70 



Dr. B. W. Richardson on the Sphygmophone. [May 15, 



hearing on the right side np to 110°, from destruction of the tympanum, 

 an instant gain down to 60°, a gain of 50° on the audiometric scale. 



In this preliminary report I have omitted many subjects of interest, 

 but I hope I have related enough to show that the world of science in 

 general, and the world of medicine in particular, is under a deep debt 

 of gratitude to Professor Hughes for his simple and beautiful instru- 

 ment, which I have christened the audimeter, or less correctly but 

 more euphoniously, the audiometer. 



Y. " Note on the Invention of a Method for making the Move- 

 ments of the Pulse Audible by the Telephone. The 

 Sphygmophone." By Benjamin Ward Richardson, M.D., 

 LL.D., F.R.S. Received May 14, 1879. 



While experimenting with the audiometer, it occurred to me that 

 I might get a secondary or telephonic sound from the movements 

 of the pulse at. the wrist. I have effected this in a very simple 

 manner, by adding a microphone to a Pond's sphygmograph. I mount 

 on a slip of talc, glass, wood, or ebonite a plate of metal or gas carbon. 

 I place the slip in the sphygmograph as if about to take a tracing of 

 the pulse. I connect one terminal from a Leclanche's cell to the 

 metal or carbon, and the second terminal from the cell to a terminal of 

 the telephone. Then I connect the other terminal of the telephone 

 with the metal rod of the sphygmograph. The instrument is now 

 ready for use. It is placed on the pulse, in the ordinary way, and is 

 adjusted, with the writing needle thrown back, until a good pulsa- 

 ting movement of the needle is secured. When the movement is in 

 full action, the needle is thrown over to touch the platinum plate, 

 which it traverses with each pulse-movement, and completes the con- 

 nexion between the telephone and the battery. The needle, in passing 

 over the metal or carbon plate, causes a distinct series of sounds from 

 the telephone, which correspond with the movements of the pulse. 

 When all is neatly adjusted, the sounds heard are three in number, 

 one long sound and two short, corresponding to the systolic push, the 

 arterial recoil, and the valvular check. The sounds are singular, as 

 resembling the two words, "bother it." The sounds can be made 

 very loud by increasing the battery power. 



This little instrument is not so good a recorder of the pulse as the 

 sphygmograph, but it may be made very useful in class, for illustrat- 

 ing to a large number of students, at one time, the movements of the 

 natural pulse, and the variations which occur in disease. I call the 

 invention the sphygmophone. 



