Each of these 10 subjects appears in only one of the 6 encyclopedias on this shelf. None is long enough to carry a page by itself, so they are gathered here by letter. Anything that grows moves out to a page of its own.
a form of microscope first proposed by Newton, in which the image formed by a small concave speculum may be viewed either by the naked eye or through an eyepiece. The object is placed outside of the tube of the microscope, and reflects its image to the speculum by means of a plane mirror, inclined at an angle of 45° to the axis of the former.
Only in Collier's New Encyclopedia
a telescope in which the rays are received on an object-mirror and conveyed to a focus, at which the image is viewed by an eyepiece.
Only in Collier's New Encyclopedia
A small mirror confined within a frame, having a small handle. These glasses are supplied by the foundry supply dealers, and are extremely useful for directing light down into the deep cavities of a mould.
Only in The Encyclopedia of Founding
in astronomy, those which measure the of a beam of light which has been reflected from the surface of some liquid, generally mercury. Sometimes it is a beam from a heavenly body, as in sextant observations with an artificial horizon, or in measuring the reflected zenith distance of a star with a meridian circle in an observatory, and sometimes it is a beam of light, or rather the want 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.
Only in Collier's New Encyclopedia
that which reflects, or 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 ple of a plane reis a familiar example flector. The material should be as smooth and highly polished as possible. Sheet tin is frequently used for common purposes, as for door, hall, or vehicle lamps, while for other purposes a more perfectly reflecting surface is employed, 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 employed for throwing the light emanating from objects placed in their foci in parallel 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 glasses, in the reflecting telescope, which is itself often simply denominated a reflector.
Only in Collier's New Encyclopedia
in physiology, those actions of the nervous system whereby an impression is transmitted along sensory nerves to a nerve center, from which again it is reflected to a motor nerve, and so calls into play 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 NERVE.
Only in Collier's New Encyclopedia
schools instituted for the training of juvenile offenders who have been convicted of an offense punishable by imprisonment. The first reformatory managed under legislative control was the one established in New York in 1824, known as the New York House of Refuge. Its success was so marked that similar institutions were established throughout the country. See JUVENILE COURTS.
Only in Collier's New Encyclopedia
All such substances as melt only at the highest temperatures that can be produced are classed as refractory. Amongst these are included some natural rocks, as sandstones, quartzites, granites, etc.; but it is not customary to use these alone for metallurgical purposes, on account of their liability to split apart at high temperatures. The principal substances employed, in varying proportions, as mixtures for furnace-linings, crucibles, retorts, fire-bricks, etc., are silica, magnesia, bauxite, steatite, clays, carbon, gannister, coke, etc. Nearly all clays require to be mixed with other materials, to counteract the tendency to shrink and crack. If it were not for these admixtures, the bricks made from some of the clays would soften and melt away when subjected to very high temperatures. A description of the materials mentioned, and numerous other refractory substances, will be found at their respective places.
Only in The Encyclopedia of Founding
CITIES OF over again. Ammonia was first used by Carré in 1860; ammonia gas driven off by heat from its solution in water is condensed in a cooled vessel under its own pressure; the original ammonia vessel is now cooled, and the liquid ammonia rapidly evaporates (its vapor being absorbed), chilling its surroundings. Anhydrous liquid ammonia has been used by Reece and others. The Bell-Coleman apparatus, greatly use in the refrigerating chambers of ciple is that compressed and cooled air will, when allowed to expand against an external resistance, so that it does mechanical work during expansion, lose heat equivalent to the energy which it has expended. Porous jars, used to keep water cool, are among the simplest kinds of refrigerating apparatus; the evaporation at the outer surface of the jar of the water passing through the porous earthenware taking latent heat from the water.
CITIES OF, in Jewish law and history, six Levitical cities divinely appointed as places of refuge to one who had committed manslaughter, and was pursued by the "Revenger" or "Avenger" of Blood. Three (Kedesh Naphtali, Schechem, and Hebron) were W. of the Jordan, and three (Bezer in Reuben, Ramoth Gilead in Gad, and Golan in the half-tribe of Manasseh, were E. of that river.
that which shelters or protects from danger, distress, or calamity; a sanctuary; a place to flee to in time of danger. Specifically, an institution for affording temporary shelter to the destitute or the homeless; a house of refuge.
Only in Collier's New Encyclopedia
a word that probably came into existence when the Protestants under Louis XIV. escaped from their oppressors to other lands. It is applied also to one who takes refuge; one who flees to a place of refuge or shelter, and to one who flies for refuge in time of persecution or political commotion to a foreign country.
Only in Collier's New Encyclopedia