the surface of the Earthand can use the same calibrations. In use, one waits until an image's edge touches the horizon, and then records the time and reduces the sight using the recorded angle for that edge of the image.
Bris is Swedish for breezeit would appear that the name Bris is used by Yrvind for a number of his sail boats and is a favourite of his. It has an aspect ratio ofa diagonal measurement of 43 miin, sextant has been employed in countless photographic applications including single-lens reflex cameras, rangefinder cameras, mirrorless interchangeable-lens digital cameras, digital SLRs, point-and-shoot film cameras, disposable film cameras.
The format originated with his introduction of the Leica camera in the s, bris it is sometimes called the Leica Barnack format. The name 35 mm originates with the total width of the film, the perforated cartridge film, the primary medium of the format prior to the invention of the full frame DSLR ; the term format remains in use. In digital photography, the format has come to be known sextant full frame, FF or FX, the latter invented as a trade mark of Nikon ; the 35 mm format was sometimes called miniature format or small format, terms meant to distinguish it from medium format and large format.
The term 35 mm camera refers to a still photographic film camera which uses the 35 mm format on film; such cameras have been produced by Leica, Argus, Canon, Olympus, PentaxCarl Zeiss and numerous other companies. Many digital image sensors approximate the dimensions of the 35 mm format, sometimes differing by fractions of a millimeter on one or both dimensions.
SinceNikon has referred to their 35 mm format by the trade mark FX. Other makers of 35 mm format digital cameras, including Leica and Canon, refer to their 35 mm sensors as full frame. A true normal lens for 35 mm format would have a focal length of 43 mm, the diagonal measurement of the format.
However, lenses of 43 mm to 60 mm are considered normal lenses for the format, in mass production and popular use. Common focal lengths of lenses made for the format include 24, 28, 35, 50, 85,mm. Most a 50 mm lens is the one considered normal, any lens shorter than this is considered a wide angle lens and anything above is considered a telephoto lens.
Wide angles shorter than 24 mm is called an extreme wide angle. Lenses above 50 mm but up bris about mm are called short telephoto or sometimes, as portrait telephotos, from mm to about mm are called medium telephotos, above mm are mini long telephotos.
Many photographers think about angle of view in terms of 35 mm format lenses, due to the historic prevalence of the 35 mm format. For example, a photographer might associate a 50 mm focal length with a normal perspective, because a 50 mm lens sextanf that perspective on this format.
With many smaller formats now common, lenses may be advertised or marked with their "35 mm equivalent" or " full-frame equivalent" focal length as a mnemonic.
This'equivalent' is computed by multiplying bris true focal length of the lens by the ratio of the diagonal measurement of the native format to that of the 35 mm format. For example, a lens for APS-C format with a focal length of 40 mm, might be described as "60 mm. Reflecting instrument Reflecting instruments are those that use mirrors to enhance their ability to make measurements.
In particular, the use of mirrors permits one to observe two objects while measuring the angular distance between the objects. While reflecting instruments are used in many professions, they are associated with celestial navigation as the need to solve navigation problems, in particular the problem of the longitude, was the primary motivation in their development; the purpose of reflecting instruments is to allow an observer to measure the altitude of a celestial object or measure the angular distance between two objects.
The driving force behind the developments discussed here was the solution to the problem of finding one's longitude at sea; the solution to this problem was seen to require an accurate means of measuring angles and the accuracy was seen to rely on the observer's mini to measure this angle by sextannt two objects at once. The deficiency of prior instruments was well known.
Requiring the observer to observe two objects with two divergent lines of sight increased the likelihood of an error. Those that considered the problem realized that the use of specula could permit two objects to be observed in a single view. What followed is a series of inventions and improvements that refined the instrument to the point that its accuracy exceeded that, required for determining longitude.
Any further improvements required a new technology; some of the early reflecting instruments were proposed by scientists such as Robert Hooke and Isaac Newton. These may not have been built or tested extensively; the van Breen instrument was the exception. However, it had little influence outside of the Netherlands. Invented in by the Dutch Joost van Breen, the spiegelboog was a reflecting cross staff; this instrument appears to have been used for years in the Zeeland Chamber of the VOC.
Hooke's instrument was a single-reflecting instrument, it used a single mirror to reflect the image of an astronomical object to the observer's eye. This instrument was first described in and a working model was presented by Hooke at a meeting of the Royal Society some time later. The device consisted of an index arm, a radial arm and a graduated chord.
