DyerF. L.MartinT. C. and MeadowcroftW. H., Edison, his life and inventions, ii (New York, 1929), Appendix, chap. 7.
2.
In August of the preceding year the wide-ranging Edison had corresponded with Draper concerning Draper's work on oxygen lines in the solar spectrum. Edison kept a spectroscope in his laboratory and knew something of solar spectroscopy, being interested at the time in the shapes of spectral lines (letters from Henry Draper to Edison dated 6, 9, 22 August 1877 in the Archives of the Edison National Historic Site (ENHS), West Orange, New Jersey).
3.
An excellent portrayal of Langley's life in science is found on BarrScott E., “The Infrared Pioneers, 3: Samuel Pierpont Langley”, Infrared physics, iii (1963), 195–206.
4.
Letter from LangleyS. P. to Edison, dated 3 December, 1877, in the ENHS Archives.
5.
Although Langley encouraged Edison, his sceptical opinion of the young inventor is betrayed by a delay of more than a month in answering Edison's letter and by his reference to assumed commercial exploitation of the device. Langley was probably one of the few physicists of the day who recognized the difficulty in building a small, sensitive, scientifically-usable infra-red detector.
6.
Scientific American, xxxix (1878), 39.
7.
JehlF., Menlo Park reminiscences, i (Dearborn, Mich., 1937), 184.
8.
BarrScott E. (American journal of physics, xxviii (1960), 42) has commented on the elusive origin of the word ‘infra-red’. It was surely coined about this time. In the literature of 1878, radiation of wavelength longer than the visible was “ultrared”, whereas in 1881 Langley and others use “infra-red”. Sometime between these dates the word was born.
9.
Powdered carbon was obtained by wiping soot from ordinary kerosine lamp chimneys, with production accelerated by turning up the wick. Edison's night watchman was asked to scrape carbon from the chimneys during odd moments and compress it into moulds of proper size, about 2 cm. across (SimondsW. A., Edison—his life, his work, his genius (London, 1935), 132). Telephone-makers, astronomers, and other users of the carbon buttons apparently never realized the casual ease with which the sensors were made, respectfully considering them another product of a secret recipe in the wizard's lab. Among the deluded were Langley, Charles Young, and J. N. Lockyer.
10.
EdisonT. A., “On the Use of the Tasimeter for Measuring the Heat of the Stars and the Sun's Corona”, American journal of science, cxvii (1879), 52–4: Edison's eclipse report to Draper, as read at the August 1878 meeting of the American Association for the Advancement of Science in St Louis.
11.
WheatstoneCharlesSir (1802–1875), who improved (but did not invent) the “Wheatstone bridge”, patented his own electrical telegraph in England at the same time as did Morse in America. The Wheatstone bridge was in common laboratory use in 1878.
12.
Thomson (1824–1907), later Lord Kelvin, had invented the mirror galvanometer to receive the extremely weak signals transmitted over the first trans-Atlantic Cable in the year 1858. Aboard the Great Eastern in 1865 and 1866, he used it to monitor the electrical condition of the second cable as it was being laid. For this work Thomson was knighted. Edison had met Thomson before 1878.
13.
The illustration is from Scientific American, xxxviii (1878), 385. The article, “Edison's Microtasimeter”, appeared five weeks before the eclipse in the 22 June edition and is the most complete technical description of the instrument. The same article reappeared in many other publications and was responsible for the quick fame of the tasimeter. The tasimeter, which appears in the foreground, is an open, horizontally-mounted model, which was apparently the original laboratory design. The horn model (in Figure 2) was finished only two days before Edison departed for the eclipse, by Edison's own admission (American journal of science, cxvii (1879), 54), although a mechanical drawing dated 12 June 1878 in the ENHS Archives shows that the eclipse instrument was at least designed more nearly one month before Edison's departure. In any case Edison's procrastination in preparing for the eclipse is bad enough to frighten most modern astronomers.
14.
This parameter failed to take into account any measure of the “blackness” of the detector, implicitly assuming the emissivity (or the absorptivity) to be unity. A better measure of detector performance is the responsivity used today, which includes allowance for non-perfect absorptance.
15.
