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Republic of KenyaThe coast of Kenya was long dominated byArabs and was seized in the 16th century bythe Portuguese. The Europeans were ex-pelled by the Omanis; the coast then cameunder the rule of the Sultan of Zanzibar, andlater leased in 1867 to the British East AfricaAssociation. The British extended their hold-ings into the interior and fixed an initialsouthern boundary with the German EastAfrica Company in 1886. Kenya is borderedon the north by Ethiopia ( PE&RS, March 2003)(861 km), on the east by Somalia (682 km),on the southeast by the Indian Ocean (536km), on the south by Tanzania (769 km), onthe west by Uganda (933 km), and on thenorthwest by Sudan (232 km). The lowestpoint in Kenya is the Indian Ocean, and thehighest point is Mount Kenya at 5,199 m.Comprised of the Nairobi Area and sevenprovinces — Central, Coast, Eastern, NorthEastern, Nyanza, Rift Valley, and Western —Kenya is slightly larger than twice the sizeof Nevada. The former Colony of British EastAfrica gained independence on 12 Decem-ber 1963.

Thanks to Morgan W. Davis, “The historyof surveying in East Africa begins with thedomination of those lands by European pow-ers in the late 1800s. The British enteredinto a number of agreements definingspheres of influence in 1886, 1890, 1891,and 1894. The present day boundaries be-tween Kenya and its neighbors are a resultof legal descriptions hashed out in negotia-tions and subsequent triangulation andboundary surveys. Negotiations between theUnited Kingdom and Germany in 1886 and1890 established spheres of influence northand south respectively, of a line beginningat the Indian Ocean near Vanga and extend-ing to the eastern shore of Lake Victoria:‘The line of demarcation starts from themouth of the River Wanga or Umbe (Umba),runs direct to Lake Jipe, passes thence alongthe eastern side and round the northern sideof the lake and crosses the Lumi River …

After which it passes midway be-tween the territories of Taveita andChaga, skirts the northern base ofthe Kilimanjaro range, and thence isdrawn direct to the point on the east-ern side of Lake Victoria Nyaza (LakeVictoria) which is intersected by the1st degree of south latitude.’

The line between the Indian Ocean andLake Jipe was surveyed by plane table. Mostof the mapping in East Africa between 1890and 1910 was a result of the boundary com-

missions. Basic topographic mapping of vary-ing quality was accomplished along the nar-row zones of the surveyed boundaries. Therewas little opportunity to extend mapping tothe interiors of the colonies. An importantoutcome of this early phase was the consoli-dation of the War Office as the authority onboundary surveys and maps in Africa. Boththe Foreign Office and the Colonial Officerelied heavily on the expertise of the WarOffice on technical matters related to sur-veying and mapping, as well as for help inwording legal descriptions in negotiations.The Topographic Section of the General Staffof the War Office played a crucial role, aswell in the policies and activities of surveydepartments in the colonies.

The colonial Survey Committee was cre-ated in an attempt to organize the mappingeffort in the British East African colonies.The first meeting was held on 14 August1905. They recommended that there be twosurvey departments, standardized topo-graphic map scales at 1:62,500, 1:125,000,1:250,000, and 1:1,000,000. In a 1907 meet-ing, they adopted the Clarke 1858 ellipsoidfor Africa. They decided on the spelling ofplace names on maps. The Committee con-tinued to be an important governing bodyup to the World War II years. Major E. H.Ellis was appointed Inspecting Officer to thedepartments in the Uganda and East AfricaProtectorates (Kenya) in order to help expe-dite work. He submitted a comprehensivereport in February 1907 in which he notedthat a topographic section had not been con-stituted. He insisted that a full section of 2officers and 6-8 surveyors be formed. Herecommended map sheets covering 45' lon-gitude and 30' latitude or 30' x 30', at1:125,000 scale for developed areas, and 1½ºlongitude by 1º latitude in undeveloped ar-eas, utilizing the rectangular polyconic pro-jection. (This was the same specification uti-lized during the same era by the British Sur-vey of India. – CJM)

