320 M O m Y WEATHER REVIEW. JULY, 1904
It is very much to be hoped that this latter record will also
be discovered. The first Fahrenheit thermometer used in this
country is supposed to have been that of Dr. Lining, of Charles-
ton, 5. C., March, 1738. His instruments were a thermometer
by Fahrenheit, presumably graduated according to Fahren-
heit's fourth or last method, and the same as now used;
another thermometer by Thomas Heath, of London, divided
into 90 equal parts, having No. 65 a t the freezing point, No.
49 at temperate, and supposed to be the same as Hawksbee's.
The hygroscope was a whip cord, which stretched five inches
between its saturated and its driest point; these five inches
were divided into a hundred equal parts analogous to our mocl-
ern scale of relative humidity.
In 1742, Dr. John Winthrop, professor at Harvarcl College,
began his record at Cambridge, Mass. He used Hawksbee's
alcohol thermometer. " The scale is divided into 100 parts,
beginning from a certain point above marked zero, and the
hundredth degree falls just about a t the bulb of the thermom-
eter. The freezing point is numbered 65'. The divisions are
upward to 8' above zero. The instrument shows the highest
temperature, but not the lowest, for i t goes into the bulb.
How it was adjusted in London I know not, but it appears to
me that the freezing point is marked considerably too high, for
having plunged the bulb into a vessel of snow, I found that
the spirit fell down to 76.5 and there rested."
In 1748, John Bartram began his record at Philadelphia,
using a thermometer graduated to the Celsius scale. There
seems to be a gap in his record between 1748 and 1758.
The record by Richard Brooke, in Maryland, extends only
from 1753 to 1755. Much more information as to early ob-
servers may be found in the memoirs by Prof. A. J. Henry and
others in Bulletin 11, part 2, but undoubtedly manuscripts
and rare printed volumes, or almanacs and newspapers still
exist and should be brought to light.-C. d.
WEATHER AND CROPS IN ARIZONA.
For the benefit of present or prospective Arizona farmers
the Agricultural Experiment Station of that State has issued
its Bulletin 48, Relation of Weather to Crops, by Alfred J.
McClatchie. Observations under ordinary climatic conditions
are scarcely applicable to Arizona, with its exceptionally low
humidity and wide range of temperature. The report is based
upon observations macle during the past six years, and the
effects of the weather upon each crop are considered in some
detail. Almonds, olives, dates, and pomegranates are among
the crops that may be successfully cultivated. According to
the author:
The total amouut of agricultural products that Arizona will yield is
limited principally by the quantity of water availahle for irrigation, but
the nature of these products is determined principally by the climate of
the region. The lowest temperature recorded at the experiment station
during the last eight years in a shelter 5 feet above the ground was 17' F.,
and the highest 1 1 9 O . The mean relative humidity i6 35 per cent, nnfl the
annual rainfall is only from 5 t o 8 inches. A larger number of crops en-
dure the low temperatures that occur than endure well the high oue6, a condition the opposite of that existing in the northern portion of the
country. Instead of crops being grown between two winters, as is the
case in the North, the most of them are grown between two sumniers.
the number that grow through the summer here being about the same
as live through the winter in the dorth.
In considering the effect of weather upon differmt crops, some diffi-
culty is experienced in di6tinguishing with certainty between the results
caused by the different phases of the weather and those caused by soil
conditions. Differences in the physical and chemical conditionh of the
soil, especially differences in the amount of alkali present, cause more or
less marked differences in the ability with which cwps resist unfavorable
weather conditions. * * * Crops affect considerably the temperatures about and ainong them.
Through the cooling effect of evaporation and radiation comlhed the
temperature becomes lower among growing plants than it is over 11are
ground. The temperatures to which crops are snhjected are, therefore,
more trying during frosty nights and less trying during hot day6 than
thermometers situated outside of their foliage would indicate. * * * During weather too cool for the normal growth oP a plant, direct sun-
shine promot- its activities and results in benefit. The almost con- tinuous bright sunshine of our winters ie, therefore, a distinct advantage
to vegetation. During the warm portion of the year parts of many plants
become overheated in direct sunshine and injury to tissue results. This
is especially true of exposed stems, fruits, and vegetables. Since the leaves are continually being cooled, more or less, by the evaporation of
moisture from their tissues, they do not become as highly heated as do
stems and tree trunks, from which no evaporation is taking place.
Hence, a plant or tree with heavy foliage that shades the other parts
has a distinct advantage over one with slight foliage, provided it is
supplied with sufflicient water. * * * Of the 80 crops discussed in a preceding part oP the bulletin, 74 thrive
best in an atmosphere having a soniewhat higher relative humidity than
prevails in southern Arizona. In some cases deciduous trees, though
abundantly watered, are so affected by the dryness oP the winter and
spring atmosphere that they put oat their leaves very tardily and incom-
pletely, presenting the appearance of having been injured by extremely
low temperatures. Very rarely is the atmosphere of the region too damp
for the proper development of any crop. * * The higher humid-
ity that accompanies i t is a benetlt, and the lower temperatures that ac-
company the suinmer showers are a relief to most crops. Local rains
are heartily welcomed, chiefly because rain falls at the fame time in the
region furnishing the supply of water for irrigation.
