Towards Bengal. Sunday, August 2nd, 1812 ... Strong gales @ the SW with hard squalls and rain and a heavy confused sea. Ship pitching and rolling violently I Prevented from performing divine Service by the state of the weather I a.m. Bridget, wife of David Kirwan, was delivered of a daughter ... Lat (latitude) 28 LESS THAN 37+. Lon (longitude) 25 LESS THAN 51+. 87 miles (covered).”

So reads an entry in Thomas Pitcher’s journal, written in pencil, three months out from Portsmouth on HC Broxbornebury’s maiden voyage to the East Indies. Rarely touched in almost 200 years, the journal now resides, remarkably preserved in its original - but flaking - maroon binding, deep in the vaults of the British Library in London. It became of great interest to my family when we discovered that an ancestor was listed as a passenger on board the ship. Martin Mulkern, a 17-year-old ensign, was off to join his regiment in India and, thanks to the library’s well indexed collection, we were able to call up the log of the Broxbornebury and follow an eventful day-by-day account as it set sail, calling only at Falmouth and Madeira on an otherwise uninterrupted five-month voyage around Africa and across the Indian Ocean.

Many thousands of similar logbooks have survived the passage of time. Each one offers a wealth of historical information for modern eyes - not only for genealogists, but for students of Britain’s rich maritime past, authors seeking inspiration and climatologists analysing sea and weather conditions hundreds of years ago.

In the age of sail, when international trade, travel and warfare were mostly conducted by sea, the maintenance of ships’ logs was not simply a bureaucratic exercise. Observations of wind, weather and sea conditions and accurate information about treacherous coastlines could mean the difference between life and death for mariners. The terms “log” and “logbook” are now broadly applied in all areas where records need to be maintained, but they have a nautical - and quite literal - derivation. In the early days of sailing, ship records were inscribed on shingles (slivers of wood hewn from logs), which were then hinged to open like a book. Later, when paper became widely available, the name “logbook” stuck.

The National Archives has a massive collection of Royal Navy logs going back to the mid-1600s. At first, they came in various forms, written by different ranks of officer. Masters’ logs were kept by the sailing masters and recorded the ship’s course and position, weather encountered, daily employment of hands (the crew) and any punishments meted out (lashes for mutinous behaviour, and so on). The masters needed to keep account of any discrepancies found when casks of food and drink were opened, so that claims could be made against suppliers at a later date. It was also their responsibility to make sketches and charts of new coastlines and harbours, which would subsequently be copied and circulated as navigational aids.

Captains’ logs during this period drew heavily on the masters’ efforts, with a few additional details, but often including a full crew list at the beginning of each voyage. Together they account for some 10,000 individual logs. To that we can add 400 admirals’ journals covering the period 1702-1916; and 164 journals from “Voyages of Discovery”, penned by such famous officers as James Cook, William Bligh and Matthew Flinders. There are also more than 5,000 lieutenants’ logs dating from 1673 to 1809, stored in a separate collection at the National Maritime Museum.

By the Victorian age, most of these variations were superseded by the general ship’s log, to be maintained by the Officer of the Watch on every naval vessel, including, in the 20th century, battleships, cruisers and aircraft carriers. All are passed on to the National Archive and account for a staggering 180,548 separate volumes up to 1976. Logs after that date are subject to the 30-year closure rule.

The British Library’s collection is accessible via their Oriental and India Office, and draws exclusively from the legacy of the long defunct East India Company. The company came into being in 1600 when Elizabeth I granted a group of English merchants the monopoly on trade with India and the Far East. Over the next two centuries, the company developed Britain’s most successful mercantile enterprise and, at its peak, robust ships known as East Indiamen were accomplishing 50 voyages a year. The earliest surviving document is exactly 400 years old and is a fragment from the journal of Roger Style, who was captain of Ascension in 1605. Within a few decades, every East India Company commander was required to deliver a journal to East India House, in the City of London, at the end of each voyage.

Even though the company eventually folded, its meticulous records provide an invaluable resource for historians. With such an abundance of historical information in the public domain, it is perhaps surprising that only relatively recently have landlubbers started to take advantage of it.

