Wegener also noted that the continents move up and down to maintain equilibrium in a process called isostasy. As an example he cited the sinking of Northern Hemisphere lands under the weight of continental ice sheets in the last ice age, and their rise since the ice melted some 10,000 years ago.
Drill that is fitted with a Pipe provides effective connection to the rig surface equipment or application with the bit and the bottom hole assembly for the purpose of pumping the Drill fluid to the bit.
The use of a seed drill can improve the ratio of crop yield (seeds harvested per seed planted) by as much as nine times. Some machines for metering out seeds for planting are called planters. The concepts involved (such as mechanisms that pick up seeds from a bin and deposit them down a tube) are largely the same.