1164 ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
Frost and Precipitation in Towa 
Frost Precipitation 
Average Date of Date of 
Station 
First Last First Last Annual 
Killing in in in in 
Autumn Spring Autumn Spring 
Charles City............ Sept. 5 May 3 Sept. 12 May 21 29.8 
Larrabee..........-.40 Sept. 20 May 11 Sept. 12 May 31 30.4 
Alta... ccc cece cee eee ee Sept. 26 May 7 Sept. 12 May 30 30.7 
Hampton............66. Oct. 2 May 4 Sept. 20 May 3l 33.2 
Fayette... ..........05. Sept. 18 May 8 Sept. 11 May 31 32.7 
Elkader.............00- Sept. 23 May 5 Sept. 11 June 1 31.2 
Sioux City....... Sept. 23 May 1 Sept. 13 May 21 25.5 
Sac City.........0.0.0e. Sept. 22 April 30 Sept. 12 May 19 31.1 
Towa Falls.............. Sept. 22 ay Sept. 12 May 31 29.8 
Grundy Center.. ....... Sept. 26 May 8 Sept. 12 May 381 34.0 
Independence........... Sept. 26 May 4 Sept. 12 May 31 27 4 
Dubuque........ 0.2... Oct. 12 April 20 Sept. 27 May 21 35.0 
Carroll... 0... 0 2. -..e. Sept. 22 May 5 Sept. 12 May 31 32.4 
Newton...... 0... .-.0e- Oct. 8 April 26 Sept. 20 May 19 33.6 
Belle Plaine............ Oct. 4 May 1 Sept. 20 May 31 34.5 
Amana........0 06.2 ee Oct. 5 April 28 Sept. 20 May 14 31.2 
Cedar Rapids ...... ... Oct. 8 April 19 Sept. 20 May 14 37.1 
Towa City............ Oct. 8 April 23 Sept. 20 May 14 32.3 
Clinton...........02000- Oct. 2 April 28 Sept. 18 May 26 32.9 
Davenport........ ..... Oct. 18 April 22 Sept. 18 May 22 32.9 
Atlantic. ....... 2. cee eee Sept. 19 May 11 Sept. 2 May 31 32.4 
Greenfield.............. Oct. 9 April 29 Sept. 18 May 21 31.7 
Des Moines............. Oct. §& April 28 Sept. 12 May 22 32.4 
Washington... ......... Oct. 7 April 23 Sept. 18 May 14 28.7 
Corning...........6.00. Oct. 2 April 26 Sept. 12 May 19 31.3 
Clarinda.............65. Oct. 6 April 19 Sept. 13 May 3 33.1 
Corydon.......... ... .| Oct. 5 April 28 Sept. 18 May 19 35.3 
Bonaparte............4. Oct. 7 April 20 Sept. 20 May 14 33.3 
Keokuk........0.. 0... Oct. 22 April 11 Sept. 18 May 2 35.1 
Irrigation Professor James H. Breasted, of Chi- 
History of Irrigation 
Irrigation is the process of watering 
land by ditches or other artificial means. 
It is generally employed where the 
rainfall is insufficient for the growing 
crops, or where it comes at unseasonable 
times. The sources of supply are snows 
in the mountains, glaciers, lakes, rivers, 
springs, underground waters obtained by 
means of pumps, artesian wells, etc. 
Ancient Irrigation 
In ancient times the inhabitants of 
Egypt along the Nile, and of Babylonia 
along the Euphrates irrigated their lands 
by means of crude systems for lifting 
water from wells, rivers and ditches. 
cago University, a noted Egyptian arch- 
aeologist, says: “The date of the earliest 
irrigation in Egypt is not less than 3500 
B. C. It is impossible to say how much 
earlier, perhaps several centuries—~may 
be five or six, or even eight.” 
Professor D. D. Luckenbil, Babylonian 
archaeologist, writes: “The earliest ref: 
erence to the digging of canals for irri- 
gation occurs in the inscriptions of Urni- 
na of Lagash, who lived about 3000 B. C. 
It is evident from inscriptions which 
date from later times, but mention 
events whose occurrence must be placed 
before the date of Urnina, that irrigation 
was known to the inhabitants of the 
Tigris and Euphrates valleys centuries 
