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THE BAROMETER.-Atmospherical Pressure is, as stated before, measured by the Barometer, which should be a mercurial one. The readings of the barometer are "corrected" for instruinental errors and reduced to 32o and to sea-level. These are necessary, since the mercury expands when the temperature rises and the column is lengthened; and two similar, barometers cannot read alike unless at the same temperature. In the same way, since the height of the column of mercury measures the weight of the column of air of equal sectional area above it, if two similar barometers be placed one directly above the other it is evident that there will be a less quantity of air above the former than above the latter instrument, and it will read lower.

The greatest depression of the barometer öccurs daily about 4 a.m. and p.m., and its highest elevation about ro a.m. and p.m.; in summer, these extreme points are reached from one to two hours earlier in the morning, and as much latëf in the afternoon.

To convert English Barometrical readings into French (inches into millimètres) or vice versa the following table will be useful.

Mil. In. Mil. In. In. Mil.

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1039

750-2539 0.3=76

2079

755-29.73 0.4-10 1

3118 760-29.92 0.5-12 7

4158

765-30.12 0.6-15 2

5197

770:30-32 07-17 8

775-30.51 0.8-20 3

715-28-15 780-30-71 0.99

720-28-35 785-30-91

725-28-54 790-31.10 31 787-4

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The following are conditions for a high barometer: (1) When the air is very cold, for then the lower strata are denser and more contracted than when it is warm. The contraction causes the upper layers to sink down, bringing a greater number of air particles, that is to say, a greater mass of air into a given vertical column of the atmosphere supposed unable to expand laterally, so that the pressure at its base is greater. (2) When the air is dry, for then it is denser than when it is moist. (3) When in any way an upper current sets in towards a given area, for this compresses the strata underneath.

Mercurial Barometer.

735-28-94 In. Mil. 29736-6 740-29-13 01-25 28 711.2 745-29-330-2=5127=698.5

THE THERMOMETER.The determination of the temperature of the air is open to much uncertainty owing to the great difficulty of securing an unexceptionable exposure for the thermometers. An ordinary thermometer consists of a fine glass tube with a bulb (cylindrical or spherical)

or

blown on one end, and partly filled with some liquid, mercury spirits of wine, usually the former. This liquid expands on being heated, and contracts again being

Conversely, the barometer stands low when (1) the lower strata are heated, causing the surfaces of equal pressure to rise, and the upper layers to slide off as already described, for by this means the mass of air pressing on each unit of area below is reduced. (2) When the air is damp, for as the density of aqueous vapour, at the temperature of 60° and pressure of 30 ins., is=0'622, air being = 1, the mixture is lighter the more vapour it contains, and consequently damp air does not press so heavily as dry on the unit of area below. When the air from any causes has an upward movement, for this of course acts in the same manner as (1). From these principles it fol

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on

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cooled. By the amount

72 90 194 SEA LEVE

6885 1183

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VERYBRY

convert

20 25 13

24 30 22

ters are

tube. Selfregistering thermom einstruments

40 50 122

36 45 113

32

40 104

highest

8

10

50

[graphic]

4

5 41

ZERO ZERO 0 0

32 WATER FREEZES

4

5

23

8

101114

into Reauniur, deduct 32, multiply by 4, and divide by 9. To convert degrees Centigrade into Fahrenheit, multiply by 9, divide by 5, and add 32. To convert Reaumur into Fahrenheit, multiply by e, divide by 4, and add 32. The diagram on previous page shows corresponding degrees.

measured in a meteorological observatory by an anemometer, of which an illustration is given below.

OF THE METEOROLOGICAL OFFICE:

North Conc.

WINDS AND STORMS.

The motion of the air, both in direction and velocity, is regulated by the distribution of atmospherical pressure at the surface of the earth, which is shown by the distribution of the readings of the barometer in the weather chart.

The force of the wind, as distinguished from its direction, is related to the amount of difference of barometrica! pressure over a given distance, and this is defined as the "gradient." Where the lines of equal barometric pressure (the "isobars") are close together, we have a steep gradient, and may hence expect strong winds to restore the atmospheric equilibrium. The force of the wind therefore does not depend on the absolute height of the barometer at any given station, but on its height as compared with that for the surrounding districts.

Storms were formerly divided into two great ciasses, circular storms (hurricanes and typhoons) and straight line storms. The former are almost the only class of storins which occur within the tropics, and are known under the general name of cyclones. Straight line

Anemometer.

storms were formerly supposed to be the usual type in temperate latit::des, inas

much as the wind will blow hard for many days together

from the same point. Later observations have shown, however, that these storms are almost without exception cyclonic in their nature, although they are not so characteristically developed as in the tropics.

