This Day or Night telescope, made by John Dollond, was designed for use in a range of lighting conditions, as its name suggests. Telescopes are optical instruments that make distant objects appear larger and closer, thereby extending the range of what the human eye can observe. The development of the telescope was gradual, shaped by a series of important advances in optical science. In 1608, the Dutch spectacle-maker Hans Lippershey discovered that when two lenses were held apart in a particular way, distant objects appeared closer. He applied for a patent for this invention, creating the first documented telescope. In 1668, Isaac Newton produced the first successful reflecting telescope, using a two-inch concave spherical mirror. This marked a major step forward, demonstrating that mirrors could overcome some of the limitations of lenses and greatly improve magnification. Further progress followed in the eighteenth century. In 1729, Chester Moor Hall developed the achromatic lens by combining two types of glass with different refractive properties. This reduced colour distortion and produced a sharper image, although some edge distortion remained. That same year, the Scottish instrument maker James Short developed parabolic and elliptical mirrors that were better suited to reflecting telescopes because they reduced optical distortion. Building on these advances, John Dollond improved the achromatic objective lens by placing a concave flint-glass lens between two convex crown-glass lenses, considerably enhancing image quality. Maker’s information. John Dollond (1707–1761), of London, was a maker of optical, scientific and astronomical instruments best known for developing the achromatic refracting telescope. He also introduced a practical heliometer, a telescope fitted with a divided lens that could be used to measure the Sun’s diameter and the angular distance between celestial bodies. The son of Huguenot refugees, Dollond first learned the family trade of silk weaving before turning his attention to optics and astronomy, in which he became highly skilled. In 1753, Dollond patented his improved lenses, the same year he had introduced the heliometer. In 1761, John Dollond was appointed as optician to George III and the Duke of York. He was also elected a Fellow of the Royal Society in May 1761, but died suddenly later that year in November. His share of the patent then passed to his eldest son, Peter. In later disputes between Peter Dollond and rival London opticians who challenged the patent, Peter consistently argued that, whatever earlier precedents may have existed, his father had independently developed a practical method for producing achromatic lenses through his command of Newtonian optics. By successfully defending the patent, the Dollond firm became one of the leading manufacturers of optical instruments. During the eighteenth and nineteenth centuries, the name ‘Dollond’ was at times used almost generically to mean ‘telescope,’ reflecting the firm’s reputation. Genuine Dollond telescopes were regarded as among the finest available. Peter Dollond (1731–1820) was the driving force behind the family business. He had founded a small optical business in 1750 on Vine Street, Halton Garden, with his father's guidance. The success of the business led to his father joining him in partnership in 1752. In 1959, J Dollond and Son opened a shop on The Strand, London. Dollonds appear to have produced both reflecting and refracting telescopes, and they possessed the technical skill to manufacture significant numbers of lenses largely free from chromatic aberration. In 1766, Peter went into partnership with his younger brother, John, and they traded under the name P and J Dollond. They supplied optical instruments for Captain Cook and George Hadley, an English lawyer and Meteorologist. In 1769, Captain Cook travelled with a Dollond telescope on the voyage to observe the Transit of Venus. Other notable customers included Thomas Jefferson and Admiral Lord Nelson. In 1781, Peter Dollond made bifocal spectacles. In 1804, young John Dollond passed away. The following year, Peter Dollond went into partnership with his nephew, George Huggins, and Huggins legally changed his surname to Dollond, and the firm remained P and J Dollond. In the early 20th century, the company sold film cameras. The firm remained in the hands of Dollond family members until 1927, when Dollond & Co. merged with James Aitchison & Co. to form Dollond & Aitchison, the well-known high street chain of opticians, which continued making and selling prescription spectacles. Now fully part of Boots Opticians, the company no longer manufactures instruments and operates exclusively as a retail business. The telescope in the collection is an excellent example of one of Dollond’s early library telescopes. Its association with one of eighteenth-century England’s leading innovators in optical development gives it considerable historical significance and makes it an important object within the collection. John Dollond’s experiments in optics advanced the understanding of the divergent properties of lenses and made a lasting contribution to the development of practical optical science. His work helped lay the foundation for major improvements in the design and performance of optical instruments. In his own time, Dollond was celebrated as the “Father of practical optics” and received widespread recognition for his achievements in the field. Dollond telescopes were associated with the renowned mariners, Captain James Cook and Admiral Lord Nelson Telescope: Dollond's Telescope, Day or Night model navigational instrument. Telescope is mounted on wooden tripod stand that has folding legs. Brass telescope with leather sheath over barrel, adjustable angle fitting with brass wing nuts that join the legs to the top frame, which is then joined to the telescope pole by an adjustable screw fitting. Manufactured by Dollond, London. Inscription reads "Dollond London, Day or Night" and "DOLLOND LONDON"flagstaff hill maritime museum and village, maritime museum, maritime village, great ocean road, warrnambool, optical instrument, achromatic telescope, heliometer, light refraction, instrument maker, lens, transit of venus, astronomical telescope, concave lens, scientific instrument, navigation, navigational instrument, astronomy, dollond, dollond london, john dollond, peter dollond, dollond telescope, day or night telescope, floor-standing telescope, library telescope, hans lippershey, isaac newton, chester moor hall, james short, captain cook, thomas jefferson, admiral lord nelson, dollond & co, aitchison & co, dollond & aitchison, boots opticians, george iii, duke of york, george huggins, george dollond, p and j dollond, j dollond and son, spectacles, cameras

