Mapping Hong Kong Part 1 – Where Are We?

Tymon Mellor: Every day we use maps, be it in our head or on our mobile phone, they guide us and lead us through our modern complex environments. Maps show us the relationships between elements, but for this article I will focus on maps that depict geography, or to be correct, cartography and the cartographers responsible for their production.

In this series of articles, I will examine some of the important maps of the territory and the cartographs that produced them. I will describe the methods adopted by the map makes and how changing technology impacted the approach to map making.

Development of Maps

Maps have been used by humans for as long as people have been able to record information. Early maps were recorded on cave paintings, etched into tusks or stones providing guidance on navigating through the countryside. The preparation of maps developed with the advancement in mathematics, geography, and the technology for their production and distribution. By the 1500s the first maps of the known world were being produced, and by the 18th century methods were being developed to allow the depiction of a curved world on a flat surface. During the 18th and 19th centuries, the major nations mapped their territories and their explorers mapped the foreign lands that they visited.

The British recognized the importance of mapping, primarily from a military perspective but also for commerce and development. Starting in 1783, the Ordinance Survey, a part of the army, used Royal Engineers to map the United Kingdon for the production of the first detailed maps of the nation. Concurrent to the mapping of the land, the Admiralty responsible for the command of the Royal Navy started producing nautical charts from 1795 for military use only. However, from 1825 the first catalogue of charts was made available to the public, listing 756 charts.

Mount Parker to Kowloon Survey Record (1847)

There are many types of maps displaying geographic data in a variety of forms, each developed for a particular function. Most people will be used to seeing mapping information in the form of highlighted road networks for use with GPS guidance systems, which is a very specific form of a vector map where the roads and surroundings are elements to be displayed as they become visible. Prior to the development of mobile computing, maps were images used to reflect the surroundings, a fixed vision established by a surveyor when the map was surveyed. This approach has the advantage of freeze framing the environment at a moment in time, allowing future generations to reflect on the changes. This advantage is also a disadvantage as the map will become out of date as the environment changes. In many places in the world, this may not be a problem, but in Hong Kong with the rapid development of urban areas and continuous provision of new infrastructure, a map will quickly become dated.

For this series of articles, the following types of maps will be discussed:

• Hydrographic charts, maps developed for seafarers, showing marine features and coasts;

• Topographic maps, capturing the ground relief and physical features; and

• Cadastral maps, showing land boundaries associated with ownership.

Maps have many uses but military and land ownership have driven the production of maps for Hong Kong. The earliest of these maps were coastal charts prepared by explorers to assist in marine navigation, particularly to the important trading port of Canton (now Guangzhou).

With the acquisition of Hong Kong Island in 1841, topographic maps became important to establish the boundaries of the colony and to plan infrastructure and development. These maps also became an important tool for the military in the establishment of facilities, communication lines and strategies for defending the colony from attack. The best available maps of the territory were surveyed by the military and classified as CONFIDENTIAL.

From the early days of the colony, land sales formed a major source of Government income, and thus, it was important to establish and document land ownership. With the expansion in 1898 of the colony into the New Territories, a detailed cadastral survey was undertaken to record land ownership. These maps still form the basis of all records to this day.

When cartographers of the day prepared a map, there were two elements to focus on, establishing the relationship between the map elements e.g. the position of a house relative to a field or path, and, the location of the elements in the context of the broader environment. The former was typically achieved using a plane-table, and the latter with survey instruments to create a survey network using triangulation.

Earliest Maps

The territory was first mapped and well recorded by Europeans on the early traders’ charts while sailing to Canton. Hong Kong Island was of little interest to these early pioneers as it was just the same as the rest of the coast line, but Lantau was an eastern marker for access to the Pearl River.

Extract from the Chart of the South China Sea (1794)

As for the Chinese maps, maps of the area have been produced from earlier times, but these were not the topographic maps that we recognise today, and which relied upon the Chinese text to provide interpretation. Two forms of map were produced[1], charts orientated to the north, similar to western charts, and a navigational strip where the coast was, drawing right to left as you would see it from a boat. The maps would provide details on the places with little regard to geographical relationships. However, every province or district had a gazetteer, responsible for maintaining maps and information about the geography, administration, economy etc.