In late 1908 one officer, three NCOs and acivilian were assembled to begin fieldworkon 1:125,000 sheets for Kijabe and Nairobi,and a special 1:62,500 sheet for Nairobi.Mapping continued until the outbreak ofWWI. The Africa Series GSGS 1764 in 33sheets at 1:250,000 scale covered bothUganda and the East Africa Protectorates.The maps were published in monochrome,principally between 1905 and 1907. Thesewere provisional sheets with a paucity ofdetail. The maps were later also published in

color. Each sheet covered 1½º longitude and1º latitude with a graticule spacing of 30'.They were reprinted in 1939-1941 duringthe East African Campaign. It was not until1953 and thereafter that Series GSGS 1764was replaced at the same scale by SeriesGSGS 4801 and subsequently Series Y503.

After WWI, the War Office was no longeravailable to do work in the African colonies.German East Africa had been assigned toGreat Britain as a mandate from the Leagueof Nations in 1919 and was renamedTanganyika. The Arc of the 30th meridian wasproposed as the foundation of triangulationin the East African colonies. Observationson a portion of the arc in western Ugandahad been taken prior to 1914, and the trian-gulation net in Uganda was tied to it. Sur-veying on the arc had been done in northernRhodesia, and it was felt that it was impor-tant to close the gap in the arc in Tanganyika.

Martin Hotine surveyed the arc of the 30th

meridian in Tanganyika between 4½° and 9°South during the years 1931-1933. Deple-tion of funds in late 1933 left a gap in the arcbetween 1½° and 4½° South. From July 1936to August 1937, a survey was conductedwholly within Tanganyika to fill the gap, con-sisting of observation angles and some azi-muths. Uganda had withdrawn from theproject due to fears that if their portion ofthe arc was connected to South Africa, theywould be forced to recompute their alreadycompleted surveys on a new projection andgrid system.

This leads to a major theme of discussionduring the years between the two great wars– that of a common datum and projection forall of British Africa. Debate raged over thistopic until the exigencies of war during theSecond World War permitted the Britishmilitary to force a solution. In a memoran-dum circulated in 1926, it was assumed thata common datum could be chosen, utilizinga meridional orthomorphic projection fromKhartoum to Cape Town. The Clarke 1880ellipsoid was suggested. During the secondConference of Empire Survey Officers (1931),it was assumed that all colonial governmentswould adopt the Transverse Mercator pro-jection because it was already accepted byEgypt, South Africa and two of the West Af-rican territories. The width of the zones couldnot be agreed upon. Kenya saw little pros-pect in adopting the proposal because itscadastral work was computed on Clarke 1858and the Cassini projection. Extension and

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re-computation of its triangulation was moreurgent than conversion of its completed sur-veys to a new datum. In January 1934, GSGSproposed a coordinated projection and gridzone embracing South Africa, South Rhode-sia, Sudan, Egypt, and the Central and EastAfrican territories. They recommended theClarke 1880 ellipsoid and the TransverseMercator projection on a 6-degree grid. Thesame parameters were recommended in ameeting of a sub-committee of the ColonialSurvey Committee on 3 October 1935.Brigadier M. N. MacLeod insisted on theadoption of the meter as the map unit. Eachtime a new recommendation would be putforward for a common set of map param-eters, one or more colonial governing bod-ies would shoot it down for various reasons.

Lord Hailey wrote An African Survey (1938)after his tour of Africa in 1935. His viewswere taken up by the Colonial Survey Com-mittee in 1939, at which time they onceagain recommended a 6-degree grid and theadoption of the meter. Whittingdale repliedthat a 2-degree system was more appropri-ate for topographic mapping and militarysurveys. Huntley showed the military ad-vantages of the 2-degree grid (artillery), andthat it was inconvenient for cadastral sur-veyors to apply the corrections that a 6-degree grid would necessitate. (The samereason for practicality continues to this dayfor NOT using the UTM grid for civil GIS andsurveying applications. – CJM) South Africatotally opposed the change from 2-degreeto 6-degree zones. There was general agree-ment on the adoption of the meter on mapgrids.

