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Naut. Mag. 1837 p. 291 M Burnett in 1837 in sailing from Lat. 4 20 N. 23 20 W to 8° N. 27°. 20' W. from 12th of March February to 15th with trade wind very hazy NE (after a squall) horizon hardly visible — all sails, rigging & mast masts covered with red dust — like that from streets of Calcutta during blowing season. — On 15th weather cleared up — "nearest land during these 4 days was 600 miles off—

— Observed same phenomenon previous year.

Naut. Mag. 1838 p 824. A critic on this paper says — coast of Africa 20° to 32 N. Lat. is desert interspersed with immense hills of loose sand — & so impregnates the air, as to make it hazy & very dangerous to navigators.— Capt. Paddock

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& May in Princess Louisa

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who was wrecked in Lat 29. says air was smoky

In 1817— Baron Roussin says survey was very difficult among other among other causes was thick fog or haze, "that prevails almost all the year on the coasts of N.W Africa." It is produced by the sands which the winds raise from the deserts"— As longs as wind keep parallel to shore, the haze reaches only to a short distance, but when the harmattan takes place (in Jan, Feb: March & often even April)— the sands from the interior by this wind which blows from the NE & to the ENE, spread through the atmosphere with tornados — all objects & stars below 30° from the horizon are hidden — (Now let us see whether all dust brought about

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this time of year. —