But, if the pasteboard be interposed so as to intercept the vibrating segments AOB, DOC, the note becomes much more distinct.
The reason of this is, that the segments of the plate AOD, BOC always vibrate in the same direction, but oppo sitely to the segments AOB, DOC. Hence, when the pasteboard is in its place, there are two waves of same phase starting from the two former segments, and reaching the ear after equal distances of transmission through the air, are again in the same phase, and produce on the ear a conjunct impression.
Brieg carries on a considerable trade, its chief manufactures being linen, embroideries, cotton and woollen goods, ribbons, leather, machinery, hats, pasteboard and cigars.
Among the many experimental confirmations which may be adduced of these proportions we will mention the following: Take a circular plate, such as is available for the production of Chladni's figures, and cut out of a sheet of pasteboard a piece of the shape Abocd (fig.
Its industries include the manufacture of tiles, pasteboard wares and gardening implements, while there are coal mines in the vicinity.