19th century velocity measurements

[Adam10mm]

The chronograph was an early 19th century invention using watches and a pen on a spool. How would that have measured muzzle velocity?

The 1873 fired 200gr bullets at a reported 1,300fps. What measuring instruments were available at the time to achieve such measurement?

140 years is a lot of time and I don't mean for it to be so archaic as if men were measuring bullet drop at distance and spending the afternoons performing complex mathematics, but was that the process?

[SlippShodd]

The ballistic pendulum was developed in the 1700s. In common use until the chrony came along.
I was shooting at one in the 1980s.

http://en.wikipedia.org/wiki/Ballistic_pendulum

mike

[357maximum]

Ballistic pendulum is some rather nifty reading

[303Guy]

It does have a problem with energy loss to heating but is seems the results were pretty reliable. I'm not sure how they worked out the losses. I studied them briefly at college, meaning we did the maths of them.

[357maximum]

...be careful doing the maths can make one's head hurt....might even kill brain cells :lol: I know this simpleton is damn glad the ohlers and chronies of the world came along.

[Adam10mm]

Interesting read on the ballistic pendulum. Thanks!

[Cap'n Morgan]

The chronograph was an early 19th century invention using watches and a pen on a spool. How would that have measured muzzle velocity?

Don't know the exact way it was done, but my guess would be a paper clad, rotating drum with a given rpm & diameter and a pen posed above. The bullet would somehow break/close an electrical circuit at the muzzle and again at a measured distance down range. This would lower/raise the pen from the rotating drum, causing it to draw a line for a short duration of time. Using simple math the length of the line could then be translated to time which again would translate to speed.

No need for watches in the above setup. That was probably an earlier approach: Stand near the target - but not TOO close[smilie=1:. Watch the shooter, and when you see a puff of smoke, start your stopwatch. When you hear the bullet impact, stop the watch. Now do the math...

[Dale in Louisiana]

Rotating drum of known diameter & RPM. Fire a bullet through it. The angular dispacement of the two holes tells the transit time for the distance equivalent to the diameter of the drum. then it's a simple ratio.

Dale in Louisiana

[Outpost75]

Dale is describing the Boulanger Chronograph, which was used by the US Army Ordnance until shortly after WW1.

http://books.google.com/books?id=bFTPAAAAMAAJ&pg=PA730&lpg=PA730&dq=boulanger+chronograph&source=bl&ots=hkAXNNuUZf&sig=onEmUQKUUl7eGRryBNHuE-mwJwA&hl=en&sa=X&ei=0OfaUYq_PKT-4APTnoCADQ&ved=0CDUQ6AEwAQ#v=onepage&q=boulanger%20chronograph&f=false

http://books.google.com/books?id=KE9HAQAAIAAJ&pg=PA521&lpg=PA521&dq=boulanger+chronograph&source=bl&ots=b2H5DQS395&sig=HYnrrYK9yVPpA5mwEf9wUrcGuIQ&hl=en&sa=X&ei=0OfaUYq_PKT-4APTnoCADQ&ved=0CDsQ6AEwAw#v=onepage&q=boulanger%20chronograph&f=false

[dudel]

Always thought they could be modified into an effective boolit trap. Boolit transfers all energy into displacing a swinging plate, then drops to a collection pan.

[303Guy]

Rotating drum of known diameter & RPM. Fire a bullet through it. The angular displacement of the two holes tells the transit time for the distance equivalent to the diameter of the drum. then it's a simple ratio.

Dale in Louisiana
I was just thinking the same thing!


Always thought they could be modified into an effective boolit trap. Boolit transfers all energy into displacing a swinging plate, then drops to a collection pan.
Hod that thought! That's not a bad idea. Care to develop it into a working model? The boolit could be directed via a curved twist to a vertically downward direction then trapped in a medium filled pot. No moving parts or perhaps moving but under spring load and a shock absorber of sorts fitted so it returns to position without swinging or oscillating.

[Doc Highwall]

I read somewhere that the chronograph that they used was over 100 feet long and the center was at 78 feet from the muzzle which was why the velocity that was quoted at 78 feet.

[Echo]

Ed McGivern made his own chrony, a rotating cylinder with a pen marking it, and had it certified by the Bureau of Standards. Back in the 20's, I think...
His 5-shots into a playing card in .8 (16/20) second stood for decades.

[Dale in Louisiana]

It is amazing when one looks at the mechanical technologies used to perform feats we do today with electronics.

I was using a "Cincinnati Timer" for time-travel analysis of high voltage circuit breakers for years. A drum rotating at a fixed and known RPM and pencil tied to the circuit breaker linkage allowed us to determine velocities and contact times with millisecond accuracy. It could be repaired in the field by a technician with a few hand tools. The unit that replaced it is microprocessor-based, costs in the mid five figures, and if it breaks, you send it to the factory.

But everybody can afford a Chrony, so I guess it's all good.

dale in Louisiana
(You kids get off mah lawn!)