CHARLES B. WARRING. US\7/ 
But as the motion is always different from what one un- 
acquainted with the peculiarities of gyrating bodies 
would expect, and is very apt to confuse him, I have 
found it very convenient to use a direction diagram, like 
figure 5, which I place plainly in view when experiment- 
Gs ee 
rsx | 
Vien i dy 
ing. If I tilt up the side of the glass plate correspond- 
ing to V T, the top goes to the right ; if I tilt up TN, it 
goes from me, and so on ; in each case the arrow denotes 
the direction when that side is highest. It must be re- 
membered that here, and all through this paper, the top 
revolves with the hands of a watch, otherwise the effect 
would be reversed. Plates II and III show paths so pro- 
duced and guided. It will be noticed, however, that the 
path is rarely parallel to the sides of the plate, but slopes 
away from it. This is due to the steady downward pull 
of gravity, causing a certain amount of slipping, or per- 
haps, it would be better to say that the oblique path is 
the resultant of two forces, the pull of gravity tending 
to send the instrument directly down the plane, and the 
lateral movement, which tends to send it, as a geologist 
might say, along the strike. 
It will readily be seen that if the glass plate is rec- 
tangular, the corresponding changes of direction must 
also be rectangular as in all the paths shown in the en- 
gravings. If the glass plate is, say, an equilateral 
triangle, the resulting paths will be a similar triangle. 
To do this satisfactorily, the experimenter will need a 
guide as for the preyious paths. Draw a small triangle 
on paper, so that the base is towards the observer. 
Then at each vertex draw a short arrow parallel to the 
side opposite, so that the heads point in the direction 
41 
