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Trains of Boulders, in Berkshire, Mass. 399 
funnel touched the ground, the gyratory and sustaining velo- 
city being checked, it would spill a portion of its ponderous 
burden, and thus strew in its march the long, narrow, and gi- 
gantic pathway of stones which we behold. So long as its 
apex dragged the bottom, this discharge would proceed, and 
there would be produced a continuous line of fragments; but 
Whenever its level undulated, either from varying depth or 
vast swells at the surface, it would touch the bottom only in- 
termittingly ; and thus it would alternately strew and miss, 
precisely as the whirlwind of the tropics moves in bounds or 
long undulating skips, now uprooting the earth, and now mov- 
ing lügh above the tops of the trees and houses. In this way 
We may explain the interruptions visible in especially the 
shorter and less regular of the trains. 
Whenever the vortex passed either. of the mountain 
barriers lying across its path we can see that its containing 
apex might have its velocity of gyration somewhat disturbed 
and retarded; and to this cause perhaps is attributable the 
increased abundance of the boulders on the south-eastern 
‘lope of the Richmond mountain. 
In relation to the alternations in the course of the train 
Where it climbs the Richmond Ridge, and again where it 
Teaches the broad valley.beyond, it is not difficult to perceive 
Ow the last or main elbow at least might be occasioned. 
We have only to reflect that the general current would natu- 
Tally change to a somewhat more southerly direction, as it met, 
In this deep, wide and unobstructed valley, with other portions 
x the coming in more nearly from the north, rushing lon- 
e udinally along the mountain chain. The extreme violence 
"ith which the blocks would be occasionally hurled from the 
apex of the revolving column, against the ground and against 
= other, will sufficiently account for several of them being 
Split, with their fragments still contiguous to each other, as if 
force which impelled them was from above, and not that of 
Onward horizontal current. — 
Vou, belie ve that the vortices or gyratory currents 
V 
c 22 