The period when kerosene was extensively used for indoor lighting was before electrical reticulation was installed in rural areas. In remote areas this was up to the mid 1900's. The kerosene lantern however was still in use, for camping and outdoor activities, well beyond this period and was eventually replaced by LPG and battery powered lighting. The transition phase to "modern" outdoor and domestic lighting lingered on the rural areas where the electrical reticulation suffered from reliable constant supply.In the Kiewa Valley, being a rural region, had reliable electrical domestic and farm supply only after the Kiewa Hydro Electricity Scheme had been fully operational. The supply was relative to how close the homestead was to the major electricity substation. This kerosene lamp was in use during the period when it was the only reliable source of domestic night time lighting. The strength of refractive light produced by this lantern/lamp hinged upon the size of the lamp(wick and glass bowl). The small size of this lamp suggests that it was for use in a small room(children's bedroom) or as providing a light for a safe walk to the outside ablutions (toilet) area. This small kerosene lamp has an enclosed "cup" body which would have contained the kerosene fuel. The top wick holder, made from brass, has an extended enclosed spout which raises the wick approximately 20mm from the bottom of the holder. The wick holder screws into the the top of the kerosene reservoir bowl and has a wick adjustment screw (light control) at one side. The small white glass light reflector bulb nestles securely onto the wick holder and is kept snug by snap designed extending "fingers". The section between the bottom of the refractive glass "light" bowl and the top of the kerosene bowl has perforations to allow air passage to feed directly to the wick.The light refracting bulb is open at the top to allow heat and smoke from the burning wick to escape upwards.On the wick control screw "CWB BRITISH MADE"kerosene reading lamp, domestic lighting, bedside light

