APPENDIX L 137

drawback of wheat growing in northern latitudes. A
difference of one or two degrees in temperature on
a single night during this period will make the differance
 between success and failure of a wheat crop, and
mean thousands or perhaps millions of dollars loss to
the region affected. Where the line between success
and failure is so narrow it becomes possible to pass
over it. The experience of half a century in all parts
of North America has demonstrated that the general
cultivation of the soil of any region tends towards the
maintenance of an equal temperature, and therefore
that many regions in which wheat did not mature
successfully while the country was in a raw condition,
become the most successful wheat producers when
cultivation has become general. It is a fact that
the regions of North America which are to-day
recognised as the great sources of the wheat supply
of the continent and of the civilised world are far
beyond what were supposed to be the climatic limits
of ‘wheat production fifty years ago.
The following is reproduced from the St. Paul,
Minnesota, Dispatch, of September 12, 1go2, as a
comparison between points in the States and
Winnipeg, Manitoba.
Watertown, S. D., Sept. 12.—A killing frost occurred
here this morning. The thermometer registered 24°.
Lisbon, N. D., Sept. 12.—Frost this morning forming
ice one-third of an inch thick, killing corn, late flax,
and much millet. Nothing but the hardiest vegetables
 survive. ‘The minimum temperature was 23°.
Towa Falls, Iowa, Sept. 12.—A severe frost prevailed
if this section last night.” Vegetation was killed and
corn was badly damaged. It is estimated that but 30
per cent. of the corn crop will be marketable, necessitating
 cutting and feeding the balance of the crop.
Plainfield, Wis., Sept. 12.~Heavy frost this morning.
The corn crop was very late and is partly killed and
damaged.
Mitchell, S. D., Sept. 12.—A heavy frost covered