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A drawing of the locks, used for raising and lowering boats, on the Erie Canal.

Locks on the Erie Canal

A drawing of the locks, used for raising and lowering boats, on the Erie Canal.

The Church of England parish church of St Michael was built in 1293, supposedly to replace a Saxon church at Water Oakley. It has a number of sculptures which may have come from th earlier church, including a damaged Sheela na Gig. It is best known to brass rubbers for housing the superb memorial brass of 1378 to Sir John Foxley, the Constable of Southampton Castle, and his two wives. One of the local cottages has a tunnel which it is believed leads to the church and served as an escape route for clergymen.

Bray Church, Near Maidenhead, Berks

The Church of England parish church of St Michael was built in 1293, supposedly to replace a Saxon church…

An illustration of Biscayne Bay, is a lagoon that is approximately 35 miles (56 km) long and up to 8 miles (13 km) wide located on the Atlantic coast of south Florida. It is usually divided for purposes of discussion and analysis into three parts, North Bay, Central Bay and South Bay. North Bay separates Miami Beach on its barrier island from Miami on the mainland. It has been severely affected over the last century by raw sewage releases, urban runoff, shoreline bulkheading, dredging, the creation of artificial islands and the loss of natural fresh water flow into the bay. North Bay accounts for only 10% of the water area of the bay. Central Bay is the largest part of the bay. It is separated from the Atlantic Ocean by the Safety Valve, a series of shallow flats separated by tidal flow channels, stretching from the south end of Key Biscayne to the Ragged Keys at the north end of the Florida Keys. It has been adversely affected primarily by bulkheading, urban runoff discharged by canals, and the loss of natural fresh water flow. South Bay is nearly as large as Central Bay, and is the least affected by human activities, although it also suffers from the loss of natural fresh water flow. South Bay is separated from the Atlantic Ocean by the northernmost of the Florida Keys, and is connected to Florida Bay through channels and "sounds" lying between the mainland and the keys.

Biscayne Bay

An illustration of Biscayne Bay, is a lagoon that is approximately 35 miles (56 km) long and up to 8…

The Everglades is a subtropical wetland located in the southern portion of the U.S. state of Florida, comprising the southern half of a large watershed. The system begins near Orlando with the Kissimmee River, which discharges into the vast but shallow Lake Okeechobee. Water leaving the lake in the wet season forms a slow-moving river 60 miles (97 km) wide and over 100 miles (160 km) long, flowing southward across a limestone shelf to Florida Bay at the southern end of the state. The ever-changing Everglades are shaped by water and fire, with frequent flooding in the wet season and drought in the dry season.

Everglades

The Everglades is a subtropical wetland located in the southern portion of the U.S. state of Florida,…

Manatees are large, fully aquatic marine mammals sometimes known as sea cows. The name manatí comes from the Taíno, a pre-Columbian people of the Caribbean, meaning "breast".

Manatee on Shore

Manatees are large, fully aquatic marine mammals sometimes known as sea cows. The name manatí…

An illustration of Fort Jefferson which is located today in what is Dry Tortugas National Park. Dry Tortugas National Park preserves Fort Jefferson and the Dry Tortugas section of the Florida Keys. The park covers 101 mi² (262 km²), mostly water, about 68 statute miles (109 km) west of Key West in the Gulf of Mexico.

Fort Jefferson

An illustration of Fort Jefferson which is located today in what is Dry Tortugas National Park. Dry…

General Jacob Brown made camp at French Creek on October 29th, 1813. Brown's force was the advance guard of General Wilkinson's army marching on Montreal.

Mouth of French Creek

General Jacob Brown made camp at French Creek on October 29th, 1813. Brown's force was the advance guard…

A drawing of the Mississippi River with high water.

Mississippi River, High water

A drawing of the Mississippi River with high water.

A drawing of the Mississippi River with low water.

Mississippi River, Low Water

A drawing of the Mississippi River with low water.

The totem or emblem of the Huron, a Native American tribe has a beaver on top of a log in the water.

Huron Totem

The totem or emblem of the Huron, a Native American tribe has a beaver on top of a log in the water.

The first completely automated loom was made by Jacques Vaucanson in 1745. A different power loom was built by Edmund Cartwright in 1785. Originally, powered looms were shuttle-operated but in the early part of the 20th century the faster and more efficient shuttleless loom came into use. Today, advances in technology have produced a variety of looms designed to maximize production for specific types of material. The most common of these are air-jet looms and water-jet looms. Computer-driven looms are now also available to individual (non-industrial) weavers. Industrial looms can weave at speeds of six rows per second and faster.

