GUEST: This was my great-great-grandfather's. He acquired it back in the early 1800s. And it was passed down from him to my great-grandfather, then my grandfather and then my mother and now mine.

APPRAISER: Wow! What an amazing provenance.

GUEST: Yeah.

APPRAISER: That's so important. We might take a moment to open here and look at this really wonderful piece here. You know what it's called?

GUEST: It's a ship's chronometer.

APPRAISER: It is indeed.

GUEST: Mm-hmm.

APPRAISER: And this was made by the firm of Parkinson & Frodsham.

GUEST: Mm-hmm.

APPRAISER: And they are London makers and they are sort of the Rolls Royce of instrument makers in the mid-19th century.

GUEST: Really?

APPRAISER: And actually they were founded around 1801. What is really important about marine chronometers is all about naval history…

GUEST: Mm-hmm.

APPRAISER: …and how important knowing what time it was.

GUEST: Yeah.

APPRAISER: Because if you didn't know what time it was, you were kind of up the creek, you know what I mean?

GUEST: Mm-hmm.

APPRAISER: Because in order to determine what the longitude was for celestial navigation, you needed to know exactly what time it was.

GUEST: Right.

APPRAISER: Now, I knew that you've got a bunch of receipts and a bunch of old records. What do those talk about?

GUEST: I think they were to calibrate it, is that correct?

APPRAISER: That's exactly right. And they were a second off, three seconds off, four seconds off. That's how important these were. So on a ship, you had two or three. Because if you were a ship owner, you would lose a ship if they weren't able to navigate. So this is actually interesting in that there's a number on the front that's 1846. But that's not the date, it's actually the number of the chronometer that it is. And actually the key here to wind it is the same number. So that's how you know it's really complete. This one was probably made around 1835. And that's about the time it came into your family.

GUEST: Right, that would be about right.

APPRAISER: Many captains?

GUEST: Seafaring captains.

APPRAISER: A seafaring family.

GUEST: Right.

APPRAISER: Have any idea what this is worth?

GUEST: I have no idea. Maybe $1,000, a couple thousand? I don't know.

APPRIASER: If you're insuring this in today's market, I would insure this for around $5,000.

GUEST: $5,000? Yeah.

APPRAISER: It is the best.

GUEST: Yeah.

APPRAISER: You can buy from this time period. It is every captain's dream to have a chronometer.

GUEST: Wow, wow, that's a really good value. But the most important value is the personal value and family value.