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St. George Reef Lighthouse
The St. George Reef Light is an inactive lighthouse built on North West Seal Rock, six miles (10 km) off the coast of northern California near Crescent City. Location The St. George Reef Light is a wave-washed lighthouse, one where the ocean hits from all sides. The location of the light on North West Seal Rock, part of the line of "Dragon Rocks" thus named by Sir Francis Drake, was selected after numerous accidents and the wreck of the overloaded ''Brother Jonathan'' on July 30, 1865. The loss of prominent people on the steamer was an impetus to the light's approval; nonetheless, it took until 1892 to complete due to the changing availability of federal construction funds. Unlike the typical lighthouse design by federal architect Ammi B. Young, which consisted of a separate keeper's cottage and light tower, the living quarters and light tower at St. George Reef Light were housed in the same medieval fortress-like structure on top of a high foundation. Construction The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fresnel Lens
A Fresnel lens ( ; ; or ) is a type of composite compact lens developed by the French physicist Augustin-Jean Fresnel (1788–1827) for use in lighthouses. It has been called "the invention that saved a million ships." The 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 and add it to the beam of a lighthouse, making the light visible from greater distances. Description The Fresnel lens redu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Humboldt Bay Life-Saving Station
The Humboldt Bay Life-Saving Station was originally built in November 1878 on the north side of the entrance to Humboldt Bay in northern California, United States near Eureka, adjacent to the site of the first Humboldt Harbor Light (1856–1892). Rebuilt in 1936 with marine railways to launch rescue surfboats, the historic facility was placed on the National Register of Historic Places on October 30, 1979. The station continues to function as an important asset of the United States Coast Guard in the Coast Guard Group/Air Station Humboldt Bay. History Early history Humboldt Bay was listed as one of the most dangerous harbor entrances in California due to the narrow wide channel with tidal currents and shifting sandbars plus unpredictable weather with high winds and heavy fog. In 1851, the United States Congress appropriated $15,000 for the Humboldt Harbor Light which entered service in 1856. The vegetable oil burning light shone from a tall tower whose keeper lived in a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lighthouses Completed In 1891
A lighthouse is a tower, building, or other type of physical structure designed to emit light from a system of lamps and lenses and to serve as a beacon for navigational aid, for maritime pilots at sea or on inland waterways. Lighthouses mark dangerous coastlines, hazardous shoals, reefs, rocks, and safe entries to harbors; they also assist in aerial navigation. Once widely used, the number of operational lighthouses has declined due to the expense of maintenance and has become uneconomical since the advent of much cheaper, more sophisticated and effective electronic navigational systems. History Ancient lighthouses Before the development of clearly defined ports, mariners were guided by fires built on hilltops. Since elevating the fire would improve the visibility, placing the fire on a platform became a practice that led to the development of the lighthouse. In antiquity, the lighthouse functioned more as an entrance marker to ports than as a warning signal for reefs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
History Of Del Norte County, California
), in California , seat_type = County seat , seat = Crescent City , parts_type = Largest city , parts = Crescent City , unit_pref = US , area_total_sq_mi = 1230 , area_land_sq_mi = 1006 , area_water_sq_mi = 223 , elevation_max_footnotes = , elevation_max_ft = 6415 , elevation_min_footnotes = , elevation_min_ft = , population_as_of = April 1, 2020 , population_footnotes = , population_total = 27743 , population_density_sq_mi = 28 , timezone = Pacific Time Zone , utc_offset = −8 , timezone_DST = Pacific Daylight Time , utc_offset_DST = −7 , postal_code_type = , postal_code = , area_code_type = Area codes , area_code = 707 , blank_name_sec1 = FIPS code , blank_info_sec1 = 06-015 , blank1_name_sec1 = GNIS feature ID , blank1_info_sec1 = , website = Del Norte County (''Del Norte'', Spanish for "Of The North"; ) is a county at the far northwest corner of the U.S. state of California, along the Pacific Ocean adjacent to the Oregon bor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Buildings And Structures In Del Norte County, California
A building, or edifice, is an enclosed structure with a roof and walls standing more or less permanently in one place, such as a house or factory (although there's also portable buildings). Buildings come in a variety of sizes, shapes, and functions, and have been adapted throughout history for a wide number of factors, from building materials available, to weather conditions, land prices, ground conditions, specific uses, prestige, and aesthetic reasons. To better understand the term ''building'' compare the list of nonbuilding structures. Buildings serve several societal needs – primarily as shelter from weather, security, living space, privacy, to store belongings, and to comfortably live and work. A building as a shelter represents a physical division of the human habitat (a place of comfort and safety) and the ''outside'' (a place that at times may be harsh and harmful). Ever since the first cave paintings, buildings have also become objects or canvasses of much artistic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lighthouses On The National Register Of Historic Places In California
A lighthouse is a tower, building, or other type of physical structure designed to emit light from a system of lamps and lenses and to serve as a beacon for navigational aid, for maritime pilots at sea or on inland waterways. Lighthouses mark dangerous coastlines, hazardous shoals, reefs, rocks, and safe entries to harbors; they also assist in aerial navigation. Once widely used, the number of operational lighthouses has declined due to the expense of maintenance and has become uneconomical since the advent of much cheaper, more sophisticated and effective electronic navigational systems. History Ancient lighthouses Before the development of clearly defined ports, mariners were guided by fires built on hilltops. Since elevating the fire would improve the visibility, placing the fire on a platform became a practice that led to the development of the lighthouse. In antiquity, the lighthouse functioned more as an entrance marker to ports than as a warning signal for reefs a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Register Of Historic Places Listings In Del Norte County, California
