164 OBSEEVATIONS ON THE WINDS. 



(91.) The Harmattan. — On the Gold Coast, as well as the "Windward 

 Coast, an Easterly wind, called the Harmattan, prevails during the months 

 of December, January, and February. This wind comes on indiscriminately, 

 at any hour of the day, at any time of the tide, at any period of the moon 

 and continues sometimes only a day or two, sometimes five or six days, 

 and it has been known to last fifteen or sixteen days. There are generally 

 three or four returns of it in every season ; it blows with a moderate force, 

 not quite so strong as the sea-breeze, which every day sets in, during the 

 fair season, from the West, W.S.W., and S.W. ; but somewhat stronger 

 than the land-wind at night, from the North and N.N.W. 



In the " Philosophical Transactions," vol. Ixxi, 1781, an account of the 

 Harmattan was first given by Matthew Dobson, M.D., F.E.S., from the 

 enquiries and observations of Mr. Norris, of which the following is the 

 substance : — 



On that part of the Coast of Africa which lies between Cape Verde and 

 Cape Lopez, a singular periodical Easterly wind, named, by the natives, 

 Harmattan, prevails during the months of December, January, and Febru- 

 ary. Cape Lopez lies to the Southward of the Line. At the Isles de Los, 

 which lie to the Northward of Sierra Leone, this wind blows from the 

 E.S.E. ; on the Gold Coast, from the N.E. ; and at Cape Lopez and the 

 Eiver Gaboon, from the N.N.E. 



The Harmattan com«s on as above described. A fog or haze always 

 accompanies it, and the gloom is sometimes so great as to render near 

 objects obscure. The s>Un is thus concealed the greatest part of the day, 

 and appears only a few hours about noon, and then of a mild red colour. 

 At 2 or 3 miles from shore the fog is not so thick as on the beach ; and at 

 12 or 15 miles distance it is entirely lost, though the Harmattan is felt for 

 30 or 35 miles off shore, and blows fresh enough to alter the course of the 

 current. 



Extreme dryness is a property of this wind. No dews fall during its 

 continuance, nor is there the least appearance of moisture in the atmosphere. 

 All vegetables are much injured, and many destroyed. The seams in the 

 sides and decks of ships become very leaky, though the planks are 2 to 3 

 inches thick. Iron-bound casks require the hoops to be frequently driven 

 tighter, and a cask of rum or brandy can scarcely be preserved ; for, unless 

 kept constantly moistened, the hoops fly off. The Harmattan has, hkewise, 

 very disagreeable effects on the skin, lips, and nose, which become sore. 



The effects of the Harmattan in evaporation are great, as will appear by 

 the following comparative statement : — At Liverpool, the annual evapora- . 

 tion is about 36 inches ; at Whydah, 64 inches ; but, under the influence 

 of the Harmattan, at the rate of 133 inches. 



This wind, though so prejudicial to vegetable life, is highly conducive to 

 health; so that fluxes, fevers, small-pox, &c., generally disappear in spite 

 of the doctor ; and it contributes to the cure of ulcers, and cutaneous 

 eruptions. The baneful effects which have beeu said to arise from the 

 prevalence of this wind proceed from the periodical rains, which fall in 

 March, April, &c., and are ushered in by the Tornados from the N.E. and 

 E.N.E., accompanied with violent thunder and lightning, and very heavy 

 ehowers. The earth, drenched by these showers, and acted upon by aq 