The author nlade a series of temperature observations by
decades for three years, with a sheltered thermometer 5 feet
above the ground, and with three unsheltered thermometers
at elevations of a few inches, 5 feet and 10 feet, respec-
tively, and also, with the view of obtaining the temperatures
to which the foliage of plants of various heights is actually
subjected, with three unsheltered thermometers at elevations
of a fedinches, 5 feet and 10 feet, respectively. These last
results have little quantitative value, as a bright-bulb ther-
mometer exposed to the sun gives neither the temperature of
the atmosphere on the one hand, nor, on the other, the tem-
perature of foliage similarly placed, but probably approaches
more closely to the former than to the latter.
The author also compares his results with the sheltered
thermometer with those obtained from a thermometer at Phoe-
nis, 2 miles distant, in a shelter 50 feet above the ground, and
finds that the minimum temperatures recorded at Phoenix are
from 3' to 6' higher. While the dry atmosphere of Arizona
is favorable to temperature inversion, it is hardly safe to as-
sume, with the author, that (' this difference is evidently due
entirely to the difference in elevation." He finds a decrease of
about 2' in the mean maximum temperature at the higher
elevation.
The undersigned is acquainted with but few researches that
suffice to show, for moderate elevations, the effect upon the
maximum temperature of height above ground. Some that
have been published are of little value, on account of their
short duration or the faulty exposure of the thermometers.
Wild, observing at Pulkowa from September, 1872, to October,
1874,' with sheltered thermometers at heights of 1.9 meters,
15.9 meters, and 26.3 meters, obtained from the 1 p. m. obser-
vations the following mean departures from the readings of
the lowest thermometer:
The direct effect of the local rainfall is not great.
At 1 5 9 At26.3
1 oletii;. I meters.
NOreNber-hIarCh.. . .I
+O. 12
I
+O. 11 April-5eptemher.. . . . -0.35 -0.37
Dines, in England, September, 1876 -September, 1878,
found a mean maximum temperature of 58.7' F. in a shelter 4
feet from the ground, with a difference of -1.23' a t an eleva-
tion of 50 feet. Glaisher, at the Royal Observatory a t Green-
wich,' with thermometers at 4 feet, 22 feet, and 50 feet, found
in the mean temperature fit 2 p. in. a decrease of 1.4' at 22
Repertorium fur Meteorologie, rol. 5, No. 2.
Quarterly .Journal of the Meteorological Society, rol. 8, p. 190.
Proc. Met. SOC., rol. 5, p. 29.
JULY, 1904.
feet and of 3.5' a t 50 feet. But hi0 observations cover only a
few weeks in the hottest part of the year, from June 25 to
August 6, and there is some uncertainty as to the protection
of the thermometers.
G. J. Symons,' with observations from April to December,
inclusive, a t elevations of 4 feet and 170 feet above ground,
finds a decrease of 1.9' F. in the mean maximum temperature
at the upper station.
This matter is also discussed by Professor Abbe in the
MONTHLY WEATHER REVIEW for 1897, vol. 25, 1). 253, second
column.
It is not at present practicable to answer the complex question as
to what may be the exact nature and amount of the reduction of a tem-
permture, wind velocity, or rainfall from elevated stations down to the exposure near the surface of the open ground. Undoubtedly on our elevated buildings the temperatures are slightly lower, the rain catch
considerably smaller, and the wind velocity frequently larger than for stations at the surface of the ground, but comparison with other s t a
tions shows that the differences do not seem so large as has often been
feared. So far as temperature is concerned, it is much more difficult to determine the true temperature of the air near the ground than at the
top of a tall building, because at the ground the wind is much diminished snd is liable to bring special streaks of hot and cold air. At the higher
level, the special streaks of hot and cold air have all merged into one
homogeneous mass, and the strength of the wind facilitates the ventila- tion of the thermometer shelter.
F. 0. S.
321
THE WEATHER OF ICELAND AND EUROPE.
An interesting paper was read by Professor Hann before
the Academy of Sciences at Vienna on January 7, entitled
I' The anomalies of the weather in Iceland, during the interval
1851-1900, and their relations to the simultaneous anomalies
of the weather in northwestern Europe." It is well known
that for many years the meteorologists of Europe have desired
telegraphic information from Iceland, with the assurance that
daily weather reports from that locality would certainly be
very helpful in making daily weather predictions. By analogy
it has been supposed that similar telegrams from Hawaii and
from the Aleutian Islands would be exceedingly useful to the
forecasters on our Pacific coast. It has even been argued
that inasmuch as weather changes do not always mean from
west to east, it might sometimes happen that reports from Ice-
land would be useful to the American forecaster. In fact,
when a great area of low pressure is central in Iceland, there
really is reason to believe that it does influence American
weather by drawing the air from our extreme north soutli-
ward over Canada and New England.
