This is a Swiss Tachymeter Timer, which says Park Watch Co. The dial is great and in color and the detail is eye catching. These were for measuring speed over a measured distance , To use a tachymeter-equipped watch for measuring speed, start the chronograph at a starting marker of a known distance. At the next marker, the point on the scale adjacent to the second hand indicates the speed (in distance between markers per hour) of travel between the two. The typical tachymeter scale on a watch converts between the number of seconds it takes for an event to happen and the number of times that event will occur in one hour. The formula used to create this type of tachymeter scale is T=3600/t where T is the tachymeter scale value; t is the time in seconds that it takes for the event to occur; and 3600 is the number of seconds in an hour. Showing 35 seconds elapsed, about 103 units by calculation As a sample calculation, if it takes 35 seconds to travel one mile, then the average speed is 103 miles/hour. On the watch, 35 seconds gives scale value 103. Similarly, if one kilometre takes 35 seconds then the average speed would be 103 km/hour.