683 LIGHT- 
fituation, as from the great ingenuity difplayed in the 
cotiftruftion of the light-houfes erefted at different pe¬ 
riods upon them, the hiftory of the different ereftions has 
been given under the article Eddystone, vol. vi. p. 24.2. 
There are two inodes of furniftiing the light from which 
thefe buildings take their name; either by open coal-fires, 
or by lamps with refleftors. The latter mode, which is 
now moft common, had been long ufed in France, but in 
^England is of recent date. The idea was fuggefted by 
the following trivial occurrence: At a meeting of a fo- 
ciety of mathematicians at Liverpool, one of the members 
propofed to lay a wager that he would read a paragraph 
of a newfpaper, at ten yards diftance, with the light of 
a farthing candle. The wager was laid; and the propofer 
covered the infide of a wooden difii with pieces of look- 
ing-g'iafs, faftened in with glazier’s putty, placed this re¬ 
flector behind his candle, and won the wager. One of 
the company viewed this experiment with a philofophic 
eye. This was Capt. Hutchinfon, the dock-mafter. And 
hence the origin of thofe reflecting light-houfes at Liver¬ 
pool, which were ereCfed in the year 1763. Mr, Hut¬ 
chinfon fays, “We have made and had in ufe at Liverpool 
refleClors of one, two, and three, feet focus, and 3, 5!, 
7~, and 13, feet diameter; the three fmall ones made, of 
tin ioldered together, and the largelt of wood covered 
with looking-glafs. The two large ones, called the fea- 
lights, lead through the channel from the fea, till the 
two Hoylake-lights are brought in a line that leads into a 
very good road-ftead to lie till it is a proper time to pro¬ 
ceed to Liverpool.” 
The next lamp upon this principle that we hear of was 
rurnifhed to a light-houfe at Hunttanton, in Norfolk, by 
Mr. Ezekiel Walker, of Lynn; who fo much improved 
-the conftruCtion of the mirrors, that he is called the in- 
, venter of refleCtors for light-houfes in Great Britain. 
In the year 1787, an aft of parliament palled for ereft- 
ing four light-houfes in the northern parts of Great Bri¬ 
tain : one on Kinnard’s Head, in the county of Aberdeen; 
one on the ifiand of North Ranaldlhaw, in the Orkneys; 
one on the Point of Scalpa, in the ifiand of Herries; and 
.a fourth on the Mull of Cantyre. Thefe were erefted 
and lighted under the directions of Mr. Walker, by Mr. 
Thomas Smith, tinplate-worker of Edinburgh, (who 
has been erroneoufly called the inventor,) and were found 
to anfwer the purpofe fo well, and at fo final! an annual 
expenfe, that the truftees obtained another aft in the year 
1788, authorizing them to ereCt a fifth light-houfe on the 
ifiand of Arran, or upon the little ifiand of Plada, near 
•the fame, which was to be done without any increafe of 
the duties authorized to be levied by the former aft. 
In thefe light-houfes, the refleftor is compofed of a 
number of fquare plane glafs mirrors, fimilar to thofe with 
which Archimedes is faid to have fet fire to the Roman 
fleet at the fiege of Syracufe; (fee Burning-Glass, vol. 
iii. p. 534.) Each of thefe mirrors is about an inch fquare ; 
and they are all difpofed. clofe to each other in the con¬ 
cave of a parabolic fegment, formed of ftucco or any other 
proper bed. Stucco has been found to anfwer the pur- 
pofe belt; and is accordingly employed in all the re¬ 
flectors of the light-houfes erefted by Mr. Walker. His 
parabolic moulds are from three to five or fix feet in dia¬ 
meter; and in the centre or apex of each is placed a long 
fhallow lamp of tin-plate, filled with whale-oil. In each 
lamp are fix cotton wicks, almoft contiguous to each other, 
which are fo difpofed as to burn without trimming for 
about fix hours. The light of thefe is reflected from each 
mirror fpread over the concave furface, and is thus mul¬ 
tiplied', as it were, by the number of mirrors. The ftucco 
moulding is covered on the back with tin-plate, from 
which a tube, immediately over fhe lamp, proceeds to the 
roof of the light-room, and ferves as a funnel, through 
which the fmoke efcapes without fullying the faces of the 
mirrors. The light-room is a cupola, or lantern, of from 
eight to twelve fides, compofed entirely of glafs, fixed in 
salt-iron frames or fafhes, and roofed with copper. On 
HOUSE. 
circular benches palling round the infide of this lantern, 
at about eighteen inches from the glafs frames, are placed 
the refleftors with their lamps, foas that the concave fur- 
faces of two or three of the refleftors front eyery point of 
the compafs, and throw a blaze of light in all directions. 
