Again, as the generality of maps have placed the coast of Arabia where Loheia stands, in the 44°, and it is the part of the peninsula that runs farthest to the westward, all the west coast of Arabia Felix will fall to be brought farther east about 3° 46´ 0´´. Before packing up our barometer at Loheia, I filled a tube with clean mercury, perfectly purged of outward air; and, on the 30th of August, upon three several trials, the mean of the results of each trial was, at six in the morning, 26° 8´ 8´´; two o’clock in the afternoon, 26° 4´ 1´´; and, half past six in the evening, 26° 6´ 2´´, fair, clear weather, with very little wind at west. At Masuah, the 4th of October, I repeated the same experiment with the same mercury and tube; the means were as follow: At six in the morning 25° 8´ 2´´; two o’clock in the afternoon, 25° 3´ 2´´; and, at half past six in the evening, 25° 3´ 7´´, clear, with a moderate wind at west, so that the barometer fell one inch and one line at Masuah lower than it was at Loheia, though it often rose upon violent storms of wind and rain; and, even where there was no rain, it again fell instantly upon the storm ceasing, and never arrived to the height it stood last at on the coast of Arabia. The greatest height I ever observed Fahrenheit’s thermometer in the shade, at Masuah, was on the 22d of October, at two in the afternoon, 93°, wind N. E. and by N. cloudy; the lowest was on the 23d, at four in the morning, 82°, wind west. It was, to sense, much hotter than in any part of Arabia Felix; but we found no such tickling or irritation on our legs as we had done at Loheia, probably because the soil was here less impregnated with salt. We observed here, for the first time, three remarkable circumstances shewing the increase of heat. I had carried with me several steel plates for making screws of different sizes. The heat had so swelled the pin, or _male_ screw, that it was cut nearly one-third through by the edge of the female. The sealing-wax, of which we had procured a fresh parcel from the India ships, was fully more fluid, while lying in our boxes, than tar. The third was the colour of the spirit in the thermometer, which was quite discharged, and sticking in masses at unequal heights, while the liquor was clear like spring-water. Masuah is very unwholesome, as, indeed, is the whole coast of the Red Sea from Suez to Babelmandeb, but more especially between the tropics. Violent fevers, called there _nedad_, make the principal figure in this fatal list, and generally terminate the third day in death. If the patient survives till the fifth day, he very often recovers by drinking water only, and throwing a quantity of cold water upon him, even in his bed, where he is permitted to lie without attempting to make him dry, or change his bed, till another deluge adds to the first.