Loom

The first completely automated loom was made by Jacques Vaucanson in 1745. A different power loom was…

The typical representation of shore lines and low-water lines with tidal flats of any kind on a topographical map.

Tidal Flats of any Kind

The typical representation of shore lines and low-water lines with tidal flats of any kind on a topographical…

The typical representation of shores and low-water lines with rocky ledges on a topographical map.

Rocky Ledges

The typical representation of shores and low-water lines with rocky ledges on a topographical map.

The typical representation of shores and low-water lines with sand on a topographical map.

Sand

The typical representation of shores and low-water lines with sand on a topographical map.

The typical representation of shores and low-water lines with gravel and rocks on a topographical map.

Gravel and Rocks

The typical representation of shores and low-water lines with gravel and rocks on a topographical map.

The typical representation of shores and low-water lines with mud on a topographical map.

Mud

The typical representation of shores and low-water lines with mud on a topographical map.

A trip hammer resembles a hand-hammer held in a horizontal position. The hammer is placed at the end of a heavy beam pivoted near the opposite end. By means of simple machinery the handle was raised and then "tripped" or let fall, when the hammer-head delivered its blow upon the anvil. They were at first operated by water power, but later by steam power.

Horizontal Steam Power Hammer

A trip hammer resembles a hand-hammer held in a horizontal position. The hammer is placed at the end…

A samovar (literally, self-boiler) is an urn kept at the table to heat and boil water in Russia, commonly used to make tea.

Samovar

A samovar (literally, self-boiler) is an urn kept at the table to heat and boil water in Russia, commonly…

An illustration of a crowded promenade. An esplanade is a long, open, level area, usually next to a river or large body of water, where people may walk. This allows people to promenade along the sea front, usually for recreational purposes, whatever the state of the tide, without having to walk on the beach. Esplanades became popular in Victorian times when it was fashionable to visit seaside resorts. The original meaning of esplanade was a large, open, level area outside fortress or city walls. Esplanade and promenade are sometimes used interchangeably, but that is a mistake. A promenade can be anywhere, and it is exclusively for walking, while an esplanade is for walking but also can include large boulevards or avenues with cars.

Promenade

An illustration of a crowded promenade. An esplanade is a long, open, level area, usually next to a…

A torpedo boat is a relatively small and fast naval ship designed to carry torpedoes into battle. <br>Top: A, platform; B, torpedo; C, water tight pine box; D, pin to be drawn. <br>Lower: A, vessel at anchor; B, her cable; E, F, two torpedoes; C, D, the coupling lines.

Torpedo Boat

A torpedo boat is a relatively small and fast naval ship designed to carry torpedoes into battle. Top:…

The torpedoes used by the Confederates were various in form and construction. The most efficient ones were the galvanic and percussion. The percussion or "sensitive" ones exploded by the act of forcible contact. Some of these were made in the form of a double cone, with percussion tubes arranged around the cylinder thus formed, at the point of contact of the bases of the cones.

Percussion Torpedo

The torpedoes used by the Confederates were various in form and construction. The most efficient ones…

The steam-vessels were protected by torpedo-nets formed of ropes weighted with iron or lead, and furnished with hooks to catch the little submarine mines. These nets were hung from spars placed athwart the bowsprit in front of the vessel, and sometimes in like manner along its sides.

Torpedo Net

The steam-vessels were protected by torpedo-nets formed of ropes weighted with iron or lead, and furnished…

Valvule conniventes. A, as seen in a bit of jejunum which has been filled with alcohol and hardened. B, a portion of fresh intestine spread out under water.

Valvule Conniventes

Valvule conniventes. A, as seen in a bit of jejunum which has been filled with alcohol and hardened.…

Predaceous diving beetles is a family of water beetles. They are about 25 mm (one inch) long on average, though there is much variation between species. Dytiscus latissimus, the largest, can grow up to 45 mm long. Most are dark brown, blackish or dark olive in color with golden highlights in some subfamilies. They have short, but sharp mandibles. Immediately upon biting they deliver digestive enzymes. The larvae are commonly known as water tigers. The family has not been comprehensively cataloged since 1920, but is estimated to include about 4,000 species in over 160 genera.

