Waltham Pocket Watch

It's a very nice piece, I hope you are displaying it!

Rather than re-inventing the wheel, I'll give you a few websites that will be of interest to you:

For a History of the company AND to check the serial number (which you don't mention) against a table to find it's age:
http://www.pocketwatchrepair.com/histories/waltham.html

Go here for more detailed information about your specific model:
http://www.nawcc-info.org/WalthamDB/walsernum.htm

It's hard to tell from the photos, but looks to be gold filled. Assuming your age is correct and the other details check out, your watch is worth about $2,000 and I would insure it for $3,500 (replacement value).

A word of advice! DOCUMENT as much as you can about the watch and it's history! Photos of grandpa wearing it, purchase receipts, inheritance documents for it, Names of owners (and a bit of their biography) all contribute to the value and interest in the item. Both for your personal future generations and for any buyers should your family eventually sell it.

Get it serviced and wind it gently once in a while to keep it lubricated. a small gel pack you get with electronics stored near (not on) it helps keep it dry (perhaps in a small display case?).

Above all Enjoy! History is of no use locked in a closet!