I. キャンベル･ストークス太陽光記録計発明のキャンベルCampbell, as Inventor of Sunshine Recorder.

・1853年、ジョン･フランシス･キャンベルは太陽光記録計（日照計）を発明し、その後、ジョージ･ストークス（Sir George Gabriel Stokes）により改良され、実用化された。この装置は150年以上も経た今日もで利用されている。キャンベルは実に興味深い人物で、弁護士の資格を持ち英国内閣の要職を勤めながら、自然科学から文学までの広い分野で第一級の研究業績を残した。日本ではカンベル日照計として知られる。

・このキャンベルは、1874年11月から1875年2月に日本に滞在し、東京では内務省地理寮による金星日面通過観測を指導した。内務省には旧知のコリン･アレクサンダー･マクヴェインが測量師長として金星日面通過観測を準備しており、それを併せて来日した。マクヴェイン自身、前年一時帰国した際、グリーニッジ王立天文台で観測手法の指南をジェームス･シムスから受けていたが、キャンベルの協力はとても心強かった。しかし、キャンベルの関与は内務省には事前に通知していなかったため、日本側の公文書や新聞には紹介されなかった。

・この偉人は社会的名誉にはまったく関心がなく、内務省による金星日面通過観測を成功裏に導いたことに天皇からご褒美を受け取るようにとの駐日英国公使ハリー･パークスからの進言を断り、さらに、本国ではエジンバラ大学からのゲール民俗学教授職勧誘を辞退した。

・キャンベルの自然科学分野の業績として、日本における金星日面通過観測以外に太陽光記録計の発明があり、キャンベルは亡くなる3年前にその発明経緯を『サーモグラフィThermograhy, 1883』としてまとめた。最近、サンチェス氏他は本書を解読し、キャンベル日照計の発明背景に議論し書物を著した。その内容を英国気象協会が以下のように要約しているので、ここに解題を付す。私もこの再販本を2020年1月10日にやっと入手した。

**Thermography,"" pp.11-12.

Thermography— The writer began to work with solar heat in 1853, and set himself to devise a new art by which to test a theory built on facts. He named the method “Thermography” in 1879 In a manual of photography, by Robert Hung (Glasgow, 1853), is a chapter on “Thermography” Following Moser, Hunt made experiments, and in 1840 he suggested the name. “When two bodies are sufficiently near, they impress their images upon each other,” even in the dark. Every thing radiates heat, more or less. The vapour of Mercury attacks a prepared metal plate, in those parts which correspond to the white ground of an engraving, pressed upon the plate. The name dates from 1840. The writer’s study sprung from amateur photography. It is based upon the action of “heat” upon materials which are not sensitive to “light.” A cold seal stamps an impression on hot wax; and a hot seal stamps cold wax. Heat, in an optical image formed by a lens, acts where “light” does not act upon the materials used, dark cameras are not needed in thermography. But the first need for the study of hot rays in sunshine’s to get out of the shade of clouds. Therefore the writer travelled to the rainless region of Upper Egypt in 1880, to work there. The results are stated in following chapters.

   Obviously materials sensitive to heat must not be sensitive to ordinary temperatures. The normal temperature about the Equator is reckoned at 80, and thermometers in hot sunshine read 150. Thermic materials must resist these temperatures, if they are to take and retain pictures. The focussed image must be hotter than the temperature which the material used resists. As in photography and other new arts, the inventor had to do his own work; to find out sensitive materials, to invent apparatus, and to work with head and hands.

II. Introduction of "New insights into the history of the Campbell‐Stokes sunshine recorder" by the Royal Meteorological Society Website.

サンチェス・ロペス他著『キャンベル=ストークス太陽光記録計の歴史に関する新たな考察』の紹介

※PDF file document is available HERE. 