A policy for military mapping was definedin July 1940, which utilized the Clarke 1880ellipsoid and the Transverse Mercator pro-jection with 5-degree zones. The centralmeridians were placed at 32° 30’E, 37° 30’E,and 42° 30’E. A scale factor reduction of0.05% was introduced to provide correctscale on two parallel meridians approxi-mately 1° 49' on either side of the centralmeridian. The scale error at the central me-ridian was about 1:2,000, and it was about1:2,200 at the edges of the grid zones. Thegrid was originally in yards, but was laterchanged to meters. This became known asthe East African War System, and it waseventually applied to an area bounded by19°N, 15°E, 12°S and the Indian Ocean. TheDirectorate of Colonial Surveys was born on1 March 1946, with Brigadier Martine Hotineas it first (and only) Director. An allowanceof £2 million was approved for this central-ized organization of geodetic and topographic

surveys. For the first time in the easternAfrican colonies, two problems, which hadplagued the survey effort from the earliestdays, were addressed: lack of funds and thelack of a centralized organizing body. In 1947,fieldwork for basic topographic mapping wascommenced. The first 1:50,000 scale sheetsof Series Y731 were produced for the KenyaEthiopia Boundary Commission. At least 470sheets were produced, virtually all of whichwere contoured, and 64 sheets along theEthiopian border.

The 1:100,000 scale sheets of Series Y633were produced between 1958 and 1968,mainly by the Survey of Kenya and the Di-rectorate of Military Survey. A general mapseries at 1:250,000 (Y503) has been derivedfrom the 1:50,000 and 1:100,000 scale sheets.The Survey of Kenya produced 42 of the 50sheets needed to cover the country. Kenyais covered by 7 sheets of the 1:1,000.000International Map of the World. The mostcommonly used geodetic parameters formaps produced by the Kenyan authoritiesare: Arc Datum 1960 referenced to the Clarke1880 (modified) ellipsoid, TransverseMercator projection with coordinates on theUTM grid.

In the 1970s, first-order EDM traverseswere run between stations adjusted on theArc 1960 Datum and Clifford triangulation. In1972-1973 the Survey of Kenya, in conjunc-tion with the U.S. Defense Mapping Agencyand the Directorate of Military Survey of theU.K. made the first experimental Doppler sat-ellite survey in Kenya. Recently the KenyaInstitute of Surveying and Mapping (KISM)took GPS observations on existing controlpoints. A. S. Lwangasi of the University ofNairobi reported the results of a datumtransformation carried out on 25 control pointsfrom Arc 1960 Datum to WGS 84 Datum:∆X = –179.1 m ±0.7 m, ∆Y = –44.7 m ±0.7 m,∆Z = –302.6 m ±2.2 m.”

In a letter dated 20th July 1989, J. R. R.Aganyo wrote for the Director of Surveys ofthe Survey of Kenya that the old Cassini-Soldner used in Kenya has the following pa-rameters: grid name: Cassini-Soldner; yearsused: since introduction of cadastral surveys;central meridians: 33°, 35°, 37°, 39° East;unit: English Foot where 1 foot = 0.30480International metres, exactly; ellipsoid:Clarke 1858 where a = 20,926,348 Englishfeet and 1/f = 294.26.

In January 2000, Russell Fox of the U.K.Ordnance Survey sent a memo to me thatwas written by the famous H. F. Rainsford on28 September 1961 with the (then) Direc-torate of Overseas Surveys:

“Since there appears to be some

confusion of thought about the ‘ori-gin’ of the trigonometric data listsproduced by this Directorate, thepurpose of this paper is to clarify theposition so far as possible.

Up to the present date, all trig.Lists have included in the preamblethe words – ‘New 1950 Arc Datum.’This denotes that the results in thelist are based on the Arc of the 30th

meridian, which was computed bythe D.O.S., from South Rhodesia toUganda, in the 1950 (circa). The val-ues of the stations accepted as astarting point in South Rhodesia hadbeen computed continuously fromSouth Africa. These Arc results havebeen held fixed since 1950, and it ishoped that they will remain so foras long as possible in the future,since they are used not only by theD.O.S., but also by the Congo andPortuguese Africa, and they providea uniform system from the Cape tothe Equator.

