The Sun.
London, England, 1849-12-31 00:00:00

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9 6 11 12
i 6 17 18 19
253. 25 261
;0 4 1

2711

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20 21 2223 E

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August
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21 ,

6 7 8
13 14 15 16
20021 22 23
17 28 29 30
34 5 6
11 12 13
17 18 19 20
,24 25 26 27

71,0ctober..

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8 9 10 11
15 lfi 17 18
22 23 24 25
,29 3 31

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11 12f
10 11(

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17 18

5j 61 7 8
12 13 14 15
19 20 2i 22
26 27 28 29

IDee4mber
9

1140
1 30

3i September;

51 Noyentber
211 I

L 3114115 1
2021 22 1.
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11 12113 1,
849,20 2.
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[PRICE SD.

'MARINE LIGHTS.
'le Harbour Connafissioners and Trinity Board of
lee are puzzled to know what to do with the
_ fights. Since the opening of the railways co-
loured lights have become co common that vessels at
sea may readily mistake the railway signal fur the
marine light, and thus life and property may be lost.
The Dundee authorities have applied to the Admiralty
for instructions and advice, and it is now perfectly
clear that something must speedily be done to remedy
the evil. A vessel was wrecked in the Tay the other
day, and the captain drowned, from having mistaken
the railway light of Perry-Port-on- Craig for the
harbour light of Dundee.
But if the harbour trustees of Dundee have felt
themselves called on to take up this matter as one of
the greatest importance to the shippir.g in-
terest, -the Harbour Commissioners of Aberdeen
ware still more imperatively bound to i:.quire
how the opening of the Aberdeen Railway will affect
our tidal lights. The line of this - railway is Lid
::lung the Et.,t coast, frczn the thy of Nigg to 8:.ono
haven. different stations will be signaled with
coloured lights at night, and the rc.d and RI-et
similar to the rtd and grten of the 41ht retcii
hour Lanterns, it need turpriEe °:.e to brat., on 4 of
these day s, that a vessel has run ashore at the Cove
or the Bay of Nigg. To those who are well
acquainted with the coast-, the Gird:et-less light is suf-
ficient, in ordinary circumstances, to prevent danger ;
but it is well known that many vessels come Ames
to the East coast, whose captains would not know
Girdleness from Kinnaird's Head light, and would
take a coloured light as a guide when a plain light
would not be seen. At any rate, when we find. the
Trinity Board of Dundee alarmed, it is high time
that the subject had engaged the attention of the
harbour authorities of Aberdeen. •
L.nd happily they have not to go far for a remedy.
The system of tidal lights and marine signals, in•
rented by our townsman Mr. Rettie, is all that can
be desired. The grand distinguishing feature of
these lights is their distinctive character. Like Mar-
ryatt's signals, they are perfectly unique. That por-
tion of his system which our trustees have adopted is
only a fractional part of his complete whole, with the
difference only of the inversion of the order of the
red for the green. If Mr. Rettie's tidal lights were
universally adopted, there would be perfect safety,
but with the present diversity of lights there is con-
stant danger. This opinion was expressed long be-
fore
.Mr. Bettie preferred any claim for infringement
of his patent, and we bold by it still, independently
of all considerations affecting that claim. With us it
is a question of humanity ;_ and on that ground we
are determined to contend for a distinctive-set of
marine lights until they are obtained.—North of
Scotland Gazette.

THE PROGNOSTICATED HIGH
TIDE.
Royal Observatory, Greenwich, Dec. 27, 1849.
Gentlemen,—ln reply to your letter of yesterday,
I have to state that I had not previously seen the
letter, of which you enclosed a copy, although I had
heard that a rumour on the probability of a large tide
on the 29th or 30th inst was now current.
There is no foundation whatever for such a rumour.
The circumstances on which the magnitude of the
tide depends are mainly these three :
The tide is high when the moon is full ; it is high
when the moon is in perigee, and it is higher when the
nnon is in the equator. (I omit all mention of the
sun's distance, because the effect of its variation is
practically quite insignificant.)
Tho largest tides usually occur on the day next
following the states of the moon which I have

Two of these circumstances occur on the 29th
(namely, the in Jon will be full and in perigee). But
the moon instead of being in the equator, will be s t
her greatest north declination ; and this circamstar C
will reduce the tide considerably.
The three increasing circumstances which I hlve
mentioned have repeatedly been c ,mbined in late
years, all tending to increase the tide ; and ytt no
mischief has been done.
I am, Gentlemen, your obedient FPI van',
G.
Messrs. Scott and Hopkins, Times' OlLce, Ply.n uth

THE ARCTIC EXPEDITION.
TO THE EDITOR OF THE TIMES.
Sir,—As the Investigator and Enterprise are to be
sent again to search for Sir John Franklin's ships,
every means of preventing their being delayed by
remaining inclosed in the ice should be made known;
and since sawing a passage through the ice has proved
tedious, and even impracticable in places where its
thickness has been great, 1 think it may be advanta-
geous to draw attention to the use which it is intended
to make of gunpowder for this purpose, in the hope
that those who may have any information on the
subject my make it public ; and I beg to state that
I had an opportunity, whilst attached to the Prussian
Royal Riginears, of seeing the report of some expe-
rimen,s made at Dantzie from which it app 'ars that
by firing a charge of db. in the cintre of ice 26
inches thick a portion of 20 feet in diameter can be
broken up. Other experiments made at Montreal,
under the direction of Colonel Holloway, of the
Royal Engineers, produced similar results, and from
these it appears that charges lodged under the ice,
where that is possible, cause the greatest effect. But
it is most desirable to obtain information on the
action of gunpowder upon thicker ice, and it is hoped
that any pers( n who may pssess such knowledge
will make it publics as soon as possible, in order to aid
in the extrication of the brave men in whose fat© all
nations are now interested.—l am, sir, your. obedient
servant, P. J.I3AtissRiGGE; Captain R.E.

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