The discovery of the first telescope in 1608 can be attributed to Hans Lippershey of the Netherlands when he discovers that holding two lenses up some distance apart bring objects closer. He applies for a patent on his invention and this becomes the first documented creation of a telescope. Then in 1668, Newton produces the first successful reflecting telescope using a two-inch diameter concave spherical mirror. This opened the door to magnifying objects millions of times far beyond what could ever be obtained with a lens. It wasn’t until 1729 that Chester Moor Hall develops an achromatic lens (two pieces of glass with different indices of light refraction combined produce a lens that can focus colours to almost an exact point resulting in much sharper images but still with some distortion around the edges of the image. Then in 1729 Scottish instrument maker James Short invents the first parabolic and elliptic, distortion-less mirror ideal for reflecting telescopes. We now come to John Dollond who improves upon the achromatic objective lens by placing a concave flint glass lens between two convex crown glass lenses. This had the effect of improving the image considerably. Makers Information: John Dollond (1707-1761) London England he was a maker of optical and astronomical instruments who developed an achromatic (non-colour distorting) refracting telescope and practical heliometer. A telescope that used a divided lens to measure the Sun’s diameter and the angles between celestial bodies. The son of a Huguenot refugees Dollond learned the family trade of silk weaving. He became proficient in optics and astronomy and in 1752 his eldest son, Peter joined his father in an optical business, in 1753 he introduced the heliometer. In the same year, he also took out a patent on his new lenses. He was elected a fellow of the Royal Society in May 1761 but died suddenly in November and his share in the patent passed to his son Peter. In subsequent squabbles between Peter and the many London opticians who challenged his patent, Peter’s consistent position was that, whatever precedents there may have been to his achromatic lenses, his father had independently reached his practical technique on the basis of his theoretical command of Newtonian optics. As a result of maintaining his fathers patent, Dollond s became the leading manufacturer of optical instruments. For a time in the eighteenth and nineteenth century the word 'Dollond' was almost a generic term for telescope rather like 'Hoover; is to vacuum cleaner. Genuine Dollond telescopes were considered to be amongst the best. Peter Dollond (1731-1820) was the business brain behind the company which he founded in Vine Street, Spitalfields in 1750 and in 1752 moved the business to the Strand London. The Dollonds seem to have made both types of telescopes (reflecting and refracting), possessing the technology to produce significant numbers of lenses free of chromatic aberration for refracting telescopes. A Dollond telescope sailed with Captain Cook in 1769 on his voyage to observe the Transit of Venus. Thomas Jefferson and Admiral Lord Nelson were also customers of the Dollonds. Dollond & Co merged with Aitchison & Co in 1927 to form Dollond & Aitchison, the well-known high street chain of opticians, now fully part of Boots Opticians. They no longer manufacture but are exclusively a retail operation.    John Dollond's experiments in optics and how different combinations of lenses refract light and colour gave a better understanding of the divergent properties of lenses. That went on to inform and pave the way for the improvement of our understanding of optics that are represented today. Dollond was referred to in his time as the "Father of practical optics" as a leader in his field he received many prestigious awards. The telescope in the collection is a good example of one of Dollonds early library telescopes and its connection with one of England's 18th-century pioneers in optical development is in itself a significant and an important item to have within the collection. Telescope: one tube ships Day and Night telescope, with a brass inner tube and a timber main tube covered in leather. Made in 1869 by Dolland, London."Dolland London" "Day or Night" "Royal National Life Boat Institution" "1869"flagstaff hill, shipwreck coast, warrnambool, maritime museum, maritime village, telescope, dolland, night and day, royal national life boat instution

Blue hard covered book with gold writing and illustrations on front cover, illustrations, 196 pages. Targetted to the general reader of the scientific principles of heat, light and sound topics include heat; light (including reflection and refraction); vision (including vision and optical illusions, the eye, chromatic aberration, spinning tops); optical illusions (including occular estimation, zollner's designs, the thaumatrope, phenakistoscope, zootrope, praxinoscope, the dazzling top); optical illusions cont. (including the talking head, ghost illusions); optical apparatus (including the eye, the streoscope, spectrum analysis, the spectroscope, the telescope and microscope, photography, dissolving views, luminous paint); spectral illusions (including a spectre, ghosts); acoustics (including the harmonograph); acoustics cont (including the topophone, the megaphone, the autophone, the audiphone, the telephone, the phonograph, the microphone). non-fictionscience, science class, scientific recreation series, light, heat, sound, ballarat ironworkers & polytechnic association

This particular lamp was made for the dinner table or "parlour". This was the most effective indoor lighting before electrical lighting was introduced in the 1940's. These table lights would have still been used after this time as emergency lighting during electrical power shortages (outages). These emergency lighting lamps, including candles, were eventually replaced by battery power. The Kiewa Valley was supplied by electricity well before many other rural regions due to the State Electricity Commission constructing the Kiewa Hydro Electricity power turbines (late 1930's to mid 1950's). Petrol and diesel generators were used in other rural regions before state wide electricity was available.The significance of this kerosene lamp to the Kiewa Valley is that it provides the proof that before the Hydro electricity scheme was established in the valley, householder and commerce relied on candle/kerosene power. Although at certain times before battery and solar energy became the night time lighters the sole source of lighting was candle power and kerosene power. The supply of both however was still required by most of the population by supply from city and larger country town suppliers. This nearly fully glass made table lamp(kerosene) has a large glass bowl/basin like kerosene storage unit with a glass circular finger handle (similar to a ordinary cup). Formed single star like patterns (50mm apart) encircle the centre of the bowl. On top of the bowl sits the metal (brass) wick holder with a small wheel protruding out one side for adjusting the wick length(increasing or decreasing the strength(regulating) of the amount of light projected. Four prongs rise from the circular base light fixture holding the windproof and refractive glass "pot belly" shield. lamp table, kerosene lamp, household lighting (non electrical)

