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celestial globe, he will find no difficulty in placing Spica Virginis in the proper position, with respect to the brazen meridian, to show its place on the 14th, by means of the brazen hour circle attached to the axis of the globe; when Spica Virginis is so placed, the situations of all the other stars and constellations whose positions are given for the 15th of May may be seen by consulting the points of the compass marked on the paper horizon of the globe. For the purpose of giving some idea of the altitudes or heights above the horizon, of the different stars and constellations at the given times, a line supposed to be drawn from the horizon to the zenith, or point over our heads, is conceived to be divided into four parts, and the points of division to be marked, from the horizon upwards, by the three fractions,, and 3. The altitude of a star, &c. on or very near the horizon, is marked 0, of a star in or near the zenith, Z, of a star of the whole line above-mentioned distant from or above the horizon, ; and so also, if the star be nearer to than to the horizon, or to than, its altitude is still marked: the same remark applies to stars near the zenith. For example, when we write Perseus Eb S, H, we mean that the constellation of Perseus is to be found, at the particular time named, in the Eb S quarter of the heavens, and that the height or altitude of its centre above the horizon is about of the line passing through it, drawn from the horizon to the zenith: this constellation therefore, at this time, should neither be marked Z nor, as its position is nearer to the division than to any other mark.

The hours, minutes, and seconds given, marked S, are the right ascension of the stars which pass the meridian of Greenwich exactly at 10 in the evening of the given day, or the sidereal time at that hour; the term right ascension will be explained in the Treatise on Astronomy. Our object in giving these positions of planets, stars, &c. is to enable any person who is acquainted with the points of the compass, to find all the most remarkable stars and constellations in sight at the time of observation without difficulty. If the time of observation be a certain number of hours before or after 10 h., all the stars will be found so many hours to the east or west of the 10 o'clock position for that evening. The positions given in the Almanac, though calculated for Greenwich, will serve well enough for any place in Great Britain or Ireland, and, except in the case of the planets, for several succeeding years, as they have no pretensions to great accuracy.

Explanation of the columns headed "Length of day," "Day's increase or decrease," ‚”“ Day breaks," and "Twilight ends.”

THE column headed "Length of day," contains the number of hours and minutes between sun-set and sun-rise, and is found by doubling the number of hours and minutes after noon, at which the sun sets. The column headed "Day's increase," expresses the number of hours and minutes, which the day has increased since the shortest day; and where the column is headed "Day's decrease," it expresses the number of hours and minutes, which the day has decreased since the longest day: for example, the length of the longest day in 1830 is put down in the column "Length of day" at 16h 34'; and on the 6th of July following, we find that the length of the day, or the number of hours and minutes between sun-set and sun-rise, is set down at 16h 24': hence the day has decreased 10' since the longest day, and accordingly in the column "Day's decrease," we find opposite July the 6th, Oh 10'. Twilight is the faint light which precedes sun-rise, and follows sun-set. It is caused by the refraction and reflection of the sun's rays by our atmosphere. Day is said to break when twilight commences. Twilight is generally supposed to exist when the sun is 18 degrees, or less, below the horizon of any place, or 108° distant from the zenith: on this supposition cur tables are founded. The times of its commencement and end, inserted in the two columns headed" Day breaks," and "Twilight ends," are obtained by resolving an oblique angled spherical triangle, in which the three sides are given to find an angle, which is called an hour angle; this angle expresses the number of hours and minutes from apparent noon at which twilight begins and ends. But though twilight is generally supposed to commence when the sun is 18° below the horizon, yet what is commonly called "Day break," that is, when the darkness of night gives place to a faint yet perceptible light in the East, rarely occurs until the sun is within about 10° of the horizon.

Equation of Time.

MANY persons suppose that they may, at all times of the year, set their clocks by the sun-dial; but this can only be done with the assistance of the column in the Almanac, headed" Equation of Time," except at four periods of the year, namely, on or about the 15th of April, the 1st of September, the 24th December, the 15th of June. At all other times, the column, Equation of Time, ought to be consulted; and when clock after sun is written above the number of minutes and seconds opposite to the day, then the clock ought to be set so much slower than the sun-dial, and the contrary; as for example, on the 3rd of June in this year the clock should be set two minutes and eighteen seconds slower than the time shewn by the sun-dial; and, on the contrary, on the 26th of June, the clock should be set two minutes and twenty seconds faster, the words clock before sun being, in this case, written above the difference.

Explanation of the Columns,

"Moon's Duration."

