Chapter XXIV: Appendix: I (1)

GENERAL CORRESPONDENCE.

TRINITY HOUSE, LONDON, E.C.,
_6th February, 1880_.

SIR,

I am directed by the board to transmit to you herewith, for the
information of the Lightning Rod Conference, copies of reports made
by Professor Faraday to this Corporation, one respecting a
remarkable stroke of lightning which occurred at the Eddystone
Lighthouse in January, 1853, and the other upon a similar accident
experienced at the Nash Lights in August, 1852.

The case to which Admiral Sullivan directed the attention of the
Conference, as stated in your letter of the 30th October last, was
probably one of these two.

Should you desire any further details in connection with this
subject, the Corporation desire me to assure you of the pleasure
with which they will afford any information at their command.

I am, Sir,
Your obedient servant,
ROBIN ALLEN.

G. J. SYMONS, Esq.

[We have been favoured with copies of three separate reports by Professor Faraday, and think that it is better to give them in chronological order. There is only one other point in the correspondence from the Trinity House which it seems necessary to mention, viz., that the sections of the copper rods now used are as under.—ED.]

MAIN CONDUCTOR.

1½ in.
]

CONNECTING BRANCHES.

1¼ in.
]

REPORT ON THE LIGHTNING RODS OF LIGHTHOUSES, 1843.

DUNGENESS.—Dungeness Lighthouse stands about 14 feet above the sea and measures 97 feet to the top of the lantern. The tower is of brick with wood floors; the roof and frame of the lantern are of metal seated upon a stone pedestal, to which it is secured. There is no conductor to the building. The weathercock is fitted with a glass repeller, and a rod similarly fitted is attached to the two copper flues which rise by the side of the lantern.

EDDYSTONE.—The height of the top of the lantern of the Eddystone above the sea is about 95 feet. The roof and framing of the lantern are of metal, secured through a stone plinth to the gallery of the tower by metal fastenings. A conductor of copper rod, ¾ inch diameter, is attached to the outside of the building; the rod rises 3 feet above the top of the lantern and terminates in the sea at low water; it is fixed to the tower and lantern by metal stays and fastenings and is isolated by glass ferules. To give stability to the building eight wrought iron ties are fixed in the interior of the house, extending downwards from the underside of the lantern floor through the next two stories, terminating by inserting the ends into the stone floor, the upper ends are riveted into an iron ring round the manhole in the ceiling and further secured by iron bolts passing through the stonework and communicating indirectly with the metal work of the lantern.

Eddystone.
]

Spurn Point High Light.
]

SPURN POINT HIGH LIGHT.—The Spurn High Light stands about 16 feet above the level of the sea, and measures 100 feet to the top of the lantern. The tower is of brick with wood floors; the roof and framing of the lantern are of metal, seated upon a stone plinth to which it is secured; the weathercock is surmounted by a glass repeller. An isolated conductor of copper rod, ¾ inch diameter, is attached to the outside of the tower rising some feet above the lantern and passing down the side of the tower below the surface of the ground.

SOUTH FORELAND.—The South Foreland High Light stands above 300 feet above the sea, and measures from the ground to the top of the lantern 67 feet. The tower is of brick, the lantern roof and framing are of metal with a cast iron pedestal; the weathercock is fitted with a glass repeller. A conductor of copper rod, ¾ inch diameter, is attached to the outside of the tower, of the same height as the weathercock. The rod is fastened to the lantern and tower with metal stays and fastenings, and passes into the ground, turning off at right angles to the tower a little below the surface. A copper flue connected with a stove in the base of the tower, passes up the centre of the tower through the roof of the lantern, to the lower end of which a copper rod has been attached, which is carried to the outside of the building into the ground.

South Foreland High Light.
]

The undersigned have, according to their instructions, met and considered the circumstances under which lighthouses are placed as respects lightning, and have arrived at the following conclusions:—

That lighthouses should be well defended from the top to the bottom.

That as respects the top, the metal of the lantern, and upwards, is sufficient to meet every need, and satisfy every desire and fear.

That for the rest of the course down the tower, a copper rod ¾ of an inch in diameter is quite, and more than, sufficient.

That at the bottom, where the rod enters the earth, it is desirable at its termination to connect it metallically with a sheet of copper 3 or 4 feet long by 2 feet or more wide; the latter to be buried in the earth, so as to give extensive contact with it.

That glass repellers are in every case useless.

That glass thimbles are not needed, but do no harm.

That if the repeller be removed, and the _point on the vane_ be terminated as the lightning rods usually are, and then the metal of the lantern be strongly attached to, and connected with, the upper end of the copper rod, and the rod continued down the tower to the earth, and the sheet of copper buried in it, such a system will be an effectual and perfectly safe lightning conductor.

That then there need be no rod end rising by the side of, and above the lantern.

That the rod may (if required on other accounts) come down on the inside of the building, or in a groove in the wall; but should not be unnecessarily removed from observation and inspection.

That all large metallic arrangements in the stonework, or other non-metallic parts of the tower of the lighthouse, such as tying bars, metal flues, &c., should be well connected, by copper, with the conductor.