Black book of 160 pages. non-fictioncrystals, light, jim thyer, polarizing microscope, refraction, dispersion, absorption spectra

Group of paper pinned together of various experiments. Items include Tail light invention for Defence Dept. 18/9/41, Heat of glass, Refractive Index Tests on Melbourne Tap Water 31/7/42, Research Data, Manufacture of the Buoys 18/1/43, Specifications 1/12/42, List of substances with their Atomic No., Symbol, Atomic Weight, Melting Point and Year of discovery and a hand drawn diagram for an experiment. Bendigo Electronic Company of Australia Pty Ltdsciences, instruments - general, scalebuoy, bill ashman collection - correspondence, bendigo electronic company of australia pty ltd, defence dept, capt slattery, f a stevenson

A Fresnel lens is a type of composite compact lens developed by the French physicist Augustin-Jean Fresnel (1788–1827) for use primarily in lighthouses.  Made from high-quality glass Fresnel lenses were used originally in lighthouses and later for many other applications They were later being used for automobile headlamps, brake, parking, and turn signal lenses, and many other applications. Fresnel lenses used in lighthouses were considered state of the art from the late 19th through to the middle of the 20th century. The subject item is a Fresnel replacement lens used in a ships navigation light. For lighthouses, these lenses have now been replaced with much less expensive and more durable aerobeacons, which themselves often contain plastic Fresnel lenses. The lens design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design. A Fresnel lens can be made much thinner than a comparable conventional lens, in some cases taking the form of a flat sheet. The simpler dioptric (purely refractive) form of the lens was first proposed by Count Buffon and independently reinvented by Fresnel. The catadioptric form of the lens, entirely invented by Fresnel, has outer elements that use total internal reflection as well as refraction; it can capture more oblique light from a light source making the light visible from greater distances.The subject item at this time cannot be associated with a historical event, person or place, provenance is unknown, the item is a replacement for a ships navigation light and it is believed to have been produced before 1950.Fresnel glass replacement lens for a navigation lamp of a ship. None warrnambool, flagstaff-hill, flagstaff-hill-maritime-museum, maritime-museum, shipwreck-coast, flagstaff-hill-maritime-village, fresnel lens, maritime light, ships navigation light, augustin-jean fresnel, lighthouse lenses, lighthouse, navigation, warning light

A Fresnel lens is a type of composite compact lens developed by the French physicist Augustin-Jean Fresnel (1788–1827) for use primarily in lighthouses.  Made from high-quality glass Fresnel lenses were used originally in lighthouses and later for many other applications They were later being used for automobile headlamps, brake, parking, and turn signal lenses, and many other applications. Fresnel lenses used in lighthouses were considered state of the art from the late 19th through to the middle of the 20th century. The subject item is a Fresnel replacement lens used in a ships navigation light. For lighthouses, these lenses have now been replaced with much less expensive and more durable aerobeacons, which themselves often contain plastic Fresnel lenses. The lens design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design. A Fresnel lens can be made much thinner than a comparable conventional lens, in some cases taking the form of a flat sheet. The simpler dioptric (purely refractive) form of the lens was first proposed by Count Buffon and independently reinvented by Fresnel. The catadioptric form of the lens, entirely invented by Fresnel, has outer elements that use total internal reflection as well as refraction; it can capture more oblique light from a light source making the light visible from greater distances.The subject item at this time cannot be associated with a historical event, person or place, provenance is unknown, the item is a replacement for a ships navigation light and it is believed to have been produced before 1950.Fresnel glass replacement lens for a navigation mast headlamp of a ship. Nonewarrnambool, flagstaff-hill, flagstaff-hill-maritime-museum, maritime-museum, shipwreck-coast, flagstaff-hill-maritime-village, fresnel lens, maritime light, ships navigation light, augustin-jean fresnel, lighthouse lenses, lighthouse, navigation, warning light