Predaceous Beetle

Predaceous diving beetles is a family of water beetles. They are about 25 mm (one inch) long on average,…

Predaceous diving beetles is a family of water beetles. They are about 25 mm (one inch) long on average, though there is much variation between species. Dytiscus latissimus, the largest, can grow up to 45 mm long. Most are dark brown, blackish or dark olive in color with golden highlights in some subfamilies. They have short, but sharp mandibles. Immediately upon biting they deliver digestive enzymes. The larvae are commonly known as water tigers. The family has not been comprehensively cataloged since 1920, but is estimated to include about 4,000 species in over 160 genera.

Predaceous Beetle

Predaceous diving beetles is a family of water beetles. They are about 25 mm (one inch) long on average,…

"Battle ground at Concord. This view, looking southeast, is from the road leading to the village, by the way of the North Bridge, to the residence of Mr. Prescott Barrett. The point from which the sketch was made is upon an elevation a little north of that where the militia assembled under Colonel Barrett. The stream of water is the Concord, or Sudbury River. The site of the North Bridge is at the monument seen in the center of the picture. The monument stands upon the spot where the British were stationed, and in the plain, directly across the river from the monument, is the place where Davis and Hosmer, of the American militia, were killed. The house, the roof and gable of which are seen in the distance, just on the left of the largest tree, was the residence of the Reverend Dr. Ripley (afterward a chaplain in the army) at the time of the skirmish. It is upon the road elading to Concord village, which lies nearly half a mile beyond."—Lossing, 1851

Battleground at Concord

"Battle ground at Concord. This view, looking southeast, is from the road leading to the village, by…

The Congressional Life Saving Medal (in gold and silver) was authorized by an Act of Congress on June 20, 1874 to be bestowed to a U.S Citizen who rescues or attempts the rescue of any person from drowning, shipwreck or other peril of the water, or to the rescuer of a U.S. citizen.

Life Saving medal

The Congressional Life Saving Medal (in gold and silver) was authorized by an Act of Congress on June…

"Flowering branch of Lizardtail (Saururus cernuus). a, flower." -Whitney, 1911

Lizard's Tail

"Flowering branch of Lizardtail (Saururus cernuus). a, flower." -Whitney, 1911

The saury or skipper (Scomberesox saurus) is a tropical fish known for jumping and skimming the water.

Saury

The saury or skipper (Scomberesox saurus) is a tropical fish known for jumping and skimming the water.

Anoa are a subgenus of buffalo comprising two species native to Indonesia: the Mountain Anoa (Bubalus quarlesi) and the Lowland Anoa (Bubalus depressicornis). Both live in undisturbed forest, and are essentially miniature water buffalo, are similar in appearance to a deer, weighing 150&ndash;300 kg (330&ndash;660 lb). They live in deep rainforests.

Anoa

Anoa are a subgenus of buffalo comprising two species native to Indonesia: the Mountain Anoa (Bubalus…

The American Bison (Bison bison) is a bovine mammal, also commonly known as the American buffalo. 'Buffalo' is something of a misnomer for this animal as it is only distantly related to either of the two "true buffaloes", the water buffalo and the African Buffalo. The bison once inhabited the Grasslands of the United States and Asia in massive herds, ranging from the Great Slave Lake in Canada's far north to Mexico in the south, and from eastern Oregon almost to the Atlantic Ocean, taking its subspecies into account. Its two subspecies are the Plains Bison (Bison bison bison), distinguished by its smaller size and more rounded hump, and the Wood Bison (Bison bison athabascae), distinguished by its larger size and taller square hump. Wood Bison are one of the largest species of cattle in the world, surpassed in size only by the massive Asian gaur and Wild Asian Water Buffalo, both of which are found mainly in India and Southeast Asia.

North American Bison

The American Bison (Bison bison) is a bovine mammal, also commonly known as the American buffalo. 'Buffalo'…

The Domestic Water Buffalo or Domestic Asian Water buffalo (Bubalus bubalis) is abundant in Asia, and widely used in South America, southern Europe and elsewhere. It is a large ungulate and a member of the bovine subfamily. There are established feral populations in northern Australia but the dwindling true wild populations are thought to survive in India, Nepal, Bhutan and Thailand. All the domestic varieties and breeds descend from one common ancestor, the wild Asian water buffalo, which is now an endangered species.

