AUC~UST, 1902. MONTHLY WEATHER REVIEW. 397
quality. Cranberries made excellent progrese and at the end of the month ranges that no gnrss was left at end of month. Prospect for winter feed were nearing maturity; the yield promises to be large and the quality Is bad in se@ions. Allalia and native hay crop all in, with average yield excellent.- W. M. W h . for State 88 a whole. Grain ripened slowly on account of cold nights, W&nning.-On the whole the month was unfavorable for growing crop but harvest was in general progress. Small crops and gardens did well and range lands. It was abnormally dry and practically amounted to a where water was suiacient for irrigation. Frosts and grasshoppers did drought. Weather was very favorable for haying, but so damaging to some damage. Stoak in good oondition.--Cllarlea E. A e W , Jr.
I n the following table are given, for the various sections of the Climate and Crop Service of the Weather Bureau, the average
temperature and rainfall, the stations reporting the highest and lowest temperatures with dates of occurrence, the stations re-
porting greatest and least monthly precipitation, and other data, as indicated by the several headings:
$2.5 -0.8
+L O -1.6
0.0
$0.7 +1.3 -0.8 -2.4
-2.6 '
Alabama . .. .. .. .. .. .. . 82.1 Arlzona . . . . . . . . . . . . . . . 81.4
Arkansas. .. .. .. .. .. .. . 80.6
California . .. _. . _. .. . . . I
71. E
Newberne ........... 107 Casagrande ......... 119 Arkadel jhia ........ 108
Mlton 4olrauo.. . . . 121 Blain: ...._..... .. 111 Wausaii ............ 105 Brent ............... 106 Garnet .............. 105
Equality ............ 103 Hallidavboro . . . . . . . Madison ............ 100 Mount Vernon . .. . . .
Illinois. .. .. .. .. .. .. . . . I
71.8
Colorado ... .. .. ... .. .. . 67.1
Florida ... .. .... . . . .. . 82.1 Georgia.. . . . . . .. .. . . . . . 80.3 Idaho.. . . . . . . . . . . . .. . . . 66.5
~~~
20
5
4
1
4
21
21
2
2
14
3
2,3 19
20
3 17 31 3 1 50 3 24
1
2
90
4
11
Indiana _..............I 74.1
Haniilton .... .. .... 52
Ashfork ............ 35
Pond ................ 51
Bodic .... .... ...... . 17
Rreckenridge ...... . 23 Macclenny, Suiiiuer. 57
Clayton .. .. .. .. .... . 55
Forney .... ._...... . 21
C'heiunng .......... . 41
Winamae ..... ..... 40
Sible .............. 37 Achifies ............. 4.0 Fords Ferry ... .... . A5 Nansfield ...... .... . 61
D e e r y l i !!; :... .. . 33
~e w err; ..... 59 Beardsky, Piprrtuur S2
Corinth ............. 64 Gstatious ..... .... .. . 47
Adel ......... ....... 25
Lynch ............. . 35 Callowav . . . . . . . . . . . . &fonit&bfill ...._... 80
Wood. . . . . . . . . . . . . . . Fort. Fairfield, Me.. . 30
Layton ...... ....... 4Il
Iowa... .. .. .. .. .. . .. .. . 69.1 Kansas ..... .... .. .... . 78.2
Kentucky . .. .. . . . . . . . . I 75.6
-1.00 -0.13
-0.56
.OO $0.19 -2.89 -2.18
-u 22
+I: 30
Louisiana ..... .... .. .. . 81.1
Mar landrud belawa 71.7 Miegigan . .. .. .. .. .. .. . 64.2
Minnesota.. . . . . . . . . . . . 65.2
Misslasippi . . . . . . . . . . 82.7 Missouri. .. . . . . . . . . . . . . 75.0 Montana ..... .... ... .. . 63.1
Nebraska. .. . . . . . . . .
1
. . 71.9
Berniuda.. . . . . . . . . . . 11. w) Letohachee.. . .. . . . . . 0. MI Flagstaff. .. . . . . .. . . . 6.10 Several stations .. . . . 0.00 Curiiing ............ 7.54 Perrv ............... 0.00 Sisson . . . . . . . . . . . . . . 4.16 Many stations.. .. . . . 0.00 Cheyenne Wells.. .. . 6.06 Pagoda .. .~ .. .. .. .. . T. Mulino ............. 9 13 Quine ............. 0.92
Harrison .. .. .. . . . . . 11: 11 Caniai. .. .. .... . . .. . 0.W Pollock .. . . . . . . . . . . . 1.32 Blackfoot, Oakley .. . 0.00
I Urbana . . . . . . . . . . . . . 9.7'5 I Antioch . . . . . . . . . . . . 0.55
Nevada. .. .. .. . . .. ._ .. . 68.9
New England. .. .. . . . . . M 8
New Jersey. .. .. .. .. . . . 70.1
I
-2.1 -3.0
$3.5
-1.3 -1.1
-1.1
New Mexico .. . . . . . . . . New York . . . . . . . . . . . North Carolina.. . . . . . North Dakota ......... Ohio. .. . . . . . . . . . . . . . . . Oklahorua aud Iudiau
Oregun . . . . . . . . . . . . . . . Penns lvania ......... Porto Rim.. . . . . . . . . . . South Carolina.. . . . . . . South Dakota. .. . . . . .. Tennessee . . . . . . . . . . . . Teras.. . . . . . . . . . . . . . Utah.. . . . . . . . . . . . . . . . .