PREFACE

--When, in 1853, J. F. Campbell designed his first sunshine recorder, he could hardly have thought that 160 years later the instrument would still be in use, having become the most commonly‐used device to measure hours of bright sunshine across much of the world since the 1880s, and playing a significant role in helping us to understand climate in the context of current climate change. Little is known, though, of the establishment of the Campbell‐Stokes recorder as the standard instrument in meteorological stations across the United Kingdom and worldwide, although some insights were given by Stanhill (2003). The present paper presents an overview of Campbell's life, along with the principal stages in the development of the Campbell‐Stokes recorder, from its initial design in 1853 to the improvements made thereto by G. G. Stokes in 1880.

The life of John Francis Campbell

--John Francis Campbell (Figure 1), also known as Young John of Islay, was born in Edinburgh in December 1821. He spent his childhood on Islay (Inner Hebrides), which had belonged to Campbell's family since the 1720s. The aristocratic lineage of his family did not stop him getting to know the Gaelic‐based culture of the island from direct contact with the local inhabitants. Hence he learnt the Gaelic language and handicraft techniques, which would later influence his adult life. After receiving secondary education at Eton, Campbell started law studies at the University of Edinburgh, although he was more interested in the natural sciences.

-The bankruptcy of his father in the late 1840s forced the Campbells to sell their country estates, including the one on Islay. The young Campbell was forced to move to London in the early 1850s, where he worked as a secretary in different jobs, such as for the Board of Health and the Lighthouse Commission. He was active in different scientific fields, including the natural sciences, photography and optics, was an enthusiastic traveller and developed a reputation as an authority on Celtic folklore (Anon., 1885).

--He was a modest man and did not seek fame or fortune from his work (Anon., 1885). As a result of his personality, he was considered an eccentric and was not always understood by his contemporaries. He was proposed as a candidate for the first Chair of Celtic studies at the University of Edinburgh in 1883 but declined the offer, preferring not to be tied down by a position or to be fitted with spikes and be pelted with jaw‐breakers, which clearly points to an attitude of hostility towards the academic world.

--Having withdrawn from his last post, during the final years of his life Campbell focused mainly on his scientific activities, as can been seen in his manuscript ‘Thermography’ (Campbell, 1883). He spent the winter months in Cannes (France) and died there in February 1885, being buried far from his beloved Highlands.

--More on the life of Campbell can be found at http://www.islayinfo.com/john_francis_campbell.html and http://www.scottishrepublicansocialistmovement.org/Pages/SRSMArticlesJohnFrancisCampbellTheFolkHeroofCelticScotland.aspx

［解説］上記はキャンベルの経歴に関するもので、＜John F. CampbellジョンF.キャンベル＞の項を参照願う。図版1の(b)で使われている写真はマクヴェイン文書にも含まれており、私はてっきり日本で撮影されたものかと思っていたが、1868年ロンドン撮影でした。1875年6月に１年間の世界旅行からロンドンに帰り着いたとき、体重は200ポンドであったといい、大変な大男だったらしい。

Campbell's first sunshine recorder

--It is well‐known that Campbell designed his first device to measure the duration of sunlight in 1853; what is less known is what motivated him to do so. It is quite possible that his interest in photography and optics influenced his early thoughts on how to measure the heat of the sun. He commented that his interest in optics and glasses came from his childhood: Some fifty years ago somebody gave a child an optical toy, a glass like the bulb and stem of a big thermometer filled with water. He then learned experimentally that a transparent ball is a magnifier, and burns fingers. Ever since that childish lesson was learned, as boy and man the writer has been striving to learn more about burning‐glasses (Campbell, 1879a). He also wrote that he knew of the theory and early experiments in the field of thermography, which were explained by Robert Hunt in a manual of photography (Hunt, 1853), stating that he began to work with solar heat in 1853, and set himself to devise a new art by which to test a theory built on facts (Campbell, 1883).

--The original design by Campbell in 1853 consisted of a glass sphere filled with water set into a wooden bowl that was charred by the sun's rays which were focused by the sphere; it was replaced every six months (Figure 2(a)). The water lens was made by a maker of lampshades in Paris, whereas the wooden bowl was obtained in London (Campbell, 1879a). In 1857 the water lens was replaced by a solid sphere of glass (Figure 2(b)). The instrument was described by Campbell in a paper entitled ‘On a New Self‐Registering Sun Dial’, published in the Report of the Council of the British Meteorological Society (Campbell, 1857).