CYCLONES.-There are two great classes of atmospheric systems, anti-cyclonic and cyclonic. Anti-cyclonic systems are characterised by very slow circulation of the air (light winds, by low temperature in winter, great "absolute" dryness of the air, at least at their centres, and consequent absence of rain, though fog may be very prevalent.

Cyclonic systems on the other hand are characterised by rapid circulation of the air causing strong winds-which appear to flow towards the centre, so that the air is supplied from below and ascends in the centre-a comparatively high temperature, much moisture, and therefore heavy rain. At the rear of the disturbance it may be very dry.

These are the winter conditions. In summer they are exactly reversed, at least in temperature. One great distinction between cyclones and anti-cyclones is that the former move over more or less large areas, whilst the latter are usually stationary. The actual force of the wind is

STORM AND WIND SIGNALS

DAY SIGNALS.

South

Cone.

Gale

Gale

probably probably from the from the Southward. Northward.

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The Cone point downwards means that gales or strong winds are to be expected, at first from the Southward, viz., from S.E. round by S. to N.W. The South Cone is hoisted if it appears probable that a gale will begin from between E. and S.E., and also that it is likely to veer towards S. or S.W.

The Cone point upwards means that Northerly gales or strong winds are probable, viz., from N.W. round by N. to S.E. If it is probable that a gale will begin from between W. and N.W., and also that it is likely to veer towards N. or N.E., the North Cone is hoistea.

The Signal is kept hoisted until dusk, ard then lowered; hoisted again the following morning at daylight, and so on for 48 hours from the time at which the message was issued from the Meteorological Office, unless otherwise ordered. At dusk, when a Signal ought to be flying, the Night Signal should be hoisted in place of the Cone-point downwards for South Cone, point upwards for North Cone.

The object of these warnings is only to make known the greater and more general disturbances of the atmosphere, and the hoisting of the Signals is a sign that an atmospherical disturbance is in existence, which will probably cause a gale, frem the quarter indicated by the Signal used, within a distance of about 50 miles of the place where the Signal is hoisted.

a

A Southerly wind is more likely to veer rapidly to a point North of West than Northerly wind is to veer to a point South of East; a gale from the Eastward is more likely to back to the Northward than to veer to the Southward.

VELOCITY OF WIND.

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UNION OF ENGLISH AND SCOTCH CROWNS.-HOUSE OF STUART.

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-UNION OF THE TWO KINGDOMS.-HOUSE OF HANOVER.

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ember 9th, 1841, was married on March | Denmark and the late Queen Louise.

THE KING'S CHILDREN

Albert Victor, DUKE OF CLARENCE, born Jan. 8, 1864, died Jan. 14, 1892. George Frederick Ernest Albert, DUKE OF CORNWALL and York, born June 3, 1865, married July 6, 1893, to Princess Mary of Teck, has issue Edward Albert, born June 23, 1894. Albert Frederick, born Dec. 14, 1895. Victoria Alexandra, born April 25, 1897.

Henry William, born March 31, 1900.

AND GRANDCHILDREN.

Louise Victoria, DUCHESS OF FIFE, born
Feb. 20, 1867, married July 27, 1889,

has issue

Alexandra Victoria, born May 17, 1891.
Maud Alexandra, born April 3, 1893.
Victoria Alexandra, born July 6, 1868.
Maud Charlotte, born Nov. 26, 1869,
married July 22, 1896, to Prince
Charles of Denmark.

Alexander, born April 6, 1871, died
April 7, 1871.

QUEEN VICTORIA'S CHILDREN, GRANDCHILDREN AND

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LOUISA, PRINCESS ROYAL,

Nov. 21 (68,000).

1. VICTORIA ADELAIDE MARY 1840 1901 Frederick Wilhelm, late German Emperor 1858

William (succ. as German Emperor 1859

Princess Augusta of Schleswig-Holstein 1881

(died June, 1888), Jan. 25.

June, 1888).

Frederic William....

1882

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THE NEW CIVIL LIST.

First Class-The King's and Queen's Privy Purse...

Second Class-Salaries of His Majesty's Household and Retired Allowances

Third Class-Expenses of His Majesty's Household

Fourth Class-Repairs and Alterations of Royal Palaces

Fifth Class-Royal Bounty, Alms, and Special Services.

Sixth Class-Unappropriated

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The nett increase over the corresponding list in the reign of Queen Victoria is £67,000. The Civil List of William IV. was £510,000; of George III. in 1815, £1,030,000; of George II., 800,000,

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