Territories.
Kalamaioo ......... 95
Milan ........ ...... 96 Pitt.sboro ........... 107 Marblehill .......... 103 Glendive .......... . 103 Bridgeport .......... 107
-3.1
-2. 3
-2.4
+O. 3 -2.1
-0.5
-1.2
-2.5
+3.1
Rioville ............ 117
Berlin Mills, N. H . . 92
Saleni .... .......... . 93 Iudian Mills . . . . . . . . .4lamagordo.. . . . . . . . 105
Onconti ............. 9.4 Chapelhill .......... 105
Qstations ... .. . . .. .. . 9G Camp Deuisuu . . . . . . 97
Manguni, Okla ...... 114
Temperature-in degrees Fahrenheit.
. . . . . 1
. . . . . . . .
a $= II
71.3 65.0 76.5 64.3 69.2 84.2
66.0 67.8 80.0 78.6 68.2 77.0 86.1 69.4
Monthly extremes.
5 Winaors ............. 3 Axtun ....... ...... -- 4 Il Linville ... ......... 13 5$ Ashlev ....... ._.. .. . 3,h Korwdli .......... . 5 Kenton, Okla .......
6 Bend ................ 31 Irwin ............... 19 Cidra ............... 22 Heath Springs . . . . . . 1 Howard ............ 421 Erasmus ............ 30 diunrillu . . . . . . . . . . . 2 Tropic ... ........... Loa . . . . . . . . . . . . . . . . . 10 Burkes Garden. .. . . . 12
7 Wilbur .............. 30 Travellers Repuse.. . 31
1 Butteruut .......... 3 R~iuthPasxCity ..... Lolabama . . . . . . . . . . . Kemnierer . . . . . . . . . .
31 30 39
26
37
50
26
34
56
55
26
43
52
23
38
27
35
30
25
~~~~~
..~
---:; Per$;; .... .... .... . 98
111 -0.9 Bowlln Gwen ...... 103
-2.7 I '!
Hancorf.Md::::::: 100
.. .. .. . . .. .. .
+2.9 Alexan%ia
1
107
-0.6 -2.0
0.0 -0.7
-3.0
tO.6
t 3 .1
-1.0
-2.6
-0.9 -2.6
-5.4 -1.3
Grants PUPS ........ 107 Hiintingtuu ........ 100 Caye ............. . 98
I Ileac{ springs . .. . . . 101
I Bowdle . . .. .. . .. .. . 101 Springfield ........ . 104
Cotulla ......... ..... 110 Green River, Ute.. . 110
Saxe ............... . 100 Newport News.. . . . . Mottingem Ranch.. . 104
Echo ..... .. .. ...... . 98 New Martiosvillc .. . Medfod . ........... 99 Theriiinplis . .. .. . . . 103
-2.24
-0.80
-0.83
-n. 16 -1.15
-1.a3 -0.56
Kent .. .. .. . . ._ .. .. . 0.00 Ranch .............. 5.25 Promontory, Suor- 0.00
Saxe ... ............ . 5.10 Stanton ............ . 0.80
Scalro-Woolev .. .. .. . 2.27 ElhSb'g, Snnnysidr 0.00
Leonard . . . :. . . . . . . . 5.90 0.97
Whitchall . . . .. .. . . . 7. I8 Westfield .. .. .. . . . . . 0.35 Daniel ....... ....... 0.13 Hyattville, Tlier- 0.00
3.70 4Y stations . .. .. .. . . .
ville.
Cuba .. . . .. . . . . . . . . .
Virginia. .. ... .. .. .. .. .
Waahington ... .. . .. .. . West Virginia. .. . .. .. .
Wisconsin. .. . . . . . . . . . . Wyouiing.. . . . . . . . .. . . .
72.9
64.6
70.4
66.5
IX S
_-
4
3;
G -
2:
I(
I
56 31
l i 12
I?, ?t
11 11 12
13 l i 2s 11 2;
7.11 30
11 ai 17 IS 17 13,17
19 13
YS
11 25
5
17 1 29 11 26 11 17 31 21
27 17
22
I8 I9
31
18, 28
-
-
& E E
I .I 4
d
3. .If 1.94
2.55
0. ob 1. s4 4.6E
3. g?
