We have in the first place to take into account the fact of the larger modern bar taking up more room than the old obsolete one of, not only Stradivari, but all the other masters of his time and before. The upper and lower end blocks have been enlarged in many instances to obtain a better hold on the upper and lower table. These alterations have been each of necessity, not of ignorance or mere whim, and moreover have proved efficacious for the end in view. The restorers, or regulators who have performed these operations must--according to the "air mass" theory--have been acting quite "in the teeth" of it and Stradivari's regulation, further there is not one fiddle in a hundred--perhaps not that--which has been in use for a generation but what shows a sinking one side or the other, or, when the modelling is full, a depression in the middle of the upper table, and very frequently a greater fulness at the back where the sound post touches and presses from the inside. These alterations, individually or collectively, alter the "air mass" of the interior, and the violin thus, according to the theory, contains within itself the elements of its own early dissolution, so far as fine quality is concerned. Facts, however, go to prove the contrary, and with the modern regulator's efforts to obtain the best amount of a good thing known to be present, it is quite probable that Stradivari himself never heard his instruments to such advantage as they may be now, notwithstanding the unreasonably high pitch to which violinists are obliged to conform their tuning. There was another theory promulgated many years back by certain people of some degree of eminence in their own walk in life. A grand discovery was announced, that the excellence of the violins of Stradivari consisted in the tonal difference between the upper and lower tables peculiar no doubt to that master. This sort of committee of scientific experimenter, violin dealer and author, did not--while centralising their efforts on the violins of one master--say whether the same relationship existed between the back and front of a Nicola Amati, Maggini or Gasparo de Salo, they made something of a slip when they mentioned the violins of the great Joseph Guarnerius as showing the same tonal difference.