Scientific Instruments (Pre 1950'ish)

Some really accurate measurements can be had with those old devices and it's a testament to the manufacturer and the user.
Yes, imagine dividing those plates into parts of degrees, minutes then seconds
And accurately.
Share some more. I've about exhausted except for an old theodolite that saw life in a coal mine. I haven't cleaned it despite its need. Part of its heritage.

avondale87 wrote in post #19059622
Some really accurate measurements can be had with those old devices and it's a testament to the manufacturer and the user.
Yes, imagine dividing those plates into parts of degrees, minutes then seconds
And accurately.
Share some more. I've about exhausted except for an old theodolite that saw life in a coal mine. I haven't cleaned it despite its need. Part of its heritage.

Not to mention that some of the measurements standards changed in 1840 - or somewhere about that time. It was bad enough when we went from cgs to mks and SI units, and then to crown it all, they metricised our currency system! That said, I’ve always used metric for scientific type formula but revert to Fahrenheit, inches, feet, miles, pounds and ounces for domestic stuff.

Barograph manufactured by Negretti & Zambra C1940-50.

Consists of:-
1. A cylindrical drum rotated by a seven day mechanical clock.
2. A pressure/vacuum unit to to expand a contract with changes in air pressure. This unit consists eight stacked and evacuated capsules.
3. The capsule stack is linked by levers to the ink-charged pen arm which draws a line on the rotating chart for seven days.
4. The chart has to be changed weekly.
5. The linkage also moves the pointer on the circular scale.
6. A thermometer.
7. A narrow drawer for charts.

Beautiful! Is it still accurate?

electronpusher wrote in post #19061074
Beautiful! Is it still accurate?

Thanks for your comment. Accurate still working without problems. The pen is original but I have resisted temptation to replace it with a felt tip replacement. Charts are still available. I also have a similar model with a larger drum to give a more expanded scale that I am still using. I will post it sometime.

Magdeburg hemispheres

Dia 2.75" (7cm) x Length 10.5" (27cm)

The Magdeburg hemispheres shown are a pair of machined brass hemispheres, with mating rims. They were used to demonstrate the power of atmospheric pressure. When the rims were sealed with grease and the air was pumped out, the sphere contained a vacuum and could not be pulled apart by teams of horses. The Magdeburg hemispheres were invented by German scientist and mayor of Magdeburg,[1] Otto von Guericke, to demonstrate the air pump that he had invented, and the concept of atmospheric pressure.

https://en.wikipedia.o​rg/wiki/Magdeburg_hemi​spheres

Interesting one that Ray
The things people came up with to prove or demonstrate principles

avondale87 wrote in post #19062758
Interesting one that Ray
The things people came up with to prove or demonstrate principles

Thanks Richard. Once the hemispheres are evacuated, even with a partial vacuum, they are practically inseparable by hand. Our friend has sold his shire horses so I can't repeat the Otto von Guericke experiment to prove the point.
I have a vacuum pump by Otto von Guericke. I have been trying to restore it for sometime but the leather cylinder washers are rather difficult to make and I have only had limited success.
Just for interest -
https://en.wikipedia.o​rg/wiki/Vacuum_pump

Ray you realise that's how we get milk!
Do you need an explanation?

We'd have to wash the lines out in the dairy and there was a main line (40mm ±) tube running full length of dairy and we'd let it suck soapy water, then run a brush by suction through the pipe.
You'd put your hand over the end of the pipe, hold till your palm was nearly sucked off then pull your hand away and wheeeeeeee. The brush would rattle right through to the vat. It was attached to a string and assuming it didn't snag and break the cord you could drag it back for another run.
Vaccum a a marvellous modern invention. Well the pump is.

Spectrometer. Pre-1900. A high quality instrument but I am unable to identify the manufacturer.
This is a typical laboratory instrument for demonstrating how light can be split into it's component colours/wavelengths.

https://en.wikipedia.o​rg/wiki/Prism_spectrom​eter

I do hope we see more in this thread - those old instruments are so beautiful, and make my mind boggle at the engineering and manufacture behind them. I'm quite clueless about that sort of thing, but I love hearing the explanations and seeing them. 'Fantastical Machinery' is how I'd describe them.

Lovely photography as well.

Ray.Petri wrote in post #19065568
Spectrometer. Pre-1900. A high quality instrument but I am unable to identify the manufacturer.
This is a typical laboratory instrument for demonstrating how light can be split into it's component colours/wavelengths.

https://en.wikipedia.o​rg/wiki/Prism_spectrom​eter

Hosted photo: posted by Ray.Petri in
./showthread.php?p=190​65568&i=i63775104
forum: Still Life, B/W & Experimental

You may like this link:
http://www.che.uc.edu …s/07.%20Spectro​scopes.pdf

You can use that spectrometer for flame tests.
https://www.degruyter.​com …2018-0013.xml?language=en

Capn Jack wrote in post #19067537
You may like this link:
http://www.che.uc.edu …s/07.%20Spectro​scopes.pdf

You can use that spectrometer for flame tests.
https://www.degruyter.​com …2018-0013.xml?language=en

Thanks for your interest Capn’ and thanks for the interesting links. I think the top link with illustrations was particularly interesting and well presented. And it was nice to see the approx dates were given for the pictures. On my picture you can see the small prism for the reference light source (Nearest to the front of picture) - this helps me date my instrument.
I have a more modern version but it is a bit bigger and heavier. I might post it when I get time to photograph it.

greyswan wrote in post #19067535
I do hope we see more in this thread - those old instruments are so beautiful, and make my mind boggle at the engineering and manufacture behind them. I'm quite clueless about that sort of thing, but I love hearing the explanations and seeing them. 'Fantastical Machinery' is how I'd describe them.

Lovely photography as well.

Thanks for your comments greyswan. I hope this thread picks up a bit because I’d like to see what’s lurking around too. These older instruments can be rather photogenic, whereas the later instruments tend to be just boxes with knobs and push buttons, with the even later ones having digital displays, and, dare I joke about it, USB ports.

Ray.Petri wrote in post #19067681
Thanks for your comments greyswan. I hope this thread picks up a bit because I’d like to see what’s lurking around too. These older instruments can be rather photogenic, whereas the later instruments tend to be just boxes with knobs and push buttons, with the even later ones having digital displays, and, dare I joke about it, USB ports.

They do have USB ports, touchscreens, Bluetooth, and ethernet too. And more automated. The ethernet connections are to get data to electronic notebooks.