At best, when the records are satisfactory, nothing can be said for the measurements of intensity but that they represent relations of more or less; the diaphragm has a minimum intensity, below which it does not vibrate, and a maximum intensity, above which the amplitude of its vibrations does not materially increase without breaking into partials and ‘blasting.’

The disc recorder, which had for a mount a modified microscope stand, was placed on the shoe of the disc stand and clamped.  The wax and disc records were adjusted at known starting-points and the stylus carefully lowered, by the rack and pinion adjustment, to the surface of the disc.  After a preliminary trial of the diaphragm the apparatus was started, and when at full speed at least two satisfactory records of the material were taken.  When the disc had made a single revolution—­a record of some ten or fifteen stanzas—­the recorder was fed inward to a new circle on the disc.  After the records were taken, a microscope with either 2 or 4 Leitz objective and a micrometer ocular was substituted for the recorder.  The phonograph recorder was raised and drawn back to its starting point, and the disc came back to its original position.  The microscope was focussed, and adjusted by the screw of the shoe until it had the record line in its field; the micrometer furnished an object of reference in the field.  The phonograph, now carrying the reproducer—­if possible without a horn, as the tones are truer—­was started.  At the first syllable of the record the apparatus was stopped by the device furnished on the ‘Commercial’ phonograph, and the plate was turned by adjusting the screw at the phonograph carriage, which changed the length of the chain connecting the two records, until the record of the first syllable was at some chosen point in the field.  In cases of records of poetry it was found better to have a set of syllables, say ’one, two, three’ prefixed to the record, for this adjustment.  The phonograph was again started, and the curve-forms representing the spoken syllables filed past the point as the phonograph repeated each syllable.  The rate was slow enough, with the objective 2, so that there was no difficulty in observing the passing syllables.  After the conformity of the phonograph record had been noted by the operator, and the subject had passed judgment on the phonograph as saying satisfactorily what he had said, the curve-forms were measured with the micrometer.  The record was fed slowly through the field by means of the chain screw on the phonograph carriage; and measurements of the lengths of syllables gave their time values.  The micrometer was passed back and forth across the form by the shoe screw, for the measurements of amplitude (intensity).  The micrometer measurements in this case could be made at least as rapidly as measurements of kymograph curves.  The measurements, with the powers used, are accurate to.01 sec.