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Elements of natural philosophy (Volume 2-3) . Angle ofincidence equalto that ofreflexion. § 76. When the pulse proceeds ina homogeneous medium from a pointof disturbance, it takes a sphericalshape, the normals all meet at thecentre of the sphere, and the raysare then said to diverge from a point,in which case the sound becomesless intense as it proceeds. Fig. 42. Diverging sound;. Intensitydiminishes: 84 NATURAL PHILOSOPHY. Convergingsound; Intensity-increases ; Fig. 43. When in the progress of the pulse it retains its spheri-cal shape, but any portion of it be-comes so modified as to present
Elements of natural philosophy (Volume 2-3) . Angle ofincidence equalto that ofreflexion. § 76. When the pulse proceeds ina homogeneous medium from a pointof disturbance, it takes a sphericalshape, the normals all meet at thecentre of the sphere, and the raysare then said to diverge from a point,in which case the sound becomesless intense as it proceeds. Fig. 42. Diverging sound;. Intensitydiminishes: 84 NATURAL PHILOSOPHY. Convergingsound; Intensity-increases ; Fig. 43. When in the progress of the pulse it retains its spheri-cal shape, but any portion of it be-comes so modified as to present itsconcavity in front, the rays will meetat some point in advance, and aresaid to converge / the sound will be-come louder and louder as it pro-gresses, and finally, when it reachesthe point of union of the rays, it willattain its maximum intensity ; for inthis position the living force, whichwas before distributed among the molecules of an ex-tended pulse, is concentrated in the few molecules of avery contracted pulse.
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