GB285420A - Improvements in and relating to a method of and devices for measuring the momentary values of varying accelerations - Google Patents

Abstract

285,420. Ambronn, R. Feb. 16, 1927, [Convention date] Vibrations, indicating, &c.-A method of and apparatus for investigating earthquakes and the propagation of artificially-produced seismic waves consists in measuring the pressure of a yieldingly suspended mass upon a pressuresensitive contact, the mass or the contact being carried by an adjustable lever balance. The variations of pressure due to vibrations or accelerations of the mass may be measured by electrical instruments measuring the variations of resistance between contacts of carbon, or piezo-electric crystals or by the optical double refraction of transparent plates. As shown in Fig. 2, the mass M is suspended from a spring F attached to one arm of a balance W, the other arm of which carries a counter-weight P. The mass carries a contact point which rests upon a fixed contact A, these contacts being in circuit with a source of supply or battery EK, Fig. 5, through a Wheatstone bridge arrangement comprising induction coils SF1, SF2, variable resistances Wi1, Wi2, and a measuring instrument Ga, the resistances being bridged by condensers C1, C2. By varying the resistances the bridge can be balanced for the direct current, so that the instrument will measure the alternating component of the pulsating current due to variations of resistance at the contacts A. Instead of attaching the mass to the arm of the balance it may be suspended from a fixed point, the contact A being carried on the balance arm. In another arrangement a compound lever balance may be provided, the mass carried by one of the levers being supported by a spring. For horizontal accelerations or vibrations the mass M may be supported as shown in Fig. 4, the pressure-sensitive contact being carried by a balance beam W provided with adjusting screws g.