When Did We Figure Out The Speed of Sound?

Apparently as far back as the New Testament, Roman seamen had a general idea of the speed of sound in saltwater.

In Acts 27, the author, a passenger on a Roman ship, describes being blown off-course by a storm, and approaching land.

“They took soundings and found that the water was a hundred and twenty feet [deep]. A short time later they took soundings again and found it was ninety feet [deep].”

So clearly by ~60 CE the Romans had it figured out, although how they got there eludes me. I’m also unclear on how they measured such small periods of time (viz, seconds), absent clocks. My guess is that they had a count of some kind: count to ten: 100 feet. Count to five: 50 feet. Etc.

This (depth measurements being called “sounding”) has nothing to do with the speed of sound:

“Sounding” derives from the Old English sund , meaning “swimming, water, sea”; it is not related to the word sound in the sense of noise or tones,[2] but to sound , a geographical term.

Why do you mention that. It has nothing to do with the speed of sound or sound at all. They would have taken a ‘sounding’ by lowering a weighted rope or chain into the water.

It appears as if I have vastly misunderstood what is meant by “soundings” then. I thought some guy sat on the bottom of the ship with his ear to the “floor,” knocked a hammer against it (or something), and he counted until he heard the echo.

Unlikely since the speed of sound is much faster in water than in the air.

I’m guessing the OP doesn’t do much reading. Naval sounding is mentioned in what seems like pretty much any book that deals with sailing, boating, or naval history.

Well, maybe “doesn’t do much reading about sailing, boating, or naval history,” which is quite different from “doesn’t do much reading.”

This has turned out to be sort of an Emily Litella thread…

but the thread title is still a reasonable question (as is the OP’s question about how seconds were measured).

See also: sounding rockets.

Also, the Long Island Sound is not a concert venue.

But back to the original topic, it’s trivially easy to measure the speed of sound in air. You can measure it at a baseball game by noting how long after you see the ball hit the bat to when you hear the sound. You just need a clear line of sight over a distance of 500 feet or so (in the bleachers) to get an easy measurement. The difference will be roughly half a second at that distance.

The ancients were clever enough to do these calculations.

I thought it was a style of music, sort of akin to the Philadelphia Sound. :wink:

But it wouldn’t be a bad band name for a group of transplanted New Yorkers playing on the west coast.

@Telemark just above.
Lighting & thunder is another good source of events that are big/slow enough to time with manual counting, not needing a clock.

Strictly, timing the interval between sight and sound can only give you the difference between the speeds of light and sound. We take it as a given that the speed of light & perception is so fast as to be effectively instant over the distances involved. But that wasn’t known to be true until somebody figured that out also.

What style of music is The Puget Sound?

@running_coach: definitely grunge.

Sure, but did they have accurate enough clocks to get a measure?

It’s easy to tell that sound moves slower than light, but an exact measure would be difficult.

For something like the OP thought sounding meant, using a form of sonar, there’d be no way to have anything close enough to give an accurate estimate of depth or distance.

Or a Billy Joel tribute band.

Sure, it’s easy to see a few miles, and a you can create a noise maker that’s visible that distance. At that distance you’re measuring in seconds, and it’s very easy to get a good approximation. They measured the diameter of the earth, this is trivial in comparison.

It’s faster in steel wire also. Recall running barbed wire as a youngster. We stretched about 3-400 feet between braced wooden posts and started stapling towards the center. The hammer noise through the wire from the other end arrived a noticeable time before the noise in the air.

It looks like the first precise scientific measurements were in the 17th century. But I’m sure there were much more casual measurements before that.

It requires some luck to have lighting strike some place that is an identifiable distance away though.

If you count them frequently, eventually you’ll pick up one that does strike an identifiable object, at a known time so you can identify it, and one you can measure or know the distance to. So, yes, some luck, but not tons, more the time to spend doing this.