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Description

Detailed British Admiralty chart of a western section of the Strait of Magellan, illustrating the Trinidad Channel. 

The following report appeared in surveys of the Admiralty for 1879:

On the western coast of South America, H.M.S. Alert, with an efficient staff of  surveyors in the early part of the year under Sir George Nares, and subsequently  under Captain Maclear has been employed on arduous service, chiefly in a critical examination of the ship channels adjacent to the 50th parallel of latitude.  Trinidad Channel directly opening into the Pacific Ocean with Concepcion Channel leading from the inner waters north of Magellan Strait into Trinidad Channel, have  all been surveyed, together with their numerous ports and temporary anchorages  likely to be useful to passing shipping. Inocentes Channel, leading to Concepcion Channel from the now well-known Guia Narrows, has also been examined and charted.

Trinidad Channel opens out a clear passage to the Pacific Ocean 160 miles to the north of Magellan Strait; and although not so secure of approach from the Pacific as the well-known entrance into the strait by Cape Pillar and the Evangelists, it will be found a valuable addition to our knowledge of these waters, as enabling ships passing into the Pacific to avoid the heavy sea frequently experienced in the higher south latitude. Similar in feature to Magellan Strait, the ocean entrance of Trinidad Channel is shoal, having only 40 fathoms water in the deepest part, the  depths gradually increasing to 300 fathoms in the inner channels. The southern shores are bounded by bold, rugged mountains, rising abruptly from the sea; whilst on the northern side a low wooded country lies between the sea and the rugged
 spurs of distant snow-clad mountains: both shores are cut up into numerous bays and inlets. In the later months of the year very few natives were seen; it is understood that at this season the Fuegians leave the inner waters for the outer seaboard, in pursuit of seals.
 
During the winter months, the Alert, having refitted at Coquimbo, then visited  St. Felix and St. Ambrose islands, and obtained a series of ocean soundings in an area unexplored by the Challenger in 1875. These islands appear to be unconnected with the South American continent, for soundings obtained midway gave a depth of 2250 fathoms (rad. ooze), with a bottom temperature of 33 5 F., both depth and temperature thus corresponding to the general bed of the South Pacific Ocean. Neither do they join the Juan Fernandez group, for the depths between reached 2000 fathoms. These several scattered islands thus appear to rise from a submarine-plateau as isolated mountains. Captain Maclear describes St. Ambrose Island as volcanic, composed entirely of lava arranged in horizontal strata very marked, intersected vertically by dykes of basalt: vegetation is scant, and the island is without water: though frequented by sea birds, the sides are too steep and rugged for guano to collect.

 

Condition Description
Minor soiling, primarily in the top right corner.
British Admiralty Biography

The British Admiralty has produced nautical charts since 1795 under the auspices of the United Kingdom Hydrographic Office (HO). Its main task was to provide the Royal Navy with navigational products and service, but since 1821 it has also sold charts to the public.

In 1795, King George III appointed Alexander Dalrymple, a pedantic geographer, to consolidate, catalogue, and improve the Royal Navy’s charts. He produced the first chart as the Hydrographer to the Admiralty in 1802. Dalrymple, known for his sticky personality, served until his death in 1808, when he was succeeded by Captain Thomas Hurd. The HO has been run by naval officers ever since.

Hurd professionalized the office and increased its efficiency. He was succeeded by the Arctic explorer Captain William Parry in 1823. By 1825, the HO was offering over seven hundred charts and views for sale. Under Parry, the HO also began to participate in exploratory expeditions. The first was a joint French-Spanish-British trip to the South Atlantic, a voyage organized in part by the Royal Society of London.

In 1829, Rear-Admiral Sir Francis Beaufort was appointed Hydrographer Royal. Under his management, the HO introduced the wind force scale named for him, as well as began issuing official tide tables (1833). It was under Beaufort that HMS Beagle completed several surveying missions, including its most famous voyage commanded by Captain FitzRoy with Charles Darwin onboard. When Beaufort retired in 1855, the HO had nearly two thousand charts in its catalog.

Later in the nineteenth century, the HO supported the Challenger expedition, which is credited with helping to found the discipline of oceanography. The HO participated in the International Meridian Conference which decided on the Greenwich Meridian as the Prime Meridian. Regulation and standardization of oceanic and navigational measures continued into the twentieth century, with the HO participating at the first International Hydrographic Organization meeting in 1921.

During World War II, the HO chart making facility moved to Taunton, the first purpose-built building it ever inhabited. In 1953, the first purpose-built survey ship went to sea, the HMS Vidal. Today, there is an entire class of survey vessels that make up the Royal Navy’s Hydrographic Squadron. The HO began to computerize their charts in the late 1960s and early 1970s. In 1968, the compilation staff also came to Taunton, and the HO continues to work from there today.