The Climate of Peoria. 35 
temperature is often very rapid. The highest temperature observed durin 
the whole period of observations was 105 on the 3lst of August, 1878, the 
lowest —27 on the 5th of January, 1884, a difference of 1382 degrees. The great- 
est range in one month (January 1874) was 87 degrees between 65 and 
—22, and the greatest range in 24 hours was observed in January, 1876, when 
the mercury went down 61 (28th, 2 P.M.) to 8 (29th, 7 A.M.)=53 degrees, and 
the same range was observed 1881 in January, when the temperatare fell from 
34 (13th, 2 P.M.) to —19 (14th, 7 A.m.). Such daily oscillations are frequent, 
particularly in December, February and April, and even in July the greatest 
difference in 24 hours was 87 degrees. 
The lowest daily mean temperature of the period in question 20.7 (on the 
8th of January), the highest 80.4 (16th of July. 
» Following the daily march of mean temperature, we commence with the 
Ist of December (the first day of the meteorological year) with a mean of 34. 
It keeps below freezing point from the 7th of December to the 24th of Febru- 
ary (with the exception of two days, the 12th of December with 32.8 and 22d 
of February with 32.3); then it rises gradually (with exception of the 4th 
of March with 30.7) during the month of March, keeps above 40 from the 
26th of March, above 50 from the 17th of April, above 60 from the 7th of May, 
above 70 from the 5th of June and reaches the maximum on the 16th of July; 
then descending gradually to 70 on the 8th of September, to 60 on the 7th of 
October, to 50 on the 25th of October, to 40 on the 16th of November, and to 
freezing point on the 29th and 30th of November. ‘That rising and falling of 
mean temperature is not quite continuous from day to day, but often oscillat- 
ing, particularly in winter and summer; but taking periods of 10 days 
(decades) dividing each month in approximately three equal parts we find 
rise and fall continuous from the first decade in January—22.6 to 2d decade in 
July=78.3 and descending again to January in the following way: 
ist decade. : 2d decade. 3d decade. Month. 
PADLUALY: vis ove ROW, Ce ifain ses és - es ae LOB diese tered teas 24.5 
DEW BEV ras ce voc) SOE) ase aca op oo eee ae sige ss SAGe orescence dh ya 29.2 
VAG ho 28. 2. Gimme tesss.. oad BE. os ce es AT Sess. or. cites 88.1 
Lg gt Ba Ee YE AS 2 ee RP Os ae BD atss ra ksiws ed 51.7 
WEN Bod ata oe ne re EDS 3... occuaeieeee CT ao cde 63.8 
BRO oes osu cei eee (U2. eS Se . . cba cde nee One ae aden eh aRe 73.38 
Ss Dy eae eee 8 Oat 1 A ee TES}. .« cceaeenens OAs abs srk dia da aes Atal 
PSUS Uiexgeuee dives (Caietigedesesssceee MeO... .edeaueens DOien coaatatdena eats 75.2 
September ...... (be Se Ga, ... bce Gas Naseectcr hay! 66.7 
OGLODEY..t.cc0si+e a te, RS ee A Oo BR d ie tcwuds oh ss 53.7 
NPM IL GL (¢55 sc ti FO a eebinele +. eats eye Oo ie uid danteaae ewe 39.4 
PISCOM DEL sues. O21 De tase dre cece occs BOs. 55. scenes Ub cree so ne Bo, 28.6 
% 
That the maximum and minimum does not coincide with the summer and 
winter solstices is explained by the accumulation of heat during the summer 
months and in the negative during the winter months. 
Comparing the result of 30 years with the march of temperature of a 
single year, we find the latter much more irregular. In 1858 after a very mild 
January followed a severe February, and the first decade of March was colder . 
than the first decade of January. In 1869 the first decade of February was 
the coldest of that winter and March colder than January. 
The mean temperature of Peoria is about the same as that of Paris in 
France under 48° 5U’ N.L., that is 8 degrees farther north than Peoria. We 
find for spring and fall about the same temperature in both localities, but a 
great difference for summer and winter. 