That the vicinity of two metallic masses without contact, or metallic communication, is to be avoided.

That, as to the South Foreland High Light, the lantern, the central stove, and the copper rod proceeding from it to the earth, connected as they now are, form a perfect lightning conductor, even without the rod that is there erected; but

That it is important casual arrangements should never be depended upon for lightning conductors; but a copper rod be established for the especial purpose: for, if the former be trusted to, the carelessness or ignorance of workmen may, at after periods, upon occasions of repair or cleansing, cause the necessary metallic connection to be left imperfect or incomplete, and then the arrangement is not merely useless but dangerous.

That, as to the Eddystone, it is desirable to connect the system of wrought iron ties in it with the lightning conductor, by joining the lower part of that iron rod which is nearest to the conductor with the latter, by a copper rod or strap, equivalent to the conductor in sectional area.

That the Dungeness Lighthouse is in a very anomalous condition; to rectify which the two repellers should be removed, and also the representative of the top of a lightning rod attached to the flue, and that then a good copper conductor should be attached to the metal of the lantern, upon the principles already expressed.

(Signed.) M. FARADAY.

_25th September, 1843._

* * * * *

23, GT. GEORGE STREET,
_25th September, 1843_.

SIR,

The reference, on the important subject of lightning conductors, is
to Mr. Faraday and to me. On receiving it I prepared drawings of the
buildings to which our immediate attention was required, with an
explanation of their present conductors.

These were considered at a meeting with Mr. Faraday, when he
explained the principles and their application to the several cases,
deduced from his copious experiments and scientific observations.

I have since received from him the accompanying Report for my
signature along with his, but the report is altogether Mr. Faraday’s
and therefore I prefer adding my approval of all it contains in this
separate sheet, and recommending that authority be given to me to
act upon it.

I am, Sir, &c.
(Signed) J. WALKER.

JACOB HERBERT, Esq.
_Trinity House._

* * * * *

ROYAL INSTITUTION,
_27th September, 1852_.

MY DEAR SIR,

I fortunately reached the Nash Low Lighthouse last Thursday, before
any repairs were made of the injury caused by the discharge of
lightning there, and found everything as it had been left: the
repairs were to be commenced on the morrow.

The night of Monday, 30th August, was exceedingly stormy, with
thunder and lightning; the discharge upon the lighthouse was at six
o’clock in the morning of the 31st, just after the keeper had gone
to bed. At the same time, or at least in the same storm, the
flag-staff between the upper and lower lights was struck, and some
corn stacks were struck and fired in the neighbourhood. It is
manifest that the discharge upon the tower was exceedingly powerful,
but the lightning conductor has done duty well—has, I have no doubt,
saved the building; and the injury is comparatively slight, and is
referable almost entirely to circumstances which are guarded against
in the report made by myself and Mr. Walker 22nd September, 1843.

The conductor is made fast to the metal of the lantern, descends on
the inside of the tower to the level of the ground, and passes
through the wall and under the flag pavement which surrounds the
tower. It is undisturbed everywhere, but there are signs of
oxidation on the metal and the wall at a place where two lengths of
copper are rivetted together, which show how great an amount of
electricity it has carried.

A water-butt stands in the gallery outside the lantern. A small
copper pipe, 1 inch in diameter, brings the water from the roof of
the lantern into this butt; it does not reach it, but terminates 10
or 12 inches above it. A similar copper pipe conducts the surplus
water from the butt to the ground, but it is not connected
metallically with the other pipe, or with the metal of the
conductor, or the lantern. Hence a part of the lightning which has
fallen upon the lantern has passed as a flash, or, as we express it,
by disruptive discharge from the outside of the lantern to this tub
of water, throwing off a portion of the cement at the place, and has
used this pipe as a lightning conductor in the rest of its course to
the ground. The pipe has holes made in it in three places, but these
are at the three joints, where, it being in different lengths, it is
put together with tow and white lead, and where of course the
metallic contact is again absent; and thus the injury there (which
is very small) is accounted for. The pipe ends below at the level of
the ground in a small drain, and at this end a disruptive discharge
has (naturally) occurred, which has blown up a little of the cement
that covered the place. Some earth is thrown up at the outer edge of
the pavement round the tower over the same small drain, which tends
to show how intense the discharge must have been over the whole of
the place.

Inside of the lantern there are traces of the lightning, occurring
at places where pieces of metal came near together but did not
touch, thus at the platform where a covering copper plate came near
to the top of the stair railing, but the effects are very slight.
All the lamps, ventilating tubes, &c., remained perfectly
undisturbed, and there was no trace of injury or effect where the
conductor and the lantern were united.

Inside of the tower and the rooms through which the conductor passes
there were and are no signs of anything (except at the rivetting
above mentioned) until we reach the kitchen or living-room which is
on a level with the ground, and here the chair was broken and the
carpet and oil-cloth fired and torn. To understand this, it must be
known that the separation between this room and the oil-cellar
beneath is made by masonry consisting of large stones, the vertical
joints of which are leaded throughout, so that the lead appears as a
network upon the surface, both of the kitchen floor above, and the
roof of the oil cellar beneath, varying in thickness in different
places up to ⅓ or more of an inch, as in a piece that was thrown
out. The nearest part of this lead to the conductor is about 9
inches or a little more distant, and it was here that the skirting
was thrown off, and the chair broken; here also that the fender was
upset and the little cupboard against the skirting emptied of its
articles. If this lead had been connected metallically with the
conductor, these effects would not have happened.