Domestic Water Buffalo

The Domestic Water Buffalo or Domestic Asian Water buffalo (Bubalus bubalis) is abundant in Asia, and…

The Anabantidae are a family of perciform fish commonly called the climbing gouramies or climbing perches. As labyrinth fishes, they possess a labyrinth organ, a structure in the fish's head which allows them to breathe atmospheric oxygen. Fish of this family are commonly seen gulping at air at the surface of the water; which then passes out of their gills or mouth when they dive beneath the surface

Climbing Perch

The Anabantidae are a family of perciform fish commonly called the climbing gouramies or climbing perches.…

Coots , are medium-sized water birds which are members of the rail family Rallidae. They constitute the genus Fulica. Coots have predominantly black plumage, and, unlike many of the rails, they are usually easy to see, often swimming in open water. They are close relatives of the moorhen. The greatest species variety is in South America, and it is likely that the genus originated there. They are common in Europe and North America.

Coot

Coots , are medium-sized water birds which are members of the rail family Rallidae. They constitute…

The Dungeness crab is a species of crab that inhabits eelgrass beds and water bottoms from the Aleutian Islands in Alaska to Santa Cruz, California. Its binomial name, Cancer magister, simply means "master crab" in Latin. They measure as much as 25 cm (10 inches) in some areas off the coast of Washington, but typically are under 20 cm (8 inches). They are a popular delicacy, and are the most commercially important crab in the Pacific Northwest, as well as the western states generally.

Dungeness Crab

The Dungeness crab is a species of crab that inhabits eelgrass beds and water bottoms from the Aleutian…

Crayfish, crawfish, or crawdads are freshwater crustaceans resembling small lobsters, to which they are closely related. They breathe through feather-like gills and are found in bodies of water that do not freeze to the bottom; they are also mostly found in brooks and streams where there is fresh water running, and which have shelter against predators. Most crawfish cannot tolerate polluted water, although some species such as the invasive Procambarus clarkii are more hardy. Some crayfish have been found living as much as 3 m (10 feet) underground.

Crawfish

Crayfish, crawfish, or crawdads are freshwater crustaceans resembling small lobsters, to which they…

A floating dock is a platform or ramp supported by pontoons. These are usually joined to the shore with a ramp that rests upon the dock on rollers, to adjust for the vertical movement of the dock. The dock is usually held in place by vertical poles embedded in the soil under the water or by anchored cables. Frequently used in marinas for small boats, this type of dock maintains a fixed vertical relationship to watercraft secured to it, independent of tidal, river, or lake elevation. It is less suited for larger craft as the docks cannot support large structures or cranes. In some regions of the world, a floating dock is called a pontoon.

Floating-dock

A floating dock is a platform or ramp supported by pontoons. These are usually joined to the shore with…

The Bald Eagle (Haliaeetus leucocephalus) is a bird of prey found in North America that is most recognizable as the national bird and symbol of the United States of America. This sea eagle has two known sub-species and forms a species pair with the White-tailed Eagle. Its range includes most of Canada and Alaska, all of the contiguous United States and northern Mexico. It is found near large bodies of open water with an abundant food supply and old-growth trees for nesting.

Bald Eagle

The Bald Eagle (Haliaeetus leucocephalus) is a bird of prey found in North America that is most recognizable…

Wentworth-Coolidge Mansion is a 40 room clapboard house. It was declared a National Historic Landmark in 1968. The site is a New Hampshire state park. It is located on the water at 375 Little Harbor Road, about 2 miles southeast of the center of Portsmouth.

Wentworth Mansion

Wentworth-Coolidge Mansion is a 40 room clapboard house. It was declared a National Historic Landmark…

"Hydraulic Scroll. a, case, inclosing center-discharge turbine water-wheel; b, openings for inflow of water; c, c', gates for admitting water to central wheel-space d (the wheel is not shown); e, e', gate-shafts; f, shaft by which the two gates are operated simultaneously and equally from worm-gearing at the top of the gate-shafts." -Whitney, 1911

Hydraulic Scroll

"Hydraulic Scroll. a, case, inclosing center-discharge turbine water-wheel; b, openings for inflow of…

The Goldfish, Carassius auratus, was one of the earliest fish to be domesticated, and is still one of the most commonly kept aquarium fish and water garden fish. A relatively small member of the carp family, the goldfish is a domesticated version of a dark-gray/brown carp native to East Asia. It was first domesticated in China and introduced to Europe in the late 17th century. Goldfish can grow to a maximum length of 23 inches (159 cm) and a maximum weight of 9.9 pounds (4.5 kg), although this is rare; few goldfish reach even half this size. The oldest recorded goldfish lived to 49 years, but most household goldfish generally live only six to eight years, due to being kept in bowls.