0.45
4.3
2.24
6.S
5.19
2. 1P
3.47 2. 07
1.52
4.35 3.77 6. 18
0. a6 3.25
0. 22
3.68 3.91
2. 73
5. SI
3. '53
2.w 1.67 3.19
0.35
2. e2
5.07 3.72
3.81
Q. 30 Q. 61
2. as
1. 57 1.40
I. 91
j. 22
6.18
-
Precipitation-In Inches and hundredths
-0.82 11 Rorkville . . . . . . . . . . .I 5.36 11 Vevay . . . . . . . . . . . . . .I 0.70
~~~~
....
Purt Hu&. . .. .. .. .
Lake Como. .. .. . . .. . Arthur
LO5 T.
7.53 Thonitou .. .. .. .. . . . 0.50 11.19 0.96
Someriet. .. .. .. .. ... . Pipcatone .. . . . . . . . . .I 10. lio Collegeville .. . . . . . . 1.32
.. . . . . . . .. . . . Galena .. . . . . . . .. . . . Glendive . . . . . . . . . . . I 2.m
I!
Manhattan . . . . . . . . . 0.00
Kirkwood ...._..... 8.74 Agate ............... 0.22
Palnietto . . . . ._. . . . . 5.13 Several statious .. . . . 0.00
I ll Nantucket, M~Hu. .. . 0.27
Callton ........ ..... 1.31
Fort Bavard . . . . . . . . 7.13
G. 05 Albuqnenlue .. . . . . .I 0.70 Adirondack Lodge.. Vollln~a . . . . .. . . . . . . . 0.79 Kinstmi ...... ...... I 8.91 11 Lenuir ..... .... .... 1 0.W
Berlin . .. .. . . . . . . . . .I 5.21
5.86
Woodbridgc . .. .. . . . Buwling Greeu.. . . . .
0.36 0.18 Denios . . . .. . . . . . . . . . Tahlequah, Ind. T . . 6.14 Jenkins, (Jkla.. .. . . . 0.31
I II
SPECIAL CONTRIBUTIONS.
OCEAN CURRENTS.
By JAMES PAGE, United States Hydrographic Ol€ ice, dated Oetoher 18, 1902.
Every method of investigation thus far employed, whether
the drift of floating objects, the comparison of the temperature
and the specific gravity of specimens drawn from widely rlis-
tant points, or the distribution of animal organisms inhabiting
different localities, all lend support to the belief that the vast
mass of water near the surface of the sea and to a very consid-
erable depth below the surface, even at a distance of thousands
of miles from the continental shores and hence far removed
from local or tidal current influence, is in motion. The con-
tinuity of this motion in certain broad and well-defined regions,
such as the Tropics, can not but impress us with the idea that
it is in a general way cyclic, that is, 'that the same water
after a lapse of time retraverses approximately the same path.
The source of the energy required to set and keep this vast
mass in motion has been productive of endless discussion. The
attractive force of the nioon. the vis inertie or lag of the water
itself, the difference in temperature and specific gravity of the
equatorial and polar regions, the unequal distribution of at-
mospheric pressure, each in its turn has been proposed and
.strenuously advocated as the true and only cause of ocean
currents. To the seaman, however, the cause of the ocean
currents has always been the winds, since the motion of the
waters of the sea takes its origin in the region where the latter
attain their maximum constancy, viz, in the region of the
trades.
The trade winds cover a belt on the earth's surface extend-
398 MONTHLY WEATHFJt REVIEW. AUGUST, 1902
ing roughly over fifty degrees of latitude from 30° N. to 20° S., including within this range a greater water area than could be
included in any other position. Throughout this wide zone
the wind blows for 90 per cent of the time from some point in
the eastern semicircle. In the Southern Hemisphere the trades
are somewhat stronger and more constant than in the North-
ern, owing probably to the freedom from interrupting land
areas. Over the eastern half of the ocean they extend far
higher in latitude than over the western. This is true of both
the northern and the southern hemispheres; the northeast
trades in the Atlantic during the northern summer often ex-
tend far up on the coast of Spain, the southeast trades clur-
ing the southern summer often extend beyond the Cape of
Good Hope. Similar conditions hold for the Pacific. The
southeast trades, too, blow well across the equator in the
Northern Hemisphere.
The trade winds, however, are not continuous throughout
the entire belt from north to south. Just north of the equator
and confined entirely to the Northern Hemisphere are two
elongated triangular areas extending east and west through
some fifteen degrees of longitude; in the case of the Atlantic
Ocean the base of the triangle rests on the coast of Africa; in
the case of the Pacific, on the coasts of Central h e r i c a and
Mexico; throughout these areas the trades are absent, their
places being taken during a large portion of the year by
light, variable winds ancl calms, during the remainder of the
year by winds whose prevailing direction is NouthwesGthe
so-called southwest monsoon of the African and American
coasts, most apparent during July, AuguRt, and September.
THE CHARACTER OF THE TRADE WINDS.