Qi sheng yan hai quan tu Coastal Map of China (1881)

With the advent of trade and the need to navigate inshore waters, the great sea faring nations of the world started to map coastlines and major rivers. As trade developed between countries, the quality of mapping improved, along with the mapping of territories and cities to reflect boundaries and land ownership. These provided the tools to raise taxes, plan infrastructure and measure the worth of an area.

Where is Hong Kong?

To be able to locate a place on the globe, you need to know two pieces of information, the latitude and longitude of the place you are looking for. The latitude gives you the position north or south of the equator, and the longitude establishes your position east or west of Greenwich (England) referred to as the prime meridian.

The Position of Hong Kong (Survey and Mapping Office)

This geographic coordinate system is almost universal, although the French still maintain an older prime meridian passing through the Paris Observatory, just to confuse things.

The calculation of these two values is complex, requiring an understanding of the shape of the earth, the stars, and some complex mathematics. Latitude (north-south) was solved through the observations of the celestial bodies, allowing you to identify how far north or south you were from the equator. A similar approach was developed for longitude, but this was much less reliable with an accuracy of a few degrees. An alternative approach was to use time. Knowing that the earth rotates a full circle or 360 degrees in 24 hours, by establishing your relative time to Greenwich, it is easy to calculate the longitude.

This approach required the ability to measure a common time across the globe. Early approaches used celestial bodies or solar eclipses that could be seen from different places at the same time. By comparing the difference in local time, it was possible to establish the difference in longitude. However, knowing the time in Greenwich was the problem, but this was eventually solved in the mid 18th century when an English instrument maker, John Harrison, developed the marine chronometer, an accurate and reliable clock. Ships’ captains could now establish the local time from the sun’s position, and the time in Greenwich or Greenwich Mean Time from the chronometer.

As with all mechanical devices, the chronometer required to be calibrated and checked on a regular basis, and thus, many ports introduced ball towers, providing a visual signal to check and adjust the machine[2]. Ensuring the accuracy of the ball tower was one of the tasks of the Hong Kong Observatory. The Observatory had a precision transit instrument used to measure the position of stars and compare their location with that defined in an astronomical almanac to determine Hong Kong Civil Time. Regular checks were made using the transit instrument to ensure the Observatories clocks were on time[3].

Transit instrument similar to the one at the Observatory

The first calculation for the location of Hong Kong was undertaken by Captain Edward Belcher shortly after acquisition of the island in January 1841. Belcher had been sent to Hong Kong to undertake a marine survey of the new colony for the preparation of the detailed chart. More on that in the next article. From a hillock at Point Albert close to Morrison Hill, he determined his position to be latitude 22° 16’ 27” and longitude 114° 10’ 48”. He also took it upon himself to name the principal peaks of Victoria, High West, Mount Gough, Mount Kellett, Mount Parker and subsequently Pottinger Peak[4].

Point Albert Identified on the 1843 Belcher Map

By 1848 the location of Hong Kong, or more precisely the post office in Victoria was established as latitude 22° 16’ 37” and longitude 114° 9’ 20”[5]. Given that 1” is equivalent to a distance of around 30.8m, this would put the post office at about 2.7km west of Morrison Hill.

With the increase in marine traffic, there was a need to provide a consistent set of known coordinates for all the key ports in Asia. Thus, in the summer of 1881, Commanders F M Green, C H Davis and Lieutenant J A Norris of the United States Navy were assigned to establish the longitudes of several eastern ports using the recently introduced telegraph[6]. Working from USS Palos, a coastal gunboat, the teams undertook the task during the summer of 1881 and winter of 1882. Commander Green arrived in Hong Kong on the 24th August 1881 to prepare for the assessment.

Location of North Barracks and Palos Pier (1903)

An observation site was built close to the harbour in the grounds of the North Barracks, adjacent to the current Chater Garden. A solid foundation was constructed for the installation of a transit instrument to establish latitude and the precise time, while a connection was made to the telegraph to establish a common time with Greenwich to compare with the location time in Hong Kong. Using a portable wooden shed as shelter, the site was named ‘Palas Pier’ after their ship, and a total of 26 observations of star pairs was taken to establish time and position. These values were then adjusted to provide the position of the cathedral tower as latitude as 22° 16’ 58.19”and a longitude of 7 hours 36 minutes and 38.1 seconds or 114° 09’ 31.1”. This represented an improvement of 6.5” or 200m on the previous coordinates for the cathedral.