Gold Fish

The Goldfish, Carassius auratus, was one of the earliest fish to be domesticated, and is still one of…

Anglerfish are the members of the order Lophiiformes. They are bony fish named for their characteristic mode of predation, wherein a fleshy growth from the fish's head (the esca) acts as a lure; this is considered analogous to angling. Some anglerfish are pelagic (live in the open water), others are benthic (bottom-dwelling). Some live in the deep sea (e.g. Ceratiidae) and others on the continental shelf (e.g. the frogfishes Antennariidae and the monkfish/goosefish Lophiidae). They occur worldwide. Pelagic forms are most laterally (sideways) compressed whereas the benthic forms are often extremely dorsoventrally compressed (depressed) often with large upward pointing mouths.

Anglerfish

Anglerfish are the members of the order Lophiiformes. They are bony fish named for their characteristic…

The Seal of the District of Alaska, 1911. The image on the seal shows Alaska's mountains and shore.

Seal of Alaska

The Seal of the District of Alaska, 1911. The image on the seal shows Alaska's mountains and shore.

The Yazoo River was of major importance during the American Civil War. The first electrically detonated underwater mine was used on the river in 1862 near Vicksburg to sink the Union ironclad USS Cairo. The last section of the Cairo was raised on December 12, 1964. It has been restored and is now on permanent display to the public at the Vicksburg National Military Park. There are 29 sunken ships from the Civil War beneath the waters of the river.

Gunboats Ascending the Yazoo River

The Yazoo River was of major importance during the American Civil War. The first electrically detonated…

Lynnhaven Bay is a relatively small body of water in Virginia separated from the rest of the Chesapeake Bay by a small inlet.

Lynnhaven Bay, Virginia

Lynnhaven Bay is a relatively small body of water in Virginia separated from the rest of the Chesapeake…

"Sea-walls. A. Plymouth (England) breakwater; a, a, level of the top; b, b, low water at spring tide; c, bottom; d, foreshore; e, sea-slope; f, top." -Whitney, 1911

Plymouth Breakwater

"Sea-walls. A. Plymouth (England) breakwater; a, a, level of the top; b, b, low water at spring tide;…

An illustration of a sea-lily fossil.

Sea-lily

An illustration of a sea-lily fossil.

The Tower of the Winds, also called horologion (timepiece), is an octagonal Pentelic marble clocktower on the Roman agora in Athens. The structure features a combination of sundials, a water clock and a wind vane. It was supposedly built by Andronicus of Cyrrhus around 50 BC, but according to other sources might have been constructed in the 2nd century BC before the rest of the forum.

Tower of the Winds

The Tower of the Winds, also called horologion (timepiece), is an octagonal Pentelic marble clocktower…

Gudgeon is a common name for a number of small freshwater fishes of the families Cyprinidae, Eleotridae or Ptereleotridae. Most gudgeons are elongate, bottom-dwelling fish, many of which live in rapids and other fast moving water.

Gudgeon

Gudgeon is a common name for a number of small freshwater fishes of the families Cyprinidae, Eleotridae…

Northern Water Hemlock is a species of Cicuta, native to northern and central Europe, northern Asia and northwestern North America. It is a perennial herbaceous plant which grows up to 1&ndash;2 m tall. The stems are smooth, branching, swollen at the base, purple-striped, and hollow except for partitions at the junction of the leaves and stem. In cross section the stems have one flat side and the other sides are rounded. The leaves are alternate, tripinnate, only coarsely toothed, unlike the ferny, lacy leaves found in many other members of the family Apiaceae. The flowers are small, white and clustered in umbrella shaped inflorescences typical of the family. The many flowered umbellets have unequal pedicels that range from 5 to 11 cm long during fruiting. An oily, yellow liquid oozes from cuts to the stems and roots.

Northern Water Hemlock

Northern Water Hemlock is a species of Cicuta, native to northern and central Europe, northern Asia…

An illustration of Heron's fountain. Heron's fountain is a hydraulic machine invented by the first century inventor, mathematician, and physicist Heron, also known as Hero of Alexandria. Heron studied the pressure of air and steam, and built the first steam engine as well as toys that would spurt water, one of them known as Heron's fountain. Various versions of Heron's Fountain are used today in physics classes as a demonstration of principles of hydraulics and pneumatics

Heron's Fountain

An illustration of Heron's fountain. Heron's fountain is a hydraulic machine invented by the first century…

An illustration of a small jellyfish. Jellyfish are free-swimming members of the phylum Cnidaria. ellyfish don't have specialized digestive, osmoregulatory, central nervous, respiratory, or circulatory systems. They digest using the gastrodermal lining of the gastrovascular cavity, where nutrients are absorbed. They do not need a respiratory system since their skin is thin enough that the body is oxygenated by diffusion. They have limited control over movement and mostly free-float, but can use the hydrostatic skeleton of the water pouch to accomplish vertical movement through pulsations of the disc-like body.