Among those who have not sailed in them the impression is
general that the trades blow day after day steadily in olie
direction and with a constant force. This is distinctly not the
case. The trade winds are quite as susceptible to variation,
ancl fortunately so, a8 the winds of higher latitudes. The one
thing about them is that, not being subject to the large varia-
tions of barometric pressure which characterize higher lati-
tudes, the wind rarely goes round the compass and, indeed,
rarely gets out of the eastern semicircle. As an example of
their constancy, let us consider the percentage of winds com-
ing from each compass point for a certain region, forinstnnce,
the square bounded by the parallels 2Oo-25O N. and the meri-
dians 50°-55' W., in the heart therefore of the northeast trades
in the North Atlantic. The figures are for the month of June
and may be regarded as giving the number of hours in each
hundred, or approximately, in four days, that the wind may
be expected to ldow from the given point:
Dimrtiun and tiiue.
N. 1 NNE. 3
NE. 17 ENE. 24
E. 33 ESE. 8
SE. 10
SSE. 4
Other squares show similar variations; some greater, some
less.
THE IMPULSE COMMUNICATED BY THE WINDS TO THE SURFACE WATER.
Let us now examine the effect of such a system of winds in
impelling through surface friction the water with which they
come in contact.
I f through any cause a thin layer of liquid is set in motion
in its own plane with a given velocity, the layer immediately
below it, and with which it is in contact, does not remain at
rest, but likewise receives an impetus. This second layer eser-
cises a like influence over the third, the third over the fourth,
and 80 on, the velocity ultimately attained by each successive
layer being proportional to its distance from the bottom layer,
which is supposed to be at rest. I n the case of sea water the
rapidity with which this velocity is propagated downward is
very slight. It has been calculated, for instance, that a period
of 239 years would elapse before a layer at a depth of 60
fathoms would attain a velocity equal to half that at the sur-
face when the surface current is flowing steadily all this time.
Such surface currents do not exist, neither do winds capable
of producing them exist. The trades, as we have seen, fluctu-
ate from day to day ancl, indeed, from hour to hour, and the
surface currents fluctuate in obedience to them.
I t has been stated, however, that the fluctuations of the
trades rarely carry them out of the eastern semicircle, and that
in point of fact 90 per cent of the winds that blow in the re-
gion of the trades do come from that semicircle. There is thus
always a westerly component in the motion of the air, coupled
with a component which is sometimes northerly, sometimes
southerly. For each alteration in the direction of the wind
there is a corresponding alteration in the direction of the sur-
face current, the new direction being the resultant of the old
direction and the direction which would be imparted to it by the
new wind acting alone. These, however, affect only the waters
immediately at the surface. Thus, to cite a specific example,
observations at the Adlergrund lightship, in the Baltic Sea,
have shown that while the water at the surface responds
almost immediately to a change in the direction of the wind,
the water at the depth of 24 fathoms does not feel its effects
until an interval of 21 hours has elapsed. The steady westerly
component is then the only one felt in the region of the trades
at some little depth below the surface, and this is sufficient to
impart to the entire body of water occupying the equatorial
regions of the earth, a westerly motion.
It is of some interest to note the velocity imparted to the
surface water by winds of a given force. A comparison of a
large number (658) of wind and current observations in the
equatorial regions gave as the set imparted by a wind of force 4
on the Beaufort scale, corresponding to 20 miles per hour, a
current velocity of 15 miles per day. The figures are taken
from the Meteorological Data for Nine 10°-squares of the
North Atlantic Ocean, published by the Meteorological Com-
mittee of the Royal Society.
The system of surface currents produced by such a system
of winds as the trades has been experimentally studied, using
for this purpose a miiiature ocean, the surface of the water
being lightly sprinkled with powder in order to render its
motion visible. As soon as the artificial wind was brought
into action, a drift was created, ancl the first tendency was for
the water to flow from all sides into the rear of the drift. This
gradually extended itself in a sheaf-like form, the marginal
threads in the fields untouched or only occasionally touched
by the air current leaving the main body, first branching out
to the right and left, then, reversing their motion, and finally
again working round to the rear of the drift. The central por-
tion of the drift followed a right-line course, in close agree-
ment with the direction of the air currents, until a perpendicu-
lar obstacle was interposed. Here the drift divided into two
streams, each flowing with the same velocity, but having half
the cross section.
This experimental Hystem of currents finds its counterpart
in nature. Under the northeast trades in the North Atlantic
and the southeast trades in the South Atlantic, we find a broad
central drift directed toward the shores of America, the drift
from the southeast trades estending well into the Northern
Hemisphere, the two uniting some distance off Cape Saint
Roque. To the right and to the left of each of these drifts
the water fringes off, the direction of the motion is reversed,
and the so-called conipensating currents manifest themselves.
Along the equatorial margin of the two main drifts, under the
AUQUST, 1902. MONTHLY WEdTHER.ICEVIEW. 399
equatorial belt of calms, these compensating currente unite to
form the counter-equatorial current, or Gluinea current, reach-
ing a maximum intensity during June, July, and August, the
months of the southwest monsoon. On the polar margin they
either return into the drift or are taken up by the general
easterly drift of the higher latitudes.
