232 
Proceedings of the Royal Society of Edinburgh. [Sess. 
I. Hand Movement Apparatus. 
The chief movements made in writing are those of the forearm, of the 
hand, and of the fingers. Of these the only movements presenting any 
difficulty for analysis are those of the fingers, and the finger movements 
are at the same time the most interesting. The isolation of the finger 
movements can be obtained by a process of elimination. In the actual 
writing we have the resultant of all the movements. The hand movement 
is the resultant of all the movements except those of the fingers. Hence, 
if we can trace the hand movement, the difference between this and the 
writing will give us the part played by the finger movement. 
Professor Charles H. Judd has devised and described an apparatus for 
tracing the hand movement during writing ( Genetic Psychology for 
Teachers, New York, 1907). Our apparatus is an improved form of this. 
In Judd’s apparatus a broad strip of metal, bent so as to grip the fifth 
metacarpal bone of the right hand, is bent back a second time on its upper 
surface, so as to hold a wooden pin, to which a tracing arrangement is 
attached by a short metal bar with hinges at each end, allowing free move- 
ment in the plane of the wooden pin and the writing or tracing style. The 
tracing style is cylindrical in shape and brought to a rounded point with 
slits so as to hold ink like a pen point, while it moves freely in a longi- 
tudinal direction through a range of about 1J inches within a light frame. 
The point is kept resting on the paper by gravity alone, and the longi- 
tudinal play is intended to allow for different inclinations of the back of 
the hand to the plane of the paper in different individuals and at different 
points in the writing. 
Judd’s apparatus is defective in several respects. In the first place, the 
position of the tracing arrangement is itself very awkward, since its plane 
is almost parallel to the back of the hand, and in writing it seems to drag 
along the surface of the paper, sometimes interfering considerably with the 
movement of the hand, and always distracting the attention of the writer. 
In the second place, the joints are not sufficiently rigid and the free move- 
ment at the joints intensifies the dragging and distracting behaviour of the 
tracing style, while it also allows the hand to move without the tracing 
point moving. In the third place — and this is the chief defect — gravity 
cannot be relied upon to keep the point constantly on the surface of the 
paper, especially where there are sudden and rapid changes in the inclina- 
tion to the paper of the back of the hand. 
In order to remedy these defects and get an apparatus on which we can 
rely for a true record of the hand movement, it is necessary to attach the 
