Newtonian telescope secondary mirror. This design reduces the size and cost of the telescope with a shorter overall telescope tube length (with the corrector extending the focal length in a "telephoto" type layout) combined with a less costly spherical mirror. Commercially produced versions of this design have been noted to be optically compromised due to the difficulty of producing a correctly shaped sub-aperture corrector in a telescope targeted at the inexpensive end of the telescope market. Newtonian telescope The Newtonian telescope, also called the Newtonian reflector or just the Newtonian, is a type of reflecting telescope invented by the English scientist Sir
Galilean electromagnetism to any consistent Galilean limit. Rousseaux gives a simple example showing that a transformation from an initial inertial frame to a second frame with a speed of v with respect to the first frame and then to a third frame moving with a speed v with respect to the second frame would give a result different from going directly from the first frame to the third frame using a relative speed of (v + v). Le Bellac and Levy-Leblond offer two transformations that do have consistent Galilean limits as follows: The electric limit applies when electric field effects are dominant