［解説］「1853年に太陽の日射時間を計測する装置を発明した。しかし、彼がどのようにしてこれを発明したかについては殆ど知られていない。幼少の頃に写真と光学に興味を持っていたと語っており、それが太陽の熱を計測しようという考えを導き出したのであろう。（『サーモグラフィThermography (1883)』執筆の）によれば、「およそ50年前、ある人物がこの少年に光学のおもちゃを与えた。水が充填された大きな温度計の球根と茎のようなガラス製であった。そして、彼は実験的に透明な球が拡大鏡であり、そして太陽光を集めて熱を作り出し指を焼くことを学んだ」とあり、独学でレンズの仕組みを学び、それに写真技術を結びつけて、高熱の太陽光焦点が湾曲面に痕跡を残させることに成功したという。私たちほとんどだれでも，レンズを太陽に向けて，その光線の焦点を紙に当てると，焦げるのを知っているであろう。火を起こすことも可能であるが，日照計では紙の密度を上げて焦げる程度に留めておけば，太陽が何時頃に照り始めて陰るのか焼け跡から分かる。

Campbell's first sunshine measurements

--We have already learned of Campbell's initial motivation for designing a device for measuring the sun's heat. But why and when did he become interested in using this device as a meteorological instrument for measuring sunshine duration?

--In order to answer this question, we need to recall that he was the Secretary of the General Board of Health in London during this time. Specifically, a crucial event may have been the cholera outbreak in London in 1854 (Anon., 1855). One of the actions taken by the Board of Health after this outbreak was to set up 13 new meteorological stations in order to complete the previously existing network in London, with the aim of studying the weather conditions during the cholera outbreak. One of these new stations was the building hosting the General Board of Health in Whitehall. In a report by James Glaisher, Superintendent of the Department of Meteorology at the Royal Observatory of Greenwich, it was stated that Campbell and John C. Haile were the observers in Whitehall (Glaisher, 1855). In this temporary observatory, they made two observations per day of different meteorological variables.

--In his report summarizing the weather conditions during the cholera outbreak, Glaisher stated that it appears that the high day temperature of London has generally been below that of the surrounding districts; nor is this remarkable, the sun's rays having first to penetrate the thick atmosphere which generally overhangs all large towns and cities, but more particularly London, and for this reason the duration of high day temperature is shorter than in the country. In order to support this description, Glaisher added an interesting note, referring to Campbell's device, to our knowledge for the first time: during the months of September and October [1854] J. Campbell, of the Board of Health, kindly furnished me with pieces of black ribbon which he had placed daily in the focus of a spherical lens at the Board of Health and which, whenever the sun shone, was marked by a burnt line, or on partially clear days by a series of holes. The duration and time of sunshine was thus shown by this ingenious contrivance of Mr. Campbell's, and would have been highly valuable in this investigation had a similar apparatus been simultaneously in action in the suburban districts (Glaisher, 1855). Several years later, Campbell mentioned that another instrument had been installed at Niddry Lodge on Campden Hill, Kensington, a suburban area in west London (Campbell, 1857; 1865), where he lived (Campbell, 1879b).

--Hence, it is obvious that Campbell himself performed daily observations of sunshine duration, at least during the first months, in the Board of Health's provisional meteorological station. Campbell was aware, especially because of his position as secretary of the Board, of the important role of sunlight in the context of human health, as well as the role it played in the process of the cholera epidemic. Thus he started to perform daily measurements in September 1854, while making the standard daily observations established by the Board of Health. A few months later he devised a method, using a bowl of mahogany, in order to obtain a six‐monthly record, perhaps for easier maintenance. Systematic measurements started during the winter of 1854 (Scott, 1885). Campbell's sundial was in continuous operation in the same building for two decades, until the winter solstice of 1874, even after the disappearance of the Board of Health in 1858 and his reassignment as secretary of the Lighthouse Commission. Indeed, Haile continued to be in charge of the recorder until his retirement in the mid‐1870s (Campbell, 1865; Scott, 1885).