Author Patrick O’Brian scoured logbooks for authentic detail to include in his seafaring adventures, the popular 21-book series that began with Master and Commander - now a Hollywood movie starring Russell Crowe (main picture). After settling in France, O’Brian had to rely on archive staff to send over photocopied chunks from journal records on his behalf. His main characters, Captain Jack Aubrey and ship’s surgeon Stephen Maturin, embodied a complementary blend of bravado and sensitivity, and their experiences served to highlight the concerns of naval men 200 years ago.

Beside the heroics and horrors of naval battles, modern readers are fascinated by the maladies that often beset long sea voyages. In those days, a crew considered themselves lucky if a properly qualified surgeon was assigned to their ship.

The National Archive holds some 800 surgeons’ logs, not just from naval vessels, but emigrant and convict ships on which medical officers were stationed. Their journals often provide the most informative and harrowing accounts of a voyage, detailing daily sick lists, surgical operations and statistics of disease and decease. They were usually written by educated men with acerbic opinions, and a random selection from the archive will always yield fascinating human stories.

The transportation of criminals to Australia was a particularly grim affair. In his 1835 journal for the Aurora, surgeon Andrew Henderson noted that 150 convicts embarked at Deptford (on the Thames) “all tolerably clean and in apparent health”. However, conditions had deteriorated long before landfall in Hobart Town, Tasmania, five months later. Henderson recorded many cases of nausea, diarrhoea, scabies and ulcers. On the matter of scurvy (a disease already established as being caused by a vitamin C deficiency), he was resolutely against the received wisdom. “I have come to the conclusion that diet alone under proper management can prevent scurvy, and that lemon juice, or any other acids, never was and never can be either a preventive or cure for scurvy - and is a perfectly useless expense for the service.”

Many innocent parties were also willing to undertake arduous journeys in the dream of a better life. In the summer of 1837, one emigrant ship, the magnificently named Augusta Jessie, set sail for Sydney, New South Wales.

Her “surgeon-superintendent”, Thomas Galloway, examined 77 different cases: 69 were discharged, but eight of them died. The fatalities were mainly toddlers who succumbed to croup and bronchitis.

On August 14, Galloway examined 14-month-old George: “This child was brought to me this morning in a state of perfect stupor, eyes insensible to the light, face flushed... The mother, an idle woman, says it has been complaining for several days, but being very backward in its teething, she supposed there was nothing that required her applying for assistance. She has a large family and has lost two children in this way before.” Further matter-of-fact entries describe George’s deteriorating health, until four weeks later he died from hydrocephalus (water on the brain).

Even the more mundane information contained in ships’ logs, such as sea and weather conditions, has found modern champions. These observations, often recorded every two hours, 200 to 300 years ago, provide a unique source of meteorological statistics, before and during the onset of the Industrial Revolution, and can be used to map climate change. An international research team, led by Dr Dennis Wheeler of the University of Sunderland, has been studying logbooks from 1750 to 1850 to compile a Climatological Database for the World’s Oceans (CLIWOC). As well as the National Maritime Museum logbooks, they have drawn from records archived in France, Spain and Holland. The initial phase of CLIWOC has come to an end, with some of its findings available on the internet and released in specialist publications.

In the modern world of digital technology and satellite navigation, barometric and instrumental data are recorded on computer, but - perhaps surprisingly - the Royal Navy still maintains an official log in the traditional manner. It is completed on the bridge by the officer of the watch, in pencil (preferable to ink, which will run if dropped in water).

The logs are kept for up to two years, before one year’s worth is dispatched to the Ministry of Defence; and these are passed on, eventually in batches, to the National Archive and made available to the public after 30 years have elapsed.

So what of the future? Captains’ logs will still be around hundreds of years from now. So perhaps it doesn’t require such a huge leap of imagination - from James Cook on Endeavour to James Kirk on Starship Enterprise - to accept that the human race will forever document the urge “to boldly go”.

* www.nmm.ac.uklibrarycatalogue www.catalogue.nationalarchives.gov.uk (Ref: ADM)www.ucm.esinfocliwoc