The electricity which in its tendency to pass to the earth took this
course, naturally appeared in the oil-cellar beneath, and though the
greater portion of it was dissipated through the building itself,
yet a part appeared in its effects to have been directed by the oil
cans, for though they were not at all injured or disturbed, the wash
or colour in the wall above four or five of them was disturbed,
showing that slight disruptive connections or sparks had occurred
there.

At the time of the shock, rain was descending in floods, and the
side of the tower and the pavement was covered with a coat of water.
This being a good conductor of electricity has shown its effects in
connection with the intense force of the discharge. A part of the
electricity leaving the conductor at the edge of the pavement and
the tower, broke up the cement there, in its way to the water on the
surface, which for the time acted to it as the sheet of copper—which
I conclude is at the end of the conductor—does, _i.e._, as a final
discharge to the earth. Also on different parts of the external
surface of the tower near the ground, portions of cement, the size
of half a hand, have been thrown off by the disruptive discharges
from the body of the tower to this coat of water: all testifying to
the intensity of the shock.

I should state that the keeper says he was thrown out of bed by the
shock. However, no trace of lightning appears in the bedroom, still
there are evidences that powerful discharges passing at a distance,
and on the other side of thick walls may affect bodies and living
systems, especially by spasmodic action, and something of the kind
may have occurred here. It may be as well for me to state that the
upper floors are _leaded_ together like that of the kitchen. The
reason why they did not produce like effect is evident in that they
from their position could not serve as conductors to the earth as
the lower course could.

The keeper said he had told the coppersmith to make the necessary
repairs in the pipe, and I instructed him to connect the waste pipe
and the upper pipe by a flat strap of copper plate. I would
recommend that the lead of the lower floor be connected metallically
with the conductor to a plate of copper in the earth. I could not
see the end of the present conductor, not being able by any tools at
the lighthouse to raise the stonework, but I left instructions with
the keeper to have it done, and report to me the state of matters.

I am, &c.,
(Signed) M. FARADAY.

THE SECRETARY,
_Trinity House_.

EDDYSTONE LIGHT.—REPORT _of_ PROFESSOR FARADAY _on Electrical Phenomenon
which occurred thereat on the 11th January, 1853_.

ROYAL INSTITUTION,
_24th January, 1853_.

MY DEAR SIR,

In reference to the remarkable stroke of lightning which occurred at
the Eddystone Lighthouse, at midday on 11th January of this year,
and made itself manifest by a partial flash discharge in the living
rooms, I have to call your attention to the drawing herewith
returned, and to the circumstances which appear (from it) to have
accompanied and conduced to the discharge.

In the body of the stone work above the store-room exist eight rings
of metal; each going round the building, and each being four inches
square of solid iron and lead. Also, latterly the bedroom and
sitting-room have been lined with a framework of iron bars, situated
vertically, and pinned by long bolts into the stonework.

The part of the tower above the floor of the living-room is,
therefore, filled with a metallic system, which, with the metal
lantern, gives a very marked character to the upper half of the
structure.

The recent metallic arrangements (but not the rings) are connected
with the lightning rod; and the copper part of this rod, beginning
at the floor of the living-room, then proceeds downwards by the
course which can be followed in the drawing, and terminates on the
outside of the rock between high and low water marks.

Considering all these circumstances, I was led to conclude that the
conductor was in a very imperfect condition at the time of low
water; and I had little doubt that I should find that the discharge
had taken place when it was in this state, and very probably with a
spring tide.

The day of the stroke was the 11th January—a new moon occurred on
the 9th, so that it was at a time of spring tide.

The occurrence took place at midday; and, according to the tide
tables, that was close upon the time of low water at Devonport. The
end of the conductor would then be 6 feet from the water, if the
latter were quiescent, and I cannot doubt that this circumstance
gave rise to that diverted discharge which became so manifest to the
keepers. Mr. Burges, with whom I have conversed about the matter,
thinks it probable that, through the violence of the waves, the
conductor does not now descend so much as is represented in the
drawing.

I think it essential that the lower end of the conductor be made
more perfect in its action; and I should prefer this being done on
the _outside_ of the tower and rock, if the rod can be rendered
permanent in such a situation.

If it be impossible to prolong and fix the lower end of the
conductor where it now is, so that it shall have large contact with
the sea at low water, then I would suggest, whether or no, on the
more sloping part of the rock, about midway between high and low
water, three or four holes could not be sunk to the depth of 3 feet,
and about 3 or 4 feet apart, and that copper rods being placed in
these, they should be connected together, and the lightning rod
continued to them.

If this _cannot_ be done, then it might be right to consider the
propriety of the making a hole through the centre of the building
and rock, about 2 or more inches in diameter, and 30 feet deep, and
continuing the conductor to the bottom.

