Theory of the String Galvanometer of Einthoven. 207 

 Table IV. 

 Threshold values of W x n//. 





H'X V/ 



C.E.M. 



H.C.S. 



F.B.r. 



M.L. 



11 



395- 



970- 



965- 



775- 



509- 



638- 



1260- 



1200- 



1265- 



597' 



970. 



1040- 



845- 



750- 



699- 



1290- 



1273- 



1330- 







1120- 

 1440- 

 1260- 

 950- 

 782- 

 842- 

 1705- 

 1508' 

 1680- 

 1980- 

 2230- 

 2500- 

 2600- 

 3120- 

 2990- 

 3220- 

 3410- 



525- 



765- 



960- 



WW* 



863' 



96L- 



1760' 



1185- 



1318' 



1740' 



I960- 



1980- 



2040- 



2190- 



2140- 



2060- 



2000- 



18 



25 



32 



39 



46 



53 



00 



67 



74 



81 



88 



95 



102 



109 



116 



1150- 

 1573- 

 1500- 

 I860- 

 2250- 

 2500- 

 1965- 

 2230- 



123 





Electrical Engineering Laboratories, 

 University of Washington, 



Seattle, Washington, U.S.A. 

 July 10, 1913. 



XXY. Theory of the String Galvanometer of Einthoven. 

 By Albert C. Orehoke, Ph.D.* 



THE theory of the transverse vibration of stretched 

 strings is very fully treated in Lord Rayleigh's ' Theory 

 of Sound 'f. The string galvanometer of Einthoven requires, 

 however, special consideration because of the manner in 

 which the impressed force is applied to the string. It is not 

 applied at a single point of the string as is the case with a 

 plucked string, a pianoforte wire, or a violin string, but 

 throughout almost its entire length, and, since an electrical 

 current forced through the string supplies the motive power, 

 the nature of the circuit external to the galvanometer has an 

 influence upon the motion of the string which must be taken 

 into the account. 



Imagine a stretched string, fixed at its two ends, having 



* Communicated by the Author. 



t Rayleigh, ' Theory of Sound,' vol. i. Chap. VI. 



