Cl.ASS X.]

ORRERIES AXD PLANETARIUMS—DIALLING.

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of this kind, are "wasted; they are of no use to the studentof astronomy, and the erroneous impressions which theygive are always displeasing to the eye of the astronomer.

If they be of any use in the lecture-room to childrenand novices, certainly Facy’s vertical orrery is the bestadapted for this purpose.

Orreries.

Faoy (No. 195, p. 431) has exhibited a vertical orrery,showing the relative periodic times of the planets. Acomet’s orbit is also introduced which extends fromwithin that of Mercury to some distance beyond Neptune .Tlie Jury voted a Prize Medal to Mr. Facy for the inge-nuity displayed by him in the construction of this orrery.

Nkwtox and Sox (No. 212, p. 434). An orrery, show-ing the motions of the earth and moon, the planets andtheir satellites. The mechanism by which these severalmovements are performed is actuated by clock-work.They exhibit a smaller orrery, constructed on the sameprinciple, but showing only the motion of the earth andmoon.

Plant (No. 215, p. 434) has exhibited an orrery, thesun being represented by a luminous body; the seasons,phases of the moon, and other natural occurrences areclearly shown. It may be used to the greatest advantagein a darkened room, when the sun of the orrery will bestshow the various changes attendant upon the differentmotions of the several bodies.

Vlanetariums.

Newton and Sox (No. 212, p. 431). A planetarium foreducational purposes, intended to show the diurnal andannual motion of the earth and moon, also the respectiveposition of their satellites. It is exhibited for cheapness.

Lk Feuvre (Jersey and Guernsey , No. 10, p. 941) hasexhibited an orrery ; it is designed to show the motion ofthe moon around the earth, her daily variation and posi-tion at the time of new and full moon, also to exhibit thecause of eclipses, either partial or total. It is intendedfor the use of schools.

Massett (Switzerland , No. 95, pp. 1272, 1273) ex-hibits a planetarium of an extremely simple construction,in which the motions of the sun, the earth, and the moonare shown. It is remarkable for its cheapness, and Ho-nourable Mention was voted by the Jury.

Moli.isox (No. 585, p. 475) has exhibited a pedestalplanisphere. The places of the stars being perforated,when the instrument is held up against a light back-ground, they appear as luminous points. It is 20 inchesin diameter, and designed for educational purposes.

Drake (No. 334, p. 449) has exhibited the model ofan instrument called a Periphau, designed for the simpleelucidation of solar and lunar phenomena. It is fur-nished with a terrestrial globe in the centre, and isintended to describe the apparent diurnal motions of thesun and moon, also the daily increase and decrease of thesun’s declination, and to determine the time of sunrise, atany place on the globe; the causes of the harvest moon,&c. The model is in diameter 6 inches, which is abouta third of the proposed size. It consists of a fixed meri-dian circle graduated on both sides; on one similarly tothe brass meridian of the common globe, and on the otherto show altitudes; a horizontal circle, showing the zodiacsigns, &c.; a terrestrial globe, placed in the centre of thesphere, which turns freely on an axis; two small peaglobes, to represent the places of the sun and moon, andwhich slide on circular wires; these Mires themselvesturn freely in their bearings. This instrument show'sreadily the time of the sun rising and setting at any placeexterior to the frigid zones, and various other phenomenaof an analogous nature.

Matthews (No. 193, p. 431) has exhibited an Astro-rama. This is a concave representation of the heavensupon a small umbrella, which opens and closes at plea-sure. The material with which it is covered is perforatedto show the places of the larger stars.

Mallocii (No. 20S, p. 443) has exhibited a mechanicalindicator for teaching geography. This is a contrivancefor rendering purely mechanical the acquirement of thefirst rudiments of geography. A map is mounted upon a

light framework, a few inches in depth, to permit thestuds to work freely. These studs themselves representcities, towns, See., on the map, beneath which is placed anindex giving the name of each place thus represented.On the same line with the printed name is placed a move-able stud. Ily keeping down one of the studs on thesurface of the map, a corresponding one in the index in-stantly rises, the printed name beside it giving therequired information.

This is an invention of Mr. Malloeh’s. The mode]which he lias exhibited is, he considers, capable of stillfurther improvement. Mr. Malloch also has exhibited amechanical indicator of eclipses.

Murdoch (No. 202, p. 431) has exhibited an eclipseindicator. This is a circular table embodying by themotion of a circle of months on a cyclo-circle, with inter-vals of 18 years 11 days, the actual results of a previouscalculation of the moments of conjunction, both for lunarand solar eclipses from 1G47 to 2001. The rules given forsetting and reading off the circles being adhered to, theprecise moment of the ecliptic conjunction and other par-ticulars are obtained.

Ryles (No. 190, p. 431) has exhibited an apparatusfor showing the ebb and flow of the tide.

Newton and Sox (No. 212, p. 434). An armillarysphere, mounted on a brass meridian and attached to abrass stand.

Zireumayr (Austria, No. 132, p. 1014). A chrono-globium and planetarium, a fiat board on which areframed the orbits of Mercury and Venus . The earth andmoon are attached to a small rolling carriage, as describedin M. Gndnal’s instrument, by which the rotation of theearth and the phases of the moon are represented. Mars is also made to revolve on his axis by a similar contriv-ance, viz., by establishing a rolling drag on the orbit.

Dink (Austria ) exhibits a globe of the earth, about fiveinches in diameter, within a glass sphere, on which areplaced the fixed stars. The positions of the sun andmoon are marked at any given moment by a simplemechanism.

Richards (No. 188, p. 431) exhibits a “geographicalinstructor,” a piece of mechanism in which the sun(represented by a gilt ball elevated on a wire) is presentedvertically, to every point of the eartli between the tropics,by a compound movement of rotation on a horizontalaxis, the revolving ball being pulled and pushed along it,by a movement to and fro corresponding in extent to thetime of the sun’s declination at the moment. The law ofthis movement is given by a train of clock-work, ofwhich one peculiarity is the prolongation of the axis ofthe globe into a very long pinion, so as to allow the teethof the driving-wheel to act upon it, however far displacedfrom a mean position. Another, that of the communica-tion of the rotary motion from the prinunn mobile by aliook-jointed axis; the to-and-fro motion of the pinionprolongation of the axis not allowing the clock-work tobe centrieally placed in some point in that direction.

Detouche and IIoudix (France, No. 15S9, p. 1253)exhibit a uranographic apparatus (erroneously describedin the Catalogue as a monographic apparatus); it con-sists of a table about six feet in diameter, in the centre ofwhich is a lamp representing the sun. The earth withthe moon attached is carried round on an arm, by a pieceof eloek-work, the primum mobile oi which is not a spring,or any internal power, but the roller on which the me-chanism rests, and which revolves as the earth is carriedround on the table. This, by a train of wheel-work,communicates to the eartli its diurnal motion, preservesthe parallelism of its axis, and gives to the moon all themovements imitative of real ones. This mechanism isthe invention of M. Guenal.

Dialling.

Newton and Sox (No. 212. p. 434 s ) exhibit a sphericalsun-dial. The hour is indicated by means of the shadowof the pole or axis of the sphere being made to fall withinside of the zodiacal belt, on the outside of which the signsof the zodiac are depicted. This is well adapted for alawn.

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