Minutes of Proceedings of The Institution of Civil Engineers, November 14, 1876.

No. 1,451. - “ The Japan Lights.” By Richard Henry Brunton, M. Inst. C.E.

   Tue Government of Japan, in entering into friendly relations with foreign powers, stipulated that certain ports were to be open, and that mercantile operations were to be confined to those places.

These ports are:

1. Hakodate, in the island of Yezo.

2. Yokohama, 20 miles from the northern capital of the country, Yedo, or Tokio.

3. Kobe, 50 miles from the southern capital, Kiéto, and near the entrance to the Inland Sea.

4. Ozaka, between Kobe and Kidto, being 20 miles from the former.

5. Nagasaki, in the south-west portion of the island of Kiusiu.

6. Niigata, on the west coast of the Main Island.

   The principal trade is at Yokohama, where from two hundred to three hundred foreign-owned vessels of large size annually resort. The next places in importance are Kobe and Nagasaki, at each of which about one hundred and seventy vessels arrive every year. Hakodate is in a high latitude, and its trade is almost entirely confined to the summer months, but it is at no time of any great extent. Niigata and Ozaka are visited by few ships. All these ports, however, are the rendezvous for a considerable native trade, which is every year increasing.

   The foreign powers arranged, and it forms one of the clauses in the existing treaties, that the Japanese Government should “ provide the treaty ports with such lights as may be necessary to render secure the navigation of the approaches to the said ports.”

   On the 17th of November, 1866, Sir Harry S. Parkes, K.C.B., H.B.M. representative, directed the attention of the Japanese Government to the existence of this stipulation, and requested that steps might be taken to carry out its purport.

   The French and American ministers shortly afterwards made similar representations, and a favourable reply was received from the Japanese ministers early in December of the same year. Sir H. S. Parkes had previously received suggestions from naval officers and others relative to the most important sites for the lights, and these he laid before the Japanese Government. The erection of eleven lights was agreed to, and Sir H.S. Parkes was requested to use his influence with Her Majesty’s Government, in order that the necessary apparatus and the assistance required to establish lighthouses might be obtained.

  The matter having been referred to the Board of Trade, that department consulted the Trinity House, and eventually, on the 6th of November, 1867, Messrs. D. and T. Stevenson, MM. Inst. C.E., the Engineers to the Commissioners of Northern Lights, were desired to select suitable persons to undertake the design and construction of the lighthouses, and to introduce the lighthouse service into Japan.

   The Board of Trade had the general management and supervision of the arrangements, while the Messrs. Stevenson, who pointed out the difficulties likely to be experienced from the constant recurrence of earthquake shocks in Japan, had charge of the construction of the apparatus for six of the lights which had been ordered.

   The Author received the appointment of Chief Engineer in February 1868, and he arrived in Japan in August of the same year.

   Out of more than twenty-five sites suggested by those to whom the matter had been referred in Japan, five points appeared to be generally concurred in. (Plate 1.) These were :—A second order revolving light at Oshima (Kashinosaki); a first order fixed light at Shiwomisaki; a first order fixed light at Iwoshima; a first order fixed light at Satanomisaki; and a lightship at Hakodate.

   It was found, however, impossible to select from the various suggestions the most advantageous positions for the remaining six lights authorized by the Japanese Government. A proposal was therefore made by Sir H. 8. Parkes to complete the necessary information by a mixed Commission of the senior naval officers of England, France, and America then in Japan, the Japanese Government being also represented on it. This Commission consisted of Captain Hewett, of the English navy; Commodore Goldsborough, of the United States navy; and Commandant Amet, of the French navy. The Japanese war-steamer “ Fujiyama” was placed at the disposal of these officers, and they visited the various points in November 1867. They agreed in recommending a first order fixed light on Noshima; a first order fixed light on Mikomoto (Rock Island); a second order flashing light on Tsurugisaki (Sagami); a third order fixed light on Kannonsaki; a red floating light at Yokohama harbour; as well as several buoys and beacons in the Gulf of Yedo.

   Some time previous to the formation of this Commission the apparatus for several lights had been ordered from France through a staff of French engineers, who were then engaged in forming an arsenal at- Yokoska, on the west coast of the Gulf of Yedo, about 10 miles from Yokohama. These were intended to light the approaches to the arsenal; but the Commission recommended that they should be placed on those points most urgently requiring illumination.

   It was afterwards found that the only spots suitable for them in the Gulf of Yedo were Noshima and Kannonsaki. The first order fixed apparatus from France was accordingly placed at Noshima, and the third order fixed apparatus at Kannonsaki, and these two lighthouses were erected under the superintendence of the French engineers above mentioned.