［解説］「キャンベルが発明した太陽光記録計がどのように実用に供されるようになったのか。その切っ掛けとなったのは、キャンベルがロンドンの衛生局事務局長に就任していた1864年，コレラの流行が最高潮に達したことによる。衛生局が取った対応は、コレラの発生と気象状態の相関関係を明らかにするためロンドン各地に既存の観測所に加えて新たに13箇所を設置することにした。ホワイトホールの衛生局事務局に観測データが集められ、グリーニッジ王立天文台の気象部担当官のジェームス･グレーシャー(James Glaisher, 1809-1906)と協力し分析を行ったところ、気温と日照時間がコレラの発生率と相関関係があることが明らかになったという。

The Campbell recorder at the Kew and Greenwich Observatories

--Just before Haile's retirement, Campbell demonstrated and explained his instrument and records to the head of the Meteorological Office, who approved them (Campbell, 1880). This meeting appears to explain the transfer of Campbell's instrument to Kew Observatory after the last bowl was measured in Whitehall in the winter of 1874 (Anon., 1875). His original instrument was used at Kew until the summer of 1897; in all over 80 bowls, one for each half‐year, were used between 1854 and 1897 (Anon., 1898). Roscoe and Stewart (1875; 1884) studied the cavities made in these wooden bowls from 1858 to 1882 and developed a method to estimate the volume of the hollows, which led them to make a connection between sunshine and sunspot frequency.

--In addition, during the first months in the new location, different experiments were in progress by Kew staff in order to obtain daily records (Anon., 1875; Scott, 1877). Specifically, after receiving Campbell's recorder and the entire series of bowls in 1873, Robert H. Scott started to consider how to perform daily records, as it is obvious that the plan of hollow wooden bowls is not suitable for such a purpose, in as much as the track of the sun for each day overlaps that for the preceding day, and the result is, at best, merely a rude representation of the general effect of the sun's heat (Scott, 1877). It is worth mentioning that Kew staff may have been unaware of the test for daily records performed by Campbell in 1854, which was only mentioned by Glaisher in 1855 and was not public knowledge.

--Scott conducted experiments to obtain daily records using a ribbon or tape inside the bowl, recognizing that Campbell had already explained this system in the description of the instrument made in 1857 (Campbell, 1857). With the assistance of R. J. Lecky and S. Jeffery, who worked with him at Kew Observatory, Scott devised a system to hold the strip of paper by means of clips along the inner surface of a ring which is concentric with the spherical lens, and whose radius is equal to the radius of the lens plus its focal length. This ring is attached to a vertical circle, along which it is moved to correspond with the varying declination of the sun (Scott, 1877). The material used for the paper was thin millboard, and he showed a table with the results from September. It seems, however, that the improvements made by Scott were not considered entirely satisfactory, and he and his colleagues continued working on it at the Meteorological Office, resulting in the modifications suggested by Stokes in 1879, which are detailed in the next section.

--Independently of this work at Kew, there was, in 1876, a request from the General Register Office of England that, because of its impact on public health, sunshine duration should be recorded at the Royal Observatory in Greenwich (Ellis, 1877). Consequently, George Biddell Airy, the Astronomer Royal at Greenwich, wrote to Campbell enquiring about the possibility of obtaining a sunshine recorder, and one was installed there in May 1876 (Ellis, 1877; 1880). Campbell was on good terms with Glaisher at Greenwich Observatory, and with his successor, William Ellis (Campbell, 1880).

--The instrument provided by Campbell to the Royal Observatory consisted of a very accurately‐formed glass sphere, measuring four inches in diameter, which was manufactured in February 1861 by James Chance of the Birmingham Glass Works (Campbell, 1865; 1879a). The sphere was supported concentrically within a well‐turned hemispherical metal bowl, which was manufactured by Sir William Armstrong at his Newcastle workshops and had engraved upon it the motto ‘Horas non numero nisi serenas’ (‘only the hours that are serene count’) (Campbell, 1879a) (Figure 3). Daily measurements were performed at Greenwich Observatory with a strip of some material being fixed in the bowl, which is removed after sunset, and a new one fixed ready for the following day (Ellis, 1877). Prior to using it, Campbell tested the instrument and found to work well upon black Indian‐rubber cloth fixed upon the metal surface, with a waterproof solution, and changed daily, clearly pointing out that such daily observations belong to an observatory supervised by meteorological observers. From Campbell's words we know that at least some daily measurements were made in London in 1874 with a set of mounted pliable bands (Campbell, 1883), which means that daily measurements were performed before the improvements made by Scott in the measurements at the Kew Observatory.