LangleyS. P., “The Bolometer and Radiant Energy”, Proceedings of the American Academy of Arts and Sciences, xvi (1881), 342–58; “Sunlight and Skylight at High Altitudes”, American journal of science, cxxiv (1882), 393–8.
16.
Scribner's magazine, xvii (1878), 88.
17.
New York Sun, 18 May 1878.
18.
New York Daily Graphic, 19 July 1878.
19.
Laramie (Wyo.) Daily Sentinel, 30 July 1878. The 10−6 F value is generally cited in the biographical accounts.
20.
Letter from Edison to LongJohn, Tubingen, Germany, 26 September 1878, in ENHS Archives.
21.
A noticeably-impatient letter from a commercial distributer of the tasimeter asks him, in October 1878, for instructions on how to calibrate the instrument (Partrick & Carter to Edison, 19 October 1878, in ENHS Archives). The request appears to have gone unanswered.
22.
Edison wrote a detailed set of instructions on how to demonstrate the tasimeter in popular presentations (notes in the ENHS Archives).
23.
New York Herald, 22 June 1878; New York Daily Graphic, 19 July 1878.
24.
“Directions for setting up and adjusting the tasimeter” and letter from Edison to LongJohn dated 26 September 1878, in ENHS Archives.
25.
London Times, 29 October 1878; New York Herald, 22 June 1878.
26.
LaramieDaily Sentinel, 30 July 1878.
27.
Letter from LangleyS. P. to Edison, 7 June 1878, in ENHS Archives.
28.
Letter from LangleyS. P. to Edison, 22 June 1878, in ENHS Archives.
29.
Telegram from LangleyS. P. to Edison, 5 July 1878, in ENHS Archives.
30.
LangleyS. P., in Reports on the total solar eclipse of July 29, 1878 (U.S. Naval Observatory, Washington, 1880).
31.
Correspondence between LangleyS. P. and Edison, 11 and 14 October 1879, in ENHS Archives.
32.
“Edison's notes for W. H. Meadowcroft” (manuscript), in ENHS Archives. Another famous, regular visitor was H. A. Rowland of Johns Hopkins University.
33.
Letter to Edison from C. A. Young, 10 June 1878, in ENHS Archives.
34.
London Daily News, as cited by LockyerJ. N. in “The Eclipse of the Sun”, Nature, xviii (1878), 430–3, p. 432. The London Times (29 October 1878) also noted Young's failure.
35.
YoungC. A., “Observations upon the Solar Eclipse of July 29, 1878 …”, American journal of science, cxvi (1878), 279–90.
36.
New York Daily Graphic, 19 July 1878.
37.
JosephsonMatthew, Edison (New York, 1959), chap. 10.
38.
U. P. Railroad Memoranda from DickeyJ. J. and DickensonE. dated 17 and 19 July 1878, in ENHS Archives.
39.
Boulder (Colo.) County News, 12 July 1878.
40.
Ibid.
41.
Reports on the total solar eclipse of July 29, 1878 (U.S. Naval Observatory, Washington, 1880).
42.
For example, YoungC. A., “Results of the Recent Eclipse”, American journal of science, cxvi (1878), 242–6; DraperH., “The Solar Eclipse of July 29th, 1878”, ibid., 227–30.
43.
Josephson, Edison, 440.
44.
Ibid., 441. Edison's remark may be compared with that given by Aristotle (in Rhetoric, Book 2) to a similar question, whether it was better to be wise or to be rich: “Rich, for we see the wise spending their time at the doors of the rich”.
45.
“Edison's notes for W. H. Meadowcroft” (manuscript), in ENHS Archives.
46.
EdisonT. A., op. cit. (Ref. 10). The Arcturus test, although described in some detail in this AAAS paper, was omitted in the original handwritten draft (in the ENHS Archives). Barker expected to prepare Edison's paper for the AAAS St Louis meeting (letter from BarkerG. F. to Edison, 12 July 1878 in ENHS Archives); Barker at least edited it and we probably have him to thank for this valuable inclusion. Whether Edison wrote the paper and whether he delivered it in St Louis we can only conjecture. He attended the meeting, and from his later comments to the press, received an unexpected grand reception from the scientists assembled there (New York Daily Graphic, 28 August 1878).
47.
