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SHILLING SCIENTIFIC SERIES
[Illustration: DR. AITKEN'S DUST-COUNTER.
R is the test-receiver; P the air-pump; M the measuring apparatus; L the
illuminating arrangements; G the Gasometer; A the pipe through which the
tested air is drawn.]
METEOROLOGY;
OR,
WEATHER EXPLAINED.
BY
J. G. M'PHERSON, Ph.D., F.R.S.E.,
GRADUATE WITH FIRST-CLASS HONOURS, AND FOR NINE YEARS
EXTENSION LECTURER ON METEOROLOGY AND MATHEMATICAL
EXAMINER IN THE UNIVERSITY OF ST. ANDREWS;
AUTHOR OF "TALES OF SCIENCE," ETC.
LONDON: T. C. & E. C. JACK,
34 HENRIETTA STREET, W.C.
AND EDINBURGH.
1905.
THE SHILLING SCIENTIFIC SERIES
_The following Vols. are now ready or in the Press_:--
BALLOONS, AIRSHIPS, AND FLYING MACHINES. By GERTRUDE BACON.
MOTORS AND MOTORING. By Professor HARRY SPOONER.
RADIUM. By Dr. HAMPSON.
TELEGRAPHY WITH AND WITHOUT WIRES. By W. J. WHITE.
ELECTRIC LIGHTING. By S. F. WALKER, R.N., M.I.E.E.
LOCAL GOVERNMENT. By PERCY ASHLEY, M.A.
_Others in Preparation_
Printed by BALLANTYNE, HANSON & CO.
At the Ballantyne Press
CONTENTS
CHAP. PAGE
I. INTRODUCTION 9
II. THE FORMATION OF DEW 13
III. TRUE AND FALSE DEW 17
IV. HOAR-FROST 20
V. FOG 23
VI. THE NUMBERING OF THE DUST 26
VII. DUST AND ATMOSPHERIC PHENOMENA 29
VIII. A FOG-COUNTER 31
IX. FORMATION OF CLOUDS 34
X. DECAY OF CLOUDS 37
XI. IT ALWAYS RAINS 40
XII. HAZE 43
XIII. HAZING EFFECTS OF ATMOSPHERIC DUST 47
XIV. THUNDER CLEARS THE AIR 49
XV. DISEASE GERMS IN THE AIR 53
XVI. A CHANGE OF AIR 55
XVII. THE OLD MOON IN THE NEW MOON'S ARMS 58
XVIII. AN AUTUMN AFTERGLOW 62
XIX. A WINTER FOREGLOW 65
XX. THE RAINBOW 68
XXI. THE AURORA BOREALIS 71
XXII. THE BLUE SKY 74
XXIII. A SANITARY DETECTIVE 78
XXIV. FOG AND SMOKE 80
XXV. ELECTRICAL DEPOSITION OF SMOKE 83
XXVI. RADIATION FROM SNOW 86
XXVII. MOUNTAIN GIANTS 88
XXVIII. THE WIND 92
XXIX. CYCLONES AND ANTI-CYCLONES 95
XXX. RAIN PHENOMENA 98
XXXI. THE METEOROLOGY OF BEN NEVIS 102
XXXII. THE WEATHER AND INFLUENZA 107
XXXIII. CLIMATE 110
XXXIV. THE "CHALLENGER" WEATHER REPORTS 114
XXXV. WEATHER-FORECASTING 116
INDEX 124
PREFATORY NOTE
I am very much indebted to Dr. John Aitken, F.R.S., for his great kindness
in carefully revising the proof sheets, and giving me most valuable
suggestions. This is a sufficient guarantee that accuracy has not been
sacrificed to popular explanation.
J. G. M'P.
RUTHVEN MANSE,
_June 10, 1905_.
METEOROLOGY
CHAPTER I
INTRODUCTION
Though by familiarity made commonplace, the "weather" is one of the most
important topics of conversation, and has constant bearings upon the work
and prospects of business-men and men of pleasure. The state of the
weather is the password when people meet on the country road: we could not
do without the humble talisman. "A fine day" comes spontaneously to the
lips, whatever be the state of the atmosphere, unless it is peculiarly and
strikingly repulsive; then "A bitter day" would take the place of the
expression. Yet I have heard "_Terrible_ guid wither" as often as
"_Terrible_ bad day" among country people.
Scarcely a friendly letter is penned without a reference to the weather,
as to what has been, is, or may be. It is a new stimulus to a lagging
conversation at any dinner-table. All are so dependent on the weather,
especially those getting up in years or of delicate health.