A conversation with Mr. Burges regarding the present state of the
Bishop’s Rock Lighthouse, now in course of construction, induces me
also to suggest the propriety of making provision for the lightning
conductor as the work proceeds.

It would be easy now to fix terminal rods of copper, and to combine
them upwards with the work. Considering the isolated and peculiarly
exposed condition of a lighthouse on this site, I would propose that
there be _two_ conducting rods from the lantern, down the outside on
opposite sides of the tower, each terminating below in two or three
prolongations, entering as proposed into the rock, or into fissures
below low water mark, so as to be well and permanently fixed.

I am, &c.,
(Signed) M. FARADAY.

THE SECRETARY,
_Trinity House_.

[The present Eddystone Lighthouse, that is the stone one erected in 1757–59 from Smeaton’s designs, has a total height from low water level to the top of the vane of 107 feet. The annexed engraving shows two conductors, the old and defective one passing down the left hand side and terminating half way between high and low water level, and the proposed new one on the right terminating in holes in the rock.—ED.]

EDDYSTONE.
]

* * * * *

[The following letter would have been placed in Appendix A. along with the replies from British Manufacturers of Lightning Conductors; but it did not arrive until long after they had been printed off.—ED.]

Please find enclosed answer to your questions. In addition to manufacturing rods, we have been protecting buildings with these rods for thirty years. We sell in this way at retail from five to six hundred thousand feet each year. We also issue a guarantee of $500 (£100) on each building that we protect, which we hold ourselves ready to make good in case of failure. Now, in this extensive business, we have only had to pay one dollar damage done by lightning. We regard this as a practical demonstration that our method of protecting buildings with iron rods is as near perfect as it can be. There is more profit to be made out of the copper rod, as it is made cheaply out of sheet copper, and can be sold much higher than the iron rod. But knowing that iron for all practical purposes is the best material for lightning rods, we feel it to be our duty to do all we can to introduce it. We would most respectfully ask the Conference to investigate this question as to what kind of metal is best for rods for practical use, iron or copper. Our own late Professor Joseph Henry pronounced in favour of iron. We have many facts in relation to buildings being struck by lightning which we could give at some future time if desired. We have gathered up a large number of points that have been melted by lightning strokes. They are melted down about ½ inch. They all look as if the same amount of heat had been applied to each, showing very clearly that the quantity of electricity in lightning strokes is quite uniform. We have never in any instance known of the rod being melted, showing that the rod which we use is of sufficient size.

* * * * *

1 & 2. We make spiral twisted iron rods weighing 45 lbs. to the hundred feet [7¼ oz. per foot]. The rod is of the same sized material throughout its length, except that a copper point, plated with silver and tipped with platinum, is screwed on the upper terminal.

3. No proportion is observed between the length and sectional area.

4. Joints are made by means of copper nuts.

5. Attached to building by means of zinc strips, or a casting that fits closely to the rod, which is screwed down.

6. The rod extends from 9 to 10 feet in the ground.

7. A circle twice the diameter of height of rod above roof.

8. All terminals on the roof are connected. There are never less than two ground rods, and these are increased as the number of upper terminals are increased.

We also manufacture copper rods, but do not use them where we protect buildings, nor do we recommend them to other dealers from the fact that our experience of thirty years has demonstrated that iron is the best material for lightning rods.

COLE BROTHERS.

MOUNT PLEASANT,
IOWA, UNITED STATES.

* * * * *

A colliery chimney near Sunderland, 180 feet high, was struck by Lightning, November 13th, 1878, and I was sent for to repair it. Upon getting to the top, which was about 15 feet diameter, I found a great many of the bricks displaced, and the upper terminal of the conductor (which was a tube 0·50 in. internal, and about 0·62 in. external diameter, and which had stood about 1 foot above the top of the chimney) had been fused and was lying on the top of the chimney, it was quite brittle, and easily broken by the hand. The upper 10 feet of ½ inch wire rope was in a similar state; it seemed as if it had been passed through an exceedingly hot furnace, and I rubbed it to dust in my hands. This 10 feet length was above the first holdfast, below the holdfast the wire rope was perfectly good. The holdfast was one of those which are driven into a wooden plug let into the wall and pinned tightly down on the rope, which had been badly bruised in the fixing—in fact, knocked almost flat. I believe that this was the cause of the accident, and that the lightning travelled down as far as this holdfast, and there meeting obstruction, returned destroying the wire and rod and shattering the brickwork. The earth connection was good, the end was buried in a trench 2 feet deep and 15 feet long.

T. MASSINGHAM.

NEWCASTLE-ON-TYNE.

* * * * *

I have been in communication with several of the principal brick builders here by whom the great majority of the chimney stalks in Glasgow and the west of Scotland are erected, and I believe the following statements may be taken as correct:—

(1) Very few stalks under ninety feet in height have lightning conductors, but, _as a rule_, the higher stalks have conductors. One of my correspondents says that “this rule holds good in four cases out of five.”

