Grids & Datums Saint Vincent and the Grenadines By Clifford J. Mugnier, C.P., C.M.S.

The cannibal warrior Carïbs arrived in Saint in 1946 by the Hydrographic Service of isting survey control marks previously set Vincent around the 14th century, and they the British Admiralty on 04 December. The by the Lands and Surveys Department

strongly resisted colonial settlers until the coordinates of Fort Charlotte (V.1) are Φo (L&SD), and I was successful in obtaining th 18 century. Christopher Columbus prob- = 13º 09' 24" N and Λo = 61º 14' 43" West of the classical St. Vincent Datum of 1946 coor- ably sighted the island on 22 January 1498 Greenwich, the reference azimuth from “V. dinates of four of the six points collocated

(St. Vincent’s Day). In 1673 the first African 1” to “V. 3” is αo = 107º 30' 13.42", the el- with GPS observations. Unfortunately, I do

slaves were shipwrecked in the Grenadines, evation of “V.2” is: Ho = 370.36 feet, and the not have a record of who it was that sent the but they managed to get to St. Vincent, in- baseline length (measured in 1945 by the information to me on official L&SD statio- termarry with the Carïbs, and became known Royal Engineers [R.E.] by catenary) from nery. I ran a solution for the three param- as the “Black Carïbs.” In 1795 the Carïbs un- “V.30” to “V.32” is 2,347.504 m. (Invar tapes eters of geocentric translation for those four successfully rose in revolt against the Brit- or wires were commonly calibrated for a points; two were listed as First Order and ish, and 5,000 or more of them were de- standard length by being supported only at two were listed as Second Order. The re- ported to Roatan Island off the coast of Hon- the ends of the tape or wire with a specific sultant relation I derived from the St. Vincent duras. The hurricane of 1898 and the volca- tension, thus the sag formed a catenary Datum of 1946 to WGS 84 is ∆X = +196 m, nic eruption of 1902 were disastrous to the curve). The reference ellipsoid is the Clarke ∆Y = +332 m, and ∆Z = +275 m. I estimate economy. In 1958 Saint Vincent joined the 1880 where: a = 6,378,249.136 m, and 1/f the horizontal accuracy to be good to about West Indies Federation, it received a new = 293.46631, the same parameters as for 1 meter for the island of Saint Vincent. Be- constitution in 1960, and it became a state Jamaica (PE&RS, May 2003). Courtesy of the cause I had zero data on collocated points on in association with the United Kingdom U.K. Military Survey, “The height of V.2 was any of the other islands, my guess is that the (PE&RS, October 2003) in 1969. Indepen- established by the R.E. party by leveling three-parameter shift values listed above are

“Some of the smaller islands are privately owned - probably not by retired cartographers.”

dence for Saint Vincent and the Grenadines from a Bench Mark on a step of the Aquatic likely good to no more than a few meters for was achieved on 27 October 1979. Encyclo- Club, Kingstown; the height of the Bench the remainder of the islands to the south pedia Britannica says, “In 1979 the Soufrière Mark was established by the R.E. party from because of the usually superb quality of work volcano (1,234 m) erupted once again, dam- mean tide gauge reading taken over a pe- produced by the Royal Engineers. Thanks to aging agriculture and the tourist trade. Hur- riod of four months.” (Note that a Metonic Dave Doyle of NGS for the NAD83 coordi- ricane Allen virtually wiped out the all-im- cycle is 18.67 years! – Ed.) nates of Saint Vincent. portant banana crop in 1980.” The coordinate system used by the Lands Ô Slightly less than twice the size of Wash- and Surveys Department of Saint Vincent Cliff Mugnier teaches Surveying, Geodesy, ington, D.C., there are 32 Grenadine islands and the Grenadines is the British West Indies and Photogrammetry at Louisiana State Uni- and cays, of which the largest are Bequia, (BWI) Grid which is based on the Transverse versity. He is the Chief of Geodesy at LSU’s Mustique, Canouan, and Union. Of a total Mercator projection where the Central Me- Center for GeoInformatics (Dept. of Civil and 389 km2, the area of Saint Vincent is 344 ridian λ = 62º W, the Scale Factor at Origin o Environmental Engineering), and his geo- km2. Some of the smaller islands are pri- m = 1999/2000 = 0.9995, and the False o detic research is mainly in the subsidence of vately owned – probably not by retired car- Easting is 400 km. Note that the unit of mea- Louisiana and in Grids and Datums of the tographers. Part of the Windward Islands, surement for this BWI Grid is the meter world. He is a Board-certified Photogram- the name dates back to the 18th century when where 1 meter = 3.2828456 feet. The strange metrist and Mapping Scientist (GIS/LIS), and English ships bound for Jamaica followed the conversion factor is likely due to an earlier he has extensive experience in the practice trade-wind passage, and stopped at islands colonial length standard that was used for of Forensic Photogrammetry. along the way. The islands constitute a north- property surveys; a common quirk of old south chain in the southern section of the British Colonies throughout the world. The contents of this column reflect the views of the Lesser Antilles and share a volcanic rock for- In 1996, the United States National Geo- author, who is responsible for the facts and accuracy of the data presented herein. The contents do not neces- mation. detic Survey (NGS) performed a GPS survey sarily reflect the official views or policies of the Ameri- The earliest geodetic survey of Saint of selected points on the island of Saint can Society for Photogrammetry and Remote Sensing Vincent was of Fort Charlotte (lighthouse) Vincent. The NGS occupied a number of ex- and/or the Louisiana State University Center for GeoInformatics (C4G).

172 February 2004 PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING