THE AMERICAN METEOROLOGIC JOURNAL
VOL. IV. ANN ARBOR, FEBRUARY
NO 10
ORIGINAL
ARTICLES WILLIAM
FERREL
One
of the most interesting books of our time is the life of James
Clerk Maxwell. It is so because the great attainments of the
professor in science serve as effective back-ground for the
very attractive personality of the man himself.
It is
not given to all men to follow even, where Maxwell led. Indeed,
the number who can read understandingly his scientific papers,
appreciating thoroughly their value, is very limited. That
this is so, emphasizes the fact that it is not altogether
upon these contributions to science, that the secret of our
great interest in the man depends. A man may be great to the
profession because of his work. To the lay mind, the charm
which most interests is the degree of intimacy it is able
to establish between itself and greatness. We always are pleased
and ready to make the personal acquaintance of greatness;
and the character of the distinguished one is doubly attractive,
when in this intimacy with common minds, it compels not less
affection than admiration from them. The character of William
Ferrel is very much alike to that of Maxwell.
Gentleness
of disposition and evenness of character are to be found in
the lives of most of those who are pre-eminent in science.
Newton's comparison of himself to a boy on the seashore, is
only the exemplification of the modesty and self-depreciation
{P. 442} that quicken minds intent on knowledge, almost with
the first aspiration. And herein, no doubt, is the reason
why, with so many men of science, the affection with which
their lives called forth remains when the admiration which
their work elicited has subsided. The rule is so general that
an exception serves but as an illustration. The life of Francis
Bacon, with all its splendors, was a failure; because he did
not display in his dealings with men the sincerity and integrity
that are so strongly insisted upon, and are so essential in
the experimental sciences. His manner of meeting the world,
the scientific minds of our time know not, nor desire to know.
It is foreign to their nature to win by yielding, and they
wait rather than adapt themselves to the moment. Their ideal
life is one marked by direct and steady, even if slow, progression,
and not one in which progress, "like that of a tacking ship,
is the resultant of opposite divergencies from the straight
path." [Huxley, "Science and the Bishops." Nineteenth Century,
October, 1887.]
The
trait of character most marked in Professor Ferrel , is just
this indifference to personal position, and an extreme diffidence.
To better understand these traits of character, it is necessary
to know something of the circumstances of birth and surroundings,
and their probable influences. These, it would seem, were
not calculated to help or encourage him in early life, in
the following the natural bent of his mind. Some men are spurred
on to fame, by the presence and admiration of friends. The
opportunities seem to but await the man; and his success is
none the less creditable, even if under such stimulus. But
in equity, the more credit must be adjudged the man, successful
under drawbacks, than to another reaching an equally exalted
station, but whose whole career had been favored by all that
weighed against his competitor. This must be remembered in
making, not improperly, I think, a comparison between two
men, Maxwell and Ferrel, very much alike in disposition and
bearing, working in fields not far removed, but under somewhat
different circumstances of life. Maxwell was the brightest
intellect that ever paused to spend itself on problems of
light and electricity. Ferrel in a less pronounced career,
with care {P. 443} and in quiet, built a science, and lifted
meteorology from a mass of observations and description, with
a few self-appearing general laws, to an exactitude requiring
the most refined methods of mathematical discussion. Maxwell's
character, like his work, is beyond criticism. His life was
without flaw, and we love his memory. Yet, "adverse circumstance,"
in Maxwell's career, was a factor altogether unknown. The
honors which he bore so well, came to him, in both time and
degree, as they should. With Ferrel, in this relation, it
has been very different, and his lot has been the usual one
of a long, wearying struggle against difficulties. His explanation
of the effects of centrifugal force, and his theory applying
it to the general atmospheric circulation, were in print many
years before proper recognition of their importance came.
The first of his papers bearing directly upon meteorology,
was published as early as 1856. It was in the form of essays,
contributed to the Nashville Journal of Medicine and Surgery.
The intention of the author was to show a possible explanation,
in the deflective effects due to the earth's rotation, of
the general circulation of the atmosphere. The diminution
of atmospheric pressure at the poles and equator, and the
increase at the tropics; the gyratory motion of storms and
the deflected courses of ocean currents, Ferrel sought to
explain, as the necessary consequences of forces which have
their origin in the rotation of the earth on its axis. This
line of reasoning, furthermore, accounted for, without straining
of facts, the prevailing wind directions in the middle latitudes.
In 1858-60, the ideas advanced in the earlier paper, which,
in addition, had been printed in small pamphlet form, were
treated of in a more extended paper, and contributed to Runkle's
Mathematical Monthly, and also reprinted in pamphlet form
shortly after. This paper was again reprinted under the title,
"Motions of Fluids and Solids on the Earth's Surface," as
one of the Professional Papers of the Signal Service.* [Professional
Papers, No. VIII. Reprinted with notes, by Frank Waldo.] In
this paper Professor Ferrel proposes a complete analytical
investigation of the general motions of fluids surrounding
the earth, as determined by given forces arising from the
combined effects of attraction, {P. 444} and the rotation
of the earth on its axis. The first half of the paper is occupied
with the discussion of the general equations of motion relative
to the earth's surface. It is necessary to have these equations
set forth clearly and understood at the outset, as they are
the working tools of the author in his solutions of the various
problems mentioned above. The more important of the results
obtained by these methods, and given in detail, in the latter
half of the paper, are:
1st.
A fluid mass surrounding the earth, and assuming that the
resistance to its motion, offered by the earth's surface,
is not considerable, will have a figure, the surface of which
is slightly depressed at the equator, bulges out at about
the latitudes of 35o , and is depressed at the poles much
more than at the equator.
2nd.
Between the parallels of 35o and the poles, the motion of
this fluid will be easterly, while between these parallels
and the equator, this motion will be westerly. This gives
an explanation for the trade winds, altogether different from
the theory ordinarily given, in which it is assumed that the
tendency of the lineal velocity of the air, to remain the
same, when moving to and from the equator, results in these
winds.
3rd.
A body free to move on the surface of the earth experiences
a force, arising from the earth's rotation, tending to give
it a right-handed deflection in the northern hemisphere, and
left handed in the southern.
< The
general laws as stated above received considerable attention
and discussion; in France, soon after publication, particularly
at different sittings of the Academy. In this country and
England they seem to have passed without comment until recent
years, when more attention has been directed to the study
of meteorology. They are now recognized by all prominent writers
as fundamental propositions in the study of meteorology. The
direct outcome of the application of these methods of reasoning
to the general motions and pressure of the atmosphere, is,
in brief, the recognition of deflective effects in general
movements, and in particular or [of?] storm movements of the
atmosphere; the determination of the places on the earth's
surface where east and west motion of the atmosphere is destroyed,
or {P. 445} in other words, the regions of calm belts, the
maximum heights of atmosphere, near the parallels of 30o,
and the general circulation of the winds. These last may be
remembered, more easily, by the aid of a comparison made near
the end of the third section of the paper.* [Professional
Papers of the Signal Service, No. VIII, page 40.] "The general
motions of the atmosphere in each hemisphere form a grand
cyclone, having the pole for its centre and the equatorial
calm belt for its limit." The denser portion of the atmosphere,
however, is in the middle, and we have descending currents
at the pole or center of the cyclone, instead of the ascending
currents so familiar in the ordinary cyclone where the more
rare portion of the atmosphere is in the center.
Incidentally,
the explanation of the destructive elements in a tornado follows
from our author's theory, and it gives the only explanation,
accounting for the peculiar features of storms of this class.**
[For an exposition of Ferrel's Theory of Tornadoes, the reader
is referred to Davis's "Whirlwinds, Cyclones and Tornadoes,"
p. 82, et. seq.] The center of a tornado may become
nearly a vacuum under the influence of centrifugal force developed
by the gyratory motion of the atmosphere. Similarly with water-spouts.
The explanation of their origin and energy follows, as a matter
of course. "A water-spout is generally first formed above,
in the form of a cloud, shaped like a funnel or inverted cone.
As there is less resistance to the motions in the upper strata
than near the earth's surface, the rapid gyratory motion commences
there first. The cold air above is drawn down, and coming
in contact with the warm and moist atmosphere ascending in
the middle of the tornado, condenses the vapor and forms the
funnel-shaped cloud. As the gyratory motion becomes more violent,
it gradually overcomes the resistances nearer the surface
of the sea, and the vertex of the funnel-shaped cloud gradually
descends lower, and the imperfect vacuum of the center of
the tornado reaches the sea, up which the water has a tendency
to ascend to a certain height, and thence the rapidly ascending
spiral motion of the atmosphere carries the spray upward until
it joins the cloud above, when the water spout is complete."
***[P. 40, loc.cit.]
{P.446}
In 1856,
Professor Ferrel wrote an article on "The Problem of the Tides,"
for Gould's Astronomical Journal (IV, 173) and in 1858 he
published in the same journal (V. 97, 113), "Influences of
Earth's Rotation on the Motion of Bodies."
Professor
Ferrel's mathematical papers on the motions of the ocean are
of equal significance with those on the motions of the atmosphere.
The familiar "Essay on the Winds and Currents of the Ocean"*
[No. I. of the "Popular Essays."] had its origin in the following
way: In conversation with his friend, Dr. W. K. Bowling, [Professor
then (1854) in the Medical College at Nashville, Tenn. Editor
of the Nashville Medical Journal, and always a warm
friend of Professor Ferrel.] Ferrel mentioned his having read
Maury's "Physical Geography of the Sea," and his disagreeing
with him on many points. Bowling desired him "to pitch into
him," as he expressed it, and furnish a review of the book
for the Medical Journal. Ferrel declined to do so,
but at length consented to furnish an essay on certain subjects
treated in the book, and notice Maury's views a little
in an incidental way. The essay is the first of six, which
have since been reprinted in Professional Paper No. XII of
the Signal Service. They may be found also:
"Essay
on the Winds and Currents of the Ocean" -- Nashville Journal
of Medicine, 1856.
"Motions
of Fluids and Solids Relative to the Earth's Surface." -
American Journal of Science. 1861.
"Cause
of Low Barometer in the Polar Regions and in the Central Part
of Cyclones." -- Nature, July, 1871.
"Relation
Between the Barometric Gradient and the Velocity of the Wind."
- American Journal of Science, November, 1874.
"Meteorological
Researches. Part II. Cyclones, Tornadoes, and Water-Spouts."
-- American Journal of Science, July, 1881.
The
last paper may be found in full, as Appendix 10 to the Coast
and Geodetic Survey Report for 1878.
These
essays, together, make the most admirable contribution to
the popular knowledge of meteorology yet given by any one
mind. Unlike his other essays, they do not require, on the
part of the reader, a very high mathematical knowledge. The
type {P. 447} of a purely professional paper is the one entitled,
"Researches on the Temperature of the Atmosphere and the Earth's
Surface."* [Professional Paper No. XIII of the Signal Service.]
This discusses the subjects of solar radiation, actinometry
and general temperature distribution, and is not adapted for
general reading. Professor Ferrel's latest contribution to
meteorology - "Recent Advances in Meteorology"**[Part II,
Chief Signal Officer's Report, 1885.] - is the best summary
of the principles and results of meteorology in existence.
There is no attempt at description of instruments, but there
is the fullest and best discussion of the problems of meteorology
and the different questions of research that can be found
anywhere. From 1882 to 1886, Professor Ferrel engaged in the
work of the Signal Office, reserving, however, a part of his
time for the Coast and Geodetic Survey, with which he had
for many years been connected. It was in 1857 that he first
became interested in the American Ephemeris and Nautical Almanac,
receiving from Professor Winlock, the then Superintendent,
through Dr. B. A. Gould, an invitation to assist in the computations
of that work. Professor Ferrel was then teaching school at
Nashville, Tenn. Removing to Cambridge, Mass., in 1858, he
began the preparation of his paper on the "Motions of Fluids
and Solids Relative to the Earth's Surface," and followed
this in 1862 with a paper read before the American Academy
of Arts and Sciences, entitled, "Note on the Influence of
the Tides in Causing an Apparent Error of the Moon's Mean
Motion." At this time, it had been shown by Delaunay and Adams
that the lunar theory did not give the observed acceleration
of 11" per century, as had been supposed, but only about 6",
and there was needed something to account for the balance.
The object of the paper was to show that, upon a very reasonable
and probable lagging of the tides, the effect might be sufficient
to cause this, by changing a little the length of the day,
the unit of time.
This
paper was read only a few weeks before Delaunay read a similar
paper before the French Academy. About this time Professor
Ferrel placed before the National Academy of Science, {P.
448} on the invitation of Professor Pierce [sic, Benjamin
Peirce], a paper containing his discovery of two converging
series with simple laws expressing the ratio between the circumference
and diameter of a circle. This was subsequently published
by the Smithsonian Institute. *[Contributions, No. 233.]
About
the same time began the famous "Tidal Researches," originally
intended for publication by the Smithsonian, but, on account
of the author's connection** [ In 1867, soon after taking
charge of the Coast Survey, Professor Pierce (sic, Peirce)
offered Mr. Ferrel a position in that office, with the special
duty of discussion of tidal observations.] with it at the
time, published by the Coast Survey. Following these came
a series of papers: "Meteorological Researches for the Use
of the Coast Pilot," Part I; "On the Mechanics and General
Motions of the Atmosphere," in 1875, Part II; "Cyclones, Tornadoes,
and Water-Spouts," in 1878, Part III; "Barometric Hypsometry
and Reduction to Sea Level," in 1881.
In 1880,
Professor Ferrel became interested in the subject of a "Maxima
and Minima Tide-Predicting Machine." A paper was read on this
subject at the meeting of the American Association for the
Advancement of Science, at Boston, and in the following year
its construction was begun by the Coast Survey, and it is
now in successful operation for tidal prediction at the office
in Washington.***[Report Coast and Geodetic Survey, 1883.]
Professor
Ferrel was born in Bedford County, Pa., January 29th, 1817.
When twelve years of age, his father moved to a farm in Berkeley
County, Va. The boy was kept rather closely at work on the
farm, but completed his common school education; and even
in that country school-house, with its oiled white paper instead
of glass for window-panes, the mind of the future mathematician
showed itself in the love for diagrams and odd scraps of scientific
intelligence. The first money ever earned, (and it was not
enough), went for the purchase of a copy of Park's Arithmetic.
The child was too diffident to ask his father for money to
buy a book, but with 50 cents earned in harvest time walked
to the store in Martinsburg, only to find that the price {P.
449} of the book was 62 « cents. The storekeeper, however,
let him have it for the amount he had. As a young man, astronomy
seemed to fire his interest, and without aid other than stray
mathematical works afforded, he worked out many problems in
connection with eclipses of the moon. The doors of his father's
barn were of soft poplar, and upon these the youth, ostensibly
engaged in threshing, drew any number of diagrams, describing
circles with the prongs of a pitchfork, and drawing lines
with one of the prongs and a small piece of board. Often in
later years, in visiting the old homestead, the Professor
would look up these diagrams. In 1839, Ferrel entered Marshall
College, Mercersburg, Pa. He was always in advance of his
class in mathematics. After reaching the Junior class, he
spent two winters teaching school in Virginia. He then entered
Bethany College, and was one of the first class to graduate
from that institution, July 4, 1844. The years following were
spent mainly in school-teaching, until asked to aid in computations
for the Nautical Almanac. It is noteworthy that in his whole
career Professor Ferrel never once sought position. Every
official position has been offered him without solicitation
on his part.
As an
illustration of his diffidence to put himself forward in any
manner, we may instance an incident in connection with his
paper on "The Effect of Tidal Action in Causing an Apparent
Acceleration of the Moon's Motion." This paper, containing
original and important suggestions, he carried to the meeting
of the American Academy at Boston time and time again, with
the intention of reading, but lacked assurance. It was
read at last, but deferred so long that it barely anticipated
the investigations of Delaunay on the same subject. Professor
Ferrel is a member of the National Academy of Sciences, of
the American Academy of Arts and Sciences of Boston, of the
Washington Philosophical Society, and honorary member of the
Austrian Meteorological Society, of the Royal Meteorological
Society, London, and of the German Meteorological Society.
A.M.
[Alexander McAdie]
St. Paul,
Minn., January, 1888.