The object of Professor Ham's investigation is to arrive at
a few general ideas as to the relation between the weather of
Iceland and of northern Europe. He has studied the monthly
and annual averages of temperature, pressure, and precipita-
tion for the last half century, as recorded a t Stykkisholm, and
more especially the departures of the individual months from
the general average, as compared with corresponding depar-
tures for the stations a t Greenwich, Brussels, and Vienna, and
with those for Ponta Delgada. The following sentences con-
tain some of his more interesting results.
As regards baronietric pressure, the departures of baromet-
ric pressure in northwestern and central Europe are in the
opposite direction to the simultaneous departures at Stykkis-
holm in 70 per cent, of the cases. The same is true of tem-
perature in only 56 per cent, and of precipitation in only 68
per cent, when we compare Iceland with Brussels.
The relation between the departures in pressure a t Stykkis-
holm and the simultaneous departures in temperature over
central and northwestern Europe is much more pronounced.
When negative departures in pressure prevailed a t Stykkis-
holm, then the probability of a simultaneous positive depar-
ture in temperature in Europe is 82 per cent. Inversely,
'Proc. Roy. SOC., vol. 35, p. 349.
when the pressure departure is positive a t Stykkisholm, then
the temperature departure is negative in 73 per cent of the
cases for northern Europe.
An area of low pressure is almost stationary during the
winter in the neighborhood of Iceland; if this low pressure
falls decidedly, the winter temperature of Europe rises; i f the
central low pressure is higher than usual, the temperature of
Europe is lower. The three largest temperature departures
for each month and the year at Greenwich were compared
with the similar departures in Iceland. Out of eighty-
three cases, 84 per cent occurred simultaneously with a great
departure in pressure in the opposite direction at Stykkis-
holm. I n general, present investigation confirms the rule
first enunciatecl by Buchan that a mild climate in northwest-
ern and central Europe is associated with low pressure over
Iceland.
Professor Hann then investigates the relation between the
simultaneous anomalies of pressure a t Ponta Delgada, Azores,
ancl Stykkisholm; also the general relation between the high
pressure of the tropical Atlantic and the low pressure of Ice-
land. On the average of forty-two cases, a rise of 4.5 milli-
meters a t Ponta Delgada means a fall of 2.4 millimeters at
Stykkisholm, and a fall of 5.1 millimeters a t Ponta Delgada
means a rise of 4.4 millimeters at Stykkisholm. In general,
the probability of an opposite change a t these two stations
is 77 per cent.
Already in 1897, Hildebrandsson, in his researches on centers
of action in the atmosphere, has given tables for ten years and
charts bringing out in a general way the relation between
pressures throughout the globe ; but Hann's studies for fifty
years give US a numerical result showing that to a certain
extent the great areas of high ancl low pressure over the land
vary inversely. The greatest positive departures of pressure
at Stykkisholm correspond in 80 per cent of the cases to nega-
tive departures at Ponta Delgada, and the great negative de-
partures a t Stykkisholm correspond to positive departures
a t Ponta Delgada in 87 per cent of the cases. If the pres-
sure over the Azores is higher than the average and at the
same time the pressure over Iceland is lower, as happened
in 70 or 80 per cent of the cases, then the gradient of pres-
sure over the Atlantic Ocean is increased. The atmospheric
machine works more intensively, and vice versa. The mean
gradient cliflerence in pressure between the Azores and Ice-
land is 14.7 millimeters in December, 18.3 in January, 14.3 in
February, and 9.8 in March. The cases where the pressure
over the Azores is unusually high and over Iceland unusually
low are especially interesting; they are not to be considered
as a result of the location of the subtropical belt of high pres-
sure, but as a consequence of an increased intensity in the
atmospheric circulation. If the northeast trade blows more
powerfully than usual, it increases the masinium pressure on
its right-hand side; but by this process the great whirl in the
North Atlantic Ocean is intensified and the pressure of the
atmosphere at its center near Iceland is diminished. There-
fore, the above-proven contrasts in the pressure anomalies
over the Azores and Iceland operate like cause and effect.
The last section of Hann's memoir deals with the relation
between Stykkisholm (65' 4') and the nearest station on the
east coast of Greenland, namely, Angmagsnlik (65' 37'), distant
about 800 miles from each other. Stykkisholm is on the west-
ern coast of Iceland. Between i t and Angmagsalik flows the
cold polar stream on the west and the warm Irminger stream
on the east, giving Greenland a cold climate and Iceland a
relatively warm one. On the average of seven years of obser-
vations, 1895-1901, the mean difference of temperature between
the two stations is greatest in February, 8.1" C., and on the
annual average is 5.3' C. The gradient of temperature per
clegree of a great circle (111 kilometers, 59.9 geographic miles,
69.1 statute miles) is 1.1" C. in winter and 0.9" on the annual