In the equatorial region of the earth we thus have in either
ocean three currents. In the North Atlantic the north equa-
torial current, due to the northeast trades; in the South At-
lantic the south equatorial current, due to the southeast trades;
between these two the counter-equatorial current, flowing at all
times, but reaching a maximum intensity and covering a masi-
mum area at the time of the southwest monsoon. These first
two are westbound, carrying the water toward the shores of
America; the third is eastbound carrying toward the shores
of Africa. They all suffer a slight displacement with the
season, in harmony with the movements of the trades, which
oscillate slightly in latitude with the movement of the sun in
declination. Also in harmony with the fact that the meteoro-
logical equator lies slightly to the north of the geographical
equator, the south equatorial current estends at all seasons
well over into the Northern Hemisphere. Corresponding again
with the fact that the southeast trades eshibit greater con-
stancy and strength than the northeast, the south equatorial
current shows higher velocity than the north, the average fdr
the latter amounting to but 13 miles in twenty-four hours, for
the former to 27 miles in twenty-four hours.
Similar statements hold for the Pacific Ocean. But from
this point let us limit ourselves to the Atlantic, the currents
for which are not only better known, but also probably better
developed, being confined to a less extensive area than the
Pacific.
In the Atlantic Ocean, then, the two drifts unite some clis-
tance off Cape Saint Rocpie, the eastern estreniity of South
America. A portion of the water is diverted to the southward
forming the Brazilian current; the main body flows west-
northwest along the coast of South America, some entering
the Caribbean Sea by way of the passages separating the
Windward Islands, the drift through these passages often at-
taining n velocity of 60 miles a day. The remainder passes
to the northward of the islands, forming the Bahama current.
In this neighborhood a series of observations by Admiral
Irminger of the Danish navy showed that the westerly drift
of the water could still be detected at a depth of 900 meters.
A striking instance of the fluctuations of the surface cnr-
rents with the winds is shown in the case of the straits sepa-
rating the Greater Antilles, the Windward, and the Mona pas-
sage. From January to April, the months when the northeast
trades are most northerly in direction and blow with masimum
force, a strong southwesterly set is felt upon entering these
passages. As the season advances and the trades weaken, at
the same time becoming southeasterly, these currents diminish
and change their direction to northwest.
Throughout the entire estent of the Caribbean Sea the drift
is westerly, save that in those portions where resistance to the
flow is offered, such as the southern coast of Cuba, return cur-
rents manifest themselves. Throughout, the Yucatan passage
the drift is northwesterly, but here again the influence of the
return current is felt, notably under Cape Ban Antonio, the
western extremity of Cuba, where southeasterly sets are fre-
quent. I n the Gulf of Mexico observations have thus far failed
to reveal any decided set of the surface water.
THE GULF STREAM.
Between the northern coast of Cuba and the Florida reefs
starts the most celebrated of all ocean currents, the Gulf
Stream. Discovered by Ponce de Leon in 1513, it has from
that time been and still is the sul>ject of scientific investigation.
In the Gulf Stream we have to deal with a current of a na-
ture entirely dimtinat from those which we have thus far con-
sidered. Thee0 were a l l due to the direct action of the wind
upon the water, producing a drift. The Gulf Stream is only
indirectly due to this cause, being the overflow of the water
heaped up by the trade-wind drift in the Caribbean Sea and
the Gulf of Mexico. Throughout a considerable portion of
its extent, its direction, even at the surface, is independent of
the wind or only slightly modified by it. .The stream reaches
its masimum strength at the point where it emerges from the
Bemini Straits between the Bahama bank on the east and the
coast of Florida on the west. The breadth of the actual cur-
rent here between Fowey Rocks and Gun Cay Light is 38 miles,
its average depth 239 fathoms, its average velocity 60 miles in
twenty-four hours, although it rises at times to 100 miles.
Farther north its breadth increases, and its velocity is corre-
spondinglydiminished. The western edge of the stream in
its northward course along the coast of the United States fol-
lows closely the 100-fathom curve, although the axis of the
stream, the line of greatest velocity, lies somewhat farther
seaward, its position varying, according to Pillsbury, with the
declination of the moon, lying (at Jupiter) 8 miles farther off
shore at time of low moon than at time of high. From Jupi-
ter to Hatteras the asis runs at a distance varying from 11 to
20 miles outside the 100-fathom curve.
The color of the stream is a perceptibly deeper blue than
that of the neighboring sea, this blueness forming one of the
standard references of the nautical novelists. The depth of
color is due to the higher percentage of salt contained, as com-
pared with the cold green water-of higher latitudes, observa-
tion having shown that the more salt held in solution by sea
water the more intensely blue is its color. Thus even in extra-
tropical latitudes we sometimes observe water of a beautiful
blue color. as for instance in the Mediterranean and in other
nearly land-locked basins, where the influx of fresher water
being more or less impeded, the percentage of salt contained
is raised by evaporation above the average.