In the roof immediately over the centre of the room is a 
hole, through which pafs all the funnels already mention¬ 
ed, and which ferves likewife to admit frefh air to the 
lamps. This light-room is firmly fixed on the top of a 
round tower, fo as to be immovable by the weather; and 
■the number of the refleftors, and the height of the tower, 
are lefs or greater according as it is the intention that the 
light (hould be feen at a lefs or a greater diftance. 
The Scilly light-houfe is alfo a light of minors; but 
they are of copper, plated with filver, and polilhed in the 
curve of the parabola, by which their light neither fpreads 
nor converges, but darts a cylinder of light to a vaft dif¬ 
tance. This light confifts of fix round mirrors, placed 
round a feventh, each twenty-two inches in diameter; 
every mirror having an Argand’s lamp in its focus, fup- 
plied with oil from behind. The frame in which thefe 
mirrors- are fixed ftands perpendicularly to the horizon, 
on a (haft united with a machine below, that turns the 
whole round every two minutes. Hence, a cylinder of 
light five feet and a half diameter fvveeps the whole hori¬ 
zon. Upon this conftruftion Mr. Walker obferves ; “It 
may be of ufe to thofe who may hereafter copy the light- 
houfe at Scilly to know, that the figure in which thofe 
mirrors are fixed is as good as any other, but not better. 
Had they been fixed in a fquare, a parallelogram, or a tri¬ 
angle, their efteft would have been juft the fame, for they 
would have appeared as one (ingle light at a very (hort 
diftance ; nay, had they been placed in a right line, their 
effeft would have been (till the fame at three miles dif¬ 
tance. For it is known from experiment, that two re¬ 
fleftor?, made of tin, placed more than ten feet afunder, 
appeared at three miles diftance as one (ingle light; and 
required to be feparated from each other more than nine¬ 
teen feet to appear two diftinft lights, when viewed at the 
fame .diftance as before. The ufe of filver for a reflefting 
furface is certainly an imperfeftionof no fmall confequence. 
Silver is fo much inferior to looking-glafs for this purpofe, 
that, for philofophers to prefer the former to the latter, 
appears to me very unaccountable. It is my humble opi¬ 
nion, that there is not a lady in the united kingdom who 
would prefer a filver difn to a looking-glafs, when (lie is 
inclined to fee a perfeft image of her face.” 
A man judging from mere theory would be very apt to 
condemn light-houfes of this kind ; becaufe the firmed 
building (hakes in a violent (form, and becaufe fuch (bak¬ 
ing, he might think, would fometimes throw the whole 
rays of light into the air, and thus miftead the bewildered 
feaman. > This opinion, we know, was aftually entertained 
of them by one of the profoundeft philofophers and moft 
fcientific mechanicians of the age. Experience, however, 
has convinced him, as well as the public at large, that 
fuch appreheniions are groundlefs, and that light-houfes 
with lamps and refleftors are, in every point of view, pre¬ 
ferable to thofe with fires burning in the open air. They 
are fupported at much lefs expenfe; their light is more 
brilliant, and feen at a greater diftance, whilft it can never 
be obfeured by fmoke, or beaten down on the lee fide by 
a violent guft of wind ; and, what is perhaps of ftiil greater 
importance, the refleftors with their lamps may be. fo va- 
rioufly placed, that one light-houfe cannot be miftaken for 
another. If we add to all this, that the lamps do not (land 
in need of trimming fo often as open fires require fuel, 
and that the light-man is never expofed either to cold or 
to wet by attending to his duty, we muft be convinced 
that light-houfes with refleftors are much lefs liable to be 
neglefted in ftormy weather than thofe with open fires; 
and that this circumftance alone would be enough to give 
the former a preference, almoft incalculable, over the latter. 
Many advantages, we think, would attend the ufe of 
gas-lights in fuch lituations. The lamps, once lighted, 
would 