   On arriving in Japan, the Author examined the sites of the lighthouses which had been decided on; and, as they were spread over 1,500 miles of coast, and there were no means of internal communication, Admiral Sir Henry Keppel, then on the Japan station, was induced to grant the use of H.M.S. “Manilla” for a voyage of inspection. In addition to collecting information and taking the requisite observations in regard to those points already decided on, the Author received instructions to inspect and report upon the best method of lighting the Inland Sea and the approaches to Kébe and Ozaka; for which purpose the Japanese Government, in the beginning of 1867, had authorized the apparatus for five additional lights. The Inland Sea, separating the main island from Kiusiu and Shikoku, is about 250 miles long, and, at some places, it is 50 miles wide; it is filled with several thousand small islands, and navigation is carried on through recognised channels between them. It may be judged, therefore, that to place a light on every point in the Inland Sea requisite to render navigation through it practicable, on dark nights, would be a work of magnitude and of doubtful utility.

   On the other hand a few lights might be so placed that, with their assistance, a considerable portion of the sea would be navigable at night, and vessels would be guided to places where they might anchor with safety and wait for daylight. |

   The proposals made by the Author were based on the following, principles. 1st. To put no light where the headlands are bold and well defined, or where no hidden dangers exist. 2nd. Where |there are difficult and dangerous channels, through which vessels could not proceed in dark weather, to place lights to lead them into a safe anchorage where they can wait for daylight; and, if possible, in such a position that advantage may be taken of them |for going through the channel. 3rd. Where a light would render a channel easy to pass through, which, without it, would be difficult, or where a light is likely to be required to give mariners a clue to their position, regarding which they may, at night, get easily confused among the numerous islands, a light should be placed.

   Having regard to these considerations, the Author fixed upon the following points at the approaches to Kébe, and Ozaka, and in the Inland Sea, as being: the most advantageous :—A third order fixed light at Tomagaishima; a fourth order fixed light at Temposan (Ozaka); a fourth order fixed light (red) at Wadanomisaki{Kobe}; a first order fixed light at Yesaki (Awaji); a fourth order fixed light at Nabeshima; a third order fixed light at Tsurishima ; a third order fixed light at Hesaki; and a fourth order fixed light at Rockuren. These proposals were laid before various nautical authorities. They received general approval, and the erection of the lighthouses was ultimately authorized.

   Soon after the completion of the first two or three lighthouses, |the Government showed its appreciation of them by deciding |that the old system of wood fires should be abolished, and that properly illuminated lighthouses should take their place. A notification was issued by the Council of State calling upon the local authorities to name the places at which local lights were needed, and instructing them that the old system of wood fires must be discontinued, The result of this notification is that many applications for small lights have been received from all parts of the country. But as the Imperial Government has, except in a few important cases, refused to bear the expense of these lights, and as the local governments are generally unable to do so, not many of the proposals have as yet been carried out. Eleven such lights are now established, and from ten to fifteen others are under consideration.

   Those which have been completed are:—A staff light on the pier in Yokohama harbour; a fifth order fixed light at Shinagawa, in Yedo harbour1 ; a fifth order fixed light at Jokashima, near the entrance to the Gulf of Yedo;' a sixth order fixed red light at Irésaki, near Mikomoto (Rock Island); a fourth order fixed hight at Sugashima, the entrance to Toba harbour; a fourth order revolving light at the entrance to Matoya harbour; a fourth orderred fixed light at Shirasu, west of Shimonoseki Straits; a staff light on Noshiaf, the easternmost point of the island of Yezo ; a staff light in Nemuro harbour, in Yezo; astaff hight at Awomori harbour ; and

a staff light at Ishi-no-maki, at the mouth of the river Kita-kami.

1 These lights were erected by the Yokoska officials.

   The Government, desirous of further perfecting the illumination of the coast, decided on erecting several ocean lights on those points most in need of illumination. These are in addition to the lights already specified, which were demanded by the treaty powers. A full and complete scheme for the illumination of the entire coast was drawn up, and those sites which were considered most important were first dealt with. Seven of these lighthouses are completed, and the positions for thirty others have been visited, examined, and reported on. Before finally deciding to erect any lighthouse, the Author submitted his proposals to the naval authorities in Japan at the time, and to many captains of vessels trading on the coast. Captain St. John, of H.M. surveying ship ”Sylvia,” gave especial attention to the matter, and rendered great assistance by his advice.

