Talk:Henry Cavendish/Archive 1

Archive 1

Endowment of Cavendish Laboratory

"He left a large estate on his death which was used to endow the Cavendish Laboratory at Cambridge University in 1871."--This appears to be in conflict with text at Cavendish Laboratory and at William Cavendish, 7th Duke of Devonshire. Jim 21:30, 4 November 2005 (UTC)

G determination

I have changed the section "Earth's mass" because there were some mistakes

His measurement of the earth's mass was accepted until the 17th century? Really? Isn't that, what, 40 odd years before he was born?

You are correct; that is an error. It should read 20th century. I'm correcting it.

The wrong century appears in reference.com, which likely took the text from Wikipedia. The correct century appears in other works. Snezzy 12:33, 28 November 2006 (UTC)

Article status

Er, is this still a stub? I'm not quite clear when stubs graduate, but this seems pretty complete. Thoughts? Mashford 21:43, 10 Mar 2005 (UTC)

Cavendish is also credited with one of the earliest accurate calculations of the density of the earth. It would be good to give the density of the earth then! How can we call this fairly complete if one of the guy's main achievements in life was to calculate something which we don't specify. I came here to know the earth's average density (not including the atmosphere), and the one web page most likely to contain the info seems to be missing it. 172.206.159.143 19:36, 28 December 2006 (UTC)

Organization

Most Wikipedia articles about scientists have the biographical material very early, so that's where I've put it in this case. I don't know if it's official policy to structure the articles that way, but plenty do so, and now this article does too. -- Astrochemist 02:43, 7 May 2007 (UTC)

Content issues

Is the "Other work" section correct? Did Cavendish really get six-significant figure data? I don't know. -- Astrochemist 02:43, 7 May 2007 (UTC)

Since the opening sentences highlight Cavendish's work on H₂, it would be good to have a section on hydrogen's discovery. -- Astrochemist 02:43, 7 May 2007 (UTC)

Is there any way more biographical information can be included?

I found this interesting quotation about Cavendish:

"He did not love; he did not hate; he did not hope; he did not fear; he did not worship as others do. He separated himself from his fellow men, and apparently from God. There was nothing earnest, enthusiastic, heroic, or chivalrous in his nature, and as little was there anything mean, groveling, or ignoble. He was almost passionless. All that needed for its apprehension more than the pure intellect, or required the exercise of fancy, imagination, affection, or faith, was distasteful to Cavendish. An intellectual head thinking, a pair of wonderfully acute eyes observing, and a pair of very skillful hands experimenting or recording, are all that I realize in reading his memorials. His brain seems to have been but a calculating engine; his eyes inlets of vision, not fountains of tears; his hands instruments of manipulation which never trembled with emotion, or were clasped together in adoration, thanksgiving, or despair; his heart only an anatomical organ, necessary for the circulation of the blood. . .

Cavendish did not stand aloof from other men in a proud or supercilious spirit, refusing to count them his fellows. He felt himself separated from them by a great gulf, which neither they nor he could bridge over, and across which it was vain to stretch hands or exchange greetings. A sense of isolation from his brethren, made him shrink from their society and avoid their presence, but he did so as one conscious of an infirmity, not boasting of an excellence. He was like a deaf mute sitting apart from a circle, whose looks and gestures show that they are uttering and listening to music and eloquence, in producing or welcoming which he can be no sharer. Wisely, therefore, he dwelt apart, and bidding the world farewell, took the self-imposed vows of a Scientific Anchorite, and, like the Monks of old, shut himself up within his cell. It was a kingdom sufficient for him, and from its narrow window he saw as much of the Universe as he cared to see. It had a throne also, and from it he dispensed royal gifts to his brethren. He was one of the unthanked benefactors of his race, who was patiently teaching and serving mankind, whilst they were shrinking from his coldness, or mocking his peculiarities. . .He was not a Poet, a Priest, or a Prophet, but only a cold, clear Intelligence, raying down pure white light, which brightened everything on which it felt, but warmed nothing—a Star of at least the second, if not of the first magnitude, in the Intellectual Firmament."

From. Wilson, G. The life of the honorable Henry Cavendish. London: The Cavendish Society, 1851.

JocelynSequoia 06:40, 28 August 2007 (UTC)

Great quotes! Why don't you add some excerpts from them to the article? --Chetvorno 15:24, 28 August 2007 (UTC)

Recent changes

I tried to clean up some of the writing, but there's still a lot more to do. Also, I removed a comment about the Earth's mass in one place because the numerical value was given in units of weight, and there was no indication of who did either the calculation or the measurement. Can these be located and put back in? -- Astrochemist 02:23, 1 September 2007 (UTC)

Need citation

I added an interesting quote from Bryant (see sources) but i have no idea how to cite it. Please help! —Preceding unsigned comment added by 76.18.198.7 (talk) 21:30, 28 November 2007 (UTC)

Minor error in gravitation experiment

Great article! It's very well written and researched. I did notice a minor technical error in the section on The density of the earth. The Cavendish experiment didn't '...measure the gravitational attraction between two 350 lb lead spheres' , but between those spheres and smaller 2 inch 1.61 lb lead spheres attached to his torsion balance beam. See the 2nd para of Cavendish's paper, online in A.S. McKenzie, ed., Scientific Memoirs, Vol.9: The Laws of Gravitation, 1900, p.59 or your ref 1,R. McCormmach & C. Jungnickel, Cavendish, 1996, p.337. --Chetvorno 18:21, 17 August 2007 (UTC)

Corrected error --Chetvorno 00:56, 28 August 2007 (UTC)

Should 'his Clapham Commons estate' be '... Common ...'? If noone objects, I'll change it. Sam Dutton (talk) —Preceding comment was added at 07:56, 19 March 2008 (UTC)

Too precise?

