The Sun.
London, England, 1855-11-16 00:00:00

INSTITUTIOIV o.le CIVIL ENGINEERS.

--
On Tuesday last—James Simpson, Esq., president, in
the chair--the paper read was "On the Construction of
Buoys, Beacons, and other Stationary Floating Bodies,"
by Mr. G. Herbert.
Floating sea marks, as ordinarily constructed, were,
it was stated, admitted to possess the defect of riding
uneasily on the waves, under which they were frequently
buried, so as to be scarcely visible, when most required,
besides which it was not an uncommon circumstance, in
heavy weather, to find that a buoy had broken its chain
and floated away. The present form of the buoys, and
the fact of the mooring chains being attached t. a point
far below the centre of gravity, sufficiently accountrd
for these and other acknowledged defects, and induced
the proposition of a form of stationary floating body,
which should have a tendency to ride easily, and to re-
tain its perpendicularity, whilst the point of attach-
ment of the mooring chain would be in such a situati
as to subject it to the least amount of strain, and not
be liable to draw the buoy down into the trough of the
'aves. With this view a wrought iron pear shaped
buoy was c ,n4ructed, of a circular form in plan, aid
terminating above in an apex, so distributing the weight
as that the centre of gravity should be sit uatcd a little
below the centre of the plan of flotation, and the bottom
'as made ci.ncave and raised up internally, so as to
form a c-,ne, to the internal apex of which the mooring
chain was attached.

This form was found so completely to answer the pur-
pose that several buoys were made by Messrs. Blown,
Lennox, and Co., for the corporation of the Trinity
Rouse, and were pronounc-d to he superior to any pre-
viously built. A bu.,y of 9 feet in heigth, 6 feet 6 in.
diameter, and having only 2 feet of the body submerged,
exhibited, under all circumstances of wind and tide, an
upright body of 7 feet out of the water. This quality of
retaining its vertical position arose from the force of the
tide, or wave, being simultaneously exerted upon one
side of the exterior of the buoy, and on the opposite side
of the interior cone ; the forces so nearly balancing each
other as to retain the floating body in an almost perpen-
dicular position.
Encouraged by the success of the first experiments
the Trinity House authorised the construction of a
wrought-iron sea beacon on the same principle. The
floating base was 20 feet in diameter, divided by radiat-
ing bulk heads into cix water-tight compartments ; it
drew 4 feet 6 inches water, and supported a tower, also
of wrought iron, 28 feet high, 7 feet diameter at the base,
and 3 feet 6 inches diameter at the top, surmounted by
an iron ball of the same diameter. This beacon was
moored in the over-fall of the sea, at the South Saud
Head of the Goodwin Sands, and was admitted to have
been the best and most conspicuous sea•raark ever laid
down. During very heavy storms, it was observed that
the greatest angle assumed by the tower did not exceed
10 deg, from the perpendicular, without any tendency
towards circular motion. When it had been afloat for
about five weeks it was observed to sink gradually during
very moderate weather, evidently from having sprung a
leak. It was conjectured that this casualty arose from
the mooring chain having been improperly fixed in the
hawse-pipe of the cone, instead of being below it, and thus
that the links were brought into contact with the plates
of the compartments, which, being only -inch in thick-
ness, were soon chafed tlrough, probably in several
Places simultaneously, and, the several compartments
becoming filled with water, the beacon was submerged.
The recurrence of such casualities in similar structures
could, in future, be easily remedied by attaching the
mooring to the proper point in the cone, as is done in the
buoys, and thus guard against the possibility of any fric-
tion against the body of the water tight compartments.
It was now proposed to carry out this principle of
construction upon a longer scale, and to erect upon the
floating base a tower sufficiently large to serve as a
substitute for a lighthouse. A plan for such a
structure, as submitted to the Trinity House by Sir
Charles Fox, was described. The floating base was
80 feet in diameter, and drew 20 feet water ; the
tov..,er was 130 feet high, 24 feet in diameter at the
base, and 14 feet at the lantern ; the weight of the
tower and lantern was 117 tons;and the totaldisplacement
of the whole building was 1,602 tons ; the centre of
gravity being 2 feet 6 inches below the surface of the
Water. The weight of a double mooring chain, the links
of which were 3 inches diameter, would be about 46
tons in about 30 fathoms of water, when under the
greatest pressure of wind and tide, and the cater ary
curve would then be about 47 deg. from the perpendicu-
lar ; the extreme pressure to which the chain would be
subject afloat would not exceed 92 tons. The security of
this Sea Light Tower would depend upon its moorings,
which, for greater certainty of holding, should probably
be Mitchell's screw moorings, within certain limits of
depth, and if the chain weighing 46 tons was not coosi
dered sufficiently strong, auy additional strength might
be added, and would only hare the effect of immersing the
floating base a few inches more. In the event of any
unforeseen occurrence causing the Sea Light Tower to
break adrift, it could immediately and with certainty be
brought up by a spare chain and anchor.
The extreme pressure of the wind upon this structure
would not exceed 34 tons, and that would only cause the
tower to incline about 1 deg. 28 min. from the perper.•
dicular. The pressure caused by the speed of the tide,
at four miles an hour, could be taken at 30 tons, upon
the immersed portion.
Some interesting observations, made by Mr. Douglass,
in 1853, at the request of the author, on the number,
height, and speed of waves, at the lighthouse in course
of construction at Bishop Rock, the most westerly of
the Sci:ly group, tended to confirm the opinion that
little or no inconvenience would result from the action
of the waves, even in that exposed locality. The state-
ment showed, generally, that waves which, when mea-
sured from the hollow to the unbroken crest, had a
height of
feet, were in number 35 in one mile, and 8 per min.
15 feet, do. 5 and 6 do. 5 per min.
20 feet, do. 3 do. 4 per min.
The new form of Sea Light-tower was proposed to
mark the sites of shoals, or rocks, or islands, which were
difficult of access. Light-houses for this purpose being
generally required as warnin4, rather than as guiding
lights, it usually was of little importance whether the
light was exactly upon the point of rock from which it
was intended to warn a ve-sal, or whether it was a
short distance from it, so that the existence of the danger
was made manifest.
It was admitted that this form of construction might
be advantageou-ly employed for " guiding" or " fair-
way" lights. The problem of exhibiting lights of any
considerable altitude in very deep water had not hitherto
been solved, and cosequently the majority of the lights
now in existence were not those leading into a ri,;ht
channel, but those which warned from a wrong one, and
so long as that plan was followed the system of light-
ing would be one-sided and defective. Practical men,
however now appeared to think that the old system
should not be continued, and as the Sea Light Tower
was capable of being moored in any depth of water, how-
ever great, it might be placed midway in any channels,
as an invitation to the right course, and thus insure to
'all vessels a safer and a speedier naviga ion.
The lighthouse on the Skerryvore Rock occupied
seven years in building, and cost upwards of 90,0001. ;
whereas, by means of the Sea Light Tower, the same
object might be accomplished iu one year, at a cost of
30,0001. The site of the Bell Rock could be equally
efficiently marked, at a cost of about 20,0001., instead of
60,000/. ; and that of the Eddystone, at about 15,000/ ,
instead of 40,0001. ; and the new form of light towers
would possess the advantage of being accessible in all
weathers.
The observations were limited to sea marks, but if the
principle of construction proved to be correct it would
evidently be applicable to floating forts, and to almost
every other description of stationary floating body,
several designs for which were exhibited.

