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Reflection Observations

in of a beam of light which has astronomy, those which measure the been reflected from the surface of some is a beam from a heavenly body, as in sextant observations with an artificial liquid, generally mercury. Sometimes it horizon, or in measuring the reflected zenith distance of a star with a meridian it is a beam of light, or rather the want circle in an observatory, and sometimes of light, which makes the shadow of the wires of a transit or meridian circle from a lamp used in the nadir observations of an observatory. ple of a plane reas a throws back rays of light, heat, etc.; a reflecting surface. In optics, a device by which the rays proceeding from a luminous or heated object are thrown back or diverted in a given direction.

The reflecting surface may be either plane or curved. In practice it is often made spherical or parabolic. A mirror is a familiar example of a plane reis a familiar example flector. The material should be smooth and highly polished as possible.

Sheet tin is frequently used for common purposes, as for door, hall, or vehicle more perfectly reflecting surface is emlamps, while for other purposes ployed, such as speculum metal or silver protected by glass. Silver is the most perfectly reflecting substance known, absorbing but 9 per cent. of the incident rays, while speculum metal absorbs 37 per cent. Glass itself, owing to its property of totally reflecting incident rays at a low angle, is used in certain cases.

Reflectors with parabolic surfaces are ing from objects placed in their foci in employed for throwing the light emanatparallel straight lines to a great distance, and for converging the heat rays from a distant object, as the sun, to a focus, and also, in connection with eye is itself often simply denominated a glasses, in the reflecting telescope, which reflector. is itself often simply denominated a physiology, those actions of the nervous system whereby an impression is transmitted along sensory nerves to a nerve a motor nerve, and so calls into play center, from which again it is reflected to some muscle whereby movements are produced. These actions are performed involuntarily, and often unconsciously, as the contraction of the pupil of the eye when exposed to strong light. See theory and practice concur in indicating REFORM ACTS