 These seven lights are situated as follows :—A second order fixed light at Siriyasaki, the north-easternmost point of the main island ; a first order revolving light at Kinkasan, east coast, north of Yokohama; a first order revolving light at Inuboyesaki, east coast, north of Yokohama; a first order revolving light at Omaesaki, south coast ; a first order flashing light at Kadoshima, west coast, north of Shimonoseki ; a second order fixed light at Yebosishima, west coast, south of Shimonoseki; and a fourth order fixed light at Haneda, Gulf of Yedo.

   The apparatus for these lights, as well as for the harbour lights already mentioned, was ordered, without the intervention of the Board of Trade, through Messrs. D. and T. Stevenson, who, in September 1871, were appointed Consulting Engineers to the Japanese Lighthouse Department.

   A complete list of the lighthouses, lightships, buoys and beacons established by the Author on the coast of Japan will be found in the Appendix.

   In designing the lighthouses the most important point for consideration was the liability of the country to the periodical recurrence of earthquakes. No definite records had been kept of these disturbances, nor could data be procured as to the localities most subject to them. It is well known, however, that slight |shocks are of frequent occurrence, and that, during the present century, fifteen shocks of a destructive character have been experienced.

   These were felt in different parts of the country, the northern capital, Yedo, being most subject to them, where five out of the fifteen occurred, the remaining ten being pretty equally distributed. The palace of the Emperor at Kidto was destroyed by an earthquake in 1828, as well as most of the temples with which that city abounded. In 1846, m the province of Shinano, on the west coast, the earth swallowed up eighteen houses, five thousand dwellings being at the same time destroyed. The most recent destructive earthquake, in the year 1855, was chiefly felt at Yedo, when the trembling of the earth continued for one month, and eighty severe shocks occurred ; about one hundred and twenty |thousand lives were supposed to have been lost on this occasion.

   Messrs. D. and T. Stevenson, on whom the duty of designing the |apparatus for the lights devolved, deemed it necessary to “‘take some steps to secure these from derangement, and the lamps from partial or total extinction on the occurrence of the many modified shocks which visit the country.” The arrangements carried out have been thus described by Mr. David Stevenson :—“ It is evident that any sudden lateral motion of the earth, on which a building rests, must be communicated to the foundation of the structure, and thence through all the rigid and unyielding materials of which it is composed to its very summit, where the violence of the shock will be aggravated by the greater elevation of the highest point of the |building above the source of motion.

   On fully considering this ; action of earthquakes, it seemed to me that what was required to neutralise their shocks was a break in the continuity of the rigid parts forming the structure, so as to prevent the propagation of the shock. . . . The plan 1 proposed for this purpose, which may, for brevity, be termed an asewsmatic joint, is the introduction of spherical balls of bell-metal, working in cups of the same material, placed between two platforms, the lower cups being fixed to beams forming the foundation, and the upper cups being |fixed to the lower beams of the superstructure, thus admitting, within a limited range, free motion of the upper over the lower part of the building1.” The Board of Trade sanctioned this arrangement for the lights first ordered, the apparatus for these being now placed on tables having an aseismatic joint on the principle described (Plate 2, Fig. 1).

1 Vide Transactions of the Royal Scottish Society of Arts, vol. vii., p. 560.

   The Author’s experience of the contrivance is not altogether favourable. He finds that, while the free motion of the upper over the lower part of a structure may neutralise the effects of an earthquake shock, such free motion will, at other times, occasion inconvenient results. Thus, were such a joint placed above the foundations of a lighthouse tower, the pressure exerted by a gale of wind on the superstructure would give rise to a motion probably equally as distressing as a severe earthquake. In the same way a person stepping on one of the aseismatic tables, for the purpose of trimming or cleaning the lamps, causes the upper part to roll to such an extent that the lamps become deranged, and in the case of revolving lights the regular motion of the clock-work machinery is destroyed.

   Messrs. Stevenson introduced a stout spring in a vertical position, the lower part of which was securely fixed, while the upper part was attached to a ball working in a socket in the centre of the upper table. This was intended to regulate the movement, but it was only partially successful. The problem is to form a joint sufficiently sensitive to move freely on the occasion of an earthquake, but so stiff that no inconvenient motion will be occasioned by ordinary disturbances. Messrs. Stevenson’s design was, for the reasons named, not adopted in any of the other lighthouses.

