A fluorescent screen seen with an illuminated scale shows the wavelength(s) of entering light. A Cylindrical Quartz Lens is provided to concentrate on the slit light from weak sources. The scale is illuminated by regular white light through a window. Ultra Violet Spectroscope. A black finished device with adjustable aperture in a storage box with eyepiece shield and clamping screw. scientific instrument, balance, spectoscope, ultra violet spectroscope, prism

The M6 was the standard periscope used on the Sherman tanks. There are two large prisms assembled in each end of a metal shell. Frequent problems with moisture and condensation resulted in the development of a new periscope made from a solid block of plastic with a reflecting surface at each end.Wartime significance.Sherman Tank Periscope Type : M6.Periscope M6. Minneapolis - Honeywell Regulator Company. #96812 1942. D.A.

Margaret MitchellA rare and vintage gold painted metal Designoscope or Kaleidoscope with a prism and turntable for creating a kaleidoscopic effect. It is very rusted and worn. It has a triangular metal tube and a heavy base. It was designed for artists and illustrators rather than children. It has a coloured separate label."Designoscope British Made"kaleidoscopes, leisure object, optical toys

A prismatic compass is a common navigation and surveying instrument which was used extensively by the Forests Commission The compass most commonly used to run a traverse line. The compass calculates bearings of lines with respect to magnetic needle. A magnetic deviation correction was needed to convert the reading to a true bearing The compass could also determine angles between the traverse and waypoints (such as hilltop features). Commonly used for navigation. Largely replaced by modern GPS technology.Ex Army WW2 prismatic compass with leather case and strap. Rugged design and made of metal the internal compass plate floats on oil to help it stabilise The user lines up the direction of travel with the hair sightline in the fliptop cover and readings are taken through the viewfinder prism (hence the name).forest measurement, surveying, forests commission victoria (fcv)

William Thomson described a new "Marine Azimuth Mirror" at the 1877 meeting of the British Association for the Advancement of Science, and patented the design in Britain and the U.S. This instrument is an example of the improved design, with a reflecting prism in place of the original mirror. Thomson introduced this form in the early 1880s. The signature indicates that it was made during the period 1900-1913. A child prodigy, William Thomson went to university at the age of eleven. At twenty-two he was appointed Professor of Natural Philosophy in Glasgow where he set up the first physics laboratory in Great Britain and proved an inspiring teacher. He primarily researched thermodynamics and electricity. On the practical side he was involved in the laying of the Atlantic telegraph cable. He was also the partner of a Glasgow firm that made measuring instruments from his own patents.An instrument of significant importance which made marine navigation easier and more accurate in the early twentieth century.An Azimuth mirror with wooden box.Kelvin & Hughs Ltd Serial No - illegible Made in Great Britainazimuth mirror, william thompson, lord kelvin, naviagtion, marine instruments

Small Binoculars Signal Corps U.S. Army. Metal with rubber eye protector Imitation leather cover with leather strap.SIGNAL CORPS,US.ARMY 1449 on front left lens piece, Serial No EE 73984 AM 6E/360 on front right lens piece. Circle with " Prism Stereo 30 ml Apart Power" written inside on back left side of lens piece. Circle with "Bausch & Lomb Optical Co.( Triangle in middle with USA inside) Rochester NY. " written inside on back right side of lens piece.

Foresters usually measure the diameter of trees at Breast Height – traditionally 4 foot, 6 inches – now 1.3 m – which is termed Diameter Breast Height Over Bark (DBHOB). Basal Area is the cross section of the tree trunk at breast height, and the sum for the stand or group of trees is expressed square feet per acre (after 1973 it was expressed in square metres per hectare). Lots of skinny trees, or a few fat ones, can have the same Basal Area, but when combined with the number of stems, Basal Area is a good indicator of stand density. Two common methods are used to measure of Basal Area – fixed area plots and angle count sampling. 1. Fixed area plots require setting out a small area, commonly 50 m x 20 m, and measuring all the trees at breast height, and doing some quick sums. 2. Angle count sampling involves a simple sweep of the forest from a fixed sampling point using a relascope, dendrometer sight, angle gauge, or glass wedge prism. This wooden builders ruler has been shaped at one end to create a shallow angle (usually less than 3 degrees). Standing in one spot, a sweep is made with the wedge held to the eye, and trees are counted as either “in” or “out”. The number of trees is multiplied by conversion factor of the wedge (10 in this case) to estimate basal area. It’s very quick and effective.Basal Area Angle Gauge The two ends fold up and one end (on the right) has been reduced in width to create a shallow angle for the viewer Home made by cutting down a wooden builder's ruler Many forestry students made their own Basal Area Angle Gauges and its thought this may be oneforest measurement, forests commission victoria (fcv)

The Living and the Dead reveals the Vietnam War as it has never been seen before - through the prism of the crucial, tangled decisions made by one man, US secretary of defense Robert McNamara. It illuminates those decisionby revealing the man; by turns cold and emotionally trumultuous; the numbers-worshipper who came to believe that the war tearing America apart was wrong, but continued to support its escalation.vietnam war, 1961-1975 - united states

The Living and the Dead reveals the Vietnam War as it has never been seen before - through the prism of the crucial, tangled decisions made by one man, US secretary of defense Robert McNamara. It illuminates those decisionby revealing the man; by turns cold and emotionally tumultruous; the numbers-worshipper who came to believe that the war tearing America apart was wrong, but continued to support its escalation. vietnam war, 1961-1975 - united states

The Living and the Dead reveals the Vietnam War as it has never been seen before - through the prism of the crucial, tangled decisions made by one man, US secretary of defense Robert McNamara. It illuminates those decisionby revealing the man; by turns cold and emotionally trumultuous; the numbers-worshipper who came to believe that the war tearing America apart was wrong, but continued to support its escalation. vietnam war, 1961-1975 - united states