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Another Mystery Tool

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Martin King 202/07/2022 17:36:51
1018 forum posts
461 photos

Hi All,

Just going through last weeks auction items and found this oddity:

arctool 1.jpg

arctool 3.jpg

arctool 2.jpg

Comes with a couple of bundles of these copper coated rods which appear to be carbon with a small central hole all the way through.

All I can think of is some sort of carbon arc setup, looks highly dangerous if that is the case.

Help welcomed.

Cheers, Martin

Dave Halford02/07/2022 17:59:56
2096 forum posts
23 photos

Carbon arc brazing torch with cables that are too thin as usual.

Exciting to use though

Paul Rhodes02/07/2022 18:01:02
48 forum posts

Martin your spot is correct. A carbon arc brazing unit. Bring the rods steadily closer till arc commences then commence heating/brazing. Unsophisticated perhaps but works well.

Adam Mara02/07/2022 18:03:11
172 forum posts
3 photos

I have an old XP welder, and it has similar carbon rods, which are for brazing rather than arc welding, never tried them though!

Don Cox02/07/2022 18:53:41
62 forum posts

Good for giving a suntan, make sure that all exposed skin is kept to a minimum, obviously appropriate eye protection needed too.

noel shelley02/07/2022 22:50:14
1445 forum posts
23 photos

Keller of Norwich used to market. Noel.

Howard Lewis03/07/2022 09:57:29
6314 forum posts
15 photos

Definitely an arc brazing torch.

I've got one, not used all that often, Very hot so has to be kept moving, but handy when needed.

Bit if a knack to keeping the arc correct.

REALLY need to cover all bare skin, otherwise severe sun burn.


Speedy Builder503/07/2022 10:11:18
2653 forum posts
219 photos

You can use them to increase the carbon content of mild steel thus making the contact area hardenable - but you also get surface "erosion".

bernard towers03/07/2022 12:02:17
691 forum posts
141 photos

Im with you there Noel they were sold from Kellers of Norwich on Cattle Market Hill.

Martin King 209/08/2022 18:42:54
1018 forum posts
461 photos

Hi all,

Here are two more mystery items from the weekends car boot haul, probably from a school physics lab, not sure what they are.

They appear to be incomplete but I do not know what is absent:

lginst 1.jpg

lginst 2.jpg

pyeinst 1.jpg

pyeinst 3.jpg

pyeinst 5.jpg

Any info would most welcome!

Cheers, Martin

DC31k09/08/2022 18:56:28
727 forum posts
2 photos

Last one is I think a moving coil galvanometer. Shine a light at the mirror and you can measure the angular deflection when a very small voltage is across the terminals. Connect it to a coil and plunge a magnet in and out.

peak409/08/2022 19:08:13
1787 forum posts
193 photos

I'd agree with the galvanometer, and I think the second item is a vacuum pump missing its bell jar.

Similar to this one

I remember replying to this article on The BBC last year with some more detailed info, but I must have deleted the email now.



Edited By peak4 on 09/08/2022 19:14:26

Willem Kotze09/08/2022 19:10:24
11 forum posts

The last item is a galvanometer. Reflected light beam for indication amplification. Low friction. Google "Galvanometer".


Martin King 209/08/2022 19:12:09
1018 forum posts
461 photos

Hi Peak4

If a vacuum pump would there have been a bell jar on the platform perhaps on a rubbers seal?


peak409/08/2022 19:16:03
1787 forum posts
193 photos
Posted by Martin King 2 on 09/08/2022 19:12:09:

Hi Peak4

If a vacuum pump would there have been a bell jar on the platform perhaps on a rubbers seal?


or maybe a grease/leather seal, I'm not sure.

See my amended earlier reply too

Also include Ballistic, in your Galvanometer searches.



Edited By peak4 on 09/08/2022 19:20:52

Bazyle09/08/2022 21:31:13
6384 forum posts
222 photos

Melted wax was also used as a seal. Used for suffocating butterflies or introducing something to kill them in the more elaborate ones.

SillyOldDuffer10/08/2022 20:37:54
8903 forum posts
1999 photos

Agree bell-jar and vacuum pump. Nice find! I expect the pump seals are leather and will need to be replaced. Plastic might work. You can still buy bell-jars, try ebay etc.

The glass bell was probably sealed with Vaseline rather than hot wax because wax was used for more permanent seals. The four experiments I remember showed:

  • air is necessary to transmit sound. (A clockwork bell gradually went quiet as the air was pumped out even though the clapper is seen to be still working).
  • air is necessary to combustion. (A lit candle goes out when the air is removed)
  • air is necessary to life. (A mouse dies when the air is pumped out.)
  • alcohol boils when the pressure is reduced even though the temperature doesn't change.


Martin King 215/08/2022 12:03:22
1018 forum posts
461 photos

Hi All.

Many thanks for the info on these items.

The vacuum pump is now on its way to a French Instrument collector after a huge amount of interest on EBay.

Cheers, Martin

Martin Kyte15/08/2022 12:50:42
2798 forum posts
53 photos

I would have said that the last one was a ballistic galvonometer. The max angle of deflection being proportional to the total charge passed.

regards Martin

Andrew Tinsley15/08/2022 14:20:48
1615 forum posts


Anyone know where you can get the copper coated carbon electrodes from. I have only a couple left. I assume Kellers are no longer!


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