METHODS OF USING BALANCED-MAGNET 

 CHRONOSCOPES 



KNIGHT DUNLAP 



The Johns Hopkins University 



The following schemes may be used equally well for installing 

 the Johns Hopkins chronoscope 1 or the Hipp as used by my 

 method 2 without armature springs. The diagrams (figs. 1 

 and 2) are given for the former instrument: in setting up the 

 latter, the circuits which operate the synchronous motor of the 

 Johns Hopkins chronoscope are of course to be omitted. 



The Johns Hopkins chronoscope operates either on (1) direct 

 current, with tuning fork interruption for the motor circuit, or 

 (2) alternating current for the motor circuit, without fork, and 

 direct current for the clutch circuits. The alternating current 

 of the usual house lighting circuit is 60 cycle, and power circuits 

 are sometimes 25 cycle : it will be assumed that one or the other 

 of these frequencies is to be employed. The first system is 

 represented in figure 1 : the second system in figure 2. 



THE MOTOR CIRCUIT 



The motor circuit and the clutch circuit may be drawn from 

 the same direct current source, which may be the 110 to 120 

 volt power circuit as indicated in figure 1, or may be storage 

 battery or rotary transformer circuit. Otherwise, the motor 

 circuit and the clutch circuit are entirely distinct, and may 

 be usefully described separately. 



In using alternating current 110 to 120 volts (the potential 



1 Dunlap: The Johns Hopkins chronoscope. 1917, Jour, of Exper. Psychol., 

 ii, 299-252. 



2 Dunlap : The Hipp chronoscope without springs. 1912, Brit. Jour, of 

 Psychol., v, 1-7. 



Poffenberger and Morgan: The Hipp chronoscope: its use and adjustments. 

 1916, Jour, of Exper. Psychol., i, 185-199. 



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