34 
the exact date of the onset in a number of cases is not given; further, 
the temperature and precipitation varies some in ditferent parts of the 
valley, and I could not obtain these data for the exact locality where 
the cases occurred. Hence the results obtained are only approximate. 
I find that of the cases upon which even an approximate comparison 
could be made 13 cases developed in the valley within seventy-two 
hours following an increase in temperature at Missoula, but no pre- 
cipitation was reported for Missoula; 45 additional cases developed in 
the valle}^ within seventy-two hours following an increase in temper- 
ature at Missoula, and precipitation is reported for Missoula during 
the same period. Thus a total of 58 cases occurred during or follow- 
ing conditions which would result in a swelling of the streams, hence 
more moist general conditions. One additional case developed during 
a decrease of temperature at Missoula, without any contemporaneous 
precipitation. 
Without laying too much stress upon these data, because of their 
incompleteness, it is rather striking that of the 59 cases in which the 
given data could be compared, 58 of them, or 98.3 per cent, occurred 
under conditions which would result in an increase in the amount of 
running water in the valley, thus apparently bearing out the popular 
view that ‘‘spotted fever” is more likely to develop during a rise 
rather than a fall of the vallev streams. 
It is also interesting to note that by far the majority of the cases 
occur on the west side of the river, which is more moist than the east; 
that the disease seems to be a disease of valleys, which are naturalh^ 
more moist than are the plains. Future investigations, therefore, 
have the interesting problem to solve whether this concurrence of 
moisture with the infection is of an}" significance or is a mere coinci- 
dence. The relation of the moisture to the tick theory is not apparent 
to me. 
Taking the monthly maximum temperature at Missoula in connec- 
tion with 88 cases which could be plotted, it was found that the lowest 
maximum was 48.1^ F. (2 cases), the highest, 87.6° F. (2 cases); 3 
cases occurred with monthly average maximum from 48.1 to 49.6° F., 
20 cases with monthly average maximum from 54.2 to 58.6° F., 34 
cases with monthly average maximum from 63 to 69° F., 26 cases with 
monthly average maximum from 71. T to 76.6° F., 5 cases with monthly 
average maximum from 80.5 to 87.6° F. 
For the same 88 cases, the lowest monthly average minimum tem- 
perature at Missoula was 22.2 (1 case), and the highest average mini- 
mum, 51.2° F. (2 cases). Four cases occurred with a monthly average 
minimum from 22.2 to 28.5° F., 38 occurred with a monthly aver- 
age minimum from 31 to 38.7° F., 44 occurred with a monthly average 
minimum from 41 to 48.7° F., and 2 with a monthly average minimum 
of 51.2° F. 
