SEISMIC METHODS 



807 



At the left of the figure is a radio for receiving the shot-time from a 

 radio transmitter connected to the firing circuit of the charge of explosive. 

 The mechanical seismometer is separated from the recorder by a light- 

 tight tube in order to obtain large optical magnification. This instrument 

 has a combined mechanical and optical amplification of over 1500. 



The Taylor mechanical seismometerf was employed extensively in 

 the Gulf Coast prior to the introduction of electric instruments. The 

 characteristic feature of the seismometer is the provision of a thread 

 suspension for the free end of the inertia mass. This suspension makes 



Fig. 496. — Layout of Taylor's early mechanical seismograph equipment in recording position. 

 a, camera carrying case; b, seismometer; c, two-way radio; d, recording camera. (Courtesy of 

 Continental Oil Co.) 



possible the conversion of the vertical motion of the inertia mass into 

 rotary motion of a mirror which is readily adaptable to registration on 

 a photographic film. The inertia mass comprises an aluminum frame 

 filled with some heavy metal (usually a lead compound). The mass is 

 pivoted by the end piece of the frame and supported by a steel spring 

 A cup partially filled with oil is provided to dampen the motion of the 

 inertia mass when the instrument is in use. Light rays reflected from 

 the mirror rigidly attached to the frame indicate the extent of the deflec- 

 tions of the inertia mass. The instrument has a combined mechanical and 

 optical magnification exceeding 10,000. 



Figure 496 shows a Taylor mechanical seismograph set up in recording 

 position, tent open. 



t ir. G. Taylor, "Seismometer," U. S. Patent 1,789,055, issued Jan. 13, 1931. 



