1899 - 1900 .] Mr Mahalanobis on a New Form of Myograph. 65 
exceed say five grams. A piece of string with a hook at each end 
connects the armature of the electro-magnet with the lever, on the 
same side as the elastic band; the string is of such length that, 
when the armature is held in contact by the electro-magnet, any 
contraction of the muscle immediately exerts a pulling force on it. 
The muscle can be stimulated by its nerve placed on the 
platinum electrodes (E), or directly by sticking in two pieces of 
thin wire led off from the adjacent binding screws connected with 
the secondary coil. 
The primary coil of an inductorium is so connected with the 
Fig. 2. — Surface view of Instrument and necessary connections. 
A, lever ; B B , clamps ; D, drum ; E, electrodes ; M, electro-magnet ; K, 
armature ; 0, elastic band ; P, pulley ; S, pin ; T, spring ; Y, support of 
drum ; Z, battery ; I. primary coil ; II. secondary coil ; III. steel spring 
for isometric contraction. 
battery as to include the electro-magnet of the myograph in the 
circuit. Instead of using an ordinary key a special device is made 
in which the revolving drum (D) is utilised for closing or opening 
the circuit. The binding screw W (fig. 2) is in contact with the 
metal support (Y) of the drum, whereas a piece of ebonite insulates 
E 
YOL. XXIII. 