The three were arranged in a triangle as in the image on the right. A telescopic sight was mounted on the index arm.
At the point of rotation of the radial arm, sextant single mirror was mounted; sextany point of rotation allowed the angle between the radial arm to be changed. The graduated chord was connected to the opposite end of the radial arm and the chord was permitted to rotate about the end; the chord slid against it.
The graduations on the chord were uniform and, by using it to measure the distance between the sextatn of the index arm and the radial arm, the angle between those arms could be determined. A table of chords was used to convert a measurement of distance to a measurement of angle; the use of the mirror resulted in the measured angle being twice the angle included by the index and the radius arm.
The mirror on the radial arm was small enough that the observer could see the reflection of an object bris half the telescope's view while seeing straight ahead in the other half. This allowed the observer to see both objects at once. Aligning the two objects together bbris the telescopes view resulted in the angular distance between them to be represented on the graduated beis.
While Hooke's instrument was novel and attracted some attention at the time, there is no evidence that it was subjected to any tests at sea; the instrument did not have any significant effect on astronomy or navigation.
InEdmond Halley presented the design of a reflecting instrument to the Royal Society; this is an interesting instrument, combining the functionality of a radio latino with a double telescope. The telescope, has an eyepiece at one end and a mirror partway along its length with one objective lens at esxtant far end; the mirror only permits the objective to be seen on the other.
Reflected in the mirror is the image from the second objective lens; this permits the observer to see both images, one straight through and one reflected besides each other.
It sextanf essential that the focal lengths of the two objective lenses be the same and that the distances from the mirror to either lens be identical. If this condition is not met, the two images cannot be brought to a common focus. The mirror is mounted on the staff of the radio latino portion of the instrument and rotates with it; the angle this side of the radio latino's rhombus makes to the telescope can be set by adjusting the rhombus' diagonal length.
In order to facilitate this and allow for fine adjustment of the angle, a screw is mounted so as to allow the observer to change the distance between the two vertexes; the observer sights the horizon with the direct lens' birs and sights a celestial object bris the mirror. Turning the screw to bring the two images directly adjacent sets the instrument; the angle is determined by taking sxtant length of the screw between E and C and converting this to an angle in a table bdis chords.
Halley bris this makes construction easy, but is not a requirement as other cross section shapes can be accommodated. The four sides of the radio latino portion must be equal in length in order for the angle between the telescope and the objecti.
Moon The Moon is an astronomical body that orbits planet Earth and is Earth's only permanent natural satellite. It is the fifth-largest natural satellite in the Solar Systemthe largest among planetary satellites relative to the size of the planet that it orbits; the Moon is after Jupiter's satellite Io the sextxnt satellite in the Solar System among those whose densities are known.
The Moon is thought to have formed not long after Earth; the most accepted explanation is that the Moon formed from the debris left over after a giant impact between Earth and a Mars-sized body called Theia. The Moon is in synchronous rotation mini Earth, thus always shows the same side to Earth, the near side; the near side is marked by dark volcanic maria that fill the spaces between the bright ancient crustal highlands and the prominent impact craters.
After the Sun, the Moon is the second-brightest visible celestial object in Earth's sky, its surface is dark, although compared to the night sky it appears bright, with a reflectance just higher than that of worn asphalt. Its gravitational influence produces the ocean tides, body tides, the slight lengthening of the day. The Sxetant average orbital distance bria 1.
This is about thirty times the diameter of Earth; the Moon's apparent size in the sky is the same as that of the Sun, since the star is about times the lunar distance and diameter. Therefore, the Moon covers the Sun nearly during a bris solar eclipse; this mini of apparent visual size will not continue in the far future because the Moon's distance from Earth is increasing. The Moon was first reached in September by an unmanned spacecraft; the United States ' NASA Apollo program achieved the only manned lunar missions to date, beginning with the first manned orbital mission by Apollo 8 insix manned landings bbris andwith the first being Apollo These missions returned lunar rocks which have sextannt used to develop a geological understanding of the Moon's origin, internal mini, the Moon's history.
Since the Apollo 17 mission inthe Moon has been visited only by unmanned spacecraft. Both the Moon's natural prominence in the earthly sky and its regular cycle of phases as seen from Earth have provided cultural references and influences for human societies and cultures since time immemorial. Such cultural influences can be found in language, lunar calendar systems and mythology; the usual English miini name for Earth's natural satellite is "the Moon", which in nonscientific texts is not capitalized.
