(4

harmattan blows from the NE & ENE, accompanied by tornados, the dust is blown far out, & is raised on high, & are so that stars & all other objects within 30° degrees of the horizon are hidden.

(From the several recorded accounts,* (6) it appears that the quantity of dust which falls on vessels in the open Atlantic is considerable, & that the atmosphere is often rendered quite hazy; but nearer to the African coast the quantity is still more considerable. Vessels have been washed several times run run on shore owing to the haziness of the air: & Horsburgh* (7) recommends all vessels, for this reason, to avoid the passage between the Cape Verd Archipelago & the continent main-land. Roussin also, during his survey, was thus much impeded in his survey. Lieut. Arlett* (8) found the water so disco discoloured* (8), that the track left of by his ship was visible for a long time; & he attributes this in part to the fine sand blown from the deserts, "with which everything on board soon becomes perfectly caked.")

(Mr Fletcher → Back of Page one This note to be at foot of Page.)

Professor Ehrenberg* has examined the dust collected by Lieut James & myself; & he finds that it is in considerable part composed of infusoria, & he determined including no less than l sixty six seven different forms. These consist of 32 species of siliceous-shielded Polygastrica; 34 forms of Phytolitharia, or the siliceous tissues of plants; and one 1 of Polythalamia. In The little packet of dust collected by myself which would not have filled a quarter of a tea-spoon, there are yet it contains 17 forms. Professor

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* z These microscopic organisms have been described in the 'Monatsberichten der Berlin Akad. der Wissensch. Mai 1844; [illeg] & part and 27 Februar 1845."

In the latter paper a full list of the names is given: the column marked St. Jago includes those collected by myself. here It may be worth here recording, that Sir A Burnes (Travels in Cabool, p. 223), in describing Khoten, a region of Upper Asia, adds, " x

Cabool, being a Personal Narrative &c by Sir Alex Burnes.

p. 223 describing Khoten a region of upper Asia when the climate is very dry, he adds "it is said that its productiveness depends upon clouds of red dust, which always fall or are blown in this part of Asia." But he thinks that the statement requires confirmation.