IX. EDUCATIONAL. 371 



1882. Orrery, lighted with gas, for the demonstration of 

 eclipses, and, by the aid of a " sablier," tracing the real orbit of the 

 moon. Ernest Recordon, Geneva. 



This apparatus shows: 



1. By means of a jet of gas behind globes, representing the celestial 



bodies, a sufficient shadow is cast to give a clear idea of eclipses and 

 the phases of the moon. 



2. The orbits of Venus, the Earth, and Mars. 



3. The difference in length of planetary years. 



4. The diurnal rotation of the Earth. 



5. The two classes of planets ; the smaller represented by Venus, the 



greater by Mars. 



6. The phases of the moon. Demonstration effected by means of a flame 



or gas. 



7. The real orbit of the moon. By means of a special contrivance, an 



epicycloidal line of fine sand is traced, which perfectly represents the 

 lunar orbit. 



1883. Selenographia, for showing all the effects of libration, 

 rotation, and elongation on the surface of the moon. 



John S. Marratt. 



This instrument, the invention of Mr. John Russell, illustrates the various 

 Lunar phenomena, the libration in latitude and polar obliquity, the libration 

 in longitude, the mean state of libration, diurnal and monthly, the periodical 

 and synodical revolutions, and how to determine the position of polar axis, 

 &c. 



1884. Planetarium or Orrery, designed by Ch. Huygens, 

 constructed by J. Van Ceulen, set in motion by clockwork. 



Professor Dr. P. L. Rijke, Ley den. 



1884a. Planisphere, with glass globe. A. Herbst, Berlin. 



1885. Model of the Solar System, made by Professor 

 Kaiser for his popular lessons on astronomy. The orbits of the 

 planets from Mercury to Jupiter are represented in their relative 

 dimensions. 



H. G. Van de Sande Bahhuysen, Director of the Observa- 

 tory at T^eyden. 



1885a. Cosmographic Clock, reproducing all the astrono- 

 mical phases of our globe, in relation to the sun. 



M. Mouret, Paris. 



1887. Model devised by the Rev. James Bradley, Savilian 

 Professor of Astronomy, &c., and used by him for illustrating his 

 discovery of Aberration. R. B. Clifton. 



For a description of this model, see Phil. Mag., Dec. 1846, vol. 29, p. 429. 



1888. Planetarium, with clockwork. Ernst Schotte, Berlin. 



1889. Tellurium and Lunarium, with clockwork. 



Ernst Schotte, Berlin. 

 Aa 2 