--Further improvements and institutionalizationIn the late 1870s, George Gabriel Stokes, a mathematician and physicist at the University of Cambridge, received a request from the Meteorological Office to improve the modifications made to Campbell's instrument by Scott at the Kew Observatory (Scott, 1877). The main improvements suggested by Stokes consisted of substituting the bowl with a metallic semi‐ring with grooves to hold the cards used for daily measurements, a new platform to support the half ring, and the use of three different cards for the equinoctial, winter and summer seasons (Stokes, 1880).

Mechanism of Campbell=Stokes Sunshine Recorder

The Meteorological Office accepted these modifications, and from then the instrument was adopted across the United Kingdom (Scott, 1885) although at some stations, such as Greenwich, Campbell's design for daily measurements remained in use for some years. Overall, the final design suggested by Stokes is almost identical to the device we know as the Campbell‐Stokes sunshine recorder (Figure 4), as only minor modifications were subsequently made in order to standardize its size, material and types of cards (WMO, 2008).

Furthermore, the modifications suggested by Stokes attempted to solve deficiencies in Campbell's previous instruments at Kew and Greenwich by means of a cheaper system, and by ensuring that it should demand little skill on the observer's part in the placing of the cards (Stokes, 1880). It is odd that Stokes refers in the text to Mr. Scott's modification of the instrument in order to perform daily measurements at Kew (as described above). A few sentences later he pointed out that the most obvious way of supporting the slip would be to make it rest against the inner surface of a hemispherical bowl, which has been the plan adopted at the Royal Observatory (Greenwich). Thus, Stokes omits Campbell's name as the author of these modifications made in Greenwich, which is quite strange as Ellis had already described the modifications made by Campbell three years earlier (Ellis, 1877).

Furthermore, in the discussion section of the paper published by Stokes, Ellis supported the instrument designed by Campbell, arguing that the paper written by Stokes appeared to give an impression that in the Greenwich instrument there was considerable liability to error in placing the strips in position. The plan was perhaps suitable only for an observer of some experience, but he might mention, that with the appliances provided, an error in this respect was of rare occurrence (Stokes, 1880). Thus, it seems that Stokes, or the Meteorological Office itself, attempted to conceal Campbell's authorship of the instrument placed at the Greenwich Observatory, as well as his contribution to the design by the Meteorological Office in the second half of the 1870s.

Indeed, a few years later Campbell wrote some sentences that seem to relate to this: A known invention, if worth anything, is apt to spread like a ring wave started by a stone, and the inventor like the stone, is apt to disappear…This small inventor has often been amused at being ignored by those who honoured his small work with notice. From that human weakness sprang ‘patents’, to protect interests of more solidity. None of these contrivances are ‘patents’. Being here printed, nobody can patent them (Campbell, 1883). From these lines we can assume that Campbell considered that the Meteorological Office, which years before had ‘honoured’ his instrument, had ignored it possibly due to its interest in patenting the instrument and making a profit from it. Moreover, in the same publication Campbell appears to criticise the modifications made by Stokes, or at least to defend his own instrument: for example, Various devices have been adopted which are intended to facilitate the placing of materials in frames, at latitudes which these frames suit when properly set. The original device projects a moving picture of the sky from zenith to horizon upon a surface, in true perspective, in any latitude. All other devices fail in proportion to their departure from the principle of concentric spheres (Campbell, 1883). Further evidence of this underestimation of Campbell's contribution to the sunshine recorder adopted by the Meteorological Office can be seen in the Reports of the Kew Committee. The report of 1880 explained that the recorder, including the modifications by Stokes, had been installed at the Observatory and also noted that Campbell had visited the station, perhaps to observe these modifications (Anon., 1880). Subsequently, in none of the following reports from 1880 to 1910 was Campbell's name mentioned, and it is only after 1911 that the ‘Campbell‐Stokes recorder’ is specified as the instrument used for measuring sunshine duration.