THE AUSTRIANS IN THE PRINCI-

PA' ITIES.

A private letter from Bucharest, dated the 3d
inst., mentions as follows :
A very serious affair has just occurred here. At 2
o'clock yesterday the English Colonel Thier was ar-
rested in his lodgings by the Austrian military authori-
ties. He was stripped of his English uniform by them,
and forced to put on the Austrian great-coat. Colonel
Thier had served as lieutenant in the Austrian army, and
passed over with his company in 1849 to the Piedmon-
tese. After the war he entered the British service, and
advanced in it to the rank of colonel. He was sent to
Cronstadt, in Transylania, the night that followed his
arrest. He was at Bucharest 10 or 12 days, having been
sent by the English Government to buy horses and
carts for-the army. He was duly accredited to the Eng-
lish agents, as also to the Ottoman authorities. Col.
Thier is a Hungarian. Ten minutes after his arrest the
Consul-General of England went to the house of Gene-
ral Coronini to reclaim the colonel. The general gave a
brief and decided refusal. Mr. Colquhoun thereupon
addressed an official letter to him on the subject, and it
is said that the reply was something to this effect :
" I seize my deserters wherever I find them. I have
" the right to cause Thier to be shot instantly, ani if the
Emperor commands me to give him up I shall break my
sword." The sensation produced here by the conduct of
the Austrians is immense. I hope you will now under-
' stand the fault committed in allowing the Austrians to
Qtta• Nag rrincfralitim • •-•- • • • - -