A Chip Log, a Log Line Reel, and a Sand Glass

The chip log, a log line reel, and the sand glass used for measuring the speed of a vessel through the water. The chip is tossed, the sand glass turned, the line let out, and the number of knots in the line are counted until the sand glass empties. The number of knots that have passed is the speed of the vessel in knots or nautical miles per hour.

This illustration is from Bowditch's New American Practical Navigator,1868, Plate VI.