The South African datum is an ar-bitrary one, as at no station werethe Astronomic and Geodetic lati-tude, longitude and Azimuth madecoincident. On the Arc itself the (A-G) values vary (sometimes quiteabruptly) between: -

latitude +20" and –30"longitude +12" and –10"azimuth +15" and –08"

The only astronomic elementsthat have been held fixed on the Arcadjustment are – in South Africa onelatitude, longitude and azimuth (buteach at a different station) and anastronomic azimuth at Kicharere inUganda, just south of the Equator.

The Year 1950 was used in the titleas a convenient epoch mainly to dis-tinguish from previous systems suchas the “1935 Arc Datum.” (originalemphasis in color)

Tanganyika was the first East Afri-can territory in which geodetictrig. control was computed basedon the Arc and used for control oftopographic surveys. It was knownthat some of this trig. was not up toprimary standards, but it was theonly work available and it was hopedthat recomputation based on the Arcwould produce results of sufficientaccuracy for the purpose required.

Since Laplace Azimuths had notbeen available for the Arc computa-

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t ion nor in Tanganyika, theTanganyika trig. was computed with-out holding fixed any azimuths,which were, in any case, of doubtfulvalue. When the trig. computationreached Malindi in Kenya from theArc it was found that the (A-G) azi-muth was approximately 20".

It was then decided that a newapproach was necessary. Put in newprimary circuits based on the Arc,and observe frequent astronomicstations and tellurometer lengths,much closer together than the oldmeasured bases. The trig. circuits(were) to be adjusted to the fixed(or nearly fixed) scale and azimuthchecks. This policy has been carriedout and results have already beencirculated for: -

The Lake CircuitUganda PrimaryKenya Primary

All these results have beenheaded, as before, ‘New 1950 ArcDatum’, because the fundamental

datum, which is the Arc, has not beenchanged. Whenever the new coor-dinates differ from the previous; thisis due to a recomputation (includingnew observations) of part of the trig.system.

To avoid any further misunder-standing in the future it is proposedto change the heading of trig. listsnow to ‘New 1960 Arc Datum.’ Mostof the Tanganyika main trig. has stillto be recomputed and a letter willbe sent to each territory indicatingthe particular trig. chains which havealready been recomputed and circu-lated under the 1950 heading.

The Figure of the Earth used is theModified Clarke 1880, for which a =6378249.145 and r = 293.465 in Inter-national Metres. The geodetic tablesused are Latitude Functions Clarke1880 Spheroid, Army Map Service, butmost D.O.S. computations are nowdone on the Electronic Computer,which computes its own geodetic fac-tors ‘ab initio’. Co-ordinates are alsoproduced on the U.T.M. projection.”

Thanks go to Washington Abuto whereinhis letter of 24 November 1997 for the Di-rector of Surveys of the Survey of Kenyaenclosed a paper detailing much of Kenya’shistory of Grids and Datums. That paper,authored by Mahinda, served as the basis ofmuch of the specific geodetic history quotedin Davis’ graduate-level term paper of 1999.

Cliff Mugnier teaches Surveying, Geodesy,and Photogrammetry at Louisiana State Uni-versity. He is the Chief of Geodesy at LSU’sCenter for GeoInformatics (Dept. of Civil andEnvironmental Engineering), and his geo-detic research is mainly in the subsidence ofLouisiana and in Grids and Datums of theworld. He is a Board-certified Photogram-metrist and Mapping Scientist (GIS/LIS), andhe has extensive experience in the practiceof Forensic Photogrammetry.

The contents of this column reflect the views of theauthor, who is responsible for the facts and accuracy ofthe data presented herein. The contents do not neces-sarily reflect the official views or policies of the Ameri-can Society for Photogrammetry and Remote Sensingand/or the Louisiana State University Center for GeoInfor-matics (C4G).

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Grids & Datums