C. B. WARRING. 137 



boat pushing against the solid bottom. The bottom 

 won't oive, and therefore the boat moves. The rim of 

 the wheel, or the surface of the axle, pushes against the 

 book-cover or the fingers. If this is on the upper side 

 the reaction sends the gyroscope forward ; if on the 

 lower, it sends it backward, and it rises and falls ac- 

 cordingly. 



But sometimes the gyroscope rises to a vertical, 

 apparently without any outside assistance — certainly 

 nothing is applied to it. You set the wheel (fig. 1) going 

 as usual. The instrument begins at once its horizontal 

 movements ; generally it falls a little first, but sometimes 

 it appears to go around without rising or falling for a 

 considerable time. Then very slowly it rises, but with 

 an increasing gyration, until at last the axis becomes 

 vertical. There it spins for a time, until its energy is 

 pretty well exhausted, and then it descends. It is very 

 interesting to watch its movements. They apparently 

 contradict not only the law. of gravitation but its own 

 previous behavior. 



I have been able to find very little in reference to these 

 extraordinary performances. 



Professor Snell, in a note, page 706, vol. ii., Amer. 

 Jour. Ed., alludes to this upward movement, and at- 

 tempts to explain it. He says : "If the wheel is spun 

 very rapidly, and elevated several degrees above the 

 horizontal position, the friction of the indentation on the 

 standard, instead of depressing the disk, will cause it to 

 rise towards a vertical." How entirely he failed to find 

 the true reason is manifest by the fact that the less the 

 friction the better the instrument rises ! The same 

 gyroscope, as I have often seen, will refuse to rise, be- 

 cause the friction of the indentation is too great, and, 

 then, when transferred to a glass plate (fig. 20), where the 

 friction is less, will rise, although in the meantime the 

 velocity of the wheel has diminished ! 



121 