In the annual reports made by Greenwich Observatory, it is clearly specified that the recorder used since 1876 is the instrument provided by Campbell. In June 1886 it is explained that a modification of the Campbell form of instrument, as arranged by Sir G. G. Stokes for use at the observing stations of the Meteorological Office was introduced to the Greenwich Observatory (Anon., 1889). It is then written that a very complete account of the Campbell‐Stokes instrument is given in the Stokes publication (Stokes, 1880). Thus, in this report by Greenwich Observatory, the name of Campbell‐Stokes is used for the final design by Stokes, but is omitted in the reports by Kew Observatory and by Stokes in his publication when the instrument was first introduced.

In 1888, Ellis, now president of the Royal Observatory in Greenwich, presented a study at the Annual General Meeting of the Royal Meteorological Society (Ellis, 1888). Therein he explained that the new Campbell‐Stokes recorder had been installed in the Observatory, this being the first time that, to our knowledge, the name ‘Campbell‐Stokes’ was used in the Quarterly Journal of the Royal Meteorological Society. There was a subsequent increase in the use of the expression, which implies that Campbell‐Stokes became the name to be used when referring to Stokes’ final design.

We believe that the use of ‘Campbell‐Stokes’ came from pressure from the staff of the Royal Observatory, or perhaps from scientists or manufacturers who considered that the addition of Stokes’ name would help to promote the instrument, as suggested also by Stanhill (2003), although we have not found evidence for this hypothesis.

Future of the Campbell‐Stokes recorders and records

With the increase in the automatic measurements of sunshine duration that have become available in the last few decades (e.g. Kerr and Tabony, 2004), the meteorological stations equipped with the Campbell‐Stokes instrument have been diminishing in number. Although the advantages of these new devices are obvious, as for example the fact that the cards do not need to be changed daily which make them useful for remote locations, traditional measurements performed in well‐maintained observatories with long‐term measurements ought to be maintained in order to avoid the introduction of inhomogeneities in these time series (Stanhill, 2003).

It is true that, with the development of surface solar radiation measurements since the 1950s, these sunshine data are less valuable. Nevertheless, the sunshine duration records have been proven to be very useful for our understanding of climate variability and change, especially regarding the decadal variations of global and direct solar radiation (e.g. Stanhill, 2003; Sanchez‐Lorenzo et al., 2008; Wild, 2009; Wood and Harrison, 2011; Sanchez‐Lorenzo and Wildm 2012) and aerosol concentrations (e.g. Horseman et al., 2008). In fact, Campbell already considered it important to increase the number of the measurements performed with his invention, as more dial records would help to settle the question of periodical increase and decrease in solar radiation (Campbell, 1879a).

Consequently, and just 160 years after Campbell's first design in 1853, an effort is to be made in the near future to compile all the traditional measurements available worldwide before this information is lost forever.

Acknowledgements

This research was supported by the Spanish Ministry of Science and Innovation project NUCLIERSOL (CGL2010‐18546). The first author was supported by a postdoctoral fellowship from the Secretaria per a Universitats i Recerca del Departament d'Economia i Coneixement, de la Generalitat de Catalunya i del programa Cofund de les Accions Marie Curie del 7è Programa marc d'R+D de la Unió Europea (2011 BP‐B 00078). The fourth author was given a grant by the Juan de la Cierva programme (JCI‐2011‐10263) of the Spanish Ministry of Science and Innovation. The fifth author was given a grant by the FPU programme (FPU AP2010‐0917) of the Spanish Ministry of Science and Innovation. Dimming/brightening research at ETH was supported by the National Centre for Competence in Climate Research (NCCR Climate) of the Swiss National Science Foundation. We wish to thank Jim Glass from the SRSM and Ron Steenvoorden for their useful advice regarding Campbell's biography, which is summarized in the first section of this paper. Equally, we also wish to thank Christoph Schaer and Gerald Stanhill for their continuous support of our work.

