This chronograph was developed for use in recording the loudness of blows from piano hammers as an artist is making an Ampico record. It records accurately the velocity of each hammer at the moment it strikes the strings.The chronograph, which is of the spark type, records on either stationary or slowly moving paper. A cylindrical drum with a spiral conductor distributes the time interval sparks at right angles to the motion of the paper.A new method of making visible the spot, where the secondary spark punctures the paper, is described. This method permits the use of a very feeble current. A secondary spark energy sufficient to puncture the paper is all that is needed. The punctured spot may be made visible regardless of its size.A simplified electrical circuit for producing the secondary spark is described.Curves and data are given showing the relationship between the velocity of the hammer and the loudness of the piano tone in sesation units.The chronograph with its auxiliary system of recording feeble sparks is applicable to many fields of scientific investigation.