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Navicula De Venetiis
A navicula de Venetiis or "little ship of Venice" was an altitude dial used to tell time and which was shaped like a little ship. The cursor (with a plumb line attached) was slid up/down the mast to the correct latitude. The user then sighted the sun through the pair of sighting holes at either end of the "ship's deck". The plumb line then marked what hour of the day it was. Some naviculas had additional information inscribed, such as the latitude of some common English towns, some zodiac signs, etc. References {{Tech-stub Sundials ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Navicula De Venetiis-MHS 2139-P7220157-gradient
''Navicula'' is a genus of boat-shaped diatom algae, comprising over 1,200 species. ''Navicula'' is Latin for "small ship", and also a term in English for a boat-shaped incense-holder. Diatoms — eukaryotic, primarily aquatic, single-celled photosynthetic organisms — play an important role in global ecology, producing about a quarter of all the oxygen within Earth's biosphere, often serving as foundational organisms, or keystone species in the food chain of many environments where they provide a staple for the diets of many aquatic species. Mobility ''Navicula'' diatoms have been observed to possess a motile ability to glide over one another and on hard surfaces such as microscope slides. Around the outside of the navicula's shell is a girdle of mucilage strands that can flow and thus act as a tank track. File:Navicula tripunctata 2.jpg, ''Navicula tripunctata''type species In zoological nomenclature, a type species (''species typica'') is the species name with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sundial
A sundial is a horological device that tells the time of day (referred to as civil time in modern usage) when direct sunlight shines by the apparent position of the Sun in the sky. In the narrowest sense of the word, it consists of a flat plate (the ''dial'') and a gnomon, which casts a shadow onto the dial. As the Sun appears to move through the sky, the shadow aligns with different hour-lines, which are marked on the dial to indicate the time of day. The ''style'' is the time-telling edge of the gnomon, though a single point or ''nodus'' may be used. The gnomon casts a broad shadow; the shadow of the style shows the time. The gnomon may be a rod, wire, or elaborately decorated metal casting. The style must be parallel to the axis of the Earth's rotation for the sundial to be accurate throughout the year. The style's angle from horizontal is equal to the sundial's geographical latitude. The term ''sundial'' can refer to any device that uses the Sun's altitude or az ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plumb Line
A plumb bob, plumb bob level, or plummet, is a weight, usually with a pointed tip on the bottom, suspended from a string and used as a vertical reference line, or plumb-line. It is a precursor to the spirit level and used to establish a vertical datum. It is typically made of stone, wood, or lead, but can also be made of other metals. If it is used for decoration, it may be made of bone or ivory. The instrument has been used since at least the time of ancient EgyptDenys A. Stocks. Experiments in Egyptian archaeology: stoneworking technology in ncient Egypt'. Routledge; 2003. . p. 180. to ensure that constructions are " plumb", or vertical. It is also used in surveying, to establish the nadir with respect to gravity of a point in space. It is used with a variety of instruments (including levels, theodolites, and steel tapes) to set the instrument exactly over a fixed survey marker or to transcribe positions onto the ground for placing a marker. Etymology The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
