1. A method for delivering information from a surface location on the Earth via a rotary drilling assembly to a downhole location or device utilizing drillstring modulation in accordance with pre-defined adaptive rules of transmission, the method comprising; Rotating the drillstring by motive means located on the surface of the earth, Measuring rotary motion of the drillstring at surface, Establishing optimal drilling rotary speed at surface then modulating the surface rotary speed in order to effect transmission of information to the downhole location or device, Modifying drilling rotary speed at surface in order to optimize the environment for rotary communications such that harmonic vibrations of the drilling assembly are thereby diminished, Identifying optimal rotary speed offset values for surface to downhole information transfer giving due consideration to limitations inherent in surface rotational, downhole equipment and the quality of downhole rotary motion, Identifying the optimal timing for surface to downhole information data sets giving due consideration to limitations inherent in surface rotational equipment, downhole equipment and the quality of downhole rotary motion, and Encoding information and selecting the appropriate format such that the information to be transmitted will be optimally received by any downhole device which is monitoring downhole drillstring rotation.