Reports of explorations and surveys, to ascertain the most practicable and economical route for a railroad from the Mississippi River to the Pacific Ocean: Vol. 1, Pt. 2

METEOROLOGICAL OBSERVATIONS.
The barometric observations at Olympia are of a barometer noted by G. W. Stevens as containing air, in April, 1854. They have a large zero error, and the succession of readings is often
such as to prove that the errors of measurement are very large. The summaries would, therefore, give no valuable data to judge of the mean position of the barometer then, or of the measures
of variation.
The hygrometric observations are not embraced in the summary, as they can only be presented accurately in deduction, or in detailed observations. The mean differences of the wet
and dry bulb are very small. In August, 1854, the mean difference at sunrise is but one and a
half degrees, at 2 p. m. 7.5 degrees, at 9 p. m. 3.2 degrees. In September, 1854, these differences are, for the respective hours, 1.4, 4.3, and 1.5 degrees. These are the dryest months
except July. It will be seen that these results differ largely from the same measures east of the
Cascade range of mountains and at Fort Benton, and prove the coast atmosphere to contain a
large proportion of moisture at all seasons. In the rainy months, the differences between the
hygrometer and the dry thermometer are very small.
Summary of Meteorological Observations at Olympia, Washington Territory.
Thermometer..8
Date., - e Remarks.
7a.m. 2p.m. 9p.m. Mean. Maxi- Mini-
MIIM. 2 M U.
mum. mum. a
0 0 0 0 0 0
April, 1854.. —.- 44.9 57.1 49. 6 50. 53 72 34.5 24 0 Profuse and almost constant rains. Frost on
the 8th, 11th, 21st, and 25th; wind irregu lar, mainly south to west and north, and
light.
May, 1854....... 48.2 63.2 53.1 54.80 83 41 8 8 Irregular and moderate rains. Heavy white
frost on 13th; winds light, and very irregular.
June, 1854....... 54.0 64.0 57. 0 58.33 74.5 49 15 7 Frequent irregular rains. Wind veryvariable;
but few clear days.
July, 1854....... —----- 55. 0 75.9 64.0 65. 00 89.4 45 0 20 Very slight rain on 15th; winds north and
northwest mainly, light; mostly clear from
7th to 27th.
August, 1854.....- 55.5 74.2 65.5 65.07 86.5 48 7 9 1.83 inches of rain. Much cloudy weather;
winds very light and irregular.
September, 1854. 53.1 69. 0 56. 9 59.67 84.5 45 6 8 1.36 inches of rain. Rains and winds irregu lar; generally cloudy.
October, 1854....- 45.3 60.2 48.7 51.40 73 38 13 6 3.14 inches of rain; rains nearly continuous
.*~~~~~~~~ ~~~from the 20th; winds south and southeast.
Heavy frost on 6th, 7th, 8th, and 9th, and
on 12th and 13th.
November, 1854.. 43.0 51.9 45.5 46.80 67 32 12 3 3.91 inches of rain; winds principally south
and southwest. Rains nearly continuous
from 17th to 24th; no snow.
December, 1854.. 39. 7 46. 0 42.0 42.57 58 31 15 3 11.32 inches rain; rains nearly continuous
from 20th. A little snow on 26th; winds
south and southwest.
January, 1855.... 38. 9 45.7 40.4 41.67 57 26 18 2 16. 62 inches of rain. Three days snow, six
inches in depth on 4th; winds south or
southward during rains and snows.
February, 1855X.. 41.0 49.7 44. 3 45.00 62 34.5 9 0 Amount of rain not measured. First part of
month generally cloudy and rainy.
,, ~ ~ ~ ~ ~ ~ ~ ~~.................,,.........................,........................
* Observations to 17th only.
76f
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