10 BULLETIIS" 1039, V. S. DEPAETMEXT OF AGRICULTURE. 



TEMPERATURE. 



The temperatures at the Belle Fourche Experiment Farm are re- 

 corded daily throughout the year by means of maximum and mini- 

 mum thermometers. During the growing season a thermograph was 

 also used. The mean monthly temperatures in degrees Fahrenheit 

 from 1908 to 1919, inclusive, are shown in Table IV. 



Table IV. — Mean monthhj temperatures (in degrees F.) at the Belle Fourehe 

 Exjieriment Farm during the T2-year period from 190S to 1919, inclusive. 



Month. 



1908 



1909 



1910 



1911 



1912 



1913 



1914 



1915 



1916 



1917 



1918 



1919 



Aver" 

 age. 







12 

 23 

 32 

 38 

 52 

 66 

 70 

 75 

 61 

 46 

 31 

 10 



18 

 8 

 46 

 51 

 52 

 68 

 76 

 68 

 59 

 51 

 31 

 25 



20 

 22 

 39 

 43 

 58 

 73 

 71 

 65 

 59 

 43 

 25 

 20 



12 

 24 

 19 

 47 

 55 

 66 

 70 

 - 68 

 52 

 45 

 38 

 28 



13 

 17 

 23 

 48 

 53 

 66 

 70 

 74 

 59 

 42 

 37 

 23 



27 

 14 

 33 

 43 

 55 

 65 

 76 

 69 

 62 

 49 

 39 

 15 



16 

 19 

 21 

 52 

 51 

 58 

 64 

 66 

 56 

 50 

 34 

 25 



5 

 22 

 34 

 42 

 52 

 60 

 74 

 67 

 58 

 43 

 32 

 13 



13 

 11 

 25 

 40 

 50 

 62 

 75 

 67 

 60 

 42 

 41 

 13 



9 

 20 

 40 

 41 

 55 

 69 

 69 

 70 

 56 

 50 

 31 

 25 



29 

 18 

 31 

 43 

 56 

 70 

 75 

 71 

 61 

 35 

 23 

 14 



16 



February 





18 



March 





31 



April 



48 

 52 

 63 

 73 

 68 

 64 

 45 

 37 

 22 



45 



May 



5a 



June. 



66 



July 



72 





69 



September 



59 



October 



45 



November 



33 



December 



19 











43 



46 



45 



44 



44 



46 



43 



42 



42 



45 



44 



44 









The average annual mean temperature was 14°. The absolute mini- 

 mum during this period was —37° F. in January, 1916, and the abso- 

 lute maximum was 109° F. in July, 1910. The temperature has not 

 been a limiting factor in the 3delds of most of the spring grains. 

 The grain sorghums and late varieties of proso, however, usually 

 were frosted before fully mature. Winter wheat suffered some injury 

 from low temperatures nearl}' every j-ear and during the winter of 

 1917-18 was almost completely destroyed. 



Table V. — Dates of killing frosts, the last in spring and the first in autumn, 

 at the Belle Fourche Experiment Farm, for each year from 1908 to 1919, 

 inclusive. 





Last frost in 

 spring. 



First frost in 

 faU. 



Frost- 

 free 

 period. 



Year. 



Last frost in 

 spring. 



First frost in 

 faU. 



Frost- 



Year. 



Date. 



Tem- 

 pera- 

 ture. 



Date. 



Tem- 

 pera- 



tute. 



Date. 



Tem- 

 pera- 

 ture. 



Date. 



Tem- 

 pera- 

 ture. 



free 

 period. 



1908 



1909 



1910 



1911 



1912 



May 20 

 May 17 

 May 23 

 May 11 

 May 4 

 Mav 6 

 May 13 



"F. 

 29 

 26 

 31 

 30 

 32 

 32 

 30 



Sept. 26 

 Sept. 23 

 Aug. 25 

 Aug. 27 

 Sept. 23 

 Sept. 24 

 Oct. 5 



°F. 

 22 

 31 

 32 

 32 

 32 

 29 

 28 



Days. 

 129 

 128 

 93 

 107 

 141 

 140 

 144 



1915 



1916 



1917 



1918 



1919 



Average. 



Mav 21 

 May 16 

 May 31 

 May 21 

 Jime 1 



May 18 



'F. 

 32 

 31 

 30 

 31 

 32 



Sept. 14 

 Sept. 14 

 Oct. 7 

 Sept. IS 

 Oct. 9 



Sept. 21 



'F. 

 31 

 28 

 20 



28 

 12 



Days. 

 115 

 121 

 145 

 120 

 130 



1914 



30.5 



28 



126 



The dates and minimum temperature of the last spring and first 

 autumn frosts each vear are shown in Table V. The latest spring 