A Fresnel lens is a type of composite compact lens developed by the French physicist Augustin-Jean Fresnel (1788–1827) for use primarily in lighthouses.  Made from high-quality glass Fresnel lenses were used originally in lighthouses and later for many other applications They were later being used for automobile headlamps, brake, parking, and turn signal lenses, and many other applications. Fresnel lenses used in lighthouses were considered state of the art from the late 19th through to the middle of the 20th century. The subject item is a Fresnel replacement lens used in a ships navigation light. For lighthouses, these lenses have now been replaced with much less expensive and more durable aerobeacons, which themselves often contain plastic Fresnel lenses. The lens design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design. A Fresnel lens can be made much thinner than a comparable conventional lens, in some cases taking the form of a flat sheet. The simpler dioptric (purely refractive) form of the lens was first proposed by Count Buffon and independently reinvented by Fresnel. The catadioptric form of the lens, entirely invented by Fresnel, has outer elements that use total internal reflection as well as refraction; it can capture more oblique light from a light source making the light visible from greater distances.The subject item at this time cannot be associated with a historical event, person or place, provenance is unknown, the item is a replacement for a ships navigation light and it is believed to have been produced before 1950.Fresnel round glass masthead replacement lens for a navigation lamp of a ship. Nonewarrnambool, flagstaff-hill, flagstaff-hill-maritime-museum, maritime-museum, shipwreck-coast, flagstaff-hill-maritime-village, fresnel lens, maritime light, ships navigation light, augustin-jean fresnel, lighthouse lenses, lighthouse, navigation, warning light

A Fresnel lens is a type of composite compact lens developed by the French physicist Augustin-Jean Fresnel (1788–1827) for use primarily in lighthouses.  Made from high-quality glass Fresnel lenses were used originally in lighthouses and later for many other applications They were later being used for automobile headlamps, brake, parking, and turn signal lenses, and many other applications. Fresnel lenses used in lighthouses were considered state of the art from the late 19th through to the middle of the 20th century. The subject item is a Fresnel replacement lens used in a ships navigation light. For lighthouses, these lenses have now been replaced with much less expensive and more durable aerobeacons, which themselves often contain plastic Fresnel lenses. The lens design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design. A Fresnel lens can be made much thinner than a comparable conventional lens, in some cases taking the form of a flat sheet. The simpler dioptric (purely refractive) form of the lens was first proposed by Count Buffon and independently reinvented by Fresnel. The catadioptric form of the lens, entirely invented by Fresnel, has outer elements that use total internal reflection as well as refraction; it can capture more oblique light from a light source making the light visible from greater distances.The subject item at this time cannot be associated with a historical event, person or place, provenance is unknown, the item is a replacement for a ships navigation light and it is believed to have been produced before 1950.Fresnel glass lens for a ships masthead navigation lamp. Nonewarrnambool, flagstaff-hill, flagstaff-hill-maritime-museum, maritime-museum, shipwreck-coast, flagstaff-hill-maritime-village, fresnel lens, maritime light, ships navigation light, augustin-jean fresnel, lighthouse lenses, lighthouse, navigation, warning light

A Fresnel lens is a type of composite compact lens developed by the French physicist Augustin-Jean Fresnel (1788–1827) for use primarily in lighthouses.  Made from high-quality glass Fresnel lenses were used originally in lighthouses and later for many other applications They were later being used for automobile headlamps, brake, parking, and turn signal lenses, and many other applications. Fresnel lenses used in lighthouses were considered state of the art from the late 19th through to the middle of the 20th century. The subject item is a Fresnel replacement lens used in a ships navigation light. For lighthouses, these lenses have now been replaced with much less expensive and more durable aerobeacons, which themselves often contain plastic Fresnel lenses. The lens design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design. A Fresnel lens can be made much thinner than a comparable conventional lens, in some cases taking the form of a flat sheet. The simpler dioptric (purely refractive) form of the lens was first proposed by Count Buffon and independently reinvented by Fresnel. The catadioptric form of the lens, entirely invented by Fresnel, has outer elements that use total internal reflection as well as refraction; it can capture more oblique light from a light source making the light visible from greater distances.The subject item at this time cannot be associated with a historical event, person or place, provenance is unknown, the item is a replacement for a ships navigation light and it is believed to have been produced before 1950.Fresnel glass replacement lens for a navigation side lamp of a ship. Nonewarrnambool, flagstaff-hill, flagstaff-hill-maritime-museum, maritime-museum, shipwreck-coast, flagstaff-hill-maritime-village, fresnel lens, maritime light, ships navigation light, augustin-jean fresnel, lighthouse lenses, lighthouse, navigation, warning light

