O. N. Rood on the Gyroscope. 259 
3rd, Yellow and indigo blue of Ist order gave easily a very 
white. The same tints in the 2nd order united with more 
Union was about the same in 8rd order. 
4th, Greenish yellow and violet of 2nd order combine to a 
white with some difficulty. The same is true of these tints be- 
longing to the 3rd order. 
oth, Green and purplish red of the 2nd order, united with 
moderate ease. The same tints in the 3d order united with 
great ease, and the resultant white could be retained very steadily. 
tom the above it will be seen that the union most easily 
takes place when the complementary tints have a low intensity. 
esame result can also be produced with the colored discs b 
shading them, when the two impressions much more readily fuse 
mio a neutral single one. 
Art, XXIX.—On an experiment with the Gyroscope; by Prof. 
O. N. Roop, of Columbia College. 
Ir a gyroscope be suspended in equilibrium by pivots at p 
amd p', and the disc be set in rotation in the direction indicated, 
and an attempt be made to cause it to rotate about a new axis 
PP, in the direction shown at A, the 
dise will tend to turn in the direction 
‘sand if the pivots p p’ are immov- 
able, pressure against them will be 
Generated in the direction s s, which 
EB ragtinee till the disc has been ro- 
has 
oo Over an arc of 180°, when this tendenc 
_.Way, to rotate rapidly about a new axis as p p’, 1 
: Notion migh Heese: 
: fri and allowed to remain undisturbed, continued in motion 
. 6 minutes, It was connected with a set of multiplying 
it was forcibly caused to revolve about the new axis pp’, 