I remember, when at Strathpeffer, the great health-resort in the North of
Scotland, in 1885, an anxious invalid at "The Pump" asking a
weather-beaten, rheumatic old gamekeeper what sort of a day it was to be,
considering that it had been wet for some time. The keeper crippled to the
barometer outside the doorway, and returned with the matter-of-fact
answer: "She's faurer doon ta tay nur she wass up yestreen." The barometer
had evidently fallen during the night. "And what are we to expect?" sadly
inquired the invalid. "It'll pe aither ferry wat, or mohr rain"--a poor
consolation!
Most men who are bent on business or pleasure, and all dwellers in the
country who have the instruments, make a first call at the barometer in
the lobby, or the aneroid in the breakfast-parlour, to "see what she
says." A good rise of the black needle (that is, to the right) above the
yellow needle is a source of rejoicing, as it will likely be clear, dry,
and hard weather. A slight fall (that is, to the left) causes anxiety as
to coming rain, and a big depression forebodes much rain or a violent
storm of wind. In either case of "fall," the shutters come over the eyes
of the observer. Next, even before breakfast, a move is made to the
self-registering thermometer (set the night before) on a stone, a couple
of feet above the grass. A good reading, above the freezing-point in
winter and much above it in summer, indicates the absence of killing
rimes, that are generally followed by rain. A very low register accounts
for the feeling of cold during the night, though the fires were not out;
and predicts precarious weather. Ordinarily careful observers--as I, who
have been in one place for more than thirty years--can, with the morning
indications of these two instruments, come pretty sure of their
prognostics of the day's weather. Of course, the morning newspaper is
carefully scanned as to the weather-forecasts from the London
Meteorological Office--direction of wind; warm, mild, or cold; rain or
fair, and so on--and in general these indications are wonderfully accurate
for twenty-four hours; though the "three days'" prognostics seem to
stretch a point. We are hardly up to that yet.
The lower animals are very sensitive as to the state of approaching
extremes of weather. "Thae sea beass," referring to sea-gulls over the
inland leas during ploughing, are ordinary indicators of stormy weather.
Wind is sure to follow violent wheelings of crows. "Beware of rain" when
the sheep are restive, rubbing themselves on tree stumps. But all are
familiar with Jenner's prognostics of rain.
Science has come to the aid of ordinary weather-lore during the last
twenty years, by leaps and bounds. Time-honoured notions and revered
fictions, around which the hallowed associations of our early training
fondly and firmly cling, must now yield to the exact handling of modern
science; and with reluctance we have to part with them. Yet there is in
all a fascination to account for certain ordinary phenomena. "The man in
the street," as well as the strong reading man, wishes to know the "why"
and the "how" of weather-forecasting. They are anxious to have
weather-phenomena explained in a plain, interesting, but accurate way.
The freshness of the marvellous results has an irresistible charm for the
open mind, keen for useful information. The discoveries often seem so
simple that one wonders why they were not made before.
Until about twenty years ago, Meteorology was comparatively far back as a
science; and in one important branch of it, no one has done more to put
weather-lore on a scientific basis than Dr. John Aitken, F.R.S., who has
very kindly given me his full permission to popularise what I like of his
numerous and very valuable scientific papers in the _Transactions of the
Royal Society of Edinburgh_. This I have done my best to carry out in the
following pages. "The way of putting it" is my only claim.
Many scientific men are decoyed on in the search for truth with a spell
unknown to others: the anticipation of the results sometimes amounts to a
passion. Many wrong tracks do they take, yet they start afresh, just as
the detective has to take several courses before he hits upon the correct
scent. When they succeed, they experience a pleasure which is
indescribable; to them fame is more than a mere "fancied life in others'
breath."
Dr. Aitken's continued experiments, often of rare ingenuity and
brilliancy, show that no truth is altogether barren; and even that which
looks at first sight the very simplest and most trivial may turn out
fruitful in precious results. Small things must not be overlooked, for
great discoveries are sometimes at a man's very door. Dr. Aitken has shown
us this in many of his discoveries which have revolutionised a branch of
meteorology. Prudence, patience, observing power, and perseverance in
scientific research will do much to bring about unexpected results, and
not more so in any science than in accounting for weather-lore on a
rational basis, which it is in the power of all my readers to further.
"The old order changeth, giving place to new." With kaleidoscopic variety
Nature's face changes to the touch of the anxious and reverent observer.
And some of these curious weather-views will be disclosed in these pages,
so as, in a brief but readable way, to explain the weather, and lay a safe
basis for probable forecastings, which will be of great benefit to the man
of business as well as the man of pleasure.
"Felix, qui potuit rerum cognoscere causas."
--VIRGIL.