A Fresnel lens is a type of composite compact lens developed by the French physicist Augustin-Jean Fresnel (1788–1827) for use primarily in lighthouses.  Made from high-quality glass Fresnel lenses were used originally in lighthouses and later for many other applications They were later being used for automobile headlamps, brake, parking, and turn signal lenses, and many other applications. Fresnel lenses used in lighthouses were considered state of the art from the late 19th through to the middle of the 20th century. The subject item is a Fresnel replacement lens used in a ships navigation light. For lighthouses, these lenses have now been replaced with much less expensive and more durable aerobeacons, which themselves often contain plastic Fresnel lenses. The lens design allows the construction of lenses of large aperture and short focal length without the mass and volume of material that would be required by a lens of conventional design. A Fresnel lens can be made much thinner than a comparable conventional lens, in some cases taking the form of a flat sheet. The simpler dioptric (purely refractive) form of the lens was first proposed by Count Buffon and independently reinvented by Fresnel. The catadioptric form of the lens, entirely invented by Fresnel, has outer elements that use total internal reflection as well as refraction; it can capture more oblique light from a light source making the light visible from greater distances.The subject item at this time cannot be associated with a historical event, person or place, provenance is unknown, the item is a replacement for a ships navigation light and it is believed to have been produced before 1950.Fresnel glass replacement lens for a navigation side lamp of a ship. W.T.G (S) and 10x7 S.STR.ENGL.125warrnambool, flagstaff-hill, flagstaff-hill-maritime-museum, maritime-museum, shipwreck-coast, flagstaff-hill-maritime-village, fresnel lens, maritime light, ships navigation light, augustin-jean fresnel, lighthouse lenses, lighthouse, navigation, warning light

Optometrists are trained to examine eyes and prescribe visual aids such as spectacles. The optometer pictured in the media section of this document dates from the 1800s. The optometer was used with various lenses to determine the refraction of the eye. Refraction means the extent to which light is bent by an individual's eye. The result can determine how short-sighted or long-sighted they are, and the strength of spectacles required. In the second half of the 1800s, ophthalmologists also devised instruments to measure the separate components of vision. Dr Jules Badal developed the pictured instrument in 1876. It was based on an optometer invented by William Porterfield in 1759. The brass stands look as though they were made for an optometer to be table mounted, with heavy brass stands and designed to hold a cylindrical object securely as would be required by an optometer. Stands appear to have been very well made and very early probably early to mid 19th Century by a well known scientific instrument maker given there are no inscriptions or marks to indicate the time period made or maker it is difficult to assume significance to these items at this point in time as well as the items are incomplete.The brass stands believed to be for mounting an early Optometer an (ophthalmic instrument) Noneflagstaff hill, warrnambool, shipwrecked-coast, flagstaff-hill, flagstaff-hill-maritime-museum, maritime-museum, shipwreck-coast, flagstaff-hill-maritime-village, stands for scientific instrument

Hard cover book,The Clinical Use of Prisms Author: Ernest Edmund Maddox Publisher: John Wright & Co Date: 1907 5th Edition Further Information: Front cover & spine blue cloth title, publisher details and author name in gilt lettering.non-fictionThe subject volume The Clinical Use of Prisms; and the Decentring of Lenses is a seminal treatise on ophthalmic optics, binocular vision, and the correction of eye muscle imbalances (strabismus and heterophoria). The book covers two core clinical topics. Prismatic Refraction, how light bends through optical prisms, and how clinicians can use prisms to measure, diagnose, and relieve eye strain (asthenopia), double vision (diplopia), and misaligned line of sight. Decentring Lenses is the second and its focusing on the mathematical and practical rules for shifting the optical center of a spectacle lens relative to the patient's pupil. By decentring a standard spherical or cylindrical lens, allowing an optometrist or ophthalmologist to create an intentional "prismatic effect" without needing to grind a separate, heavy prism into the glassflagstaff hill, warrnambool, shipwrecked-coast, flagstaff-hill, flagstaff-hill-maritime-museum, maritime-museum, shipwreck-coast, flagstaff-hill-maritime-village, the clinical use of prisms, book, ernest f. maddox