Another important fact in connection with the Gulf Stream is
its almost tropical temperature, clue to the fact that its high ve-
locity enables it to reach the middlelatitudes with verylittle loss
of heat. Upon entering its limits, the temperature of the sea
water frequently shou~s a rise of 10' and even 15'. It was
this fact that gave to the stream in the later years of the
eighteenth century and the earlier years of the nineteenth an
importance in the minds of navigators that it no longer pos-
sesses. In those days the chronometer, invented by Harrison
in 1765, was still an experiment. Instrun~ents were crude and
nautical tables often at fault. The result was that the deter-
mination of the longitude wnu largely a matter of guesswork;
n vessel after a voyage from the channel to America was often
out of he? reckoning by degrees instead of by minutes. The
idea, first suggested by Benjamin Franklin, that the master of
a vessel, by observing the temperature of the surface water,
could tell the moment of his entry into the Gulf Stream, and
hence could fix his position to within a few miles, was hailed
with delight. The method was published in 1799 by Jonathan
Williams in a work lengthily entitled " Thermometrical Navi-
gation, being a series of esperimeiits and observations tending
to prove that by ascertaining the relative heat of the sea water
from time to time, the passage of a ship through the Gulf
Stream, and from deep water into soundings, may be discov-
ered in time to avoid clanger." In this work he makes the
patriotic comparison of the Gulf Stream to a streak of red,
white, and blue painted upon the surface of the sea for the
guidance of American navigators.
The discovery of the stream is also alleged to have exercised
a curious effect upon the coinnierre of some of our southern
cities. In early days, when the only known sailing route was
by way of the trades, it was the custom for vessel8 making the
voyage from Europe late in the year to winter and refit at
400 AUGUET, 1902
tabulated in the current charts used by nevigators, or the move-
ments of the waters as they actually take place, we were for a
long time wholly ,dependent upon ships' observations. When
at sea the position of a vessel at noon of each day is deter-
mined by two independent methods. The first of these is
known as the position by observation, and as its name implies,
means the position of the vessel as found by actual astro-
nomical observation. The second is known as the position by
dead reckoning, and is the position as found by reckoning up
the vessel's progress from noon of the previous day, the com-
pass giving the direction, the log the speed. In a majority of
cases these two positions fail to agree. The astronomical po-
sition is then assumed to be correct, and the difference be-
tween them is set down as the current during the intervening
twenty-four hours.
Thus let A be the position' by observation at noon of a given
clay; B' the position by dead reckoning at noon of the follow-
ing day, i. e., the position derived from a consideration of the
course and distance during the intervening twenty-four hours.
Suppose, however, that astronomical observations show that
the actual position of the vessel at noon of the second day is
at B. In this case R' B will be set down in the log as the
current experienced during the intervening twenty-four hours.
In case no astronomical observations can be obtained, as hap-
pens in fog or cloudy weather, the position by dead reckoning
has to be adopted as the best obtainable, with the result that
if such weather continues for several days in succcession, as
sometimes happens at certain seasons of the year, the true po-
sition of the vessel may differ considerably from the assumed
position. To lessen the chance of disaster these current charts
have been constructed, giving the results of current observa-
tions in the past, and the master of a vessel, by reference to
them, is able to profit by the experience of those who have
sailed over the same waters in previous years, and to some
extent correct his own dead reckoning.
The current charts of the various oceans published by the
British Admiralty, the charts which are universally employed
by navigators, are the result of many thousands of observa-
tions taken since 1830. A glance at these charts will make
plain the difficulty which confronts the navigator when ap-
proaching a dangerous coast, such as that of Newfoundland
or of France, and compelled to rely upon his dead reckoning.
For a knowledge of the motions of the water throughout
longer periods of time we are forced to depend upon the drift
of floating objects, derelicts, wreckage, floating bottles bear-
ing messages, and the like. All these objects are charted on
the drift charts of the United States Hydrographic Office month
by month. Two special attempts recently made to study the
currents of the sea by this method deserve attention. The
first is an effort to obtain a knowledge of the currents in the
Arctic Ocean. Stout oaken casks, each one numbered and
bearing a message, have been distributed by the Philadelphia
Geographical Society among the whalers bound for the Arctic
Ocean by way of Bering Sea, who winter in the vicinity of the
mouth of the Mackenzie River. These casks are to be placed
upon the ice as far eastward as circumstances permit, and the
expectation is that they will enter the Atlantic Ocean either by
Davis Strdt or Barents Sea.' be noticed by passing vessels, and
picked up. A letter from Dr. Bryant, the president of the
society, states that 35 out of the 50 casks have been already sent
out, and that in his opinion they may be looked for on the other
side of the circumpolar area about 8 year from the spring of
1902.
The second project is the proposed investigation of the cur-
rent in the neighborhood of Ushant and Finisterre by means
of floating bottles. This has been undertaken by Lloyds, the
great firm, of ship underwriters and has probably been sug-
'That part of the Arctic Ocean between Spitzbergen, Nova Zembla, and Greenland.
