X.
A METEOROLOGICAL NOTE.
The Lake Nyassa region of Africa knows only two seasons--the rainy and the dry. The former begins with great regularity on the opening days of December, and closes towards the end of April; while during the dry season, which follows for the next six months, the sun is almost never darkened with a cloud. At Blantyre, on the Shiré Highlands, the rainfall averages fifty inches; at Bandawé, on Lake Nyassa, a register of eighty-six inches is counted a somewhat dryish season.
The barometer in tropical countries is much more conservative of change than in northern latitudes, and the annual variation at Lake Nyassa is only about half an inch--or from 28.20 inches in November to 28.70 inches in June. The diurnal variation, according to Mr. Stewart, is rarely more than twenty-hundredths of an inch.
The average temperature for the year at Blantyre, where the elevation is about three thousand feet above sea-level, is 50° Fahr., but the mercury has been known to stand ten degrees lower, and on one exceptional occasion it fell 2° below freezing point. At Lake Nyassa, half the height of Blantyre, 85° Fahr. is a common figure for mid-day in the hottest month (November) in the year, while the average night-temperature of the coldest month (May) is about 60°. The lowest registered temperature on the Lake has been 54°, and the highest--though this is extremely rare--100° Fahr. When the Livingstonia Mission occupied the promontory of Cape Maclear, at the southern end of Nyassa, in 1880, one of the then staff, Mr. Harkess, had the energy to keep a systematic record of the temperature, and I am indebted to his notebook for the following table. The figures represent observations taken at 6 A.M., 12 noon, and 6 P.M. A dash indicates that the observation was omitted for the hour corresponding. The wet bulb reads on an average 10 degrees lower.
TABLE OF TEMPERATURES AT LAKE NYASSA.
May June July Aug. Sept.
1 70 62 64 67 68 80 75 73 74 79 75 76 74 73 75
2 -- 60 64 68 69 77 78 74 -- 79 -- 73 -- 74 75
3 67 65 62 65 66 76 78 74 -- 75 76 74 70 -- 74
4 68½ 64 -- 62 71 79 71 73 -- 77 78 70 -- -- 79
5 68 64 63 76 -- 79 74 -- -- -- 76 74 71 -- --
6 -- 64 64 70 65 75½ 77 72 77 81 75 76 74 -- 77
7 66 67 64 61 72 79 78 71 79 80 75 75 71 -- 77
8 65 66 64 -- 70 74 74 -- -- 80 74 74 71 -- 81
9 -- 68 65 62 70 77 76 75 79 81 -- 73 73 -- 77
10 67 68 66 61 -- 75 75 -- 81 80 74 73 71 -- 77
11 69 66 -- 62 70 75 76 76 79 79 -- 75 73 -- 79
12 -- 66 69 65 -- 75 75 77 81 -- 71 72 -- 76 --
13 65 -- 70 72 76 73 80 79 74 -- 77 78
14 67 63 68 71 73 74 77 81 71 -- 75 78
15 68 64 -- 66 72 76 74 -- -- 75 75 72 76 -- 77
16 71 64 68 67 -- 77 74 79 75 79 75 70 78 73 77
17 68 64 65 -- -- 78 74 77 -- -- 77 72 -- 76 76
18 72 71 68 68 73 80 74 75 75 78 78 72 76 72 77
19 65 64 69 -- -- 74 -- 77 75 -- 76 77 79 74 --
20 63 -- 67 68 75 74 76 76 -- 82 76 74 74 75 80
21 67 65 64 64 71 75 72 75 -- 85 75 68 75 75 78
22 70 63 67 -- 72 75 66 75 78 81 -- 65 76 75 79
23 58 65 -- 70 67 77 79 82 70 74 77 78
24 -- 62 64 68 73 76 -- 76 69 82 76 -- 74 66 81
25 67 61 66 63 74 77 -- 74 75 -- 75 -- 75 71 78
26 67 63 67 64 -- 75 75 79 72 -- 75 -- 76 73 --
27 69 -- 65 65 73 77 72 74 77 84 74 -- 71 77 82
28 70 -- 65 70 73 78 72 76 79 81 77 -- 74 78 79
29 68 63 65 -- 68 80 71 72 76 82 77 72 75 -- 80
30 -- 64 63 67 74 75 74 78 79 82 76 -- 75 77 80
31 67 65 66 74 76 79 74 76 83