What are these tools used for?

[OCNC]

My nephew recently came into posession of some vintage machinist tools. Among them were the two pictured below. Does anyone know what they're used for? The upper one is by Starrett and the lower by Craftsman. Rotating the shaft on the right causes the dial to rotate. The rubber cone on the tip of the Craftsman suggests that it was intended to be pressed into the center of a shaft. The Starrett may be incomplete as it lacks a similar cone. The end of it's shaft is hollow.

Chris

[gmfoster]

They are Tachometers. Uses for measuring speed of things.. You count the turns in a given amount of time... Can also be used for linear speed.. Have to be used in conjunction with a known time frame and a little math..

[scott m]

ocnc, gmfoster is 100 % correct they are rpm indicators and I would add that you insert the point of it into a hole (center drill or otherwise) to take the rpm (or is it feet per minute? may need conversion) reading of a shaft or similar part. They often come with rubber wheels of different sizes and for different applications. You hold the rubber wheel against a pulley or what have you and as it spins you watch your clock or watch. Watch it . Scott.