(2) A chimney being struck by lightning is an extremely rare occurrence in this district. One builder of long experience (Mr. McDonald) says, “I have known of several stalks that were struck by lightning, that had no conductors. I cannot point to one that was struck by lightning and had a conductor.” Another firm of old standing (Allan and Mann) say—“In our experience we have not known of a chimney stalk, with lightning conductor fixed, damaged by lightning.” Another firm (Bell, Hornsby and Co.) say—“In our experience we have not known an ordinary stalk with or without a conductor struck by lightning,” and Mr. Goldie says—“During the last twenty years I can remember only one such case,” and he is not sure whether the stalk had a conductor or not. There are three cases known to have occurred in Glasgow, but I never heard of any others among the hundreds—I may say thousands—of chimneys which are here. The great stalk at St. Rollox was struck shortly after its erection. A stalk at the works of Messrs. Alexander Paul and Co., was struck about nine years ago. Mr. Goldie makes the remark—and I think it is well worthy of notice—that in all these cases the accident happened shortly after the completion of the stalk. In these circumstances the stalk would still, no doubt, contain a large amount of moisture.

I think the St. Rollox stalk had a conductor fixed before it was struck, but I am not aware whether either of the others had.

Mr. Higginbotham (Todd and Higginbotham) tells me that the stalk at their works was struck before it was quite completed. It was _very slightly_ injured. It was afterwards struck as mentioned in my letter. On that occasion it had a lightning conductor.

The damage done was not very serious, but necessitated the binding of the stalk with numerous iron hoops—as thus strengthened it still stands. Mr. Higginbotham says that the opinion at the time was that the conductor saved the stalk from complete destruction, but that it was too small.

They, therefore, had it replaced by a much heavier one—copper rope ⅜th of an inch diameter, kept 1½ inches from the brickwork by glass insulators—which still remains.

J. HONEYMAN.

140, BATH STREET, GLASGOW.

* * * * *

There was no lightning conductor of any kind at Wells Church. The electric fluid struck the east side of the Tower just above the ridge of the nave roof. The tower stands, or stood, at the west end. I enclose an account of the fire from a local paper:—

WELLS.—TOTAL DESTRUCTION OF THE CHURCH.—“Near midnight of Saturday last, August 2nd, 1879, a terrific thunderstorm burst over this town and a large district around, causing most intense alarm and unfortunately ending in sad disaster. The storm raged throughout the night, and was accompanied in many places by a perfect deluge of rain. Between three and four a.m. of Sunday, the 3rd, it appeared to reach its height, the lightning being of a most vivid and alarming nature, and the thunder reverberating in continuous peals. A lull then occurred, but between five and six a.m. the storm again burst out with great fury, and at 5.50 the electric fluid struck the church on the eastern face of the tower immediately above the apex of the roof, driving out a large portion of the stone work, the flints flying hundreds of feet around. One large stone fell upon the roof of a house, near the east window, and penetrated to the room below, which was fortunately unoccupied; but the tenant, Mr. R. Wharf, who slept in the next room, was aroused, and one or two persons in the road seeing what had occurred, and observing smoke directly after issuing from the roof of the church, raised an alarm of fire, which quickly awakened the whole town.

R. M. PHIPSON.

NORWICH.

* * * * *

The first visible injury to Wells Church was the “skinning” of a portion of the tower (about 10 feet high by 5 feet broad) extending downwards from the east window of the tower (_i.e._, the window which looked over the roof of the nave,) to the point at which the lead-covered nave joined the tower. The lightning is believed to have set fire to the roof at this point, and also to have travelled along the lead roof to the chancel, and in crossing the vestry to have ignited the surplices, as the church was seen to be on fire at both ends before the middle was touched. The “skinning” was accompanied by great disruptive force, as the stones from the tower were not only shot the full length of the church, but one large one fell on the roof of a house 60 feet beyond the east end of the church.

WELLS, NORFOLK.

F. LONG.

* * * * *

As your questions in the _Times_ of to-day allude only to protection to _buildings_ from lightning, I need not say anything on the perfect protection afforded to Her Majesty’s ships by the conductors of Sir Snow Harris, from the time they were used in every ship in the service.

H.M.S. “Beagle,” Commander FitzRoy, was one of the first ships fitted with them. At Monte Video a heavy shock of lightning passed down the mainmast and through the ship without doing the slightest injury; but as the vane staff which tapered to a fine point, was fused at the point, it enables me to answer one of your questions. The copper was melted till the diameter was about one eighth of an inch, but below that point the conductor was not injured in any way.

You will like to know a case in which a copper wire acted as a perfect conductor, _though fused throughout its length_. It was at Monte Video, in the house of the English Consul, a flag-staff was struck, and conducted the lightning through a flat roof, near the bell wire of a suite of rooms (the wire ran in sight near the cornice) through a hole in each dividing wall, and then down to the bell in the basement; the wire was melted into drops like shot, which burnt a row of small holes in the carpet of each room. A dark mark, on the cornice above, showed where the wire had been. At the bell there was a slight explosion, and some little damage, but I do not recollect whether anything acted partially as a conductor from that point, and so carried off that part of the charge.

This, I think, shows that even an ordinary bell wire will act as a conductor for a rather strong stroke of lightning, as the large flag-staff was shattered.