This is a set of 30 photographs of Royal Australian Survey Corps (RA Svy) personnel from Central Comd Fd Svy Unit (Adelaide) on Aerodist survey operation - Project C4 in Eastern Arnhem Land, Northern Territory in 1967. Photos of personnel were taken either at the operations base at Numbulwar or the main base at Gove (Nhulunbuy). RA Svy conducted nineteen Aerodist operations for 12 years from 1964 to 1975. Aerodist MRC2 was a tellurometer-based system adapted for aircraft to accurately measure distances between non-intervisible ground survey stations, using the aircraft as an intermediate station. Lower order geodetic results could be achieved by survey network trilateration. The measured distances between stations formed survey networks from which each station’s latitude and longitude was computed. Aerodist MRC2 was RA Svy’s major horizontal control survey tool for mainly medium scale topographic mapping (scale 1:100,000 Class A being spatially accurate to within 50 metres) in PNG, northern NT, north-west WA, Kalimantan Barat (West) Indonesia, Sumatra Indonesia, Gulf of Carpentaria and Cape York, QLD. In 1967, the Aerodist MRC2 Master equipment was installed in the aircraft featured in this set of photos, Executive Air Services’ (Essendon VIC) Grand Aero Commander VH-EXX. It was the same aircraft type and company contracted to Division of National Mapping for Aerodist MRC2 surveys. From July to October 1967 the aircraft was attached to Central Comd Fd Svy Unit (Adelaide - Major Don Ridge) on Project C4 eastern-Arnhem Land NT, where 317 Aerodist lines measuring 17,300 line miles were successfully completed. This was the most productive Aerodist project thus far. The most common helicopter used by RA Svy up to 1972 was the civilian Bell 47G-2 and the Sioux Light Observation Helicopters (LOH), the Australian Army’s equivalent featured in this photo set. These light observation helicopters had a limiting load carrying capacity of up to about 500 pounds. By comparison, one Aerodist team including two people weighed up to 1,500 pounds. Source: Royal Australian Survey Corps – Aerodist Years 1964-1975 by Peter Jensen. Refer to Item 9061.26P for more photos taken during this Aerodist survey operation.This is a set of 30 photographs of Royal Australian Survey Corps (RA Svy) personnel on Aerodist survey operations in Eastern Arnhem Land, Northern Territory in 1967. The photographs are on 35mm negative film and scanned at 96 dpi. They are part of the Army Survey Regiment’s Collection. .1) to .4) - black & white, 20th August 1967, Project C4 Aerodist Operations Base - Numbulwar, NT. .5) - Photo, black & white, 1967. Probable wrecked Indonesian fishing vessel. .6) to .8) - Photo, black & white, 1967. Unidentified survey operations base, L to R: unidentified personnel. .9) - Photo, black & white, 1967. Unidentified survey operations base, unidentified soldier driving a Haflinger 4x4 Light utility vehicle. .10) - Photo, black & white, 1967. Unidentified survey operations base, L to R: unidentified technician. .11) - Unidentified technician reading two survey altimeters to compute corrections to the measured distances for atmospheric refraction and to compute the sea level distances from the slope distances aircraft to the ground stations. .12) - Photo, black & white, 1967. Survey operations base, L to R: unidentified (x3), W01 Pat Wood BEM, unidentified. .13) to .16) - Photo, black & white, 1967. Unidentified personnel operating remote Aerodist MRC2 ground instruments. .17) to .18) - Photo, black & white, 1967. Unknown RA Svy office location. .19) to .20) - Photo, black & white, 1967. Aerodist MRC2 Master equipment. .21) to .22) - Photo, black & white, 1967. Aero Commander VH-EXX probably at Gove, NT, Central Comd Fd Svy Unit (Adelaide) – OC Major Don Ridge. .23) to .25) - Photo, black & white, 1967. Aero Commander VH-EXX probably at Gove, NT. Unidentified personnel. .26) - Photo, black & white, 1967. Aero Commander VH-EXX probably at Gove, NT. Aerodist antenna pods are visible on the aircraft. .27) to .29) - Photo, black & white, 1967. Australian Army Sioux Light Observation Helicopter (LOH) probably at Gove, NT. .30) - Photo, black & white, 1967. Panelled U337 survey station, visible as a white cross on aerial identification photo..1P to .2P – date and location on edge of film negative. .5P to .28P – no annotations .29P - annotated in white ‘RW-JEP Gove NT’ .30P - annotated in white ‘U337 Spool No1 Jun67’royal australian survey corps, rasvy, army survey regiment, army svy regt, fortuna, asr, aerodist, surveying, central comd fd svy unit