THE absence of the Light of the Moon is indicated by lines referring to each hour of the night. This enables the reader, at one glance, to see what hours are light, and what dark, in any given night, without computation. Thus, on the 12th of January from midnight till eight o'clock in the morning, when the sun has risen, the moon is up, which is shewn by the columns of each hour not having any black lines across ;-but on the evening of the same day, after sun-set, we find the hour columns, from 4 to 5, 5 to 6, 6 to 7, 7 to 8 with black lines across, and those hours are therefore dark: the column 8 to 9 is about a quarter dark; the moon then rising at a quarter past 8. The quantity of moonlight is known by referring to the next column of "The Moon's Age."

Explanation of the columns "

High Water at London.".

Laplace has given the following expression from which the time of high water can be obtained.-Mécanique Céleste, vol. ii. p. 234.

tan 2 (nt +-'-2)=π

L

3 cos2 v sin 2 (−4)

L

3 Cos2 + cos v cos 2 (4)

v

nt+-'is the hour angle of the moon at the time of high water; Lis the mass of the sun, r the distance of the sun from the earth, the declination of the sun, the right ascension of the sun, L', r, v', and the corresponding quantities for the moon, but this appears to be incorrect, or at least indistinct: it should be

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the times of high water have been calculated from this expression neglecting the declinations of the luminaries, supposing

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in her mean distances as determined by Laplace from the observations of the tides made at Brest by order of the French Government. The following table gives the number of minutes, which, if the time of the moon's southing is on the left hand side, is to be subtracted from, and if on the right hand side to be added to, the time of the moon's southing+1 hour 29 minutes. This supposes the establishment of the Port of the London Docks to be 2 hours.

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The constants λ and λ were obtained by a discussion of more than 9000 observations of the time of high water, which have been made at the London Docks. The method which was adopted in this determination is explained at some length in the Companion to the Almanac, and the coincidence shewn between theory and observation is truly wonderful.

J. W. L.

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TIDE-TABLE-The time of High Water at London has been calculated upon the principles stated in the preceding page; and with the benefit of the actual observations of a number of years. The following List is derived from books of Navigation. We shall endeavour to verify these statements in succeeding years, as far as possible; and in the Companion to the Almanac will be given some plain and practical directions, by which persons residing at the Outports may calculate the Tides for themselves.

Aberdeen

Alderney

Antwerp

Ilfracombe
Jersey

h. m. sub. 0 16

add 3 59

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Lerwick Harbour

sub. 4 16

Berwick

14

Liverpool, floating light off,

3 41

Bideford

3 29

Ditto, Rock Perch, entrance to,

3 5

'Blakeney Harbour

3 59

Loch Foyle

add 3 59

Blexen

sub. 31

Margate

sub. 2 46

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Milford Haven

add 2 59

Brest Harbour

Brill, the

add 2 29

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Buchanness
Calais
. Campleton
Cape Clear
Cardigan Bar

Carmarthen

Cherbourg

sub. 2 1

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2 31

Newhaven

sub. 3 1

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Bay

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Christchurch Harbour

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Cork Harbour

add 2 29

Pool Harbour

sub. 5 14

Cowes

3 16

Port Glasgow

2 16

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Port Patrick

3 1

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To find the time of High Water at the above Places, it will be necessary to add, or subtract, as the case may be, from the time of High Water at London. For example:-On the 1st of January, the morning High Water at London Bridge is at 6h. Im.; the High Water at Dover Harbour is 3h. 11m. earlier; subtract, according to the direction, 3h. 11m. from 6h. 1m., and the time of High Water at Dover Harbour, on that day, will be found to be at 2h. 50m.

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HOLIDAYS KEPT AT THE PUBLIC OFFICES IN 1830.

CUSTOM-HOUSE, EXCISE, & STAMP OFFICE.
Good Friday, April 9.

King's Birth-day, kept April 23.
Restoration King Charles II. May 29.
Coronation, July 19.

Christmas Day, December 25.

INDIA HOUSE.

The Treasurer's and Accomptant's Offices keep the same Holidays as the Customs, but the Transfer Office keeps the same days as the Bank.

EXCHEQUER, BANK, and SOUTH-SEA HOUSE.

(Any Holiday falling on a Sunday, is kept on the Monday, excepting Saints Days)

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JANUARY.

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Th 24 St. John Baptist..

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M 25 Conversion of St. Panl. k

F 29 George IV. accession...
S 30 Charles I. martyrdom. k
31 George IV. proclaimed.

FEBRUARY.

Tu 2 Purif. B. V. M..

14 Valentine..

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Tu 23 Shrove-Tu. St. Matthias k
W 24 Ash-Wednesday..

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Tu 29 St. Peter and Paul..... k

Th 15 St. Swithin

M 19 Geo. IV. crowned

25 St. James

AUGUST.