III. Consideration考察（added in October 14, 2019）

(1) 幼少期における科学に対する素直な関心を発展させてきた。おそらく1830年頃のキャンベルは温度計の球根部に目をつけた。当時の気温計球根部は現在のものよりもずっと大きく、その球根部を太陽にかざして太陽光を一点に集めると、そこはとても熱く、紙を焦がした。一種のレンズであるが、通常のレンズと違うのは太陽の動きに関係なく焦点が結ばれることである。

(2) エジンバラ大学で自然科学や博物学をしっかり学び、その後、法学を学び直して弁護士資格をとった。30歳になっていた。

(3) 従弟のアーガイル公爵を補佐するかたちで、さまざまな協会の事務局を掌ることになり、衛生局事務局長Secretary of Board of Health時代に気象観測と向き合うことになった。すなわち、コレラの流行と気象（天候）との関係を解明することで、気象観測所をロンドン市内に増設した。気象データを分析したところ、気温と日照時間がコレラの流行と密接な関係にあることが分かった。日照時間を計るために、キャンベルの太陽光記録計が有効であった。その後、ストークスの改良を経てキュー観測台やグリニッジ王立天文台にも採用された。こう考えると、1850年代、建物の室内環境に科学の関心が向けられ、建築基準法に通気と日照のために窓の大きさが規定されていった過程がわかる。

(4) 太陽光記録計には写真撮影の原理を応用したもので、キャンベルが光学や写真術にも長けていた。1870年代に実用化されると、世界各地の気象観測所に備え付けられ、現在まで使用されている。とても美しい観測器機で、１万円以内なら私も欲しい。

(5) サンチェス他著の本書には、キャンベルが金星日面通過に対してどれほどの関心を持っていたかは何も述べられていない。が、『ネーチャー』誌に見えるように、1873年から1874年にかけての英国の科学雑誌は金星日面通過観測を気象学及び天文学の一大イベントとして紹介しており、当然、キャンベルも感心を持っていたであろう。

(6) 日本に金星日面通過観測のための器機を持ってきたことを考えると、来日の目的がそれであったことは確か。カメラはもって来ていなかったが、ブラックのカメラを望遠鏡接眼レンズに固定する間に合わせの装置を工夫した。

(7) キャンベルが事務局長を務めていた衛生局の下部組織に衛生保護協会 (Sanitary Protection Association)というものがあり、マクヴェインの親友であるコモス・イネスが運営に関わっていた。このイネスの甥がウィリアム・バートンで、1887年に日本に来ることになる。単なる偶然なのだろうか。

カメラ・オブスクラ、ジョン・ハモンド著

p.88.ロバート・ランバーと・プレイフェア中佐

p.89.ウエッジウッドはエカテリーナから膨大な陶磁器セットの注文を受ける。絵柄はイギリスの風景。千を超える風景を写し取るために、彼はカメラ・オブスクラを用いた。協力者にトマス・ベントリーがいた。

p.94.ダニエルとウィリアムのダニエル画家はインドでカメラ・オブスクラを用いた。

p158．スコットランドのキルマーノックのトマス・モートンは、1818年に観測塔を建設した。内部にニュートン式望遠鏡、グレゴリー式望遠鏡、そしてカメラ・オブスクラを設置した。

p.160.モートンはエジンバラに引き続き、1835年、ダンフリーズにも望遠鏡とカメラ・オブスクラを納品した。

p.168.1856年にはカールトン・ヒル（ゴシック・タワー）とショートの民間天文台にそれぞれカメラ・オブスクラは設置されていた。その後、ゴシック・タワーの物がアウトルック・タワーに場所ヲ移動したらしい。その後、解体修理され，新た恣意装置となった。

ロンドン大学ユニヴァシティ・カレッジのディオニシアス・ラードナー教授は『科学と技術の博物学(1855)』において、各種のカメラ・オブスクラについて極めて端的に記載を行った。