264 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1957 



would have to be rotated around an axis parallel to the earth's axis. 

 The sun, moon, and planets were to be represented by illuminated 

 disks driven by a suitable gearing in such a way that the epicycle 

 orbits of the objects would be truly represented. It soon became evi- 

 dent that it was impossible to solve the problem in this manner, and 

 the outbreak of the war put a stop to the work. 



Dr. W. Bauersfeld of the Zeiss works in Jena is credited with the 

 suggestion that the new instrument be a projector : 



The great sphere (the planetarium dome) shall be fixed; its inner white 

 surface shall serve as the projection surface for many small projectors which 

 shall be placed at the center of the sphere. The reciprocal positions and 

 motions of the little projectors shall be interconnected by suitable driving 

 gears in such manner that the little images of the heavenly bodies, thrown 

 upon the fixed hemispheres, shall represent the stars visible to the naked 

 eye, in position and motion, just as we are accustomed to see them in the 

 natural clear sky. 



After hostilities, work was begun once again on a planetarium that 

 would incorporate all the advantages of the large globes and the 

 orreries — a device that would reproduce the skies of nature just as 

 accurately as possible. 



In August of 1924, after nearly 5 years of design and construction 

 in the famous Zeiss plant in Jena, the first modern planetarium instru- 

 ment was produced. The illusion of reality surpassed the expectations 

 of von Miller and even the Zeiss people themselves. 



The prototype instrument was limited in latitude motion and had 

 only one spherical star projector, but these faults were corrected. 

 Soon, the dumbbell-shaped device, which has since become synonymous 

 with popular astronomy lecturing, was in production. Twenty-five 

 of these later models were built ; most of them were installed in Europe, 

 and six have been erected in the United States : 



Planetarium Location Date of opening 



Adler Planetarium Chicago May 10,1930 



Fels Planetarium Philadelphia Nov. 1,1933 



Griffith Observatory and Planetarium.- Los Angeles May 14,1935 



American Museum-Hay den Planetar- New York Oct. 2, 1935 



ium. 



Buhl Planetarium and Institute of Popu- Pittsburgh Oct. 24,1939 



lar Science. 



Morehead Planetarium Chapel Hill, N. C May 10,1949 



The projection apparatus that resulted is a weird-looking instru- 

 ment about 12 feet long, with a large globe at each end. These two 