1 Lammas..

Tu 24 St. Bartholomew..

SEPTEMBER.

Th 2 London burnt.
Tu 14 Holy Cross ..

S 18 George 1. & II. landed.

Tu 21 St. Matthew

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M 18 St. Luke....

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OCTOBER.

Th 28 St. Simon and Jude.... k k

NOVEMBER.

M 1 All Saints

k k

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Tu 2 All Souls.

k

Th 4 King William landed..

k

F 5 Powder-plot

k

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Tu 9 Lord Mayor's Day

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Tu 30 St. Andrew.

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26 St. Stephen.

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M 27 St. John.

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F 9 Good Friday.

. M 12 Easter Monday Tu 13 Easter Tuesday.

W 14 Easter Wednesday.

F23 St. Geo., King's birth-d. 25 St. Mark..

MAY.

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S 1 St. Philip and James... k

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TERMS AND RETURNS, 1830.
HILARY TERM begins January 23-Ends February 12.

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Essoign. Exc.
Jan. 20 21

TRINITY TERM begins June 11-Ends June 30.

On the Morrow of the Holy Trinity..

Ret.

27 | 28 Wed.

27 28

Appear. 22 | 23 Sat. 29 30 Sat.

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EASTER TERM begins April 28-Ends May 24.

April 25 26

May 2 3

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June 7 8

9! 11 Frid.

In 8 Days of the Holy Trinity

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In 15 Days of the Holy Trinity..

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From the Day of the Holy Trinity in 3 Weeks

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N. B. No Sittings in Westminster Hall on the 2d of February, Ascension Day, and Midsummer Day.-The Exchequer opens eight days before any term begins, except Trinity, before which it opens but four days.

OXFORD TERMS.
Begins.

Note. The first and last days of every Term are the first and last days of Appearance.
Mich. Term. Oct. 10..Nov.12,m... Dec. 16
The Commencement will be July 6.
TERMS IN ENGLAND
Usually taken in Leases.

Hilary Term......Jan. 14..

Easter Term...... .Apr. 21..

Ends.
Apr. 3
.May 28

Trinity Term.....June 2.......July 10
Michaelmas Term..Oct. 11.......Dec. 17
The Act will be July 6.

CAMBRIDGE TERMS.

Begins. Divides. Ends.

2

Hilary Term.Jan. 13.. Feb. 21, m...Apr.
Easter Term.Apr. 21..May30, m...July 9

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25 March. Ladyday | 29 Sept.. Mich. Day 24 June... Midsum. 25 Dec... Christmas IN SCOTLAND.

Candlemas. Feb. 2 | Lammas... Aug. 1 Whitsunday May15 | Martinmas. Nov. 11 This term, in Scotch leases, does not depend upon the moveable Feast of Whitsuntide, but is permanent.

TRANSFER DAYS.

AT THE BANK.

AT THE SOUTH SEA HOUSE.

Stock-Tues. Thurs. and Frid...."

Dividends
due.

Div. due.

3 per Cent. Reduc.-Tues. Wed. Apr. 5, 3 per Cents. Mon. Wed. and

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Jan. 5, July 5

34 per Cent.-Tues. Thur. & Frid.

3 per Cent. Old Ann.-Mon. Wed.
and Frid...

Apr. 5,

Oct.10

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3perCent. NewAnn.-Tu.Th.&Sa.
3 per Cent. 1751-Tues. & Thurs.
AT THE EAST INDIA HOUSE.
Stock-Tuesday, Thursday, and Jan. 5,
Saturday

Jan. 5,

July 5

3 per Cent. Cons.-Tues. Wed.
Thurs. and Frid.

Long. Ann. to Jan. 1860.-Mon.
Wed, and Sat.

4 per Cent. New.-Tues. Wed. Jan. 5,
Thurs. and Frid.
JJuly 5

4 per Cents. 1826-Mon. Wed. and Apr.5, Frid...

Life Annuities, if transferred be-
tween Jan. 5, and Apr. 4, or be-
tween July 5 and Oct. 9

If transferred between Apr. 5, and
July 4, or between Oct. 10, and
Jan. 4...

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July 5 (Mar.31 Sept.30

Tickets for preparing Transfer of Stock must be given in at each Office before 1 o'clock.-At the East India House before 2.

Private Transfers may be made at other times than as above, the Books not being shut, by paying at the Bank and India House 2s. 6d. extra for each Transfer.-At the South Sea House, 3s. 6d.

Transfer at the Bank must be made by half-past 2 o'clock; at India House by 3'; at South Sea House by 2-on Sat. by 1.

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