62 
Proceedings of Royal Society of Edinburgh. [sess. 
A New Form of Myograph and its Uses. By S. C. 
Mahalanobis, B.Sc., F.R.M.S., F.R.S.E., Assistant Lecturer 
on Physiology, University College, Cardiff. 
(Read December 18, 1899.) 
In connection with some investigations dealing with the velocity 
of muscular contraction under different conditions, I found it 
necessary to design a special apparatus for certain experiments. 
It subsequently occurred to me that, with some modification, this 
instrument could with advantage be used for various myographic 
purposes. I was thus induced to make the necessary additions 
and alterations — adapting the instrument for some special, as well 
as for most of the ordinary experiments in which a myograph is 
used. 
A. Description of the Apparatus. 
The instrument has a T-shaped lever (A) turning on a short 
axle passed through the centre of the head and so pivoted as to 
admit of free horizontal movements of the lever. To the long arm 
of the lever is attached a piece of straw provided with a writing 
point which records its history on a horizontal cylinder. The 
short arms have a number of holes into which S-shaped muscle 
hooks can be inserted. At a little distance from the support of 
the lever — at about the middle of the ebonite plate (G) that forms 
the base or floor of the instrument there is a fixed block of ebonite 
(C) forming a small support for two strips of brass (B) that are 
used as clamps. The two pieces of brass are insulated from one 
another — each being held on the top of the ebonite block by means 
of a pair of milled-head screws. Just behind the clamps there is a 
small upright rod (F) carrying a pair of electrodes (E) that can be 
held at any level. Still further back and near a corner there 
stands a firm pillar (H) supporting an electro-magnet (M) with 
adjustments for movements in two directions, i.e., the electro- 
magnet can be raised or lowered and also moved backwards or 