I am anxious to call the attention of your conference to a point that it will be interesting to clear up. That is, whether a conductor should be a _solid_ rod, or in a shape to give the largest amount of _surface_ in the section? When I tell you that Faraday and Harris each told me that the other “knew nothing about it,” because they differed entirely on this point, I think you will see the importance of it. I had at the time to approve of the conductors for lighthouses. I will, if you wish it, give you more particulars on this point, as I believe it has never yet been settled: lighthouses having been fitted with Faraday’s, and ships and public buildings with Harris’ conductors. The one being a solid bolt, the other a hollow tube or double thin plates.

If Harris was right there is an unnecessary amount of copper in Faraday’s solid conductors; if Faraday is right, there is an unnecessary outlay in putting a given amount of copper into the shape of a tube, instead of using it as a solid rod.

B. J. SULIVAN, _Admiral_.

P.S.—You should get from the Trinity House particulars of a case in which, with a good solid conductor, the iron floor of a lighthouse, aided by some lead in the wall, diverted the lightning from the conductor, and caused damage inside. I think it was a Portland lighthouse, but it is so many years since that I may not be right.

TREGEN, BOURNEMOUTH.

* * * * *

Three or four years since, I was looking out of my office window in Finsbury, when a flash of lightning struck the tower of the church of St. Giles’, Cripplegate, towards which my sight happened at the time to be directed. As a portion only of the flag-staff, placed at one corner of the tower, was destroyed, I obtained permission to ascend the tower and discover the reason. I found a substantial copper rope conductor fixed in a somewhat careless fashion to the back of the tower, and passing some distance into the earth. This copper rope was about an inch in diameter, and was carried upwards, under and over several projections and cornices, and across the roof of the tower to its centre—where it stood erect, and evidently did its assigned work admirably. Clumsy and unsatisfactory as the fixing of this bent copper rope seemed to me to be, it is quite certain that it was most efficient; and had it not been for the flag-staff, capped with lead, which was carried up considerably higher than the copper rope, no evidence whatever of the lightning’s path would have been revealed. As it was, the discharge of lightning struck the leaden cap of the flag-staff, and descended down the wet, wooden pole, until the summit of the copper-rope conductor in the centre of the tower was reached, when the discharge flew across to the metallic earth conductor, leaving the lower part of the flag-staff unhurt, but shattering to splinters that portion which was higher than the summit of the copper rope.

RICHARD HERRING.

27, ST. MARY’S ROAD, HIGHBURY.

* * * * *

A small public-house of mine (the “Wheatsheaf”) stands at Trolley Bottom, in the parish of Flamstead, between St. Albans and Dunstable. On Wednesday, August 6th, 1879, about 2 p.m., during a storm, not otherwise very severe, my tenant was seated by the tap-room window (A on the plan) his wife being seated opposite to him, and having the window on her left, whilst she held her child with her right hand; there were at the same time in the room about five men besides. A sharp flash of lightning occurred, and the poor woman (when the smoke cleared away) was observed to have fallen backwards. She gasped twice, never spoke, and died immediately, and bore no further mark of injury, I understand, than a slight mark as of scorching on her neck, below the left ear. I fail to recollect whether her clothing was scorched or not, the child’s shoe and sock were both burnt, but she, herself, was unharmed. All present were sensible of an atmosphere heavily laden with sulphurous fumes; but, excepting as above, were absolutely unhurt.

On visiting the house about a week afterwards, with a view to its repair, I found a small round hole as if made with a bullet in a pane of the window (A) close to which the woman was sitting, but could discover no further injury either to the other panes, the window-frame, the floor, or anything in the room. In the parlour, B, the window-frame was violently wrenched outwards two or three inches, several of the panes were broken, one sash-line being scorched, as also the frame and linings in places, especially in the neighbourhood of the sash-weights (iron). The wooden chimney-piece E, was slightly moved from its position, the various articles upon it were scattered, and a bottle of ink which stood there, was thrown with some violence to the ceiling. The upper part of the chimney to that room, G, and a portion of the wall, of which it was a part, forming the gable end to the house were shattered, and at H a stout post, contiguous to the house wall, and supporting the roof of a lean-to, was split and wrenched from its position. The windows and frames upstairs, C D, were in the same state as that at B. The chimney, K, to the tap-room, was quite uninjured, and no harm was done to any part of the back of the house.

ELEVATION. PLAN.
]

Flamstead is about four miles from Luton, and six from St. Albans, and stands on high land. Trolley Bottom is a hamlet half-a-mile distant, and is, as its name implies, low-lying. My house is, perhaps, the lowest in position there. It faces the North-West.

I fear that my experiences will be found to have but little bearing upon the main point you have in view, viz., the comparative merits of different descriptions of Lightning Conductors. I venture to think, however, that they are not altogether without interest as illustrating the effects of lightning in a by no means exposed situation.

I am writing only from memory what was told me at the time, and should you desire further information on any points, shall be happy to endeavour to obtain it for you.

It would interest me very much to know how it is to be accounted for that, whilst in the room in which the poor woman was struck, no further damage was done, other parts of the house were, comparatively speaking, wrecked.

JOHN EDWARD GROOME.

KING’S LANGLEY.

