A text-book of the diseases of the ear for students and practitioners . ption for the upper,middle, and lower tones. In addition to the fundamental tone, a number of over-tones are producedwhen the prongs of most tuning-forks are struck against a hard substance;these tend to destroy the effect of the examination. To overcome this annoy-ance, the author proposed weighting the prongs of the tuning-fork with twobrass clamps, fastened by screws. The over-tones can also be overcome bypressing the lower ends of the prongs together near their place of author has recently had forks made with
A text-book of the diseases of the ear for students and practitioners . ption for the upper,middle, and lower tones. In addition to the fundamental tone, a number of over-tones are producedwhen the prongs of most tuning-forks are struck against a hard substance;these tend to destroy the effect of the examination. To overcome this annoy-ance, the author proposed weighting the prongs of the tuning-fork with twobrass clamps, fastened by screws. The over-tones can also be overcome bypressing the lower ends of the prongs together near their place of author has recently had forks made without clamps, which were filedat the lower and inner sides of the prongs near their place of curvature ;these accomplished the same effect as the forks described above, weightedwith clamps. Upon striking one of these forks against a soft substance, noover-tones are perceptible. In the small tuning-fork of Blake, which has aclear fundamental tone, the upper ends of the prongs are very much , Lucae and others, have constructed an apparatus to produce a. Fig. 86. constant stroke, which consists of a tuning-fork connected with a hammermade of steel. This instrument is not of much value, because in the courseof time the strength of the beat becomes altered by the wearing out of thespring. Gradenigot has recently proposed an optical method by which the degreeof vibratory intensity of the tuning-fork can be read off by the naked eyewith a fair amount of accuracy. He uses for this experiment low tuning-forks of forty to eighty vibrations, at the upper ends of which a black triangleis drawn on a white background, and which is divided into three parts byparallel lines (Fig. 86). If the tuning-fork is struck, two pale triangles, witha short black triangle common to both, appear during the greatest excursions ;the latter enlarges superiorly as the vibrations become less, while the twopale triangles gradually emerge into one. By the distance at which thesetwo triangles are
Size: 2361px × 1058px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectear, booksubjecteardi