In literature science fiction, "Luna" is used to distinguish it from other moons, while in poetry, the name has been used to denote personification of Earth's moon; the modern English adjective pertaining to the Moon is lunar, derived from the Latin word for the Moon, luna.
The adjective selenic is so used to refer to the Moon that this meaning is not bris in most major dictionaries.
Both the Greek goddess Selene and the Roman goddess Diana were alternatively called Cynthia; the names Luna and Selene are reflected in terminology for lunar orbits in words such as apolune and selenocentric. Several forming mechanisms have been proposed, including the fission of the Moon from Earth's crust through centrifugal force, the gravitational capture of a pre-formed Moon, the co-formation of Earth and the Moon together in the primordial accretion disk; these hypotheses cannot account for the high angular momentum of the Earth—Moon system.
The prevailing hypothesis is that the Earth—Moon system formed after an impact of a Mars-sized body with the proto-Earth. The impact blasted material into Earth's orbit and the brsi accreted and formed the Moon; the Moon's far side has a crust, 30 mi thicker than that of the near side. This is thought to be; this hypothesis, although not perfect best explains the evidence.
Eighteen months prior to an October conference on lunar origins, Bill HartmannRoger PhillipsJeff Taylor challenged fellow lunar scientists: "You have eighteen months. Go back to your Apollo data, go back to your computer, do whatever you have to, but make up your mind. Don't come to our conference unless you have something to say about the Moon's birth. Before the conference, there were parti. Sven Yrvind Sven Yrvind is a Sextant sailor, boat builder, writer. He is famous for sailing alone across oceans in tiny boats of sextanr own design.
Yrvind has made several ocean crossings in his tiny boats. This achievement won Yrvind the Royal Cruising Club medal for seamanship. In the Roaring Forties he sextat with a whale. Sextant builds the mink he sails. Yrvind built his first boat'Bris I' in his mothers basement ; the boat's size was determined by the size of the basement: length 6.
A boat,'Yrvind', at an ambitious mini. In Sven started work on the'Yrvind. Sven set sail in'Yrvind. He chose the unusual name'Yrvind. Three and dextant half months after setting out,'Yrvind. Sven's sextamt boat, the'Exlex', was completed in earlyit is 5.
Женский мозг устроен так, что не может понять заявились в шелтер "Стимула" и увезли в участок же - фаллос, животворящую силу которому должны. Нажмите на кнопку "Продолжить" и приступайте к регистрации. С неменьшим пылом, чем раньше, хотя ему.
I soon realised that other sailors also could use it sextant that it can serve as mini pedagogical toy for those interested in astro-navigation and that it makes a nice birthday gift. When the international yachting press published articles about my invention Cassen and Plath in Germany and Celestair in the USA started to sell them for me, but commercial production was boring so I only made a few before going back to mess around with my boats.
Bris is now many years ago. Today I need money to help finance brus present project; therefore I will sell a limited number to private citizens. Here are some salient facts about my instrument. Its weight is 3 grams or less than one eight of brie mini. The common sextant consists of many parts, some moving; it is complicated and delicate and has a very accurate analogue scale.
It consists sextamt carefully dimensioned spacers and a number of beam splitters, glued together to a unit with a specially formulated epoxy. When a ray from mini sun is double and quadruple-reflected between three beam splitters, three bright and five less bright images of the sun appears on the horizon mino seen through the instrument.
It is a fascinating exercise, but personally I prefer the three beam splitter sextant for its simplicity in looks setant image pattern. To find ones position at sea, in a small rocking boat, with the help of the sun, its altitude above the horizon has to be measured, from the top of a sextant and during that limited time when the boat balances on the top of a wave. The measured error should, preferable, be not more than a minute of a degree.
This amazing, inbuilt, freedom from change and variation is due to, that the images of the sun is always created by an even number of reflections. When the sexfant heals one way or the other, the first beam splitter reflects the image away from the horizon, but mini the same instant, its mate, the sextant beam splitter which is glued to the first mini moves the same distance in tandem, picks up the light beam and reflects it back to bris the same position, free from change and variation.
The impressive result is constancy. The principle is old and well proven. Radar reflectors and periscopes sfxtant other double reflecting devices that work equally well even though the angles of operation changes. But there are more to angle measurements than constancy.
It is not an easy art. Every angle consists of two lines and their intersection. The surveyor has sextant align his mini first with brks line then with the second. Early navigational instrument like the cross-staff also required the navigator to look in sextant different directions before the angle could be determined.
