Jackie ex­am­ines the his­tory be­hind Ma­clear's Bea­con

Cape Argus - - FRONT PAGE - By Jackie Loos

WHAT would the Cape Penin­sula be with­out its iconic moun­tain chain? A sandy, wa­ter­less, windswept waste, un­able to sup­port more than a few hun­dred peo­ple at best. Be­sides at­tract­ing vis­i­tors and pro­vid­ing de­light­ful vis­tas, the moun­tains sup­ply shel­ter, spe­cial mi­cro-cli­mates and enough wa­ter to sup­port di­verse forms of life, in­clud­ing a unique flo­ral king­dom that de­lights botanists and gar­den­ers.

Viewed from the north, Ta­ble Moun­tain re­lies on its mas­sive ram­parts and flat­tened top for im­pact and makes no great statement about its high­est point.

In­deed, it’s im­pos­si­ble for first-time vis­i­tors to tell where the sum­mit might be with­out some guid­ance or a map.

It is, in fact, a 35- to 45-minute walk from the up­per ca­ble sta­tion to Ma­clear’s Bea­con (1087m) on the east­ern side of the moun­tain, where the ground is 19m higher than it is at the ter­mi­nal.

The bea­con con­sists of a man-made rock cairn named in hon­our of Her Majesty’s As­tronomer at the Cape, Thomas Ma­clear (1794-1879), who was knighted in 1860.

In 1844, Ma­clear asked his able as­sis­tant Wil­liam Mann to build a “pile” as part of an am­bi­tious project to ver­ify and ex­pand the data col­lected by the French as­tronomer Abbe Ni­co­las de La­caille dur­ing the pre­vi­ous cen­tury, with ref­er­ence to the Cape Arc of the Merid­ian (an imag­i­nary due north-south line in­tended to sup­ple­ment sim­i­lar mea­sure­ments in the north­ern hemi­sphere).

In­ter­est­ingly, some­thing had gone amiss with De La­caille’s lat­i­tude mea­sure­ment and he ended up “prov­ing” that the Earth was pear-shaped, not round like an or­ange. (Mann was later able to cor­rect this per­cep­tion, and ev­ery­one was happy again!)

As­sisted by be­tween 20 and 35 labour­ers, Mann set to work in De­cem­ber 1844. The com­pleted cone-shaped pile was 5m high and formed one of three ma­jor tri­an­gu­la­tion points built to mea­sure the cur­va­ture of the Earth.

The en­tire mound was painted with lamp-black to make it more vis­i­ble.

At first the cairn had no name, but it be­came known as Ma­clear’s Bea­con.

Hav­ing served its sci­en­tific pur­pose, the pile was in­te­grated into the ge­o­detic and trigono­met­ri­cal sur­vey net­work that made ac­cu­rate prop­erty sur­veys pos­si­ble.

Its use­ful­ness grad­u­ally de­clined, how­ever, and it col­lapsed into a shape­less heap in the 1920s.

It was re­stored 50 years later to mark the cen­te­nary of Ma­clear’s death in 1979, when a Na­tional Mon­u­ments Coun­cil plaque com­mend­ing the as­tronomer was ce­mented into its side.

The orig­i­nal rocks were reused but the pile may have lost a bit of height in the process.

For­tu­nately for mod­ern vis­i­tors who like to clam­ber up the cone to be pho­tographed, the lamp-black­ing was not re­newed.

The views are, of course, stu­pen­dous.

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