LockyerJ. N., “The Coming Eclipse”, Nature, xviii (1878), 410–2. Lockyer later urged Edison to send information on his inventions to Nature before giving it to other publications (letter from Lockyer to Edison, 15 October 1878, in ENHS Archives).
48.
BarkerG. F., “On the Results of the Spectroscopic Observation of the Solar Eclipse of July, 1878”, American journal of science, cxvii (1879), 121–5.
49.
The most objective account is found in Josephson, Edison, 176; the most coloured is probably in Simonds, Edison, 134. The version given here is a composite account.
50.
“Edison's notes for W. H. Meadowcroft” (manuscript), in ENHS Archives. A verbatim account is given in Dyer, Martin and Meadowcroft, Edison, i, 231.
51.
“Edison's notes for W. H. Meadowcroft” (manuscript), in ENHS Archives.
52.
New York Herald, 30 July 1878.
53.
New York Daily Graphic, 28 August 1878.
54.
BarkerG. F., “On the Total Solar Eclipse of July 29, 1878 (Read before the American Philosophical Society, Nov. 15, 1878)”, a tract of 12 pages apparently privately printed.
55.
DyerMartin and Meadowcroft, Edison, i, 231.
56.
E.g., Simonds, Edison, 134.
57.
New York Herald, 30 July 1878.
58.
New York Daily Graphic, 19 July 1878; New York Daily News, 29 July 1878.
59.
MichelsonA. A. and PeaseF. G., “Measurement of the Diameter of α Orionis with the Interferometer”, Astrophysical journal, liii (1921), 249–59.
60.
AllenC. W., Astrophysical quantities (London, 1955). The modified van de Hulst coronal radiances given by Allen were increased by a factor 2 to bring them into agreement with currently-accepted measurements.
61.
DyerMartin and Meadowcroft, Edison, i, 231.
62.
London Times, 29 October 1878.
63.
New York Herald, 30 July 1878.
64.
New York Daily Graphic, 28 August 1878.
65.
BarkerG. F., op. cit. (Ref. 54).
66.
LockyerJ. N., op. cit. (Ref. 47).
67.
LockyerJ. N., ibid., 430. Lockyer, at 42, was already known for a certain pompous omniscience when it came to eclipses. He was probably not offended by a friend's poem: “And Lockyer, and Lockyer, Gets cockier, and cockier; For he thinks he's the owner Of the solar corona” (cited in CortieA. L., “Sir Norman Lockyer 1836–1920”, Astrophysical journal, liii (1921), 233–48, p. 241).
68.
YoungC. A., op. cit. (Ref. 42).
69.
Memoirs of the Royal Astronomical Society, xli (1879), 246. Langley discounted the validity of Edison's measurement, and was apparently unaware of Magrini's, for 22 years later he bestowed credit for the first demonstration of heat in the corona to his associate, AbbotC. G., at the solar eclipse of 1900 (LangleyS. P., Science, xi (1900), 974).
70.
New York Daily Graphic, 27 August 1878.
71.
Scientific American, xxxix (1878), 112.
72.
New York Herald, 22 June 1878.
73.
Letter to Edison from Capt. PerryH., 2 December 1879, in ENHS Archives.
74.
Miscellaneous letters to Edison in ENHS Archives, 2 July 1878 to 3 January 1880.
75.
New York Herald, 22 June 1878; London Times, 29 October 1878.
76.
Letter to Edison from BrowningJ., 7 September 1878, in ENHS Archives. Edison sent the Rawlins tasimeter to Browning, who evidently later returned it, for in 1880 Edison gave the same instrument to the British Patent Museum, South Kensington, London as a display piece. A working model of the tasimeter is preserved today at the Edison Institute of the Henry Ford Museum in Dearborn, Michigan.
77.
Letters to Edison from Partrick & Carter, 19 October 1878 to 14 March 1879, in ENHS Archives.
78.
Letter from LongA. L., September 1879, with Edison's penned reply, in ENHS Archives.
79.
Letter to Edison from W. F. Barrett, 18 October 1878, in ENHS Archives.
80.
English mechanic and world of science, no. 703, 13 September 1878.
81.
LangleyS. P., “The Actinic Balance”, American journal of science, cxxi (1881), 187–98, p. 188.
82.
LangleyS. P., “The Bolometer and Radiant Energy”, 343.