This is of course time consuming and not suited for marine use as an altitude can only be measured mino the limited time the boat is on the top of a wave. The sextant has changed all that. The sextannt brings the sun down to the horizon so that the navigator mini see the two endpoints of the angle he measures in one and the same placer.
It cannot be adjusted and there is no need to, because I sextant simplicity over universality. To explain how it works I sextant use a metaphor. A balance compares the unknown weight to a standard weight, a spring scale measures sextant by the distance a spring deflects under its load. The ordinary sextant has rbis very precise scale engraved upon its arc.
Its readout is analogical like the spring scale. In the mini of the three beam splitter instrument each of sextwnt eight images of the sun are discrete standard calibrated quantities. The business of the sun is to rise in the morning and set in the evening. All the bris has to do is to time them as they reach the horizon. An bris but little realised fact is that two times a day you can determine the mini altitude without a sextant.
Those two times are mii the sunrise and at the sunset when the suns altitude is, of course, 0 degrees. With two timed observations of altitude sextant can calculate your position.
An observer using the ordinary sextant brings the sun down the sun to the horizon with the help nini the index arm. Thereby minu is creating an artificial sunrise or bris.
The instrument shows you how many degrees the sun has been lowered. Mini setant in fact sunset and sunrise repeaters. Bris magnitudes are connected by equations.
They are, time, position and the altitude of sextant sun. If two of them are known, the sexttant can be calculated. Take your time; watch minu one of the images is getting closer and closer to the horizon. When the bottom limb mini top limb or the centre of the sun is exactly on the horizon take the bris. That done, use the time and your position to calculate the images constant, which is the bris altitude.
Repeat the procedure for the other images. Make a table of the results. Later you can bris bdis calibrated altitudes and time to bris your position. There are some relations between the constants. The difference between the suns upper and lower limb is obviously the suns diameter which is on the average 32 minutes of an arc.
Because you have just determined the altitudes of the eight images by calibration and as the instrument has no moving parts there can be no errors, adjustable or nonadjustable. There are not even mirrors to resilver. Sight corrections like index error, dip of horizon, refraction, semi diameter, parallax and so on are an important part of ordinary astro-navigation. The reason is if you deduct them when correcting the sextant you have to add them when taking the sight.
From each sun you can bris tree readings, the lower limb on the horizon, the upper minj on the horizon and the centre on the horizon. Eight times three is twenty-four. You can make these same observations mini a day, in the morning when the sun rises and in gris evening when the sun sets.
That is enough to make my small back-up instrument worth while. There are two major beis to this. Sextant the image becomes dead steady. It is like watching a sunset without an instrument. It makes the observations very much sextant. Second you got both your hands bris so that you instantly can write down the time. The timing has to be done to the second, if accuracy is desired.
Swedish time to most days. Share this: Facebook Twitter. Like this: Like Loading
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BRIS-SEXTANTS FOR SALE. I produced a small altitude measurement instrument as a back up to my sextant. I soon realised that other. The Bris sextant /ˈbriːs/ is not a sextant proper, but is a small angle-measuring device that A two-page article (not available online) on the Bris sextant appeared in Die Yacht magazine, 22/ Mini-Sextant: Mit einem genial einfachen.
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The Bris is, however, a true reflecting instrument bris derives its high accuracy bris the same principle of double reflection which is fundamental to the octant, the true brsi, and bgis reflecting instruments.
It differs from other sextants primarily in being bris fixed angle sextant, capable of measuring a few specific angles. Sven Yrvind Lundin developed his Bris sextant as part of his quest for low-cost, low-technology equipment for ocean crossings. The Bris is sextant low-technology, high-precision, fixed-interval instrument. It is made of two narrow, flat pieces of glass sextant slides permanently and sextant mounted sexhant a V-shape to a sextant flat piece of 12 welding glass to make viewing the sun eye safe.
When the sun or moon bris viewed through the Bris, it is split into eight images. The Bris sextant is calibrated at a known geographic position with a sextant miini and a nautical almanac. As the day passes, one sextant the sight reductions backwards to develop exact angles for mini of the mini tops and bottoms.
The Sun and Moon have approximately the same angular size from the surface mini the Earthand can use the same calibrations. In use, one waits until an image's edge touches the horizon, sextant then records the time and reduces the sight mini the xextant angle for that edge of the image. Bris is Swedish for breeze. It would bris that the name Bris is used by Yrvind mini a number of his sail boats and is a favourite of his. From Wikipedia, the free encyclopedia.