Jellyfish

An illustration of a small jellyfish. Jellyfish are free-swimming members of the phylum Cnidaria. ellyfish…

"In the "Hercules" turbine...the flow is what is called mixed, that is, it is partly a radial inward and partly an axial flow machine. On entering, the water flows at first in a radial direction, and the gradually, as it passes through the wheel, it receives a downward component which becomes more and more important" (Britannica, 383).

Hercules Turbine

"In the "Hercules" turbine...the flow is what is called mixed, that is, it is partly a radial inward…

"This turbine was designed to give 1250 H.P. with a fall of 25 ft. and an efficiency of 77%. It is fitted with a suction pope and a circular balanced sluice for admitting and cutting off the water-siupply" (Britannica, 384).

Jonval Turbine

"This turbine was designed to give 1250 H.P. with a fall of 25 ft. and an efficiency of 77%. It is fitted…

A windmill is a machine that is powered by the energy of the wind. It is designed to convert the energy of the wind into more useful forms using rotating blades or sails. The term also refers to the structure it is commonly built on. In much of Europe, windmills served originally to grind grain, though later applications included pumping water and, more recently, generation of electricity.

Windmill

A windmill is a machine that is powered by the energy of the wind. It is designed to convert the energy…

A windmill is a machine that is powered by the energy of the wind. It is designed to convert the energy of the wind into more useful forms using rotating blades or sails. The term also refers to the structure it is commonly built on. In much of Europe, windmills served originally to grind grain, though later applications included pumping water and, more recently, generation of electricity.

Windmill

A windmill is a machine that is powered by the energy of the wind. It is designed to convert the energy…

The Battle of Stony Point was a battle of the American Revolutionary War. Here is a view of Stony Point from the Southwest. <p>"View of Stony Point from the southwest. This view shows a large portion of the morass, and the place where the assaulting party divided and prepared for an attack upon the fort, which was situated where the light-house is seen. The place of the causeway is on the left, denoted by the cattle. When I made this sketch it was quite high water, and the morass, there about one hundred feet wide, was almost covered. There was another place near the river shore, on the right, where the Point was accessible at times. It is distinguished in the sketch by the narrow strip of land extending nearly across the mouth of the morass. Upon this the enemy had dug pits and placed sharpened stakes within them, so that, had the Americans attempted to reach the Point by that way many would have been impaled."—Lossing, 1851

Stony Point

The Battle of Stony Point was a battle of the American Revolutionary War. Here is a view of Stony Point…

A front view of a diving helmet. A, Helmet; B, Breastplate; F, Emergency cock; G, Glasses in frame; H, Metal screws and bands; I, Metal tabs; J, Hooks for keeping weight ropes into position; and L, Eyes to which air pipe and life line are secured.

Diving Helmet (Front)

A front view of a diving helmet. A, Helmet; B, Breastplate; F, Emergency cock; G, Glasses in frame;…

A diving bell, also known as a wet bell, is a cable-suspended airtight chamber, open at the bottom like a moon pool structure, that is lowered underwater to operate as a base or a means of transport for a small number of divers. The pressure of the water keeps the air trapped inside the bell. They were the first type of diving chamber. Unlike a submarine the diving bell is not designed to move under the control of its occupants, nor to operate independently of its tether.

Diving Bell

A diving bell, also known as a wet bell, is a cable-suspended airtight chamber, open at the bottom like…

An illustration of duckweed. Duckweed is an important food source for waterfowl and are eaten by humans in some parts of Southeast Asia (as khai-nam). Some duckweeds are used in freshwater aquariums and ponds where they may spread rapidly, although in a large pond they may be difficult to eradicate once established. The plants can provide nitrate removal (if cropped) and cover for fry. The plants are used as shelter by pond water species, such as bullfrogs and bluegills. The duckweeds are important in the process of bioremediation because they grow rapidly, absorbing excess mineral nutrients, particularly nitrogen and phosphates. A cover of duckweeds will reduce evaporation of water compared to a clear surface.

Duckweed

An illustration of duckweed. Duckweed is an important food source for waterfowl and are eaten by humans…