   From the observations of those who have examined the effects of earthquakes, and have given their attention to the subject, it may be accepted that there is a double motion in all shocks, the first movement tending to overthrow, while the second tends to restore the equilibrium. If, therefore, a building could be constructed with sufficient power of resilience, its overthrow or destruction ‘could not occur so long as the oscillation caused by the earthquake did not go beyond its limit of equilibrium.

   This seems to have been the leading principle in the native architecture of the country. The houses are constructed with a light wooden framework, without diagonal struts or ties of any kind. The roofs are heavy, and the uprights which support them are mortised into horizontal beams at the top and at the bottom. The buildings are evidently designed to have a maximum of elasticity, and they can, no doubt, be, and often are, moved off the vertical to a great extent without fracture. Their efficacy in resisting severe earthquakes, however, is questionable. The system further seemed open to the objection of excessive weakness, and consequent inability to withstand the other disturbing forces to which a building is exposed.

  The only alternative method that seemed feasible was to give the lighthouses great weight and solidity, thereby adding to their inertia and checking their oscillation. It has been laid down by Professor Palmieri of Naples, probably the most experienced earthquake observer in the world, that although solidity and strength in a building do not afford perfect protection against an earthquake, still so long as fracture does not occur, absolute overthrow is almost impossible. This principle of solidity combined with strength was the one adopted by the Author in designing the lighthouses, and in carrying out the different details of their construction..

   The various lighthouses were constructed of stone or brick, wood or iron, a8 found most suitable for the locality. They are generally circular at the base, and the walls have a straight batter on the outside, and are plumb on the inside. Forming a semicircle round the bases are two store-rooms, one for oil, and the |other for dry stores. Paint, fuel, and additional store-rooms are erected in the grounds. The lightkeepers’ dwellings are of stone or brick, and contain from six to eight rooms: the kitchens and | outhouses are in separate buildings. The grounds are surrounded by a stout fence or wall, about 8 feet high.

日本の主要貿易は横浜であり、そこには200から300隻の大型貨物船がやってくる。神戸と長崎がその後に続き、70隻から100隻の貨物船が年間到着する。函館は高緯度の所にあり、貿易が行われるのは夏期に限られる。新潟と大阪には数えるだけの貨物船しか入港しない。これらの港は、現地貿易の集まるとことであり、年々増加の傾向にある。

外国の権力は日本政府と次のような協定を結んだことにより、「条約港に出入りする船舶の安全航行のため必要とされる灯りを備えなければならない」ことになった。1866年11月17日、パークス公使は日本政府にこの条約の実行を求めた。

フランスとアメリカの公使も、イギリス公使に続いて同じような要求を行い、同年12月、日本政府閣僚からそれを受け入れる返事があった。パークス公使は海軍将校とその他の関係者から灯台建設の重要地についての提案を受け取っており、それを日本政府に伝えた。そして、11箇所に灯台を建設することに合意し、パークス公使はこれらの建設のための資材と人員の手配をイギリス政府に頼んだ。

　この要請は商務省にもたらされ、そして同省化のトリニティハウスに相談したところ、1867年11月6日にエジンバラのデヴィッド＆スティヴンソン技術事務所に、灯台設計と施工管理を行う人員を任命し、灯台運営を行う人員を派遣することになった。そして、私は、1868年2月に主任技師に選ばれ、同年8月に日本に到着した。

日本において関係者から提案された25箇所のうち、最初に建設したのは次の5箇所だった。

大島の樫野崎灯台、二等廻転

潮岬灯台：一等固定

伊王島灯台：一等固定

佐多の岬灯台：一等固定

函館灯台：灯台船

日本政府から承認された残りの6箇所の灯台は、設置場所を決定するのは難しかった。パークス公使の助言に従い、イギリス、フランス、アメリカの海軍の上級士官に意見を聞いて決定した。この顧問委員会は、イギリス海軍のヒュウィット、アメリカ海軍のゴールドボロー、フランス海軍のアメットであった。彼らは、1867年11月に「冨士山」号に乗り込み、灯台建設の候補地を視察した。そして、野島に一等固定式、神子元島に三等固定式、剱崎に二等固定式、観音崎に三等固定式、横浜港に赤色浮き灯台、そして江戸湾に数個のブイとビーコンを設置することになった。

この委員会創設の少し前、数台の灯台用装置がフランス人技術者の手を通して発注された。彼らは横浜の西方10マイルほど離れた横須賀の工廠建設に従事していた。これらの灯台は工廠へ出入りする箇所を照らすためのものであり、そこで委員会は最も緊急を要する箇所に灯台を建設することを提案した。後になって、江戸湾において適当な箇所は野島崎と観音崎の二つであった。フランスからの一等固定装置は、従って前述したフランス人技師たちの監督で建設された。