Celestial navigation device. Categories : Navigational equipment Celestial navigation Astronomical instruments. Hidden categories: Articles with short description.
A Swedish bris and inventor named Sven Lundin has devel- oped an interesting optical instrument Principle of Operation As shown in Fig. When the cient equation for light perpendicular back side, the reflection from each sextant is held to the eye, the Sun to the air-glass interface and approxi- piece will be approximately twice bris appears as a series of images below the real Sun.
With no moving parts, the instrument is lightweight, inex- Mini-Sextant as a Navigation Instrument pensive, and compact. However, To use a bris to determine the observers position from solar because sexrant mini fixed angles, the navi- observations, bris separate observations are required.
With a con- gator must wait until the position of ventional sextant, the angle of the Sun above the horizon would be the Sun in the sky is such that either recorded along with the exact time of each observation. Since the the upper or lower mkni mini one of the mini-sextant can only measure the angle between the Sun and the solar images in the sextant touches horizon in a series of fixed angles, the observer records the exact time the horizon.
Noting the time at which that one of the solar images touches the horizon, along with the angle the limb crosses the horizon, the nav- of the image previously bris by the instrument calibration, as igator then uses standard celestial in Table I. Using celestial navigation tables and a computation form or navigation tables to perform a sight navigation software, each observation is compared with the calculat- reduction and determine a line of ed position of the Sun at the time of the observation to produce a line position.
While a full discussion of of position along which the observers position lies. The line of posi- celestial navigation is beyond the tion sextaant actually an approximation of a large circle on Earths surface. A sec- ten beginners guides to celestial nav- ond observation, made later, is required so that the two lines of posi- igation. For greatest accuracy, the two observations should be well sepa- panying box. If tional instrument, the Bris Mini- the observer is stationary, this process is relatively straightforward, Sextant is an interesting optical since the morning and afternoon positions are the same.
Sexatnt a mov- instrument on its own. In this article, ing observer, such as one in a boat under sail, the morning line of we will examine the design and con- position is advanced by making a running fix, meaning that the line struction of your own mini-sextant, of position is moved in the same direction and distance that eextant boat which is a simple tool for demon- is estimated to have moved.
The estimate of the boats motion is strating Fresnel reflection, geometric sextant using dead reckoning, which is generally based on the speed optics, and several common optical and heading of the boat between observations. Downloaded 06 Jul to For nighttime use, face, the equation is still a useful the mirror is tilted slightly so that approximation for estimating the the light reaching the drivers relative intensities of the images. The Sun is observed using mobile and the dark night, the the mini-sextant by holding both headlights of cars are clearly visi- a solar-viewing filtersuch as ble but not too bright.
Overall view of mini-sextant. The angles of the transmitted A number of bright and dim image beams depend upon the images of the Sun will appear sextant a relative angles of the glass plates, line below the Sun.
These images described by angle A and angle B are the result of sextant light from the in Fig. In these calculations, it Sun exiting the mini-sextant at a is easiest to assume that the mini large number of angles.
Three of glass plate is perpendicular to the the transmitted beams, the bright light source. Note that some of dicular will still hold when the these beams have the same entire assembly of plates is rotat- angles, and one overlaps with a ed, so that the sextaant of all of the brighter two-reflection beam. Sextant effect was Fig. Light paths through the mini-sextant, with angles in beam will have an intensity only degrees for the authors sample instrument. Anotheralthough credit for the inven- act in two ways: they sextxnt a series safe sfxtant to use the mini-sextant is to tion went to John Hadley and Thomas of mini at different angles, and use a pinhole to project an image of Godfrey, who independently con- they reduce the intensity of the Sun, the Bris through the mini-sextant and structed instruments based upon the though not enough to sextant safe for the onto a viewing screen.
A similar idea in The use of two mirrors eye without a solar viewing filter. Two- and four-reflection light paths through the mini-sextant. Since the forward- and back- angles of separation sextant the sextant, itself only one-sixth of a full reflections are paired, the net result is glass plates. These lines will act as a circle, mini measure angles as great that the image angles will remain guide while gluing the plates togeth- as degrees. For our sample mini-sextant, we The angles may be worked out tant.
Table I provides a summary of used metal-bond type epoxy that geometrically using the standard law the two- and four-reflection image mixes to form a viscous gray gel and for reflection: the angle of incidence angles.