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I was in a house at Cannes (France) belonging to my late father on the occasion of its being struck by lightning about five or six years ago.

The storm in which it occurred was a very short one, consisting of only four explosions, _every one_ of which took effect on some building in Cannes.

The rain was falling in torrents, and to this I consider we owed our safety as the shoots and stack-pipes being full of water acted as conductors. The villa stood high, but another building _very_ much higher, and on higher ground, was within 100 yards. The lightning struck the metal cowl of a brick chimney, which, being an addition, was led down outside the walls of the house.

In the explosion the front of the grate of the room to which this chimney belonged, together with fire-irons, &c., were all projected across the room (a large one), about 30 feet; but no marks of lightning having entered the room were apparent. In fact the lightning after blowing up this chimney, together with much of the roof and wall of the house (great portions of the solid masonry of which I found 50 and 60 yards off!) appears to have left the chimney and, taking the course of the iron shoot round the house, to have divided into _three_ streams, each of which ultimately found its way down a separate stack-pipe, melting in its way all the soldering of the joints, but otherwise leaving them uninjured.

One stream passed thus into a well, the door of which (locked the night before) was burst open, I presume by the sudden expansion of the air, another stream of the electric fluid passed into an underground drain, which it burst up, hurling into the air the trees planted above it, the third passing across a level asphalt roof, which it melted in spite of the water lying on it, descended into the earth harmlessly.

You will see by this that the amount of electric fluid must have been very great to require all these modes of dispersion, and it suggests the question whether the diameter of the ordinary conductors would be sufficient to carry off so great a stream. Of course, in this case, there was no conductor, and therefore no means of testing it.

H. RADCLIFFE DUGMORE.

THE LODGE,
PARKSTONE, DORSET.

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Thank you very much for the Pamphlet, which I have read with great interest. Messrs. W. & W. (page 6) state that conductors in masts (like Harris’s) are “most objectionable.” The best answer to that is: that while ships were struck in the Navy, and lives lost every year before they were introduced, no ship fitted with them ever received the slightest damage; and since all ships were ordered to be fitted—now about 30 to 35 years—I have never heard of the slightest damage, or the loss of one life—that fact upsets all theories on the subject!

Then connections between the higher and lower masts, and especially at right angles, are objected to on the ground that at a bend the conductor may be fused; such a thing was never heard of in the thousands of conductors that must have been fitted in the navy. Even if the movable plate were turned back the lightning following the longest conductor would leave one mast for the other, as the conductor went right over the mastheads, and the two conductors nearly touched each other.

At Spring Grove, near Isleworth, the church had a high spire which was fitted with a conductor, but the Vicarage was struck and some damage done to it, though, I think, much nearer to the tower than its height. I believe many are contented with one or two conductors to a building that should have many more. My small house here is about 70 feet long by 38 feet wide, and I have seven conductors—one to each chimney.

If it is once decided beyond dispute, that copper conducts in proportion to its _volume_; then a rod, or flat-plate, of about the proportions of one to four or five, for the purpose of fitting closer round projections, would be the cheapest and simplest form; but if it conducts in proportion to _surface_ then of course a tube, _double_ plate, or wire rope, would give the greatest protection at a given cost.

I firmly believe in the surface theory of Harris. I had been with him often when he made experiments nearly fifty years since, and witnessed a strip of tin foil of the thinnest kind, and about ¼ inch wide, protect a model mast of about six inches in diameter from electric shock, that without it split the mast to pieces, aided by a small hole through its centre filled with gunpowder. And I always thought that the surface-conducting theory of Harris was indisputable. But about 20 years since, having to approve a proposal of the Trinity House for a new conductor of a Lighthouse, which, like previous ones, was an inch in diameter copper rod called “Faraday’s Plan,” I thought I would go up to the Royal Institution and ask him why he did not use a copper tube instead, giving much greater conducting power with less copper. I did so, and he asserted positively that the conducting power depended entirely on the volume of copper in the section of the conductor, no matter whether it was in a bolt, plates, or tube; and that if Harris said differently, “He knows nothing whatever about it;” of course, I approved the rod conductor. But singularly enough, though I had not seen Harris for years, he came to town a few days after, and came to the Board of Trade to see me, and bring me a piece of his large tube conductor, with a connection, that he was fitting to the Houses of Parliament. When I told him what Faraday’s opinion was, he answered, “Then he knows nothing about it.” I was still inclined to believe in Harris; but a few years after, a young Indian R.E. Officer—Lieut.-Col. Stewart—whose death not long after was a serious loss to the service, was sent home to procure the electric cables for connecting different Indian ports. I was asked by the Secretary of the Indian Office to give him all the help I could. One day he came to me with a piece of the cable he proposed using. Inside the iron wires was a single stout copper wire about ⅒ of an inch in diameter. I asked him why he had not the central wire of several strands as usual, as I believed it would greatly increase the conductive power. He said that he had _carried out a number of experiments on this point_ before deciding; and that he was satisfied the conducting power depended on the _amount_ of _copper_ in the conductor, and consequently a solid wire was better than one of the same size made up by twisting small wires together.