Charleston or Savannah before attempting to reach the more
northern ports of Boston and New Pork. The prevalence of
northwesterly gales along the coast during the winter season
renders the passage a trying one even to the larger ships and
with the better navigation of the present time. The southern
cities thus became, to a certain degree, half-way houses on the
voyage, greatly to the benefit of their trade. With the aid of
a thermometer, homver, a vessel once making the stream was
enabled to remain within it and to be thus borne along by the
current until the desired northing was made, after which she
headed up for port. Thus the necessity for making Charles-
ton or Savannah was obviated and the advantage which they
had hitherto enjoyed as commercial centers was lost.
From Hatteras the course of the stream leaving the coast
bears toward the east-northeast. It ceases to exist as a stream
currentthat is, as a current which runs independently of the
winds-shortly after crossing the fortieth parallel; even pre-
vious to that, the current observations in the square bounded
by 35O-4O0N., 65'-70' W. (off the coast from Hatteras to
Sandy Hook) show for September, the month of masimum
frequency, but 33 per cent of the whole number of observa-
tions setting northeast-i. e., only 7 per cent more than 25
per cent, which would be the number if there were no directive
influence whatever. I n this latitude the Gulf Stream becomes
part and parcel of the general easterly drift which characterizes
the waters of the ocean north of 35' in a manner quite analo-
gous to the westerly drift of the Tropics and due to the same
cause, namely, the prevailing winds, which, however, show none
of the persistency of the trades.
The winds of the North Atlantic Ocean-as also of the several
other oceans, the South Atlantic, South Pacific, North Pacific,
and the Indian-are governed mainly by the presence of an
almost permanent area of high barometer covering the main
body of the ocean, around which the winds constantly circu-
late; the circulation in the Northern Hemisphere is in the
same direction as the hands of a clock; in the Southern Hem-
isphere in a contrary clirection, or in either hemisphere r r with
the sun,'' as it is expressed by sailors. In the North Atlan-
tic the center of this area lies somewhat to the southwest of
the Azores. On the southern slope of this barometric area
the winds have an easterly direction, the northeast trades; on
the northern slope, a westerly. These westerly winds, how-
ever, exhibit none of the constancy of the trades, being fre-
quently interrupted by the wind systems proper to the alternate
areas of high and low barometer which move across continent
and ocean from west to east, and which form the governing
feature of our own weather, the wind backing to the southeast
with falling pressure, but hauling to northwest with rising,
just as in the case of the trades, only to a much less extent.
There is, however, a sufficient easterly component remaining
to impart to the waters of the sea below the surface a distinct
easterly motion, while on the surface itself there is apparently
an utter lack of definite direction other than the fact that the
direction of the current ordinarily agrees with the direction of
the wind. How true this is may be gathered from a compari-
son of the observed winds and the observed currents for a
given area. Take, for instance, the 5' square included be-
tween the parallels 40' and 45' N., 30' and 35O W.-about
the middle of the Atlantic Ocean: The total number of wind
observations recorded for the square was 8,806: that of reli-
able current observations, 719. Dividing each of these up into
quadrants and setting the currents under that wind quadrant
to *hich they are due, we have the following percentages:
NE. SE.
Winds. .................................... 16 90
Currents .................................. 90 18
THE CONSTRUCTION OF CURRENT CHARTS.
SW. NW.
36 28
31 31
the sea as
AUQUST, 1902. MONTHZY WEA!FEER BEVIEW.
gested by the number of vessels lately lost in that vicinity;
owing to the fact that they were out in their reckoning. The
bottles, which are of gutta percha, are to be sealed and thrown
into the sea by passing vessels, each one containing a label
showing the date and the position at which it was cast adrift.
They are then supposed to drift ashore and to be recovered.
The expense involved is considerable. On the bottle it is
stated that a reward of five francs will be paid for the return
to any of His Majesty’s consuls-an instance of liberality of
expenditure in the acquisition of knowledge which is almost
unprecedented. -
SUMMER MEEITING OF THE AMERIUAN FORXISTRY ASSOCIATION.
By Prof. ALFRED J. HENRY, U. S. Weather Bureau.
The American Forestry Associahion held its summer meeting
at Lansing, Mich., August 27-28,1902, under the joint auspices
of the Michigan Forestry Commission and the Michigan Agri-
cultural College. The sessions were held in the State Capitol
‘and the Botanical Laboratory of the Agricultural College,.Hon.
Charles W. Garfield, Vice President of the Association for
Michigan, in the chair.
The papers read and discussed at the meeting were for the
most part upon practical problems in forestry and forest man-
agement, particularly as applied to the conditions which obtain
in Michigan. It is gratifying to note in this connection that
the people of that State, and indeed those of other States as
well, are fully alive to the great necessity of taking prompt
action looking to the preservation of their rapidly disappear-
ing forests.
The advanced position thnt Michigan has taken in industrial
affairs during recent years and the development of new indus-
tries has drawn rather heavily upon her water resources. The
question of the constancy of stream flow and the possibility of
developing additional power is now receiving attention so that
a very substantial as well as a sentimental interest attaches to
the preservation of the forests on the headwaters of her prin-
cipal rivers.
