JOHNSON%nuhub.acs.northeastern.edu@CSNET-RELAY.ARPA (11/04/86)
From: "I am only an egg." <JOHNSON%nuhub.acs.northeastern.edu@CSNET-RELAY.ARPA>
At one time I was informed that early coal miners used candles on
their helmets to provide light in the mines. This would cause an
explosion now and them because of coal gas build-up. Someone
discovered that by putting a metal cage around the flame, the candle
could be safely used in the mine.
Does anybody know whether or not this is true, who discovered it
and why it works?
Chris Johnson
Northeastern Universitystirling@fortune.UUCP (Patrick Stirling) (11/07/86)
> At one time I was informed that early coal miners used candles on >their helmets to provide light in the mines. This would cause an >explosion now and them because of coal gas build-up. Someone >discovered that by putting a metal cage around the flame, the candle >could be safely used in the mine. > Does anybody know whether or not this is true, who discovered it >and why it works? >Chris Johnson >Northeastern University I'm 'F'ing instead of 'r'ing beacuse I don't think your return path will work. I dimly recall from school that the lamp was called a 'Davies safety Lamp', presumably invented by Davies (!). It worked, I think, on the principle that the metal shield would conduct heat well enought to prevent the flame front of the burning bas from getting through the shield. The lamp also worked as a coal gas indicator - when there was coal gas present, the candle flame had a blue (I think) aura. patrick {ihnp4, hplabs, amdcad, ucbvax!dual}!fortune!stirling
earl@phred.UUCP (Daddy Earl) (11/11/86)
In article <238@sri-arpa.ARPA> JOHNSON%nuhub.acs.northeastern.edu@CSNET-RELAY.ARPA writes: > > At one time I was informed that early coal miners used candles on >their helmets to provide light in the mines. This would cause an >explosion now and them because of coal gas build-up. Someone >discovered that by putting a metal cage around the flame, the candle >could be safely used in the mine. > > Does anybody know whether or not this is true, who discovered it >and why it works? > >Chris Johnson >Northeastern University This is what is called a "DAVEY LAMP". It is named after Humphrey Davey, an early scientist. I don't know if he discovered the principle or if he was just the one to put it to use. I was told that it works due to the fact that the metal screen conducts heat away from the gas too fast for the flame to pass through. This can be demonstrated with a candle and some metal window screen. The screen has to be fine enough to do the job, but still coarse enough to let light through. Marine supply houses sell "flame screen" to put between the manifold and the carb. to help prevent stack fires in boats. It is fun to play with. Try puting the flame of a butane lighter to a piece of screen and you will find that it won't go through. You can also light the gas on the other side of the screen and it won't get back to the lighter. If someone has more information, I would like to hear it too. If my information is incorrect please let me know (no flames please, I've got screen over my CRT so it wouldn't do any good anyway 8-) ). Hope to hear more.
dave@inset.UUCP (Dave Lukes) (11/11/86)
In article <145@fortune.UUCP> stirling@fortune.UUCP (Patrick stirling) writes: >I dimly recall from school that the lamp was called a 'Davies safety Lamp', >presumably invented by Davies (!). It worked, I think, on the principle >that the metal shield would conduct heat well enought to prevent the >flame front of the burning bas from getting through the shield. The lamp >also worked as a coal gas indicator - when there was coal gas present, >the candle flame had a blue (I think) aura. >patrick Right about the lamp, wrong about the inventor: 1) The name was Davy (Sir Humphrey): President of the Royal Society 2) He DIDN'T invent it: it was actually invented (many years before I seem to remember) by George Stephenson(sp?) of Stephenson's Rocket and Locomotion fame. It was known in the north of England as the Geordie Lamp. A royal commission eventually determined this some while later. (Although it didn't decide whether he'd stolen it or not!). This is a classic example of social and professional snobbery: Davy was an upper-class scientist, while Stephenson was a working class (unqualified) engineer: guess who got believed initially, in spite of the fact that the Geordie Lamp had been IN USE for years prior to Davy's invention (if indeed he did invent it independently). Yours angrily (:-), -- Dave Lukes. (...!inset!dave) ``Fox hunting: the unspeakable chasing the inedible'' -- Oscar Wilde
campbelr@hpdsd.UUCP (Bob Campbell) (11/12/86)
Yes, the candle works. If you are ever in Chicago, visit the Museum of Science and Industry. Among the exhibits there is a "working" coal mine that you can take tours through. At the end they demonstrate the miners lamp. I recall it had something other than a candle in it, but all that matters is a flame. If the wire mesh around the candle is intact, the flame will flash but will not pass the screen. If even a tiny hole exists in the mesh, the mine itself will explode. There are boxes at the top of the shaft to test the lamps before entering the mine. I believe that they are still used to test for gas by mine engineers, but the average miner uses electric lights. Bob Campbell - Hewlett Packard Information Technology Group hpdsd!campbelr@hplabs.HP.COM
msb@dciem.UUCP (Mark Brader) (11/18/86)
> Right about the lamp, wrong about the inventor: > 1) The name was Davy (Sir Humphrey): President of the Royal Society Well, having seen 3 different wrong spellings, I can resist no longer. The name is Sir Humphry Davy! By the way, if you visit Penzance, you can see his statue, on the main street just near the railway station.
pmk@prometheus.UUCP (Paul M Koloc) (11/18/86)
In article <780001@hpdsd.UUCP> campbelr@hpdsd.UUCP (Bob Campbell) writes: >At the end they demonstrate the miners lamp. I recall it had something >other than a candle in it, but all that matters is a flame. Candles burn with a higher temperature and there is all the trouble with the dripping, running wax. Gas jet flames were better. The one I had, if memory serves, used Calcium Carbide "stones" and by dripping water on them they would generate acelylene gas. This burns with a very smokey flame (lots of radiating surface) and a cup of the stuff (fuel) would last for quite a spell (as they used to say). Naturally, Union Carbide and Carbon Company made the fuel. +---------------------------------------------------------+--------+ | Paul M. Koloc, President: (301) 445-1075 | FUSION | | Prometheus II, Ltd.; College Park, MD 20740-0222 | this | | {mimsy | seismo}!prometheus!pmk; pmk@prometheus.UUCP | decade | +---------------------------------------------------------+--------+
firth@sei.cmu.edu (Robert Firth) (11/24/86)
> At one time I was informed that early coal miners used candles on >their helmets to provide light in the mines. This would cause an >explosion now and them because of coal gas build-up. Someone >discovered that by putting a metal cage around the flame, the candle >could be safely used in the mine. > Does anybody know whether or not this is true, who discovered it >and why it works? >Chris Johnson >Northeastern University The miners' safety lamp was invented by Sir Humphrey Davy. It works because the metal cage conducts the heat away sufficiently to cool the burning gases below the ignition point, so the flame cannot get out of the cage. Incidentally, this still leaves the problem of the miner being asphyxiated by the coal gas. An additional feature is that the candle flame burns bluish when gas is present, which warns the miners. Before that, they used canaries (when the canary drops dead, move out).