The instrument that measures the force of an object pulled along a surface is called a dynamometer.

Here's why:

* Force: A dynamometer measures the force applied to an object. In this case, the force is the pull along the surface.

* Measurement: Dynamometers typically use a spring or a strain gauge to measure the force. When the object is pulled, the spring stretches or the strain gauge deforms, and the amount of stretch or deformation is proportional to the force applied.

* Units: Force is usually measured in Newtons (N).

Let me know if you'd like to know more about how dynamometers work!