Historical measurement of velocity

[unbalancedbutfair]

I'm not quite sure where this topic belongs but I thought this was the best place for it.

I'm reading "Ammunition its history, development and usage" by Melvin Johnson Jr and Charles Haven- published in 1943. They include copies of a lot primary sources- advertisements, government documents and the like that specifically relate to firearms.

The one that caught my attention was a table from 1884 with trajectory and velocity information for Army calibers. The one in 1853 specifically about the Springfield lists rise of the bullet's trajectory over time- but doesn't include velocity. So I have two questions really. First, how did we go about measuring velocity in this time period? Trajectory is easily enough computed. Did they work backward from trajectory to get the muzzle velocity? Second, did velocity really not begin to measured until after the civil war and the popularization of cartridges?

[Red Badger]

You know - that is a really great question!  I don't have an answer either.  I am sure there was such a critter for for cannon and field pieces but maybe not for rifles.

[Patocazador]

Newton published his book concerning motion, calculus, etc. in 1687 so I'm pretty sure they had the ability to calculate velocity by the mid-1800s. 

[unbalancedbutfair]

Yes the laws of motion do allow calculation. If you know projectile mass and muzzle velocity any fool can calculate the parabola, and the derivatives of each point will give you the velocity (and thus also the energy) at that point. But that starts with the knowledge of the muzzle velocity. I'm not even sure you could accurately measure bullet flight time using the technology of the time. And granted most of my advanced math is in statistics rather than calculus, but I'm not sure even if you had distance, flight time, and bullet mass that is adequate information to calculate muzzle velocity. But obviously the techniques or technology did exist by 1884.

If you know what measurements they could accurately enough take to calculate the rest by all means let me know.

I'd considered perhaps they fired into a pendullum at point blank range to measure energy at a known distance. If that would allow accurate enough measurement, I think you could calculate muzzle velocity (and thus the rest of the universe) from that. But I don't KNOW that that's what they did. I've not run across any description of this in any of my reading. Sources, links, and useful conjecture are all welcome. I'm groping fairly blind here.

[Patocazador]

I don't know how accurate it would be but they could calculate the speed of sound at the location by knowing the altitude and temperature. (I believe Newton figured that out too.) Then the interval between the flash of the weapon being fired and the sound of the the shot would allow them to determine the velocity. A team of observers with stopwatches would probably be necessary to get a semi-accurate determination.

[unbalancedbutfair]

If you measured the interval between flash and sound- how does that give you velocity of the bullet? It seems that would allow you to calculate the distance between you and the firearm- but I'm not sure how that would help with calculating bullet speed.

I suppose if you had synchronized timing and picked a point equidistant from the shooter and the target- and then assigned one person to trigger at impact of bullet and the other to trigger upon seeing the flash- you'd have a semi accurate measure of flight time. ---- But for that to work decently it'd have to be long enough distance that rise and drop would already be an issue. So I'm not sure that would put you any closer to actual muzzle velocity.

[Hanshi]

If you know the weight (mass) of the bullet and the weight (mass)  of a pendulum gong, the velocity would be registered by the distance the pendulum swings when hit by the bullet.  All you need is a scale to measure the swing.  Energy equals mass x velocity.  The energy minus the mass equals velocity.  As long as you know any two of the parameters you can calculate the third.

[Red Badger]

If you know the weight (mass) of the bullet and the weight (mass)  of a pendulum gong, the velocity would be registered by the distance the pendulum swings when hit by the bullet.  All you need is a scale to measure the swing.  Energy equals mass x velocity.  The energy minus the mass equals velocity.  As long as you know any two of the parameters you can calculate the third.

Wow your smart..... 

[unbalancedbutfair]

The pendulum was my best guess too. Turns out was used http://en.wikipedia.org/wiki/Ballistic_pendulum though they used more complicated math to measure the force.

but by the 1800s they used two pieces of paper, one near and one far, both rotating at a known speed along the drive shaft.  The bullet was fired parallel to the drive shaft, and then they figured out based on the difference in the holes how fast the bullet was travelling.  By 1840 they had a clock started and stopped by the bullet's interaction with magnetic fields. Huh.

[beowulf]

this answers the question of how cannon muzzle velocity was measured .  makes my head hurt just looking at the caculations    http://arc.id.au/CannonBallistics.html

[unbalancedbutfair]

That's really cool! 

You can calculate muzzle velocity from the charge of powder and gun characteristics. So they could both model with math- and measure (albeit with a crapton of math) empirically. That's really interesting. Thanks!

[Red Badger]

and they didn't have pocket calculators either!