__NOTOC__ This is a list of the National Register of Historic Places listings in Del Norte County, California. This is intended to be a complete list of the properties and districts on the National Register of Historic Places in Del Norte County, California, United States. Latitude and longitude coordinates are provided for many National Register properties and districts; these locations may be seen together in a Google map. There are 14 properties and districts listed on the National Register in the county. Current listings See also *List of National Historic Landmarks in California *National Register of Historic Places listings in California *California Historical Landmarks in Del Norte County, California This list includes properties and districts listed on the California Historical Landmark listing in Del Norte County, California. Click the "Map of all coordinates" link to the right to view a Google map of all properties and districts with latitud ... ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Lighthouses In The United States
This is a list of lighthouses in the United States. The United States has had approximately a thousand lights as well as light towers, range lights, and pier head lights. Michigan has the most lights of any state with over 150 past and present lights. Lighthouses that are in former U.S. territories are not listed here. Most of the lights in the United States have been built and maintained by the Coast Guard (since 1939) and its predecessors, the United States Lighthouse Service (1910–1939) and the United States Lighthouse Board (1852–1910). Before the Lighthouse Board was established, local collectors of customs were responsible for lighthouses under Stephen Pleasonton. As their importance to navigation has declined and as public interest in them has increased, the Coast Guard has been handing over ownership and in some cases responsibility for running them to other parties, the chief of them being the National Park Service under the National Historic Lighthouse Preservation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Candela
The candela ( or ; symbol: cd) is the unit of luminous intensity in the International System of Units (SI). It measures luminous power per unit solid angle emitted by a light source in a particular direction. Luminous intensity is analogous to radiant intensity, but instead of simply adding up the contributions of every wavelength of light in the source's spectrum, the contribution of each wavelength is weighted by the standard luminosity function (a model of the sensitivity of the human eye to different wavelengths). A common wax candle emits light with a luminous intensity of roughly one candela. If emission in some directions is blocked by an opaque barrier, the emission would still be approximately one candela in the directions that are not obscured. The word ''candela'' is Latin for ''candle''. The old name "candle" is still sometimes used, as in ''foot-candle'' and the modern definition of ''candlepower''. Definition The 26th General Conference on Weights and Measures (C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Register Of Historic Places
The National Register of Historic Places (NRHP) is the United States federal government's official list of districts, sites, buildings, structures and objects deemed worthy of preservation for their historical significance or "great artistic value". A property listed in the National Register, or located within a National Register Historic District, may qualify for tax incentives derived from the total value of expenses incurred in preserving the property. The passage of the National Historic Preservation Act (NHPA) in 1966 established the National Register and the process for adding properties to it. Of the more than one and a half million properties on the National Register, 95,000 are listed individually. The remainder are contributing resources within historic districts. For most of its history, the National Register has been administered by the National Park Service (NPS), an agency within the U.S. Department of the Interior. Its goals are to help property owners and inte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Humboldt Bay
Humboldt Bay is a natural bay and a multi-basin, bar-built coastal lagoon located on the rugged North Coast of California, entirely within Humboldt County, United States. It is the largest protected body of water on the West Coast between San Francisco Bay and Puget Sound, the second-largest enclosed bay in California, and the largest port between San Francisco and Coos Bay, Oregon. The largest city adjoining the bay is Eureka, the regional center and county seat of Humboldt County, followed by the city of Arcata. These primary cities, together with adjoining unincorporated communities and several small towns, comprise a Humboldt Bay Area with a total population of nearly 80,000 people. This comprises nearly 60% of the population of Humboldt County. The bay is home to more than 100 plant species, 300 invertebrate species, 100 fish species, and 200 bird species. In addition, the bay and its complex system of marshes and grasses support hundreds of thousands of migrating and l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lighthouse
A lighthouse is a tower, building, or other type of physical structure designed to emit light from a system of lamps and lenses and to serve as a beacon for navigational aid, for maritime pilots at sea or on inland waterways. Lighthouses mark dangerous coastlines, hazardous shoals, reefs, rocks, and safe entries to harbors; they also assist in aerial navigation. Once widely used, the number of operational lighthouses has declined due to the expense of maintenance and has become uneconomical since the advent of much cheaper, more sophisticated and effective electronic navigational systems. History Ancient lighthouses Before the development of clearly defined ports, mariners were guided by fires built on hilltops. Since elevating the fire would improve the visibility, placing the fire on a platform became a practice that led to the development of the lighthouse. In antiquity, the lighthouse functioned more as an entrance marker to ports than as a warning signal for reefs a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