日本に到着して、灯台建設予定地の検分に取り掛かった。そこは1500マイルに及ぶ海岸線で、国際的な通信網はなく、そのため、ジャパン・ステーション総監のヘンリー・ケペル総督がマニラ号を提供してくれることになった。候補地の情報を集め、その位置を子細に観測する事以外に、神戸と大阪のある内海に最良の投光器を取り付ける方法を報告するように日本政府から指示を受けた。1867年初めに、当地に5箇所の装置を設置することを承認していた。内海は、本州から四国と九州を分断し、およそ250マイルの長さがあり、広いところでは50マイルの幅があった。そこには数千の小さな島島があり、いくつかの承認されたチャンネルを通って航海が行われていた。おそらく、夜間の航行のためにここには要所総てに投光器を設置しなければならない。

私が提案は次を基本にしている。第一は、大きくよく見える岬、あるいは隠された危険のない場所には投光器は置かない。第二に、条件の悪い天候の時に航行ができないような危険な水路。第三は。以上のことを考えて、神戸と大阪のアプローチ、内海の次の地点に設置することを決めた。第三等固定灯台：苫がい島、第四等固定灯台：矢崎（淡路）、第四等灯台：ロックレン。

日本政府は海岸の灯光を完全なものにしようと、それが必要な地点に海洋灯台を建設することに決めた。上記に挙げた条約に基づく灯台の他に、どこに灯台を設置すべきか調査を行った。7台の灯台が完成し、他の30台の位置を訪問し、報告書を作成した。同時に、この国の沿岸を航行する船舶の艦長たちにも報告書を送り助言を求めた。測量船シルヴィア号のセント・ジョン提督からは大変有益な助言を頂いた。

これらの投光装置は商務省を経ずに、デヴィッド＆トーマス・スティヴンソン技術事務所に注文し、1871年9月から日本の灯台寮の顧問技師に任命された。灯台建設に於いて最も注意したのは、地震であった。この国にはまだ公式な地震記録はなく、軽微な地震は頻発し、今世紀中に破壊的な地震が15回もあったと言われている。

　地震に至るところで起き、15回の大地震のうち、江戸の周辺では5回、他の10回は各地に分散する。京都御所は1828年の大地震で倒壊し、多くの寺院も甚大な被害を受けた。1846年に信濃地方を襲った大地震は、18戸の家を飲み込み、5000戸の家屋が倒壊したと言われている。一番最近の地震は1855年のもので、江戸で最も揺れが酷く、地面の揺れが一月続き、その間80回もの大震動が起きて、100,2000もの人命が失われたらしい。スティヴンソン事務所は、灯台装置の設計の任務として、「その国に起きる振動によって装置に狂いや、機器に損傷が生じないように対策を講じる」として、デヴィッド氏は「地面の突然の水平の動きは構造物の基礎に伝えられなければ、剛の固い材料を通して、衝撃力が上に行くほど増幅することは明らかである」と説明している。

これを熟考すれば、衝撃を無効化するために必要なものは、構造物を構成する剛性部分の連続の分割と思われる。この目的のために私が考えたのは、簡潔に言えば耐震ジョイントと呼ぶべきもので、金属球を二つのキャップの間に配置するというものである。下部キャップは基礎を形成する梁の上面に取り付けられ、また上部キャップは上部構造の梁の下面に取り付けられ、その間に鉄球を置けば、上部構造には下部構造からの振動は最小となろう。イギリス商務省は発注した灯台にこのような工夫をすることに承認し、図に示した原理に基づく耐震ジョイントがテーブルの上に取り付けられることになった。

スティブンソン兄弟氏は軸部に強力なスプリングを導入した。下部は頑丈に固定され、上部には中央のソケットに鉄球可動装置が取り付けられた。これは挙動を規制することを狙ったものであるが、部分的に成功したに過ぎなかった。問題は、地震の際に此のジョイントが十分自由に動くようにすることであった。しかし、あまりにも頑丈に固定されていた。そのため、スティブンソン・デザインは他の灯台にはまったく採用されなかった。

総ての仕事は二人の副技師の助けで実行された。ジェームス・マックリチー氏とS.フィッシャー氏である。部局には書記官1人と事務員2人が雇用され、他のヨーロッパ人は異なった時期にそれぞれの業務のために雇われた。一人は鉄工の監督のために1人、装置の調整と修理のための職工2人、大工・銅工1人、船大工1人、石工4人、そして灯台守15人である。