6 REPORT OF THE MALARIA EXPEDITION. 
Wc will content ourselves by giving a table extracted from the work of Major L, M. 
Wilson, R.A.M.c. [i6]. The statistics are based on admissions to hospital among the troops in 
Sierra Leone during seven years (1892-98), and on the meteorological returns of the same period. 
dverage monthly Admission rates among the troops, and average monthly Rainfall, Humidity, and 
Temperature in Sierra Leone during seven years (1892-98). 
Month. 
Average admissic 
Non-European. 
n rate per looo. 
European. 
Average 
Rainfall in 
inches. 
Average 
Humidity. 
Average 
Temperature 
in shade. 
January ... 
52 
93 
.80 
70.2 
80.8 
47 
99 
.86 
68.2 
81.0 
March 
63 
59 
1.24 
67.7 
81.7 
April 
86 
4-jO 
o7o 
81 6 
May 
99 
225 
14.08 
75-3 
80.3 
June 
128 
347 
18.62 
77.1 
79-2 
July 
171 
413 
33-34 
83.0 
78.3 
August ... 
116 
281 
38.96 
84.0 
77.7 
September 
91 
173 
29.85 
82.2 
78.8 
October ... 
67 
121 
'4.63 
79.1 
79-4 
November 
72 
125 
5-41 
75.0 
80.5 
December 
64 
92 
1.26 
71.9 
80.7 
j Annual 
1056 
2134 
163.41 
75.0 
So.o 
Judging from these figures Wilson remarks, " The largest number of cases occur in 
the middle of the rainy season." Though many of tlie cases recorded in the rains may be 
relapses due to wettings, chills, etc., this can scarcely account for the quadruplication of the 
admissions shown in the table ; and it would therefore appear that the period of fresh infections 
sets in (or at least increases) with the rains, and ceases (or at least diminishes) with them. 
Wilson also thinks that "The white troops suffer more in proportion than the black." 
He gives the annual average death-rate of the wiiite troops from malarial fever at 42.9 per 
mitle, as against 5.9 per tnille for the black troops. Similarly, he thinks that "Each battalion 
of the West India Regiment suffers exceptionally from fever the first year of its service on 
the coast." Such differences point rather to variations in immunity, than to variations in 
frequency of infection in the groups concerned. 
It is hardly necessary to compare tliese statistics of Sierra Leone with similar figures 
for many other stations in the empire ; but it will be instructive to give some ratios taken 
from the Annual Report of the Sanitary Commissioner with the Government of India for 1897. 
For the whole European Army of India during that year the admissions per milk of 
strength for malarial fever were 420.1 ; and the deaths per mille were i.o — far below the 