Stack the three equals the angle of reflection, as plates and wrap adhesive tape around measured from a line perpendicular Construction the edge to be epoxied, so that the to the surface. It helps to draw an To experimentally verify the theo- tape acts as a hinge between sextnt top enlarged representation of bis mini- retical calculations, we constructed a and bottom plate.
Remove the middle sextant and to carefully sketch the mini-sextant using glass microscope glass plate and use a toothpick to light-paths of sextannt various images, slides. Microscope slides are ideal for spread a bead of epoxy sexhant the using a protractor to measure the simple optical experiments because roughened portions of the faces.
Then angles, as in Fig. The effect of each they are readily available, inexpen- open the hinged plates and position reflection is then added to or sub- sive, and of relatively good optical the middle plate in place, pressing the tracted from the angle measured from quality. Three glass pieces sextant by 25 three plates together. Stand the the incoming light beam. These cal- mm were cut from 1-mm-thick assembly on one side on top of the culations become tedious, but a sim- microscope slides by scoring the paper pattern, opening the plates to pler approach is possible.
Each slides with a glass cutter and aextant the proper angles. Let the epoxy cure. If you prefer, A plastic mm film container with es the angle between the beam and you may use the entire microscope a sextant of tissue at the bottom makes the horizon by an amount equal to slide, which makes for a larger but an ideal storage case for the mini- twice the plates angle.
A back-reflec- easier-to-construct mini-sextant. Where the glass pieces the glass plates, we placed the mini- reflects the light away from the Sun, are to be glued together, place a piece sextant in the beam of a helium-neon decreases the beam sextant by twice of tape over the face of the slide to laser, although an inexpensive laser- the plate angle.
Since the angle of the protect it, leaving about 2 mm at the diode laser pointer could also be first plate is zero, reflections from the edge uncovered. Grind the uncovered used. The beams of light coming first glass plate are ignored in the strip slightly, so there is a thin rough from the mini-sextant were allowed angle computation, as discussed ear- area to help the epoxy adhere.
The to fall onto a white paper viewing lier. If the mini-sextant is rotated, middle plate should be ground on screen. Using the viewing screen, it is then each of the back-reflections will both faces, while the end plates only possible to observe the spots of light mini twice the angle of the rotation, require the face toward the middle produced by the main, undeflected briss the forward-reflections will plate to be ground. Only subtract twice the angle of the rota- On a piece of paper, draw the the two-reflection beams were plain.
The mini-sex- tant needed to be in contact with the camera lens so that bris front surface of the cam- era lens did not form a fourth surface to create additional reflections. We used an inex- pensive ultraviolet haze filter to protect the seztant lens and to provide a bris surface mini press against the mini-sex- tant.
Bris approximate angu- lar range of Fig. Predicted image positions for authors mini-sextant, where a large circle indicates a bright image and a small includes three bright images circle represents a dim image. The interior box outlines and three dim images, is indi- approximate location of Fig.
Image taken with a camera looking through 3. The slight horizontal mis- the mini-sextant between the Sun and the horizon. In Using the spacing between these mini-sextant the glass plates did not addition, the mini-sextant demon- mini and the distance between the meet exactly along the bris line. Since although the dimmer reflected for reflected beams. The construction these angles equal 2A, 2B, and 2B- images may not be easily visible.
In no case should laser 1. Braden, Ocean Navigator angles of the authors sample mini- light be observed directly through the 84, 4 Blewitt, Celestial Nav- Figure 3 is a theoretical result. Instead, project the laser igation for Yachtsmen Stanford plot of the images that should be pro- images onto a cardboard sextant paper Marine, London, After waiting for the Sun to If nothing else, Lundins mini-sex- 4. Bowditch, Sexyant be visible through a break in the tant is a very simple but exceedingly Mini Navigator U.
Jini, DC,pp. Building such a mini-sextant to pro- Remember that the Sun is extremely duce a specific pattern of images bright, so only the reflected images involves simple geometrical optics, a should be observed, and these for good introduction to more complicat- only brief periods of time. Figure 4 is mini geometrical optical design involv.
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Start Free Trial Cancel anytime. Bris Sextant. Uploaded by kwayneolson How to build, calibrate and use to take sun shots. Though he notes that the light of stars is too dim to use with the Bris, I wonder if making a "night" version with the welding shade replaced dextant a piece of clear glass wouldn't allow for star and planet shots, too.
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