This of course shook my confidence in Harris’ theory; but it is a point that can be easily decided by experiments on a larger scale; and I hope your Committee will be able to decide it finally.

Messrs. W. & W. prefer to a conductor on the masts a wire rope carried down from the truck, stopped to a back stay. The following fact will show its danger:—A French frigate, some fifty years since, had one so fitted as an experiment; while striking T.G. masts the conductor formed a large bight as the mast was lowered; a man standing on cap or cross-trees—I forget which—formed a shorter conductor between two parts of the wire rope and was killed without any other damage being done.

B. J. SULIVAN.

BOURNEMOUTH.

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With reference to your recent letter in the “Times,” I shall be glad if you will inform me whether there has come under the consideration of the Conference the question of lightning conductors on board iron ships with _iron_ masts; for my part they would seem to be useless, and that if the iron mast have sufficient metallic communication, through the bottom, with the outside of the ship either by means of the screw shaft or in some other way; no additional conductor, copper ribbon, or strip, down the masts and along the decks over the ship’s side, or copper tube down the shrouds and over the ship’s side could be of the slightest benefit.

In some ships one or other of these arrangements has been adopted, and in others both have been applied at same time.

C. M. L. McHARDY.

FERN HILL COTTAGE, WINDSOR FOREST.

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I have observed your letter in “The Architect” of Saturday last. With reference to the subject on which it treats, I chance to have noticed since my residence here (a period of eight years) what I suppose to be an unusual frequency of lightning striking objects immediately round this spot, and the neighbourhood generally.

This inference is suggested by the fact that within the period mentioned lightning has fallen within fifty yards of the same spot three times—that this summer (one of those occasions) two other houses, both (say) within 500 yards in a direct line from this spot, were also struck—and generally, I believe, more objects are struck in this neighbourhood than usually happens to be the case.

My idea may be a fallacy, for I have no sort of statistics by which to test it; but if you suppose it is not so, and if such points come within the scope of your inquiry, I should be glad to send you a map marked with the spots where, and the dates when, lightning has fallen in or near this town. The only local peculiarities I notice are: 1. An unusual number of houses close to this have lightning conductors (a mere coincidence, and not placed there on any impression like my own). 2. We are at the bottom of a deep bay of parabolic plan which may influence the movements of electrical disturbance. 3. A soil of sand and gravel containing much oxide of iron.

A. BALDRY.

ATHELNEY, BOURNEMOUTH, HANTS.

[Mr. Baldry kindly supplied the map, and we find that a half circle of half a mile radius struck from the cliff-edge half a mile west of Bournemouth Pier includes the churches of St. Peter, with one conductor, and Holy Trinity with three; eight private houses with conductors, of which four houses have one each, and the other four have two, five, six and seven respectively, and within this area six objects are known to have been struck—three in the year 1879, two in 1871, and one in 1870. We do not know of any English locality where there are so many houses with conductors; but there are many more remarkable cases of repeated injury within small areas—_e.g._, in one storm in June, 1878, there were at least eight separate buildings injured within a circle of half a mile radius struck from the Metropolitan Cattle Market in the north of London.—ED.]

* * * * *

It occurs to me that it is worth while for the delegates of the Royal Institute of British Architects to raise the question, and, if possible settle, whether or not the gas pipes which permeate many buildings might or might not be utilized as lightning conductors; and whether any risk of gas explosion would be incurred thereby.

In my own practice there occurred the case of a lofty building, with a domed roof, and a sun-burner with a 1½ inch gas-pipe to supply it, rising to the summit of the dome, and a large iron cowl over the sun-burner.

The same circumstance occurs in most modern theatres. If the cowl were struck by lightning there was perfect metallic connection thence to the street gas mains—and one of larger sectional and superficial area than an ordinary lightning conductor would give.

H. D. DAVIS.

2, FINSBURY CIRCUS, CITY, E.C.

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Lightning conductors have been a great hobby with me for many years, and I have induced a great number of clergymen and others to fix them to their towers and houses. During my time in the navy and merchant service I witnessed many fearful effects of lightning, and for the last thirty years I have been striving to persuade my friends to secure their houses from these terrific visitations. On the 24th December, 1699, the upper half of the fine steeple of this town was hurled to the ground, and a large portion of the church broken in. Pinnacles were then substituted for the upper portion of the steeple, to which I have had an efficient conductor attached. As far as I can gather from records, and from the abortions so frequently substituted for the original pinnacles of towers, I have come to the conclusion that _nearly every tower in this country_ has been struck by lightning during the last 400 years, when nearly all the towers were built. Many years since, the Illustrated News gave a sketch of a beautiful steeple (in Norfolk, I believe) destroyed by lightning. It was stated that this was the second steeple which had met with so sad a fate. After the destruction of the first, a second steeple was built by subscription, at a cost of £1,000, and the scaffolding had been removed only ten days when, during a terrific thunderstorm, this second steeple was entirely destroyed! I wrote immediately to the incumbent to ask about the _conductor_, and his answer was that none had been fixed, but that it was quite decided that an efficient one should be attached to _the third steeple_! This would almost appear incredible, and I regret that I did not dot down the name of the Parish and other data, but I think it was about 20 years since.