During the last thirty-five years vast tracts of Michigan pine
lands have been cut over and the merchantable timber removed.
In many districts the lumberman has been succeeded by the
agriculturist, and prosperous farming communities have been
established. In other districts, especially in the region north-
west of Saginaw Bay, the attempt at farming has not been as
successful as might be wished. Many tracts of land from
which the lumber has been removed were abandoned, and in
course of time reverted to the State.
From the lands thus acquired the State has set apart about
57,000 acres in Roscommon, Crawford, and Oscoda counties as
a forest preserve. At the same time a commission was ap-
pointed to have charge, not only of the forest preserve, but
also of all matters relating to forests and forest management
wherein the State was an interested party. Naturally much of
the discussion of the meeting turned upon the measures best
adapted to the reclamation of the waste lands, pine barrens as
they are locally known, in the forest preserve and elsewhere
in the State. These lands are for the most part unfit for agri-
cultural purposes. The soil is sandy, coarse in texture, so
coarse in fact that its capillary power is exceedingly low. The
rain that falls upon it soon passes far below the roots of the
scanty flora that now subsists upon it and is lost so far as plaut
life is concerned. That such a condition is not of recent ori-
gin is clearly shown by the fact that the present flora of the
region is composed largely of species which have developed
structural forms adapted to much less humid regions. On the
other hand it should be remembered that a great part of these
abandoned lands was once covered by a growth of magnificent
white and Norway pine. The important quastion is therefore
c‘Cm not these trees be grown again?”
5a-a
401
The onmmua of opinion aa expressed at the meeting was
in the h a t i v e , but on certain of the poorer lands it would
be necessary to first plant trees of a relatively low order in
the economy of nature, as for example, the jack pine, a tree
that will grow on lands that have been fire-swept and aban-
doned by other forest trees, or left to waste by the farmer.
The forest, as was pointed out by Dr. Clifford, performs simul-
taneously two important functions, soil.fixation and soil better-
ment. The improvement of the soil would be a comparatively
slow process, yet with the gradual formation of humus and
with the added protection of the trees the moisture conditions
would also improve, especially as regards the conservation of
the snowfall, much of which is now wasted. Thus the way
would be paved for the return of the better species of trees.
Mr. Thomas H. Sherrard of the Bureau of Forestry, United
States Department of Agriculture, gave a general description
of the physical characteristics of the lands in the forest pre-
uerve. He classed the existing forest covering as (1) Swamp;
(2) Jack pine plain; (3) Oak flat; (4) Oak ridge, and (5)
hardwood lands, and showed the distribution of these typeu
in n representative township. Mr. Sherrard also gave an esti-
inate of the possible production of a second crop of timber on
these lands based upon measurements of existing second
growth.
The climatologist mill be interested chiefly in the delibera-
tions of the several sessions respecting the destruction of the
forests, the blighting effect of forest fires, and the diminution
of stream flow clue to these causes. Fortunately for the State,
the scars made upon her surface are not so deep or lasting as
they might have been under different conditions as to climate
and topography. The rainfall is generally abundant for all
needs, though not heavy enough to cut and seam the surfaces
from which the timber has been removed. Then, too, owing
to the humid climate, the original forest has in many cases
become covered with a second growth of native trees or under-
brush, thus preserving the character of the original covering.
So far as can be judged from the scanty data available, de-
forestation has not changed the climate to an appreciable
degree. -~
THE PERMANENUY OF PLANETARY ATMOSP-S, AUCORDING TO THE KINETIU THEORY OF GASES.
By S. R COOK, Case School of Applied Science, Cleveland, Ohio, dated September 3,1902.
1. HISTORICAL.
. Since the development of the kinetic theory by Clausius,
Meyer, and Maxwell, and especially since i t has beeu shown by
Maxwell and Boltzmann that the molecules of any gas may
have velocities ranging from zero to infinity, it has been a
problem of intense interest to many scientists to determine the
probability that the inolecules of highest velocity may escape
from the outer limits of an atmosphere, and hence deduce
the condition of atmospheric permanence.
The vast extent of the gaaeous envelope of the sun, the ab-
sence of an atmosphere around the moon, the extent and per-
manency of the atmosphere of the earth and the probable exist-
ence of atmospheres on the planets are problems that arouse
and hold the interest alike of astronomers and physicists.
According to the nebular hypothesis, these bodies at on0
time all belonged to the same nebulous mass. It may then
very naturally be assumed that under similar [temperature]
conditions they would each contain the same forms of matter
in their atmospheres. Various hypotheses, both chemical and
physical, have been presented to explain the absence of all free gases from the surfnce of the moon. The presence of certain
markings on Mars, that appeared to be accounted for by a b
inospheric conditions, has caused much interesting specuh-
tion and scientific discussion as to the probable constitution
of this pIanet’s atmosphere. The existence at times of what