Cavendish also accurately determined the composition of Earth's atmosphere. He found that 79.167% is "phlogisticated air", now known to be nitrogen and argon, and 20.8333% is "dephlogisticated air"

Now that is accurate indeed; percentages specified up to 3 or 4 decimal places. However, these percentages are conspicuously close to simple fractions 19/24 and 5/24. Anybody know if that was what Cavendish really reported? --Jmk (talk) 12:38, 12 May 2009 (UTC)

I have not found Cavendish's original numbers, but the book "Cavendish: the experimental life" by Jungnickel and McCormmach gives, on page 358 [1], only two decimal places and says even that is too precise:

... the concentration of oxygen in the atmosphere is, according to Cavendish, 20.83 percent, which is remarkably near the currently accepted value of 20.95 percent. In making this comparison, it should be noted, Cavendish is credited with a somewhat greater precision than he would likely have claimed.

If this is true, then Wikipedia is surely mistaken in reporting 3—4 decimal places. Does anybody have any other information on this issue? --Jmk (talk) 13:34, 23 July 2009 (UTC)

20.8333%? Six significant figures is a bit hard to swallow. The Alembic Club reprinted some of Cavendish's papers. His original work may be there. - Astrochemist (talk) 21:52, 23 July 2009 (UTC)

In this version of the same book the author explains that remark in more detail in footnote 12 at the bottom of page 261 going over to page 262:

...in this subsequent paper, in 1784, Cavendish noted that his dephlogisticated air contained impurities amounting to one thirtieth of its volume, which led him to suspect that common air contains one fifth part dephlogisticated air (that is, closer to 20 percent than to 20.83 percent).

SpinningSpark 18:27, 24 July 2009 (UTC)

It took me a long time, but I finally tracked down Cavendish's words. I rewrote the relevant section of the article. As always, assistance is welcome. Astrochemist (talk) 21:28, 25 July 2009 (UTC)

Great work. Thanks Astrochemist! --Jmk (talk) 10:03, 27 July 2009 (UTC)

Pronunciation of "Cavendish"?

Can anyone supply the correct pronnunciation of "Cavendish"? I recall hearing a lecture years ago where the speaker said the the second syllable of the name is accented.

Tashiro (talk) 22:03, 5 September 2011 (UTC)

G, mass of earth, density of earth

The article says: "It is not unusual to find books that erroneously describe Cavendish's work as a measurement either of the gravitational constant (G) or the Earth's mass,[15][16] and this mistake has been pointed out by several authors.[17][18] In reality, Cavendish's stated goal was to measure the Earth's density, and his result was later used to calculate G. The first time that this constant was used was in 1873, almost 100 years after the Cavendish experiment.[19] Cavendish's results also can be used to calculate the Earth’s mass." This doesn't really make much sense. The radius of the earth has been known, at least approximately, since ancient times. By Cavendish's time it was known pretty accurately. If its radius is known, then knowledge of its density is equivalent to knowledge of its mass. Similar considerations apply to G. The question of how Cavendish *conceptualized* or *described* his measurement is a separate one from the question of how it can actually be interpreted.--75.83.69.196 (talk) 06:40, 14 September 2011 (UTC)

The Cavendish experiment directly yields density without any knowledge of Earth's radius. So yes, G and M can be calculated from the result with a knowledge of R, but that is not what is being measured. The claim is referenced; do you have any references to present in contradiction? SpinningSpark 16:30, 14 September 2011 (UTC)

Either Green or Maxwell is lying or ...

.... or the author of this passage has it completely worng:

• Cavendish's electrical experiments did not become known until they were collected and published by James Clerk Maxwell a century later, in 1879,

But George Green knew about (one of) them in 1828:

• noticing an excellent paper, presented to the Royal Society by one of the most illustrious members of that learned body, which appears to have attracted little attention, but which, on examination, will be found not unworthy the man who was able to lay the foundations of pneumatic chymistry, and to discover that water, far from being according to the opinions then received, an elementary substance, was a compound of two of the most important gasses in nature.

• It is almost needless to say the author just alluded to is the celebrated CAVENDISH, who, having confined himself to such simple methods, as may readily be understood by any one possessed of an elementary knowledge of geometry and fluxions, has rendered his paper accessible to a great number of readers; and although, from subsequent remarks, he appears dissatisfied with an hypothesis which enabled him to draw some important conclusions, it will readily be perceived, on an attentive perusal of his paper, that a trifling alteration will suffice to render the whole perfectly legitimate.

• Footnote: In order to make this quite clear, let us select one of CAVENDISH's propositions, the twentieth for instance, and examine with some attention the method there employed. The object of this proposition is to show, that when two similar conducting bodies communicate by means of a long slender canal, and are charged with electricity, the respective quantities of redundant fluid contained in them, will be proportional to the $n-1$ power of their corresponding diameters:

(Cited from Green's well known Essay on the Application of mathematical Analysis to the theories of Electricity and Magnetism.) --Rwst (talk) 15:20, 9 June 2008 (UTC)

OK, I've completed the section, and added a reference to the mentioned paper. --Rwst (talk) 15:41, 9 June 2008 (UTC)

As communication wasn't as easy then as it is today (no search engines either), it's entirely possible Maxwell simply didn't know about Green's writing on this. Some more recent secondary sources on this issue would not hurt. Have mörser, will travel (talk) 20:03, 25 September 2011 (UTC)

Was he born in France?

In 1731 Nice belonged to the Duchy of Savoy. --83.59.157.182 (talk) 21:06, 25 September 2013 (UTC)