An observatory had been proposed for Hong Kong in 1877 by the Surveyor General, the expatriate Chilean John MacNeil Price. It was to be located on Mount Elgin in Kowloon, a small hill at the back of Tsim Sha Tsui village. As momentum grew for the scheme, Major Henry Palmer of the Royal Engineers took over the project and prepared details of the buildings and their use.

Borrowing equipment from Commander Green, Major Palmer took it upon himself to establish the latitude of the proposed facility. Thus, he had a platform constructed on the side of Mount Elgin, just below where the observatory building was to be placed and proceeded to establish the latitude of the new facility[7].

He observed 48 stars, forming 28 pairs over 11 nights in January and February 1882, and after making corrections for errors he calculated the latitude of observation as 22° 18’ 11.91” and subsequently revised to 22° 18’ 11.89”[8]. He did not seem to be interested in calculating the longitude but did note that it was important to maintain the survey position to allow the location of the transit instrument to be calculated.

The new Observatory was completed by the end of 1883[9] and with its new transit instrument, it established and maintained the local time for the community and mariners. The coordinates of the instrument at the Observatory were recorded as latitude 22° 18’ 12” and longitude 114° 10’ 25” and this became the de-facto setting out point for the territory and was recorded on the contemporary charts.

Hong Kong Chart 1459 (1888)

The details of how the coordinates were established were lost, however E B Reed the Superintendent of Surveys demonstrated in 1929 that the longitude could be calculated using the longitude of Palas Pier and adjusted by an offset of 3,966 feet previously survey by the Public Works Department survey network[10].

Following a series of lunar observations[11], in 1885 the value of longitude was revised to 114° 10’ 27.9”. This value was shown on the 1888 map of Hong Kong but was not reflected in the nautical charts of 1888 and 1900.

Map from the 1888 Hong Kong Almanack

With advancements in technology, by 1925 there was a new solution to the problem, radio transmissions. Between the 3rd September and 1st November, 1925 simulation observations were made at the Royal Observatory in Greenwich and the Hong Kong Observatory of the Bordeaux rhythmic time signals broadcast on the radio. Over 13 occasions, the time difference between Greenwich and Hong Kong was recorded, establishing a time difference of 7 hours 36 minutes 41.25 seconds giving a longitude of 114° 10’ 18.75” and latitude 22° 18’ 13.20”.

Notice of the change in longitude (1926)

Since the founding of the colony, the British military had taken a keen interest in the survey of the territory and the production of accurate mapping. The Royal Engineers undertook several mapping exercises over the years and brought discipline and order to the haphazard approach taken by the survey division of the Public Works Department. Instrumental to this exercise was Brigadier H St J L Winterbotham CMG, DSO, the Director General of the Ordinance Survey in Southampton and responsible for the preparation of the territory’s maps under the Geographical Section General Staff (GSGS).

In 1924, with the visit of the aircraft carrier HMS Pegasus, the military took the opportunity to undertake a full aerial survey of the colony and address the known discrepancies with the survey network, more this in a later article. A new triangulation or trig station was established at the Observatory, station zero on the 2nd Feb 1929[12]. This was set 38’ 4.5” feet due south of the transit instrument. The engineering and survey arm of the Government, the Public Works Department was tasked with establishing the coordinates of the new station using the existing survey network. It was coordinate at latitude 22° 18’ 12.82” longitude 114° 10’ 18.75”[13] and became the basis for all the future surveys of Hong Kong.

Trig station Zero, 38.4ft due south of the Transit Instrument

The details of the survey were provided by the Superintendent of Surveys to Winterbotham in March 1929[14] along with how the station connected to the established survey network. The latitude of the survey station is remarkably close to the survey position of Major Palmer’s observations. Given the presence of an existing substantial foundation trig zero may have been built on the early platform.

Survey Triangulation for the Trig Zero (1929)

After reviewing the state of the survey network and documentation, in 1927 he noted a number of discrepancies in the data provided by the Public Works Department[15] including:

  • Survey stations missing coordinates
  • Coordinates given for Tai Mo Shan station based on the old station that had been destroyed while the new station was at a different location
  • No value provided for the Observatory’s transit instrument, but taken as 22° 18’ 13.2” and 114° 10’ 18.75” but a check of the survey data suggested that the coordinates had been calculated based on 22° 18’ 12.10” and 114° 10’ 27.90”

He noted, “It is considered however, that, not only in the interests of Imperial Defence, but also in the interests of the Colony itself, full data as to the work of Triangulation in the field for Hong Kong and the Leased Territories should be recorded at the War Office”. Thus, the mapping of Hong Kong once more became the responsibility of the military who would produce the first of the 1:20,000 scale set of maps of the territory.

