Eyepiece ramsden eyepiece. Another old design, invented by the English instrumentmakerJesse ramsden (1735-1800) in 1782. In this case, the two plano-convex lens http://www.daviddarling.info/encyclopedia/E/eyepiece.html
Extractions: A combination of lenses, also known as an ocular , used to magnify the image formed by the objective of a telescope . In practice, eyepieces contain at least two lenses: the field lens , which faces the objective and collects the light from it, and the eyelens , which faces the observer and magnifies the image. A field stop (a circular aperture) inside the eyepiece limits the field of view , helping to give it a sharp edge. There are various types of eyepiece design, from very simple achromatic lenses to complex eyepieces with many optical elements. Usually, the more complex an eyepiece, the more optical corrections, and the better eye relief and wider field of view. On the other hand, adding many glass surfaces dims the image and may also increase internal reflections, or ghosting. OPTICS AND OPTICAL PHENOMENA
Extractions: var GLB_RIS='http://www.economicexpert.com';var GLB_RIR='/cincshared/external';var GLB_MMS='http://www.economicexpert.com';var GLB_MIR='/site/image';GLB_MML='/'; document.write(''); document.write(''); document.write(''); document.write(''); A1('s',':','html'); Non User A B C ... A chain can be any of the following: keeping together to avoid falling apart, drifting away, theft , fleeing (of a prisoner) jewellery a mathematical term used in algebraic topology a totally ordered subset of a partially ordered set , used in set theory a measure of length within the Imperial system of measurement , the chain equal to 22 yard This article is about the unit of measure known as the yard''. For other definitions, see Yard (disambiguation). A yard (abbr. yd is an imperial unit of length, defined as 3 feet or 36 inches, which is exactly 0. 9144 metres, presuming international inche s, formerly used in
Biography-center - Letter R www.treasuretroves.com/bios/ Ramsay.html; ramsden, Jessewww -history.mcs.st-and.ac.uk/~history/Mathematicians/ramsden.html; Ramsey, Frank http://www.biography-center.com/r.html
Extractions: random biography ! Any language Arabic Bulgarian Catalan Chinese (Simplified) Chinese (Traditional) Croatian Czech Danish Dutch English Estonian Finnish French German Greek Hebrew Hungarian Icelandic Indonesian Italian Japanese Korean Latvian Lithuanian Norwegian Polish Portuguese Romanian Russian Serbian Slovak Slovenian Spanish Swedish Turkish 505 biographies R abinow, Jacob
- Port Cities open frame design to reduce weight and wind resistance when in use. CreatorJesse ramsden. Date c1785. Credit line National Maritime Museum, London http://www.portcities.org.uk/london/server/change/storyInPictures/contentType/Co
Extractions: UK Bristol Hartlepool Liverpool ... Feedback Explore this site Browse the site by time About maritime London Early port Tudor and Stuart port 18th-century port ... 20th-century port Browse the site by topic People and places Port communities Crime and punishment Leisure, health and housing ... Send an e-card 2 of 5 Pictures Repro ID: Description: The sextant was first made in the late 1850s by the London instrument maker John Bird, then one of the finest makers in the city. He was commissioned to produce an instrument similar to the octant with a wider field of measurement. Like the octant, the sextant enables the angular distance between two points to be measured, for instance the Sun and the horizon or two stars. This example was made by one of the great instrument makers of the 18th century, Jesse Ramsden. The sextant is usually made of brass and has a very open frame design to reduce weight and wind resistance when in use. Creator: Jesse Ramsden Date: Credit line: National Maritime Museum, London Search