A map of the world Description automatically generated

Triangulation of Hong Kong (1930)

While Winterbotham was trying to sort out the survey data, the Observatory during a period from the 1st January 1927 to 31 December 1929 took 285 observations of the Bordeax time signal to verify the longitude of the transit instrument[16]. They also took 916 observations from the Nauen (Germany) time signal. The two results were different by 0.07 seconds but the mean matched the result from the 1925 survey. A further correction of 0.03 seconds was identified for the time the signal took to travel around the world but for consistency, the Observatory decided to maintain the 7 hours 36 minutes 41.25 seconds or 114° 10’ 18.75” as the official value.

In 1930 the new survey of the territory was completed by the British military and the coordinates were adjusted by the GSGS, establishing the Observatory[17] as:

Longitude: 114° 10’ 18.75”

Latitude: 22° 18’ 13.20”

Map Projections

We cannot discuss cartography without touching on projection, the means of converting the three-dimensional world into a two-dimension representation. There are many forms of projection, but they all rely on two important features: assumptions on the shape of the earth and how best to depict it; and, that you can maintain the shape or the distance between points but not both. These become particularly sensitive as you approach the poles, but for a small area such as Hong Kong located close to the equator, the effects are not significant. The early maps did not record the projection adopted or the assumptions on the shape of the earth, but along with errors and changing datums, errors in the order of hundreds of metres can be found making it harder to compare data. However, with the help of modern software many of the limitations can be overcomed.

Comparison of Longitude and Latitude between 1845 and Current

In the next article, I will introduce you to Captain Edward Belcher, a man no one liked. His crew of HMS Sulphur considered him a bully, he had his fellow officers court martialled and his superiors wanted rid of him. His short-lived marriage ended after he twice infected his wife with venereal disease, but this was the man who quite literally put Hong Kong on the map.



  1. Mapping Hong Kong, A Historical Atlas, Hal Empson, 1992
  2. Hong Kong’s Meridian Marks Traces of Time Past, Stephen Davies, Shun Chi-ming, Yip Tsan-pong, Journal of the Royal Asiatic Society Hong Kong Branch , 2021, Vol. 61 (2021), pp. 7-43
  3. Hong Kong Meridian (II) – IN Search of the Magic Stones,
  4. Europe in China, The History of Hong Kong from the beginning to the year 1882, E J Eitel, 1895
  5. Hong Kong Almanack, 1848
  6. Telegraphic Determination Of Longitudes In Japan, China, And The East Indies; Embracing The Meridians Of Yokohama, Nagasaki, Wladiwostok, Shanghai, Amoy, Hong- Kong, Manila, Cape St. James, Singapore, Batavia, And Madras, 1881 and 1882
  7. On a Determination of the Latitude at Mount Elgin, in the Kau-Lung Peninsular, Major H Spencer Palmer, 1882
  8. The Hong Kong Government Gazette, 16 Dec 1882
  9. A Brief General History Of The Royal Observatory, L Starbuck, 1951
  10. Letter C Clementi, Governor to Lieutenant Colonel Amery MP, 26 March 1929, WO 181 113
  11. Hong Kong’s Meridian Marks Traces of Time Past, Stephen Davies, Shun Chi-ming, Yip Tsan-pong, Journal of the Royal Asiatic Society Hong Kong Branch , 2021, Vol. 61 (2021), pp. 7-43
  12. Report of the Director of the Royal Observatory, Hong Kong for the Year 1929
  13. Triangulation of Hong Kong and New Territories, War Office 1930, FO 925 25307
  14. Letter C Clementi, Governor to Lieutenant Colonel Amery MP, 26 March 1929, WO 181 113
  15. Preparation of New Map of Hong Kong, Winterbotham, WO 181 79, 28 June 1927
  16. Report of the Director of the Royal Observatory, Hong Kong for the Year 1929
  17. Triangulation of Hong Kong and New Territories, War Office 1930, FO 925 25307

This article was first posted on 19th February 2024.

Related Indhhk articles:

  1. Mapping of Hong Kong Part 2 – 1841 The Belcher Map

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